®
®
Intel StrongARM SA-1100
Microprocessor
Developer’s Manual
August 1999
Order Number: 278088-004
Contents
Introduction......................................................................................................................1-1
ARM™ Architecture........................................................................................... 1-6
1.4.1 26-Bit Mode .......................................................................................... 1-6
1.4.2 Coprocessors........................................................................................ 1-6
1.4.3 Memory Management........................................................................... 1-6
1.4.4 Instruction Cache.................................................................................. 1-6
1.4.5 Data Cache........................................................................................... 1-6
1.4.6 Write Buffer........................................................................................... 1-7
1.4.7 Read Buffer........................................................................................... 1-7
Functional Description.....................................................................................................2-1
ARM™ Implementation Options......................................................................................3-1
3.2.1 Power-Up Reset ................................................................................... 3-2
3.2.2 ROM Size Select .................................................................................. 3-2
3.2.3 Abort ..................................................................................................... 3-3
3.2.4 Vector Summary................................................................................... 3-4
3.2.5 Exception Priorities............................................................................... 3-4
Instruction Set .................................................................................................................4-1
Coprocessors ..................................................................................................................5-1
Internal Coprocessor Instructions...................................................................... 5-1
5.2.1 Register 0 – ID...................................................................................... 5-2
5.2.2 Register 1 – Control.............................................................................. 5-3
5.2.5 Register 4 – RESERVED...................................................................... 5-4
5.2.6 Register 5 – Fault Status ...................................................................... 5-4
5.2.7 Register 6 – Fault Address ................................................................... 5-4
5.2.9 Register 8 – TLB Operations ................................................................ 5-5
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Caches, Write Buffer, and Read Buffer...........................................................................6-1
6.1.1 Icache Operation .................................................................................. 6-1
6.1.2 Icache Validity ...................................................................................... 6-1
6.2.1 Cacheable Bit – C................................................................................. 6-3
6.2.2 Bufferable Bit – B.................................................................................. 6-3
6.2.3 Software Dcache Flush ........................................................................ 6-4
6.3.1 Bufferable Bit........................................................................................ 6-5
6.3.2 Write Buffer Operation.......................................................................... 6-5
6.3.3 Enabling the Write Buffer...................................................................... 6-6
Read Buffer (RB)............................................................................................... 6-6
Memory-Management Unit (MMU)..................................................................................7-1
7.1.1 MMU Registers..................................................................................... 7-1
7.3.2 Buffered Writes..................................................................................... 7-2
Mini Data Cache................................................................................................ 7-3
Clocks .............................................................................................................................8-1
Core Clock Configuration Register.................................................................... 8-2
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SA-1100 Developer’s Manual
System Control Module...................................................................................................9-1
9.1.1 GPIO Register Definitions..................................................................... 9-2
9.1.1.3 GPIO Pin Output Set Register (GPSR) and
9.1.1.4 GPIO Rising-Edge Detect Register (GRER) and
9.1.2 GPIO Alternate Functions..................................................................... 9-9
9.1.3 GPIO Register Locations.................................................................... 9-10
9.2.1.2 Interrupt Controller IRQ Pending Register (ICIP) and
9.3.4 RTC Trim Register (RTTR)................................................................. 9-19
9.3.5 Trim Procedure................................................................................... 9-19
9.4.2 OS Timer Match Registers 0–3
9.4.6 Watchdog Timer ................................................................................. 9-24
9.4.7 OS Timer Register Locations.............................................................. 9-25
9.5.1 Run Mode ........................................................................................... 9-26
9.5.2 Idle Mode............................................................................................ 9-26
9.5.3 Sleep Mode......................................................................................... 9-27
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9.5.6 Pin Operation in Sleep Mode.............................................................. 9-32
9.5.7 Power Manager Registers.................................................................. 9-33
9.6.1 Reset Controller Registers ................................................................. 9-42
Memory and PCMCIA Control Module..........................................................................10-1
Overview of Operation..................................................................................... 10-1
10.1.2 Types of Memory Accesses ............................................................... 10-4
10.1.3 Reads ................................................................................................. 10-4
10.1.4 Writes ................................................................................................ 10-4
10.1.5 Transaction Summary ....................................................................... 10-4
10.1.6 Read-Lock-Write................................................................................. 10-5
Memory Configuration Registers.................................................................... 10-6
10.2.2 DRAM CAS Waveform Shift Registers
Dynamic Interface Operation......................................................................... 10-14
10.3.1 DRAM Overview ............................................................................... 10-14
10.3.2 DRAM Timing ................................................................................... 10-15
10.3.3 DRAM Refresh ................................................................................. 10-18
10.4.1 ROM Interface Overview .................................................................. 10-19
10.4.3 SRAM Interface Overview ................................................................ 10-22
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10.6.1 32-Bit Data Bus Operation............................................................... 10-27
Initialization of the Memory Interface............................................................. 10-34
Alternate Memory Bus Master Mode ............................................................. 10-35
Peripheral Control Module.............................................................................................11-1
11.6.1 DMA Register Definitions.................................................................... 11-7
11.6.2 DMA Operation................................................................................ 11-13
11.6.3 DMA Register List............................................................................. 11-14
LCD Controller............................................................................................... 11-16
11.7.1 LCD Controller Operation ................................................................. 11-18
11.7.1.3Input FIFO............................................................................ 11-23
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11.7.11.1LCD Disable Done Flag (LDD)
11.7.11.2Base Address Update Flag (BAU)
11.7.11.3Bus Error Status (BER)
11.7.11.4AC Bias Count Status (ABC)
11.7.11.5Input FIFO Overrun Lower Panel Status (IOL)
11.7.11.6Input FIFO Underrun Lower Panel Status (IUL)
11.7.11.7Input FIFO Overrun Upper Panel Status (IOU)
11.7.11.8Input FIFO Underrun Upper Panel Status (IUU)
11.7.11.9Output FIFO Overrun Lower Panel Status (OOL)
11.7.11.10Output FIFO Underrun Lower Panel Status (OUL)
11.7.11.11Output FIFO Overrun Upper Panel Status (OOU)
11.7.11.12Output FIFO Underrun Upper Panel Status (OUU)
Serial Port 0 – USB Device Controller........................................................... 11-56
11.8.1 USB Operation ................................................................................. 11-56
11.8.2 UDC Register Definitions.................................................................. 11-63
11.8.3 UDC Control Register....................................................................... 11-64
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11.8.4 UDC Address Register ..................................................................... 11-66
11.8.12 UDC Data Register........................................................................... 11-75
11.8.13 UDC Status/Interrupt Register.......................................................... 11-76
11.9.1 SDLC Operation ............................................................................... 11-79
11.9.1.4Control Field ........................................................................ 11-80
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11.9.1.6CRC Field ............................................................................ 11-81
11.9.2 SDLC Register Definitions................................................................ 11-84
11.9.3 SDLC Control Register 0 .................................................................. 11-85
11.9.4 SDLC Control Register 1 .................................................................. 11-88
11.9.5 SDLC Control Register 2 .................................................................. 11-92
11.9.7 SDLC Data Register......................................................................... 11-94
11.9.8 SDLC Status Register 0 ................................................................... 11-96
11.9.8.1End/Error in FIFO Status (EIF)
11.9.8.2Transmit Underrun Status (TUR)
11.9.8.3Receiver Abort Status (RAB)
11.9.8.4Transmit FIFO Service Request Flag (TFS)
11.9.8.5Receive FIFO Service Request Flag (RFS)
11.9.9 SDLC Status Register 1 ................................................................... 11-99
11.9.9.1Receiver Synchronized Flag (RSY)
11.9.9.2Transmitter Busy Flag (TBY)
11.9.9.3Receive FIFO Not Empty Flag (RNE)
11.9.9.4Transmit FIFO Not Full Flag (TNF)
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11.9.9.5Receive Transition Detect Status (RTD)
11.9.9.6End of Frame Flag (EOF)
11.9.9.7CRC Error Status (CRE)
11.9.9.8Receiver Overrun Status (ROR)
11.10.1 Low-Speed ICP Operation.............................................................. 11-104
11.10.2 High-Speed ICP Operation............................................................. 11-105
11.10.4 UART Control Register 4................................................................ 11-111
11.10.6 HSSP Control Register 0................................................................ 11-112
11.10.7 HSSP Control Register 1................................................................ 11-116
11.10.8 HSSP Control Register 2................................................................ 11-117
11.10.9 HSSP Data Register....................................................................... 11-119
11.10.10.1End/Error in FIFO Status (EIF)
11.10.10.2Transmit Underrun Status (TUR)
11.10.10.3Receiver Abort Status (RAB)
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11.10.10.4Transmit FIFO Service Request Flag (TFS)
11.10.10.5Receive FIFO Service Request Flag (RFS)
11.10.10.6Framing Error Status (FRE)
11.10.11.1Receiver Synchronized Flag (RSY)
11.10.11.2Transmitter Busy Flag (TBY)
11.10.11.3Receive FIFO Not Empty Flag (RNE)
11.10.11.4Transmit FIFO Not Full Flag (TNF)
11.10.11.5End-of-Frame Flag (EOF)
11.10.11.6CRC Error Status (CRE)
11.10.11.7Receiver Overrun Status (ROR)
11.10.12UART Register Locations.............................................................. 11-127
11.10.13HSSP Register Locations.............................................................. 11-127
11.11 Serial Port 3 - UART.................................................................................... 11-128
11.11.3 UART Control Register 0................................................................ 11-131
11.11.5 UART Control Register 3................................................................ 11-135
11.11.6 UART Data Register....................................................................... 11-137
11.11.7.1Transmit FIFO Service Request Flag (TFS)
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11.11.7.2Receive FIFO Service Request Flag (RFS)
11.11.7.3Receiver Idle Status (RID)
11.11.7.4Receiver Begin of Break Status (RBB)
11.11.7.5Receiver End of Break Status (REB)
11.11.7.6Error in FIFO Flag (EIF)
11.11.8.1Transmitter Busy Flag (TBY
11.11.8.2Receive FIFO Not Empty Flag (RNE)
11.11.8.3Transmit FIFO Not Full Flag (TNF)
11.11.8.4Parity Error Flag (PRE)
11.11.8.5Framing Error Flag (FRE)
11.11.8.6Receiver Overrun Flag (ROR)
11.12 Serial Port 4 – MCP / SSP........................................................................... 11-145
11.12.1 MCP Operation............................................................................... 11-146
11.12.5 MCP Data Registers....................................................................... 11-158
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xiii
11.12.6.1Audio Transmit FIFO Service Request Flag (ATS)
11.12.6.2Audio Receive FIFO Service Request Flag (ARS)
11.12.6.3Telecom Transmit FIFO Service Request Flag (TTS)
11.12.6.4Telecom Receive FIFO Service Request Flag (TRS)
11.12.6.5Audio Transmit FIFO Underrun Status (ATU)
11.12.6.6Audio Receive FIFO Overrun Status (ARO)
11.12.6.7Telecom Transmit FIFO Underrun Status (TTU)
11.12.6.8Telecom Receive FIFO Overrun Status (TRO)
11.12.6.9Audio Transmit FIFO Not Full Flag (ANF)
11.12.6.10Audio Receive FIFO Not Empty Flag (ANE)
11.12.6.11Telecom Transmit FIFO Not Full Flag (TNF)
11.12.6.12Telecom Receive FIFO Not Empty Flag (TNE)
11.12.6.13Codec Write Completed Flag (CWC)
11.12.6.14Codec Read Completed Flag (CRC)
11.12.6.15Audio Codec Enabled Flag (ACE)
11.12.6.16Telecom Codec Enabled Flag (TCE)
11.12.12SSP Status Register...................................................................... 11-181
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11.12.12.1Transmit FIFO Not Full Flag (TNF)
11.12.12.2Receive FIFO Not Empty Flag (RNE)
11.12.12.3SSP Busy Flag (BSY)
11.12.12.4Transmit FIFO Service Request Flag (TFS)
11.12.12.5Receive FIFO Service Request Flag (RFS)
11.12.12.6Receiver Overrun Status (ROR)
11.12.13MCP Register Locations................................................................ 11-183
11.13 Peripheral Pin Controller (PPC)................................................................... 11-184
DC Parameters..............................................................................................................12-1
Absolute Maximum Ratings............................................................................. 12-1
AC Parameters..............................................................................................................13-1
Module Considerations.................................................................................... 13-2
MCP Signals.................................................................................................... 13-3
Package and Pinout ......................................................................................................14-1
Debug Support ..............................................................................................................15-1
Instruction Breakpoint...................................................................................... 15-1
Data Breakpoint............................................................................................... 15-1
Boundary-Scan Test Interface.......................................................................................16-1
Pull-Up Resistors............................................................................................. 16-2
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16.5.1 EXTEST (00000) ................................................................................ 16-3
16.5.3 CLAMP (00100).................................................................................. 16-3
16.5.4 HIGHZ (00101) ................................................................................... 16-4
16.5.5 IDCODE (00110) ................................................................................ 16-4
16.5.6 BYPASS (11111)................................................................................ 16-4
Test Data Registers......................................................................................... 16-5
16.6.1 Bypass Register ................................................................................. 16-5
Boundary-Scan Interface Signals.................................................................... 16-7
Register Summary ......................................................................................................... A-1
3.6864–MHz Oscillator Specifications............................................................................ B-1
Specifications ....................................................................................................B-1
B.1.1 System Specifications ..........................................................................B-1
B.1.1.1. Parasitic Capacitance Off-chip
B.1.1.2. Parasitic Capacitance Off-chip
B.1.2 Quartz Crystal Specification .................................................................B-3
32.768–kHz Oscillator Specifications............................................................................. C-1
C.1.1 System Specifications ..........................................................................C-1
C.1.1.3.Startup Time ............................................................................C-1
C.1.1.5.Parasitic Capacitance Off-chip
C.1.1.6.Parasitic Capacitance Off-chip
C.1.2 Quartz Crystal Specification .................................................................C-3
Internal Test ................................................................................................................... D-1
Test Unit Control Register (TUCR)....................................................................D-1
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SA-1100 Developer’s Manual
Figures
DRAM Single-Beat Transactions................................................................... 10-16
Burst-of-Eight ROM Timing Diagram............................................................. 10-20
10-10 Flash Write Timing Diagram (2 Writes).......................................................... 10-24
10-11 PCMCIA Memory Map................................................................................... 10-26
10-14 PCMCIA Voltage-Control Logic ..................................................................... 10-31
10-15 PCMCIA Memory or I/O 16-Bit Access.......................................................... 10-32
10-16 PCMCIA I/O 16-Bit Access to 8-Bit Device.................................................... 10-33
11-10 Passive Mode Beginning-of-Frame Timing.................................................... 11-51
11-11 Passive Mode End-of-Frame Timing ............................................................. 11-52
11-12 Passive Mode Pixel Clock and Data Pin Timing............................................ 11-53
11-13 Active Mode Timing ....................................................................................... 11-54
11-14 Active Mode Pixel Clock and Data Pin Timing............................................... 11-55
11-15 NRZI Bit Encoding Example .......................................................................... 11-58
11-16 IN, OUT, and SETUP Token Packet Format ................................................. 11-60
11-17 SOF Token Packet Format............................................................................ 11-60
11-18 Data Packet Format....................................................................................... 11-60
11-19 Handshake Packet Format ............................................................................ 11-60
11-20 Bulk Transaction Formats.............................................................................. 11-61
11-21 Control Transaction Formats ......................................................................... 11-62
11-23 SDLC Frame Format ..................................................................................... 11-80
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11-24 HP-SIR Modulation Example....................................................................... 11-104
11-26 4PPM Modulation Encodings ...................................................................... 11-105
11-27 4PPM Modulation Example ......................................................................... 11-106
11-29 Example UART Data Frame........................................................................ 11-128
11-30 NRZ Bit Encoding Example – (0100 1011).................................................. 11-129
11-31 MCP Frame Data Format ............................................................................ 11-147
11-32 MCP Frame Pin Timing ............................................................................... 11-147
11-36 Motorola* SPI Frame Format....................................................................... 11-171
11-37 National Microwire* Frame Format.............................................................. 11-172
11-38 Transmit/Receive FIFO Data Format .......................................................... 11-173
Memory Bus AC Timing Definitions................................................................. 13-2
LCD AC Timing Definitions.............................................................................. 13-3
MCP AC Timing Definitions............................................................................. 13-3
Quad Flat Pack – 1.4mm (LQFP).................................................................... 14-1
Tables
9-2
Signal Descriptions............................................................................................ 2-4
Vector Summary................................................................................................ 3-4
SA-1100 Power and Clock Supply Sources and States
Pin State During Step...................................................................................... 9-32
Reset Controller Register Locations................................................................ 9-43
SA-1100 Transactions..................................................................................... 10-5
Memory Interface Control Registers................................................................ 10-6
BS_xx Bit Encoding....................................................................................... 10-13
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SA-1100 Developer’s Manual
Peripheral Unit GPIO Pin Assignment............................................................. 11-6
Valid Settings for the DDARn Register......................................................... 11-10
11-10 USB Bus States............................................................................................. 11-57
11-11 Endpoint Field Addressing............................................................................. 11-59
11-12 Host Device Request Summary..................................................................... 11-63
11-21 PPC Control and Flag Register Locations................................................... 11-193
SA-1100 Developer’s Manual
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Introduction
1
1.1
Intel® StrongARM® SA-1100 Microprocessor
The Intel® StrongARM® SA-1100 Microprocessor (SA-1100) is the second member of the
StrongARM® family. It is a highly integrated communications microcontroller that incorporates a
32-bit StrongARM® RISC processor core, system support logic, multiple communication
channels, an LCD controller, a PCMCIA controller, and general-purpose I/O ports.
As does the Intel® StrongARM® SA-110 Microprocessor (SA-110), the first member of the
StrongARM family, the SA-1100 provides power efficiency, low cost, and high performance.
Figure 1-1 shows the features of the SA-1100. The shaded boxes are features that have carried over
with few or no changes from the SA-110. The nonshaded boxes are new or updated features for the
SA-1100.
Figure 1-1. SA-1100 Features
Read Buffer
16KB
Instruction
Cache
JTAG
IMMU
8KB
®
Intel
Data Cache
®
DMMU
*
StrongARM
CPU
512-byte
MiniDcache
Write
Buffer
General-Purpose
I/O
Interrupt
Controller
Serial
Controllers
Memory/
Controller
DMA
Controller
LCD
Controller
Real-Time
Clock
Interval
Timer
* StrongARM is a registered trademark of ARM Limited.
A6830-01
SA-1100 SA-1100 Developer’s Manual
1-1
Introduction
Table 1-1.
Features of the SA-1100 CPU for AA and EA Parts
• High Performance
• 3.3 V I/O interface
— 150 Dhrystone 2.1 MIPS @ 133 MHz
— 220 Dhrystone 2.1 MIPS @ 190 MHz
• Low power (normal mode)†
— <230 mW @1.5 V/133 MHz
— <330 mW @ 1.5 V/200 MHz
• Integrated clock generation
— Internal phase-locked loop (PLL)
— 3.686 MHz oscillator
• 208-pin thin quad flat pack (LQFP)††
• 256 mini-ball grid array (mBGA)
• 32-way set-associative caches
— 16 Kbyte instruction cache
— 8 Kbyte write-back data cache
• 32-entry memory-management units
— Maps 4 Kbyte, 8 Kbyte, or 1 Mbyte
• Write buffer
— 32.768 kHz oscillator
— 8-entry, between 1 and 16 bytes each
• Read buffer
• Power-management features
— Normal (full-on) mode
— 4-entry, 1, 4, or 8 words
— Idle (power-down) mode
• Memory bus
— Sleep (power-down) mode
• Big and little endian operating modes
— Interfaces to ROM, Flash, SRAM,
and DRAM
— Supports two PCMCIA sockets
†
Power dissipation, particularly in idle mode, is strongly dependent on the details of the system design.
†† Package nomenclature has been modified due to industry standardization of packages. LQFP is 1.4mm
thick, thin quad flat pack. Please note that no modification has been made to the package itself.
Table 1-2.
Features of the SA-1100 CPU for CA and DA Parts
• High Performance
• 256 mini-ball grid array (mBGA)
— 180 Dhrystone 2.1 MIPS @ 160 MHZ • 32-way set-associative caches
— 250 Dhrystone 2.1 MIPS @ 220 MHz
• Low power (normal mode)†
— <430 mW @ 2.0-V/160-MHz
— <550 mW @ 2.0-V/220-MHz
• Integrated clock generation
— Internal phase-locked loop (PLL)
— 3.686-MHz oscillator
— 16 Kbyte instruction cache
— 8 Kbyte write-back data cache
• 32-entry memory-management units
— Maps 4 Kbyte, 8 Kbyte, or 1 Mbyte
• Write buffer
— 8-entry, between 1 and 16 bytes each
• Read buffer
— 32.768-kHz oscillator
— 4-entry, 1, 4, or 8 words
• Memory bus
• Big and little endian operating modes
• 3.3-V I/O interface
— Interfaces to ROM, Flash, SRAM,
and DRAM
• 208-pin thin quad flat pack (LQFP)††
— Supports two PCMCIA sockets
†
Power dissipation, particularly in idle mode, is strongly dependent on the details of the system design.
†† Package nomenclature has been modified due to industry standardization of packages. LQFP is 1.4mm
thick, thin quad flat pack. Please note that no modification has been made to the package itself.
1-2
SA-1100 Developer’s Manual
Introduction
Table 1-3.
Changes to the SA-1100 Core from the SA-110
• Data cache reduced from 16 Kbyte to
• Hardware breakpoints
8 Kbyte
• Memory-management unit (MMU)
• Interrupt vector address adjust capability
• Read buffer (nonblocking)
enhancements
• Process ID mapping
• Minicache for alternate data caching
Table 1-4.
Additional Features Built into SA-1100 Chipset
• Memory controller supporting ROM,
• Twenty-eight general-purpose I/O ports
Flash, EDO, standard DRAM, and SRAM
• Real-time clock with interrupt capability
• On-chip oscillators for clock sources
• Interrupt controller
• LCD controller
— 1-, 2-, or 4-bit gray-scale levels
— 8-, 12-, or 16-bit color levels
• Power-management features
— Normal (full-on) mode
• Serial communications module supporting
SDLC
— Idle (power-down) mode
• 230-Kbps UART
— Sleep (power-down) mode
• Touch-screen, audio, telecom port
• Infrared data (IrDA) serial port
— 115 Kbps, 4 Mbps
• Four general-purpose interruptible timers
• 12-Mbps USB device controller
• Synchronous serial port (UCB1100,
• Six-channel DMA controller
• Integrated two-slot PCMCIA controller
UCB1200, SPI, TI, Wire)
SA-1100 Developer’s Manual
1-3
Introduction
1.2
Overview
The SA-1100 Microprocessor (SA-1100) is a general-purpose, 32-bit RISC microprocessor with a
16 Kbyte instruction cache, an 8 Kbyte write-back data cache, a minicache, a write buffer, a read
buffer, and a memory management unit (MMU) combined in a single chip. The SA-1100 is
software compatible with the ARM™ V4 architecture processor family and can be used with ARM
support chips such as I/O, memory, and video. The core of the SA-1100 is derived from the core of
the SA-110 Microprocessor (SA-110), with the following changes:
• Reduction in size of the data cache from 16 Kbyte to 8 Kbyte
• Addition of a 512-byte mini data cache that allocates data based on MMU settings
• Addition of debug support in the form of address and data breakpoints
• Addition of a four-entry read buffer to facilitate software-controlled data prefetching
• Addition of vector address adjust capability
• Addition of a process ID register
The logic outside the core and caches is grouped into the following three modules:
• Memory and PCMCIA control module (MPCM)
— Memory interface supporting ROM, Flash, DRAM, SRAM and PCMCIA control signals
• System control module (SCM)
— Twenty-eight general-purpose interruptible I/O ports
— Real-time clock, watchdog, and interval timers
— Power management controller
— Interrupt controller
— Reset controller
— Two on-chip oscillators for connection to 3.686 MHz and 32.768 kHz crystals
• Peripheral control module (PCM)
— Six-channel DMA controller
— Gray/color, active/passive LCD controller
— 230 Kbps SDLC controller
— 16550-compatible UART
— IrDA serial port (115 Kbps, 4 Mbps)
— Synchronous serial port (UCB1100, UCB1200, SPI, TI, µWire)
— Universal serial bus (USB) device controller
1-4
SA-1100 Developer’s Manual
Introduction
The instruction set comprises eight basic instruction types:
• Two make use of on-chip arithmetic logic unit, barrel shifter, and multiplier to perform
high-speed operations on data in a bank of 16 logical registers (31 physical registers), each 32
bits wide.
• Three classes of instructions control data transfer between memory and the registers: one
optimized for flexibility of addressing, one for rapid context switching, and one for swapping
data.
• Two instructions control the flow and privilege level of execution.
• One class is used to access the privileged state of the CPU.
The ARM instruction set is a good target for compilers of many different high-level languages.
Where required for critical code segments, assembly code programming is also straightforward,
unlike some RISC processors that need sophisticated compiler technology to manage complicated
instruction interdependencies.
The SA-1100 is a static part and has been designed to run at a reduced voltage to minimize its power
requirements. This makes it a good choice for portable applications where both of these features are
essential.
1.3
Example System
Figure 1-2 shows how the SA-1100 can be used in a hand-held computing device.
Figure 1-2. SA-1100 Example System
UART or LocalTalk
Communications
Gray Scale
or
Color LCD
Display
Tablet / Serial
Keyboard
®
®*
Intel StrongARM
SA-1100
Portable
3.686
MHz
Codec
Communications
Microcontroller
Infrared
Communications
32.768
KHz
USB Synchronization
Port
Glue Logic
DRAM
ROM
PCMCIA Interface
(Flash, Modem)
Flash
* StrongARM is a registered trademark of ARM Limited.
A6870-01
SA-1100 Developer’s Manual
1-5
Introduction
1.4
ARM™ Architecture
The SA-1100 implements the ARM V4 architecture as defined in the ARM Architecture Reference,
28-July-1995, with the following options:
1.4.1
1.4.2
26-Bit Mode
The SA-1100 supports 26-bit mode but all exceptions are initiated in 32-bit mode. The P and D bits
do not affect the operation of SA-1100; they are always read as ones and writes to them are
ignored.
Coprocessors
The SA-1100 supports MCR and MRC access to coprocessor number 15. These instructions are
used to access the memory-management, configuration, and cache control registers. In addition,
coprocessor 15 provides control for read buffer fills and flushes, and hardware breakpoints. All
other coprocessor instructions cause an undefined instruction exception. No support for external
coprocessors is provided.
1.4.3
Memory Management
Memory management exceptions preserve the base address registers so that no code is required to
restore state. Separate translation lookaside buffers (TLBs) are implemented for the instruction and
data streams. Each TLB has 32 entries that can each map a segment, a large page, or a small page.
The TLB replacement algorithm is round robin. The data TLBs support both the flush-all and
flush-single-entry operations, while the instruction TLBs support only the flush-all operation.
1.4.4
1.4.5
Instruction Cache
The SA-1100 has a 16 Kbyte instruction cache (Icache) with 32-byte blocks and 32-way
associativity. The cache supports the flush-all function. Replacement is round robin within a set.
The Icache can be enabled while memory management is disabled. When memory management is
disabled, all memory is considered cacheable by the Icache.
Data Cache
The SA-1100 has an 8 Kbyte data cache (Dcache) with 32-byte blocks and 32-way associativity.
The cache supports the flush-all, flush-entry, and copyback-entry functions. The copyback-all
function is not supported in hardware. This function can be provided by software. The cache is read
allocate with round-robin replacement.
The Dcache has been augmented with a 16-entry, two-way set associative minicache that allocates
when the MMU b and c bits are 0 and 1, respectively. This cache is accessed in parallel with the
main Dcache. Replacement victims in this cache are replaced based on a least-recently-used (LRU)
algorithm. This cache is useful for applications that access large data structures and would
normally thrash the main Dcache. Instead, these data structures can be mapped so that they allocate
into the minicache and only replace data from the same structure.
1-6
SA-1100 Developer’s Manual
Introduction
1.4.6
1.4.7
Write Buffer
The SA-1100 has an eight-entry write buffer with each entry able to contain 1 to 16 bytes. A drain
write buffer operation is supported.
Read Buffer
The SA-1100 has a four-entry read buffer capable of loading 1, 4, or 8 words of data per entry. This
facility permits software to preload data into the buffer for use at a later time without blocking the
operation of the processor. Software can flush either a single entry or the entire buffer (four
entries). The read buffer is controlled through system control coprocessor 15 and can be enabled
for use in user mode.
SA-1100 Developer’s Manual
1-7
Functional Description
2
This chapter provides a functional description of the Intel® StrongARM® SA-1100 Microprocessor
(SA-1100). It describes the basic building blocks within the processor, lists and describes the pins,
and explains the memory map.
2.1
Block Diagram
The SA-1100 consists of the following functional blocks:
• Processor
The processor is the ARM™ SA-1 core with a 16 Kbyte instruction and 8 Kbyte data cache
(Dcache). The instruction (I) and data (D) streams are translated through independent
memory-management units (MMUs). Stores are made using a four-line write buffer. The
performance of specialized load routines is enhanced with the four-entry read buffer that can be
used to prefetch data for use at a later time. A 16-entry minicache provides a smaller and logically
separate data cache that can be used to enhance caching performance when dealing with large data
structures.
• Memory and PCMCIA controller
The memory and PCMCIA control module (MPCM) supports four banks of standard or EDO DRAM
on a 32-bit data width. ROM (standard and burst), Flash memory, and SRAM are also supported.
ROM and Flash can be either 16 or 32 bits wide. SRAM width is limited to 32 bits. Expansion devices
are supported through PCMCIA control signals that share the memory bus data and address lines to
complete the card interface. Some external glue logic (buffers and transceivers) is necessary to
implement the interface. Control is provided to permit two card slots with hot-swap capability.
• Peripherals
The peripheral control module (PCM) contains a number of serial control devices, an LCD
controller as well as a six-channel DMA controller to provide service to these devices:
– An LCD controller with support for passive or active displays
– A universal serial bus (USB) endpoint controller
– An SDLC communications controller
– A serial controller with supporting 115 Kbps and 4 Mbps IrDA protocols
– A 16550-like UART supporting 230 Kbps
– A CODEC interface supporting SPI, µWire, TI, UCB1100, and UCB1200
• General system control functions
The system control module (SCM) is also connected to the peripheral bus. It contains five blocks
used for general system functions:
– A real-time clock (RTC) clocked from an independent 32.768 kHz oscillator
– An operating system timer (OST) for general system timer functions as well as a watchdog mode
– Twenty-eight general-purpose I/Os (GPIO)
– An interrupt controller
– A power-management controller that handles the transitions in and out of sleep and idle modes
– A reset controller that handles the various reset sources on the processor
SA-1100 Developer’s Manual
2-1
Functional Description
is a functional diagram of the SA-1100.
Figure 2-1. SA-1100 Block Diagram
Intel®
StrongARM®
SA-1100
Instruction
*
PC
Icache
3.686
MHz
PLL
OSC
OSC
JTAG
and
Misc
Test
IMMU
(16 Kbytes)
ARM™*
SA-1
Core
Dcache
(8 Kbytes)
Addr
32.768
KHz
DMMU
Minicache
RTC
Load/Store Data
Processing
Core
OS Timer
General-
Purpose I/O
Write
Read
Buffer
Buffer
Interrupt
Controller
Memory
and
PCMCIA
Control
Module
(MPCM)
Power
Management
System
Control
Module
(SCM)
System Bus
Reset
Controller
LCD
Controller
DMA
Controller
Bridge
Peripheral Control
Module (PCM)
Peripheral Bus
Serial
Channel 0
UjSB
Serial
Channel 1
SDLC
Serial
Channel 2
IrDA
Serial
Channel 3
UART
Serial
Channel 4
CODEC
* ARM is a trademark and StrongARM is a registered trademark of ARM Limited.
A6832-01
2-2
SA-1100 Developer’s Manual
Functional Description
2.2
Inputs/Outputs
Figure 2-2. SA-1100 Functional Diagram
UDC-
Serial
L_DD(7:0)
L_FCLK
L_LCLK
L_PCLK
L_BIAS
Channel 0
(USB)
UDC+
RXD _1
TXD_1
LCD
Control
Serial
Channel 1
(SDLC)
RXD _2
TXD _2
Serial
Channel 2
(IrDA)
®
Intel
GP(27:0)
GPIO
Ports
RXD _3
TXD _3
®*
Serial
Channel 3
(UART)
StrongARM
SA-1100
nCAS(3:0)
nRAS/(3:0)
nOE
TXD _C
RXD _C
[208-pins]
Memory
Control
Serial
Channel 4
(CODEC)
nWE
SCLK _C
SFRM _C
nCS(3:0)
BATT_FAULT
VDD_FAULT
PWR_EN
nPOE
Power
Management
nPWE
nPIOR
TCK_BYP
nPIOW
TESTCLK
PEXTAL
PCMCIA
Bus
Signals
nPCE<2:1>
PSKTSEL
nPREG
nPWAIT
nIOIS16
PXTAL
Clocks, Reset
and Test
TEXTAL
TXTAL
nRESET
nRESET_OUT
ROM_SEL
Address
Bus
A<25:0>
Data Bus
TCK
TDI
D<31:0>
VDD
TDO
TMS
JTAG
VDDX
Supply
VSS/VSSX
nTRST
* StrongARM is a registered trademark of ARM Limited.
A6975-01
SA-1100 Developer’s Manual
2-3
Functional Description
2.3
Signal Description
The following table describes the signals.
Key to Signal Types: n – Active low signal
IC – Input, CMOS threshold
ICOCZ – Input, CMOS threshold, output CMOS levels, tristatable
OCZ – Output, CMOS levels, tristatable
Table 2-1.
Signal Descriptions (Sheet 1 of 3)
Name
A<25:0>
Type
OCZ
Description
Memory address bus. This bus signals the address requested for memory
accesses.
Bits 21..10 carry the 12-bit DRAM address, the static memory devices, and the
expansion bus receive address bits 25..0.
D<31:0>
ICOCZ
OCZ
Memory data bus.
nCS<3:0>
Static chip selects. These signals are chip selects to static memory devices such
as ROM and Flash. They are individually programmable in the memory
configuration registers.
nOE
nWE
OCZ
OCZ
Memory output enable. This signal should be connected to the output enables to
begin driving data onto the data bus.
DRAM write enable. This signal should be connected to the DRAM write enables
to perform writes. This signal is used in conjunction with CAS<3:0> to perform
byte writes.
nRAS<3:0>
nCAS<3:0>
nPOE
OCZ
OCZ
OCZ
OCZ
OCZ
OCZ
OCZ
IC
DRAM RAS. These signals should be connected to the DRAM row address strobe
(RAS) pin.
DRAM CAS. These signals should be connected to the DRAM column address
strobe (CAS) pins.
PCMCIA output enable. This PCMCIA signal is an output and is used to perform
reads from memory and attribute space.
nPWE
PCMCIA write enable. This signal is an output and is used to perform writes to
memory and attribute space.
nPIOW
PCMCIA I/O write. This signal is an output and is used to perform write
transactions to the PCMCIA I/O space.
nPIOR
PCMCIA I/O read. This signal is an output and is used to perform read
transactions from the PCMCIA I/O space.
nPCE<2:1>
nIOIS16
nPWAIT
PSKTSEL
PCMCIA card enable. These signals are output and are used to select a PCMCIA
card. Bit one enables the high-byte lane and bit zero enables the low-byte lane.
I/O Select 16. This signal is an input and is an acknowledgment from the PCMCIA
card that the current address is a valid 16-bit wide I/O address.
IC
PCMCIA wait. This signal is an input and is driven low by the PCMCIA card to
extend the length of the transfers to/from the SA-1100.
OCZ
PCMCIA socket select. This signal is an output and is used by external steering
logic to route control, address, and data signals to one of the PCMCIA sockets.
When PSKTSEL is low, socket zero is selected. When PSKTSEL is high, socket
one is selected. This signal has the same timing as the address lines.
nPREG
OCZ
OCZ
PCMCIA register select. This signal is an output and indicates that, on a memory
transaction, the target address is attribute space. This signal has the same timing
as address.
L_DD<7:0>
LCD controller display data.
2-4
SA-1100 Developer’s Manual
Functional Description
Table 2-1.
Signal Descriptions (Sheet 2 of 3)
Name
L_FCLK
Type
OCZ
Description
LCD frame clock.
LCD line clock.
L_LCLK
L_PCLK
L_BIAS
TXD_C
RXD_C
SCLK_C
SFRM_C
UDC+
OCZ
OCZ
OCZ
OCZ
IC
LCD pixel clock.
LCD ac bias drive.
CODEC transmit.
CODEC receive.
CODEC clock.
OCZ
OCZ
OCZ
IC
CODEC frame signal.
Serial port zero transmit pin (UDC).
Serial port zero receive pin (UDC).
Serial port one transmit pin (SDLC).
Serial port one receive pin (SDLC).
Serial port two transmit pin (IrDA).
Serial port two receive pin (IrDA).
Serial port three transmit pin (UART).
Serial port three receive pin (UART).
General-purpose input output.
UDC-
TXD_1
OCZ
IC
RXD_1
TXD_2
OCZ
IC
RXD_2
TXD_3
OCZ
IC
RXD_3
GP<27:0>
ROM_SEL
ICOCZ
IC
ROM select. This pin is used to configure the ROM width. It is either grounded or
pulled high. If ROM_SEL is grounded, the ROM width is 16 bits. If ROM_SEL is
pulled up, the ROM width is 32 bits.
PXTAL
IC
Input connection for 3.686-MHz crystal.
Output connection for 3.686-MHz crystal.
Input connection for 32.768-kHz crystal.
Output connection for 32.768-kHz crystal.
PEXTAL
TXTAL
OCZ
IC
TEXTAL
PWR_EN
OCZ
OCZ
Power enable. Active high. PWR_EN enables the external power supply.
Negating it signals the power supply that the system is going into sleep mode and
that the VDD power supply should be removed.
BATT_FAULT
VDD_FAULT
nRESET
IC
IC
IC
Battery fault. Signals the SA-1100 that the main power source is going away
(battery is low or has been removed from the system). The assertion of
BATT_FAULT causes the SA-1100 to enter sleep mode. The SA-1100 will not
recognize a wake-up event while this signal is asserted.
VDD fault. Signals the SA-1100 that the main power supply is going out of
regulation (shorted card is inserted). VDD_FAULT will cause the SA-1100 to enter
sleep mode. VDD_FAULT is ignored after a wake-up event until the poser supply
timer completes (approximately 10 ms).
Hard reset. This active low signal is a level-sensitive input used to start the
processor from a known address. A low level will cause the current instruction to
terminate abnormally, and the on-chip caches, MMU, and write buffer to be
disabled.
When nRESET is driven high, the processor will restart from address 0. nRESET
must remain low until the power supply is stable and the internal 3.686-MHz
oscillator has come up to speed. While nRESET is low, the processor will perform
idle cycles.
SA-1100 Developer’s Manual
2-5
Functional Description
Table 2-1.
Signal Descriptions (Sheet 3 of 3)
Name
Type
Description
nRESET_OUT OCZ
Reset out. This signal is asserted when nRESET is asserted and deasserts when
the processor has completed resetting. nRESET_OUT is also asserted for "soft"
reset events (sleep and watchdog).
nTRST
IC
Test interface reset. Note this pin has an internal pull-down resistor and must be
driven high to enable the JTAG circuitry. If left unconnected, this pin is pulled low
and disables JTAG operation.
TDI
IC
JTAG test interface data input. Note this pin has an internal pull-up resistor.
TDO
OCZ
JTAG test interface data output. Note this pin does not have an internal pull-up
resistor.
TMS
TCK
IC
IC
JTAG test interface mode select. Note this pin has an internal pull-up resistor.
JTAG test interface reference clock. This times all the transfers on the JTAG test
interface. Note this pin has an internal pull-down resistor.
TCK_BYP
TESTCLK
VDD
IC
IC
—
—
Test clock PLL bypass. When TCK_BYP is high, the TESTCLK is used as the
core clock in place of the PLL clock; when low, the internal PLL output is used.
This signal has no relation to the JTAG TCK pin.
Test clock. TESTCLK is used to provide the core clock when TCK_BYP is high. It
should be tied low if TCK_BYP is low. This pin should be used for test purposes
only. An end user should ground this pin.
Positive supply for the core. Nine pins are allocated to this supply; eight pins are
labeled VDD. The ninth pin, labeled VDDP is dedicated to the PLL supply and
should be tied directly to the VDD power plane with the other eight VDD pins.
VDDX
Positive supply for the pins. Twenty pins are allocated to VDDX, labeled VDDX1,
VDDX2 and VDDX3. All of these pins should be tied directly to the VDDX power
plane.
VSS
—
—
Ground supply. Nine pins are allocated to VSS, including one for the PLL.
Ground supply for the I/O pins. Eighteen pins are allocated to VSSX.
VSSX
2-6
SA-1100 Developer’s Manual
Functional Description
2.4
Memory Map
Figure 2-3 shows the SA-1100 memory map. The map is divided into four main partitions of
1 Gbyte each.
The bottom partition is dedicated to static memory devices (ROM, SRAM, and Flash) and to the
PCMCIA expansion bus area. It occupies addresses 0h0000 0000 through 0h3FFF FFFF. This
space is divided into four 128 Mbyte blocks for static memory devices and two 256 Mbyte blocks
for PCMCIA.
The static memory space is intended for ROM, SRAM, and Flash memory. The bottom partition (at
0h0000 0000) is assumed to be ROM at boot time. The width of the boot ROM is determined by
the state of the ROMSEL pin. The PCMCIA interface is divided into Socket 0 and Socket 1 space.
These partitions are further subdivided into I/O, memory and attribute space.
The next partition (0h4000 0000 to 0h7FFF FFFF) is reserved. Accessing this reserved space
results in a data abort exception.
The third partition (0h8000 0000 to 0hBFFF FFFF) contains all on-chip registers (except those
specified by the ARM V4 architecture). This block is further subdivided into four blocks of
256 Mbyte each. They contain control registers for the major functional blocks within the
processor (MECM, SCM, PCM). The LCD and DMA controllers are separate from the rest of the
PCM and occupy the top 256 Mbyte partition.
The fourth partition (0hC000 0000 to 0hFFFF FFFF) contains DRAM memory. The bank sizes for
DRAM are fixed at 128 Mbyte each. With multiple banks implemented, there probably will be
gaps in the map that should be mapped through the memory-management unit. The next 128 Mbyte
block in this partition is mapped within the memory controller and returns zeros when read. This
function is intended to facilitate rapid cache flushing by not requiring an external memory access to
load data into the cache. This space is burstable. Writes to this space have no effect. The top
384 Mbyte of this partition is reserved. Accessing this space causes a data abort exception.
SA-1100 Developer’s Manual
2-7
Functional Description
Figure 2-3. SA-1100 Memory Map
Reserved (384 Mbyte)
Cache flush replacement data
Reads return zero
128 Mbyte
Zeros Bank (128 Mbyte)
DRAM Bank 3 (128 Mbyte)
DRAM Bank 2 (128 Mbyte)
DRAM Bank 1 (128 Mbyte)
DRAM Bank 0 (128 Mbyte)
Dynamic Memory
512 Mbyte
0hC000 0000
LCD and DMA Registers (256 Mbyte)
Memory and Expansion Registers (256 Mbyte)
System Control Module Registers(256 Mbyte)
Peripheral Module Registers (256 Mbyte)
Internal Registers
1GB
0h8000 0000
0h4000 0000
Reserved (1GB)
PCMCIA Socket 0 Space (256 Mbyte)
PCMCIA Socket 1 Space (256 Mbyte)
PCMCIA Interface
512 Mbyte
0h2000 0000
0h0000 0000
Static Bank Select 3 (128 Mbyte)
Static Bank Select 2 (128 Mbyte)
Static Bank Select 1 (128 Mbyte)
Static Bank Select 0 (128 Mbyte)
Static Memory
(ROM, Flash, SRAM)
512 Mbyte
2-8
SA-1100 Developer’s Manual
ARM™ Implementation Options
3
The following sections describe ARM™ architecture options that are implemented by the
Intel® StrongARM® SA-1100 Microprocessor (SA-1100).
3.1
Big and Little Endian
The big endian bit in the control register sets whether the SA-1100 treats words stored in memory
as being stored in big endian or little endian format. Memory is viewed as a linear collection of
bytes numbered upwards from 0. Bytes 0 to 3 hold the first stored word, bytes 4 to 7 hold the
second, and so on.
In the little endian scheme, the lowest numbered byte in a word is considered to be the least
significant byte of the word and the highest numbered byte is the most significant. Byte 0 of the
memory system should be connected to data lines 7 through 0 (D<7:0>) in this scheme.
In the big endian scheme, the most significant byte of a word is stored at the lowest numbered byte
and the least significant byte is stored at the highest numbered byte. Therefore, byte 0 of the
memory system should be connected to data lines 31 through 24 (D<31:24>).
The state of the big endian bit changes the location of the bytes only within a 32-bit word. The
accessed bytes are changed for the load byte, store byte, load halfword, and store halfword
instructions only. Instruction fetches and word load and stores are not changed by the state of the
big endian bit, except when those accesses are performed with memory on 16-bit data busses. See
Chapter 10 for details on configuring bus widths for various memory types.
These conventions are identical to those of the SA-110. In addition, the SA-1100 DMA controller
is programmable by channel as to the endian format of the transfer. For DMA transfers, all
memory accesses are words. Then the data is buffered and transferred to/from the device as
halfwords or bytes. When the words are assembled or disassembled, the endian format of the
channel is observed. For details on how DMA data is transferred relative to the endian format of
3.2
Exceptions
Exceptions arise whenever there is a need for the normal flow of program execution to be broken;
for example, so that the processor can be diverted to handle an interrupt from a peripheral. The
processor state just prior to handling the exception must be preserved so that the original program
resumes when the exception routine has completed. Many exceptions may arise at the same time.
The SA-1100 handles exceptions by making use of banked registers to save state. The contents of
PC and CPSR are copied into the appropriate R14 and SPSR, and the PC and mode bits in the
CPSR bits are forced to a value that depends on the exception. Interrupt disable flags are set where
required to prevent otherwise unmanageable nestings of exceptions. In the case of a reentrant
interrupt handler, R14 and the SPSR should be saved onto a stack in main memory before
reenabling the interrupt; when transferring the SPSR register to and from a stack, it is important to
SA-1100 Developer’s Manual
3-1
ARM™ Implementation Options
transfer the whole 32-bit value, and not just the flag or control fields. When multiple exceptions
arise simultaneously, a fixed priority determines the order in which they are handled. The priorities
are listed later in this chapter. Most exceptions are fully defined in the ARM Architectural
Reference. The following sections specify the exceptions where the SA-1100 implementation
differs from the ARM Architectural Reference.
SA-1100 initiates all exceptions in 32-bit mode. When an exception occurs while running in 26-bit
mode, the SA-1100 saves only the PC in R14 and the CPSR in the SPSR of the exception mode.
The 32-bit handler must merge the condition codes, the interrupt enables, and the mode from the
SPSR into R14 if a handler is to run in 26-bit mode.
3.2.1
Power-Up Reset
When the nRESET signal is low, SA-1100 stops executing instructions, asserts the nRESET_OUT
pin, and then performs idle cycles on the bus.
When nRESET is high again, SA-1100 does the following:
1. Overwrites R14_svc and SPSR_svc by copying the current values of the PC and CPSR into
them. The values of the saved PC and CPSR are not defined.
2. Forces M<4:0>=10011 (32-bit supervisor mode) and sets the I and F bits in the CPSR.
3. Forces the PC to fetch the next instruction from address 0x0000 0000.
4. Based on the state of the ROM_SEL pin, fetches this first instruction from either 16-bit
(ROM_SEL low) or 32-bit (ROM_SEL high) space. The SA-1100 memory controller
assembles the data into words in the case of a 16-bit wide ROM.
At the end of the reset sequence, the MMU, Icache, Dcache, and write buffer are disabled.
Alignment faults are also disabled, and little-endian mode is enabled. During power-up, nRESET
must be negated no earlier than 150 milliseconds after VDD and VDDx are stable to allow the
internal 3.686-MHz oscillator to stabilize. After the negation of nRESET, the PLL begins its
internally timed locking sequence. Note that the assertion of nRESET is destructive because the
state of the real-time clock and the contents of DRAM are lost.
Boundary-Scan Test Interface for details.
3.2.2
ROM Size Select
The ROM width may be selected using the ROM_SEL pin. This pin is sampled during the assertion
of nRESET. The value is stored in the memory controller for use during ROM accesses. If this
signal is high during RESET, then the ROM is selected to be 32 bits wide. If it is low during
RESET, then the ROM width is 16 bits. There is no provision for 8-bit ROMs in the SA-1100.
3-2
SA-1100 Developer’s Manual
ARM™ Implementation Options
3.2.3
Abort
An abort can be signalled by the internal memory-management unit, through a data breakpoint, or
by a reference to reserved memory. An abort indicates that the current memory access cannot be
completed or that a prespecified breakpoint address and (optionally) data pattern has been reached.
For instance, in a virtual memory system, the data corresponding to the current address may have
been moved out of memory onto a disk, and considerable processor activity may be required to
recover the data before the access can be performed successfully. The SA-1100 checks for an abort
during memory access cycles. When aborted, the SA-1100 responds in one of two ways:
1. If the abort occurred during an instruction prefetch (a prefetch abort), the prefetched
instruction is marked as invalid but the abort exception does not occur immediately. If the
instruction is not executed, for example, as a result of a branch being taken while it is in the
pipeline, no abort will occur. An abort will take place if the instruction reaches the head of the
pipeline and is about to be executed.
2. If the abort occurred during a data access (a data abort), the action depends on the instruction
type.
a. Single data transfer instructions (LDR, STR) will abort with no registers modified.
b. The swap instruction (SWP) is aborted as though it had not executed, though externally
the read access may take place.
c. Block data transfer instructions (LDM, STM) abort on the first access that cannot
complete. If write-back is set, the base is NOT updated. If the instruction would normally
have overwritten the base with data (for example, an LDM instruction with the base in the
transfer list), the original value in the base register is restored.
When either a prefetch or data abort occurs, the SA-1100 performs the following:
1. Saves the address of the aborted instruction plus 4 (for prefetch aborts) or 8 (for data aborts) in
R14_abt; saves CPSR in SPSR_abt.
2. Forces M<4:0>=10111 (abort mode) and sets the I bit in the CPSR.
3. Forces the PC to fetch the next instruction from either address 0x0C (prefetch abort) or address
0x10 (data abort).
To return after fixing the reason for the abort, use SUBS PC,R14_abt,#4 (for a prefetch abort) or
SUBS PC,R14_abt,#8 (for a data abort). This will restore both the PC and the CPSR, and retry the
aborted instruction.
The abort mechanism allows a demand paged virtual memory system to be implemented when
suitable memory management software is available. The processor is allowed to generate arbitrary
addresses, and when the data at an address is unavailable, the MMU signals an abort. The processor
traps into system software, which must work out the cause of the abort, make the requested data
available, and retry the aborted instruction. The application program needs no knowledge of the
amount of memory available to it, nor is its state in any way affected by the abort.
SA-1100 Developer’s Manual
3-3
ARM™ Implementation Options
3.2.4
Vector Summary
Table 3-1 lists byte addresses, and they normally contain branch instructions pointing to the
relevant routines. These addresses (except the reset vector) can be changed (to 0xFFFF xxxx)
through the vector adjust facility (bit 13, register 1, coprocessor 15). The vector adjust is cleared at
reset and cannot modify the reset vector.
Table 3-1.
Vector Summary
Address
Exception
Mode on Entry
Supervisor
0x00000000
0x00000004
0x00000008
0x0000000C
0x00000010
0x00000014
0x00000018
0x0000001C
Reset
Undefined instruction
Software interrupt
Abort (prefetch)
Abort (data)
Not used
Undefined
Supervisor
Abort
Abort
—
IRQ
IRQ
FIQ
FIQ
3.2.5
Exception Priorities
When multiple exceptions arise at the same time, a fixed priority system determines the order in
which they will be handled:
1. Reset (highest priority)
2. Data abort
3. FIQ
4. IRQ
5. Prefetch abort
6. Undefined instruction, software interrupt (lowest priority)
Note that not all exceptions can occur at once. Undefined instructions and software interrupts are
mutually exclusive because they correspond to particular (nonoverlapping) decodings of the
current instruction.
If a data abort occurs at the same time as a FIQ, and FIQs are enabled (that is, the F flag in the
CPSR is clear), the SA-1100 will enter the data abort handler and then immediately proceed to the
FIQ vector. A normal return from FIQ will cause the data abort handler to resume execution.
Placing data abort at a higher priority than FIQ is necessary to ensure that the transfer error does
not escape detection; the time for this exception entry should be added to worst-case FIQ latency
calculations.
3-4
SA-1100 Developer’s Manual
ARM™ Implementation Options
3.2.6
Interrupt Latencies and Enable Timing
The ability to recognize an IRQ or FIQ interrupt is, in part, determined by the I and F bits of the
CPSR. To ensure that a pending interrupt is taken, an interrupt-enabling write to CPSR (msr
instruction) must be separated from an interrupt-disabling write to the CPSR by at least two
instructions.
3.3
Coprocessors
The SA-1100 has no external coprocessor bus, so it is not possible to add external coprocessors to
this device.
The SA-1100 uses the internal coprocessor designated 15 for control of the on-chip MMU, caches,
clocks, and breakpoints. Coprocessor 15 is also used for read-buffer fills and flushes. If a
coprocessor other than 15 is used, then the SA-1100 will take the undefined instruction trap. The
coprocessor load, store, and data operation instructions also take the undefined instruction trap.
Permissions are set so that access to coprocessor 15 is privileged except where protection is
programmable with respect to the read buffer operations.
SA-1100 Developer’s Manual
3-5
Instruction Set
4
This section describes the instruction timing for the Intel® StrongARM® SA-1100 Microprocessor
(SA-1100).
4.1
4.2
Instruction Set
The SA-1100 implements the ARM™ V4 architecture as defined in the ARM Architecture
Reference, 28-July-1995, with previously noted options and additions.
Instruction Timings
Table 4-1 lists the instruction timing for the SA-1100. The result delay is the number of cycles that
the next sequential instruction would stall if it used the result as an input. The issue cycles are the
number of cycles that this instruction takes to issue. For most instructions, the result delay is zero
and the issue cycles is one. For load and stores, the timing is for cache hits.
Table 4-1.
Instruction Timings
Instruction Group
Data processing
Result Delay
Issue Cycles
0
1..3
1..3
0
1
Mul or Mul/Add giving 32-bit result
Mul or Mul/Add giving 64-bit result
Load single – write-back of base
Load single – load data zero extended
Load single – load data sign extended
Store single – write-back of base
1
2
1
1
1
2
1
0
1
MAX
Load multiple (delay for last register)
Store multiple – write-back of base
1
0
(2, number of registers loaded)
MAX
(2, number of registers loaded)
Branch or branch and link
0
2
1
0
0
2
1
1
1
3
1
2
MCR
MRC
MSR to control
MRS
Swap
SA-1100 Developer’s Manual
4-1
Coprocessors
5
The operation and configuration of the Intel® StrongARM® SA-1100 Microprocessor (SA-1100) is
controlled with coprocessor instructions, configuration pins, and memory-management page
tables. The coprocessor 15 instructions manipulate on-chip registers that control the configuration
of the cache, write buffer, MMU, read buffer, breakpoints, and other configuration options.
Note: The gray areas in the register and translation diagrams are reserved and should be programmed 0
for future compatibility.
5.1
Internal Coprocessor Instructions
The on-chip cache, MMU, write buffer, and read buffers are controlled using MRC instructions and
MCR instructions. These operations to coprocessor 15 are allowed only in nonuser modes except
when read-buffer operations are explicitly enabled. The undefined instruction trap is taken if
instructions MRC and MCR.
Figure 5-1. Format of Internal Coprocessor Instructions MRC and MCR
31
28 27
24 23
21 20 19
16 15
12 11
8
7
5
4
3
0
OPC_2
CRm
1
1
1
0
n
1
1
1
1
1
CRn
Rd
Cond
Cond
ARM™ condition codes
1 MRC register read
0 MCR register write
SA-1100 register
n
CRn
Rd
ARM register
OPC_2
CRm
Function bits for some MRC/MCR instructions
Function bits for some MRC/MCR instructions
SA-1100 Developer’s Manual
5-1
Coprocessors
5.2
Coprocessor 15 Definition
The SA-1100 coprocessor 15 contains registers that control the cache, MMU, and write buffer
operation as well as some clocking functions. These registers are accessed using CPRT instructions
to coprocessor 15 with the processor in any privileged mode. Only some of registers 0–15 are
valid; the result of an access to an invalid register is unpredictable. Table 5-1 lists the coprocessor
15 control registers.
Table 5-1.
Cache and MMU Control Registers (Coprocessor 15)
Register
Register Reads
Register Writes
0
1
2
3
4
5
6
7
8
9
ID
RESERVED
Control
Control
Translation table base
Domain access control
RESERVED
Translation table base
Domain access control
RESERVED
Fault status
Fault status
Fault address
Fault address
RESERVED
Cache operations
TLB operations
RESERVED
RESERVED
Read buffer operations
RESERVED
10..12
13
RESERVED
Read process ID (PID)
Read breakpoint
RESERVED
Write process ID (PID)
Write breakpoint
Test, clock, and idle
14
15
5.2.1
Register 0 – ID
Register 0 is a read-only register that returns an architecture and implementation-defined
identification for the device.identification for the device.
31
24 23
16 15
4
3
0
Part Number
44
Architecture Version
Stepping
ARM architecture version
01 = Version 4
Architecture Version
Part Number
Stepping
Part number
A11 = SA1100
Stepping revision of SA-1100
1 = B stepping
2 = C stepping
8 = D stepping
9 = E stepping
11 = G stepping
5-2
SA-1100 Developer’s Manual
Coprocessors
5.2.2
Register 1 – Control
Register 1 is a read/write register containing control bits. All writable bits in this register are forced
low by reset. The shaded bits (also labeled r) are reserved and are not readable or writable.
13
31
12
9
8
7
6
5
4
3
2
1
0
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r X
I
r
r
R S B 1 1 1 W C A M
M bit 0
A bit 1
C bit 2
W bit 3
B bit 7
S bit 8
R bit 9
I bit 12
Enable/disable
0 – On-chip memory-management unit disabled
1 – On-chip memory-management unit enabled
Address fault enable/disable
0 – Alignment fault disabled
1 – Alignment fault enabled
Data cache enable/disable
0 – Data cache disabled
1 – Data cache enabled
Write buffer enable/disable
0 – Write buffer disabled
1 – Write buffer enabled
Big/little endian
0 – Little endian operation
1 – Big endian operation
System
This bit selects the access checks performed by the memory-management unit.
See the ARM Architecture Reference for more information.
ROM
This bit selects the access checks performed by the memory-management unit.
See the ARM Architecture Reference for more information.
Instruction cache enable/disable
0 – Instruction cache disabled
1 – Instruction cache enabled
X bit 13
Virtual interrupt vector adjust
0 – Base address of interrupt vectors is 0h0000 0000
1 – Base address of interrupt vectors is 0hFFFF 0000
Bits 14..31
Unused.
Undefined on Read. Writes ignored.
SA-1100 Developer’s Manual
5-3
Coprocessors
5.2.3
Register 2 – Translation Table Base
Register 2 is a read/write register that holds the base of the currently active level 1 page table. Bits
<13:0> are undefined on read, ignored on write.
31
14 13
0
Translation Table Base
5.2.4
Register 3 – Domain Access Control
Register 3 is a read/write register that holds the current access control for domains 0 to 15. Refer to
the ARM Architecture Reference for a description of the domain structure
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
9
8
7
6
5
4
3
2
1
0
5.2.5
5.2.6
Register 4 – RESERVED
Register 4 is reserved. Accessing this register yields unpredictable results.
Register 5 – Fault Status
Reading register 5 returns the current contents of the fault status register (FSR). The FSR is written
when a data memory fault occurs or can be written by an MCR to the FSR. It is not updated for a
<31:10> are undefined on read, ignored on write. Bit 9 is set when a data breakpoint is taken and
can be cleared by an MCR operation. Bit 8 is ignored on write and is always returned as zero.
Refer to the ARM Architecture Reference for a description of the domain and status fields.
31
10
9
8
7
4
3
0
D 0
Domain
Status
5.2.7
Register 6 – Fault Address
Reading register 6 returns the current contents of the fault address register (FAR). The FAR is
written when a data memory fault occurs with the virtual address of the data fault or can be written
by an MCR to the FAR.
31
0
Fault Virtual Address
5-4
SA-1100 Developer’s Manual
Coprocessors
5.2.8
Register 7 – Cache Control Operations
Register 7 is a write-only register. The CRm and OPC_2 fields are used to encode the cache control
operations. Operation for all other values for OPC_2 and CRm is unpredictable.
Function
Flush I+D
OPC_2
0b000
CRm
0b0111
Data
Ignored
Flush I
0b000
0b000
0b001
0b001
0b100
0b0101
0b0110
0b0110
0b1010
0b1010
Ignored
Flush D
Ignored
Flush D single entry
Clean Dcache entry
Drain write buffer
Virtual address
Virtual address
Ignored
5.2.9
Register 8 – TLB Operations
Register 8 is a write-only register. The CRm and OPC_2 fields are used to encode the following
TLB flush operations. Operation for all other values of OPC_2 and CRm is unpredictable.
Function
OPC_2
0b000
CRm
0b0111
Data
Flush I+D
Flush I
Ignored
Ignored
Ignored
0b000
0b000
0b001
0b0101
0b0110
0b0110
Flush D
Flush D single entry
Virtual address
SA-1100 Developer’s Manual
5-5
Coprocessors
5.2.10
Register 9 – Read-Buffer Operations
The read buffer is controlled and accessed through register 9 of coprocessor 15. The functions
supported are: flush-all buffers, flush-a-single entry, load-an-entry (1, 4 or 8 words), and
enable/disable user mode access.
The CRm and OPC_2 fields are used to encode these control operations. All other values for
OPC_2 and CRm are undefined and the results of using them are unpredictable.
Function
OPC_2
0b000
CRm
0b0000
Data
Flush all entries
Flush Buffer 0
Flush Buffer 1
Flush Buffer 2
Flush Buffer 3
Ignored
Ignored
Ignored
Ignored
Ignored
0b001
0b001
0b001
0b001
0b010
0b010
0b010
0b010
0b010
0b010
0b010
0b010
0b010
0b010
0b010
0b010
0b100
0b101
0b0000
0b0001
0b0010
0b0011
0b0000
0b0100
0b1000
0b0001
0b0101
0b1001
0b0010
0b0110
0b1010
0b0011
0b0111
0b1011
0b0000
0b0000
Load Buffer 0 with one word
Load Buffer 0 with four words
Load Buffer 0 with eight words
Load Buffer 1 with one word
Load Buffer 1 with four words
Load Buffer 1 with eight words
Load Buffer 2 with one word
Load Buffer 2 with four words
Load Buffer 2 with eight words
Load Buffer 3 with one word
Load Buffer 3 with four words
Load Buffer 3 with eight words
Disable user-mode MCR access
Enable user-mode MCR access
Virtual address
Virtual address
Virtual address
Virtual address
Virtual address
Virtual address
Virtual address
Virtual address
Virtual address
Virtual address
Virtual address
Virtual address
Ignored
Ignored
read buffer.
5.2.11
Registers 10 – 12 RESERVED
Accessing any of these registers yields unpredictable results.
5-6
SA-1100 Developer’s Manual
Coprocessors
5.2.12
Register 13 – Process ID Virtual Address Mapping
The SA-1100 supports the remapping of virtual addresses through a process ID (PID) register. The
6-bit PID value is OR’ed with bits 30..25 of the virtual address when bits 31..25 of the virtual
address are zero. This effectively remaps the address to one of 64 “slots” in the lower 2 Gbyte
address space. The following table shows the OPC_2 and CRm field encodings used to access the
process ID register. This register is zero at reset and if left unmodified, effectively disables the
remapping function. As such, no explicit enable or disable function is necessary. Reserved bits read
as zero and must be written as zero. This register is readable and writable.
Function
Access process ID register
OPC_2
0b000
CRm
0b0000
The following figure shows the format of the process ID register.
31
25 24
0
30
r
Process ID
Reserved
SA-1100 Developer’s Manual
5-7
Coprocessors
5.2.13
Register 14 – Debug Support (Breakpoints)
The SA-1100 supports address and data breakpoints through register 14 of coprocessor 15. The
Support”. The following table shows the OPC_2 and CRm field encodings used to access the
address and data breakpoints.
Function
OPC_2
0b000
CRm
0b0000
Access data breakpoint address register (DBAR).
Access data breakpoint value register (DBVR).
Access data breakpoint mask register (DBMR).
0b000
0b000
0b000
0b0001
0b0010
0b0011
Load data breakpoint control register (DBCR).
-----------------------------------------------------------------
DBCR Bit
Action
-----------------------------------------------------------------
lw
0 = Disable load watch
1 = Enable load watch
saw
sdw
0 = Disable store address watch
1 = Enable store address watch
0 = Disable store data watch
1 = Enable store data watch
Write instruction breakpoint address and control register (IBCR).
0b000
0b1000
Low-order address bit is the address break enable/disable bit.
Register not readable.
The DBCR register is a 3-bit register used to control the enabling and disabling of the data
breakpoints. Bits 0..2 are valid and positioned as shown below. Bits 3..31 are reserved. These bits
read as zeros and writes have no effect.
31
2
1
0
sdw saw lw
Reserved
The IBCR is a write-only register used to load an address breakpoint address and to set an enable
bit for the function. If an address is loaded with bit 0 (E) set, then the address is enabled as a
breakpoint. If bit zero is cleared, then the breakpoint is disabled. Bit 1 is reserved and should be
written to zero.
31
0
2
1
r
E
Instruction Address Breakpoint Value
5-8
SA-1100 Developer’s Manual
Coprocessors
5.2.14
Register 15 – Test, Clock, and Idle Control
Register 15 is a write-only register. The CRm and OPC_2 fields are used to encode the following
control operations. Operation for all other values of OPC_2 and CRm is unpredictable.
Function
OPC_2
0b001
CRm
Enable odd-word loading of the linear feedback shift
register ( LFSR)
0b0001
Enable even-word loading of LFSR
Clear LFSR
0b001
0b001
0b001
0b010
0b010
0b010
0b010
0b0010
0b0100
0b1000
0b0001
0b0010
0b0100
0b1000
Move LFSR to R14.abort
Enable clock switching
Disable clock switching
RESERVED
Wait for interrupt
SA-1100 Developer’s Manual
5-9
Caches, Write Buffer, and Read Buffer 6
To reduce effective memory access time, the Intel® StrongARM® SA-1100 Microprocessor
(SA-1100) has an instruction cache, a data cache, a write buffer, and a read buffer. All except the
read buffer are transparent to program execution. The following sections describe each of these
units and give all necessary programming information.
6.1
Instruction Cache (Icache)
The SA-1100 contains a 16 Kbyte instruction cache (Icache). The Icache has 512 lines of 32 bytes
(8 words), arranged as a 32-way set associative cache, and uses the virtual addresses generated by
the processor core. The Icache is always reloaded a line at a time (8 words). It may be enabled or
disabled via the SA-1100 control register, and is disabled on the assertion of nRESET or through a
System Control Module for details.) The operation of the cache, when memory management is
enabled, is further controlled by the cacheable or C bit stored in the memory-management page
table. If memory management is disabled, all addresses are marked as cacheable (C=1). When
memory management is enabled, the C bit in each page table entry can disable caching for an area
of virtual memory.
6.1.1
Icache Operation
In the SA-1100, the instruction cache is searched regardless of the state of the C bit; only reads that
miss the cache are affected. If, on an Icache miss, the C bit is a one or the Memory Management
Unit (MMU) is disabled, a linefetch of 8 words is performed and it is placed in a cache bank with a
round-robin replacement algorithm. If, on a miss, the MMU is enabled and the C bit is a zero for
the given virtual address, an external memory access for a single word is performed and the cache
is not written.The Icache should be enabled as soon as possible after reset for best performance.
6.1.2
Icache Validity
The Icache operates with virtual addresses, so care must be taken to ensure that its contents remain
consistent with the virtual-to-physical mappings performed by the memory management unit. If the
memory mappings are changed, the Icache validity must be ensured. The Icache is not coherent
with stores to memory, so programs that write cacheable instruction locations must ensure the
Icache validity. Instruction fetches do not check the write buffer, so data must not only be pushed
out of the cache but the write buffer must also be drained.
6.1.2.1
Software Icache Flush
The entire Icache can be invalidated by writing to the SA-1100 cache operations register (register
7). The cache is flushed immediately when the register is written, but note that the following
instruction fetches may come from the cache before the register is written.
SA-1100 Developer’s Manual
6-1
Caches, Write Buffer, and Read Buffer
6.1.3
Icache Enable/Disable and Reset
The Icache is automatically disabled and flushed on the assertion of nRESET. Once enabled,
cacheable read accesses cause lines to be placed in the cache. If the Icache is subsequently
disabled, no new lines are placed in the cache, but the cache is still searched and if the data is
found, it will be used by the processor. If the data in the cache must not be used, then the cache
must be flushed.
6.1.3.1
6.1.3.2
6.2
Enabling the Icache
To enable the Icache, set bit 12 in the control register. The MMU and Icache may be enabled
simultaneously with a single control register write.
Disabling the Icache
To disable the Icache, clear bit 12 in the control register.
Data Caches (Dcaches)
The SA-1100 contains two logically separate data caches: the main data cache and the mini data
cache (or minicache). The main data cache, an 8 Kbyte write-back Dcache, has 256 lines of 32
bytes (8words) in a 32-way set-associative organization. It is intended for use during most data
accesses. This cache allocates on loads to spaces marked B=1 and C=1. Replacements in the main
data cache are selected according to a set of round-robin pointers. At reset, the pointer in each
block of the Dcache points to way zero of each 32-way block. As lines are allocated, the pointers
are incremented to the next way of the set. After way 31 is allocated, the next linefill replaces (and
copies back to memory, if dirty) the data in way zero. The minicache is a 512-byte write-back
cache. It has 16 lines of 32 bytes (8 words) in a two-way set-associative organization and provides
an alternate caching structure for dealing with large data structures that could thrash the main data
cache. This cache allocates on loads to spaces marked B=0 and C=1. Replacements in the
minicache use the same round-robin pointer mechanism as in the main data cache. However, since
this cache is only two-way set-associative, the replacement algorithm reduces to a simple
least-recently-used (LRU) mechanism.
The Dcaches are accessed in parallel and the design ensures that a particular line entry will exist in
only one of the two at any time. Both Dcaches use the virtual address generated by the processor
and allocate only on loads (write misses never allocate in the cache). Each line entry contains the
physical address of the line and two dirty bits. The dirty bits indicate the status of the first and the
second halves of the line. When a store hits in the Dcaches, the dirty bit associated with it is set.
When a line is evicted from the Dcaches, the dirty bits are used to decide if all, half, or none of the
line will be written back to memory using the physical address stored with the line. The Dcaches
are always reloaded a line at a time (8 words).
The Dcaches allocate only on loads and according to the settings of the B and C bits in the MMU.
If B=0 and C=1, the memory access allocates into the minicache. If B=1 and C=1, the memory
access allocates into the main data cache. The Dcaches should be flushed prior to changing the
bufferable and/or cacheable state of the page table mapping.
The main data cache and the minicache are enabled and disabled via the SA-1100 control register,
and are disabled on nRESET as well as software, sleep, and watchdog reset. The operation of the
Dcaches is further controlled by the cacheable or C bit and the bufferable or B bit stored in the
6-2
SA-1100 Developer’s Manual
Caches, Write Buffer, and Read Buffer
memory-management page table. For this reason, in order to use the Dcaches, the MMU must be
enabled. The two functions may be enabled simultaneously with a single write to the control
register.
Note: The Dcaches operate with virtual addresses, so care must be taken to ensure that their contents
remain consistent with the virtual-to-physical mappings performed by the memory-management
unit. If the memory mappings are changed, the validity of the Dcaches must be ensured.
6.2.1
Cacheable Bit – C
The cacheable bit determines whether, on load misses, the data being read should be placed in one
of the two data caches. Cache hits are not affected by the cacheable bit; if a data access hits in the
cache, the data is assumed to be valid and the load or store is performed. Typically, main memory is
marked as cacheable to improve system performance and I/O space as noncacheable to stop the
data from being stored in SA-1100’s cache. For example, if the processor is polling a hardware flag
in I/O space, it is important that the processor is forced to read data from the external peripheral,
and not a copy of initial data held in the cache.
6.2.1.1
Cacheable Reads – C = 1
A linefetch of 8 words will be performed and it will be placed in a cache bank with a round-robin
replacement algorithm.
6.2.1.2
Noncacheable Reads – C = 0
An external memory access will be performed and the cache will not be written.
6.2.2
Bufferable Bit – B
The bufferable bit does not affect writes that hit the Dcaches. If a store hits in the Dcaches, the store
is assumed to be bufferable. Write-backs of dirty lines are treated as bufferable writes. See the
Section 6.3, “Write Buffer (WB)” on page 6-5 for more information on the B bit.
Table 6-1 summarizes the effects of the B and C bits on the Dcaches.
Table 6-1.
Effects of the Cacheable and Bufferable Bits on the Data Caches
Load
Store
B
0
C
0
Cache Hit
Cache Miss
Cache Hit
Cache Miss
Deliver cache data. Load from memory.
Store to either cache.
– Mark line dirty.
Store to memory.
– No allocate.
– No allocate.
0
1
1
1
0
1
Deliver cache data. Allocate to minicache.
Store to either cache.
– Mark line dirty.
Store to memory.
– No allocate.
Deliver cache data. Load from memory.
– No allocate.
Store to either cache.
– Mark line dirty.
Store to memory.
– No allocate.
Deliver cache data. Allocate to main data cache. Store to either cache.
– Mark line dirty.
Store to memory.
– No allocate.
SA-1100 Developer’s Manual
6-3
Caches, Write Buffer, and Read Buffer
6.2.3
Software Dcache Flush
The SA-1100 supports the flush and clean operations on single entries of the Dcaches by writes to
the cache operations registers. The flush whole cache is also supported. Note that since this is a
write-back cache, in order to prevent the loss of data, a flush whole must be preceded by a
sequence of loads to cause the cache to write back any dirty entries. The memory controller in the
SA-1100 provides an internally decoded memory space to perform coherent Dcache flushing. This
space resides in the upper 512 megabytes of the memory map (starting at virtual address
0hE000 0000) and, when accessed, is detected by the memory controller, which then returns zeros
without incurring an external memory latency.
The following code causes the main data cache to flush all dirty entries:
;+
;Call:
;
;
;
R0 points to the start of a 8192 byte region of readable data used
only for this cache flushing routine.
bl writeBackDC
;Return:
;
R0, R1, R2 trashed
;
Data cache is clean
;-
writeBackDC
movr0, 0hE0000000
addr1, r0, #8192
l1
ldr r2, <r0>, #32
teqr1, r0
bnel1
mcrp15, 0, r0, c7, c6, 0
movpc, r14
A similar routine may be written to flush the minicache. To perform this flush, the MMU B and C
settings must be as described above. The invalidate-all operation also invalidates the minicache.
6.2.3.1
Doubly Mapped Space
Since the Dcaches work with virtual addresses, it is assumed that every virtual address maps to a
different physical address. If the same physical location is accessed by more than one virtual
address, the cache cannot maintain consistency, since each virtual address has a separate entry in
the cache, and only one entry is updated on a processor write operation. To avoid any cache
inconsistencies, doubly mapped virtual addresses should be marked as noncacheable.
6.2.4
Dcaches Enable/Disable and Reset
The Dcaches are automatically disabled and flushed on the assertion of nRESET. Once enabled,
cacheable read accesses cause lines to be placed in the Dcaches. If subsequently disabled, no new
lines are placed in the Dcaches, but they are still searched and if the data is found, it is used by the
processor. Write operations continue to update the Dcaches, thus maintaining consistency with the
external memory. If the data in the Dcaches must not be used, then the Dcaches must be flushed.
6-4
SA-1100 Developer’s Manual
Caches, Write Buffer, and Read Buffer
6.2.4.1
Enabling the Dcaches
To enable the Dcaches, make sure that the MMU is enabled first by setting bit 0 in the control
register, then enable the Dcaches by setting bit 2 in the control register. The MMU and Dcaches can
be enabled simultaneously with a single control register write.
6.2.4.2
Disabling the Dcaches
To disable the Dcache, clear bit 2 in the control register.
6.3
Write Buffer (WB)
The SA-1100 write buffer is used to improve system performance by buffering up to 8 blocks of
data of 1 to 16 bytes, at independent addresses. It can be enabled or disabled via the W bit (bit 3) in
the SA-1100 control register. The buffer is disabled and all entries are marked empty following
reset. Operation of the write buffer is further controlled by the cacheable or C bit and the
bufferable or B bit, which are stored in the memory-management page tables. For this reason, in
order to use the write buffer, the MMU must be enabled. The two functions can be enabled
simultaneously with a single write to the control register. For a write to use the write buffer, both
the W bit in the control register and the B bit in the corresponding page table must be set. It is not
possible to abort buffered writes externally. Stores will not merge with other data at the same line
address in the write buffer with the exception of store multiples, which do merge.
6.3.1
6.3.2
Bufferable Bit
This bit controls whether a write operation may use the write buffer. Typically, main memory is
bufferable and I/O space unbufferable.
Write Buffer Operation
When the CPU performs a store, the Dcaches are first checked. If one of the Dcaches hits on the
store and the protection for the location and mode of the store allows the write, then the write
completes in the Dcaches and the write buffer is not used. If the location misses in the Dcaches,
then the translation entry for that address is inspected and the state of the B and C bits determines
which of the three following actions are performed. If the write buffer is disabled via the SA-1100
control register, writes are treated as if the B bit is a zero.
6.3.2.1
Writes to a Bufferable and Cacheable Location (B=1,C=1)
If the write buffer is enabled and the processor performs a write to a bufferable and cacheable
location, and the data is in one of the caches, then the data is written to that cache, and the cache
line is marked dirty. If a write to a bufferable area misses in both data caches, the data is placed in
the write buffer and the CPU continues execution. The write buffer performs the external write
sometime later. If a write is performed and the write buffer is full, then the processor is stalled until
there is sufficient space in the buffer. No write buffer merging is allowed in the SA-1100 except
during store multiples.
SA-1100 Developer’s Manual
6-5
Caches, Write Buffer, and Read Buffer
6.3.2.2
6.3.2.3
Writes to a Bufferable and Noncacheable Location (B=1,C=0)
If the write buffer is enabled and the processor performs a write to a bufferable but noncacheable
location and misses in the Dcaches, the data is placed in the write buffer and the CPU continues
execution. As with the cacheable case, merging is allowed only on store multiples. The write buffer
performs the external write sometime later.
Unbufferable Writes (B=0)
If the write buffer is disabled or the CPU performs a write to an unbufferable area, the processor is
stalled until the write buffer empties and the write completes externally. This requires several
external clock cycles.
6.3.3
Enabling the Write Buffer
To enable the write buffer, ensure that the MMU is enabled by setting bit 0 in the control register,
then enable the write buffer by setting bit 3 in the control register. The MMU and write buffer can
be enabled simultaneously with a single write to the control register.
6.3.3.1
Disabling the Write Buffer
To disable the write buffer, clear bit 3 in the control register. Any writes already in the write buffer
will complete normally, but a drain write buffer needs to be done to force all writes out to memory.
Note: The write buffer is used for copy-backs from the Dcaches even when they are disabled.
6.4
Read Buffer (RB)
The SA-1100 contains a software-programmable read buffer that can increase the performance of
critical loop code by prefetching data. The RB enables the preallocation of read-only data into one
of four 32-byte buffers without stalling the pipe. For subsequent loads that hit in the RB, data is
sourced from the buffer instead of the Dcaches at a rate of 1 word per core clock. Also, because
the programmer specifies which entry of the RB is used, critical data can be “locked” in to
eliminate bus latency.
The RB is controlled using coprocessor 15, register 9, and provides the capability to allocate 1
word, a half-line (4 words), or a full line (8 words) into one of four entries of the RB. (See
Chapter 5, “Coprocessors” for a detailed RB coprocessor description.) Half-line loads are
automatically aligned onto half-block boundaries (the lower four address bits are ignored).
Full-line loads are automatically aligned onto line boundaries (the lower five address bits are
ignored). For partial cache line RB loads, only the words actually fetched are marked valid and can
be sourced from the buffer. A small queue is used to ensure that subsequent RB load instructions go
out in order.
When an RB allocate instruction is executed, the virtual address is looked up in the TB to check for
a translation hit and possible access violations. If the access misses in the TB, the pipe is stalled
until the page is fetched through the normal hardware tablewalk mechanism. If an access violation
occurs, the RB load is NOP’d. For example, an RB allocate instruction can generate a data abort.
Once the RB allocate has received a TB hit and no access violations, a bus access is requested that
fills the appropriate buffer without stalling the core pipeline. Subsequent load instructions to this
virtual address result in an RB hit and data is sourced from the appropriate entry to the core.
6-6
SA-1100 Developer’s Manual
Caches, Write Buffer, and Read Buffer
Any two data words with the same virtual address may not be contained in the RB at the same time.
If an RB allocate references a data word that is already contained in another RB entry, then the old
RB entry is invalidated and the new allocation is performed. It is possible for a portion of a cache
clock at a given virtual address to be contained in one RB entry while another portion of the same
block is contained in another RB entry. However, a given word can not be in more than one entry at
a time.
If a load instruction misses in the RB, then a normal cache fill is performed (provided the cache is
enabled and the page is marked cacheable). It then presents the possibility of having a partial line
resident in the RB as well as having the line present in one of the Dcaches. This presents coherency
issues that must be managed by software. If this situation does occur and the addressed data is in
both the Dcache and the RB, then the data is sourced from the RB. If an RB entry contains a partial
cache block (1 or 4 words), then those words will be sourced from the RB while the remaining
words are sourced from the data cache or memory.
RB allocate instructions are not affected by the cache enable bit (bit 2 in the control register) or by
the C bit in the MMU. Any RB allocate to a valid RB entry causes that RB entry to be invalidated,
followed by a new allocation for the desired data. This occurs regardless of the address of the data
currently in the buffer. For example, back-to-back RB allocate instructions to the same entry at the
same address will invalidate the entry caused by the first instruction prior to performing the second
fill.
An RB allocate or a load instruction that is issued to an RB entry currently being filled will stall
until the fill completes. If a data abort is signaled on a read buffer allocate, the fill completes. After
that, if a load to that entry is attempted, a data abort exception is issued. The coprocessor 15
register provides the ability to invalidate individual entries in the RB or to invalidate the entire
buffer in one operation. RB coherency must be managed in software. Writes to addresses present in
the read buffer are not written into the buffer. Specific RB entries must be invalidated before
writing to the addresses or changing the page tables of the entries. Coherency is not checked
between the RB and the WB. The WB should be drained prior to performing an RB load.
SA-1100 Developer’s Manual
6-7
Memory-Management Unit (MMU) 7
This chapter describes the memory-management functions.
7.1
Overview
The Intel® StrongARM® SA-1100 Microprocessor (SA-1100) implements the standard ARM™
memory-management functions using two 32-entry fully associative translation buffers (TBs). One
is used for instruction accesses and the other for data accesses. On a TB miss, the translation table
hardware is invoked to retrieve the translation and access permission information. Once retrieved,
if the entry maps to a valid page or section, then the information is placed into the TB. The
replacement algorithm in the TB is round robin. For an invalid page or section, an abort is
generated and the entry is not placed in the TB.
7.1.1
MMU Registers
Management Unit (MMU) coprocessor 15 registers supported by the SA-1100.
7.2
MMU Faults and CPU Aborts
The MMU generates four faults:
• Alignment fault
• Translation fault
• Domain fault
• Permission fault
Alignment faults are generated by word loads or stores with the low-order two address bits
nonzero, and by load or store half words when the low-order address bit is a one. Translation faults
are generated by access to pages marked invalid by the memory-management page tables. Domain
faults and permission faults are generated by accesses to memory that are protected by the current
mode, domain, and page protection. See the ARM Architecture Reference for more information. In
addition, an external abort may be raised on external data accesses.
7.3
Data Aborts
The SA-1100 takes a data abort exception due to: MMU-generated exceptions, accessing reserved
memory space, and assertion of the abort pin while accessing expansion memory. Writes to
memory areas marked as bufferable ignore the external abort pin.
SA-1100 Developer’s Manual
7-1
Memory-Management Unit (MMU)
7.3.1
Cacheable Reads (Linefetches)
A linefetch can be safely aborted on any word in the transfer. If an abort occurs during the
linefetch, the cache is purged so it will not contain invalid data. If the abort happens before the
word that was requested by the access is returned, the load is aborted. If the abort happens after the
word that was requested by the access is returned, the load completes and the fill is aborted (but no
exception is generated).
7.3.2
Buffered Writes
Buffered writes cannot be externally aborted. Therefore, the system should be configured such that it
does not perform buffered writes to areas of memory that are capable of flagging an external abort.
7.4
Interaction of the MMU, Icache, Dcache, and Write
Buffer
The MMU, Icache, Dcache, and WB can be enabled or disabled independently. The Icache can be
enabled with the MMU enabled or disabled. However, the Dcache and WB can only be enabled
when the MMU is enabled. Because the write buffer is used to hold dirty copy-back cached lines
from the Dcache, it must be enabled along with the Dcache. Therefore, only four of the eight
combinations of the MMU, Dcache, and WB enables are valid. There are no hardware interlocks
on these restrictions, so invalid combinations will cause undefined results.
Table 7-1.
Valid MMU, Dcache, and Write Buffer Combinations
MMU
Dcache
Write Buffer
Off
On
On
On
Off
Off
Off
On
Off
Off
On
On
The following procedures must be observed.
To enable the MMU:
1. Program the translation table base and domain access control registers.
2. Program level 1 and level 2 page tables as required.
3. Enable the MMU by setting bit 0 in the control register.
7-2
SA-1100 Developer’s Manual
Memory-Management Unit (MMU)
Note: Care must be taken if the translated address differs from the untranslated address because the three
instructions following the enabling of the MMU will have been fetched using “flat translation”,
and enabling the MMU may be considered a branch with delayed execution. A similar situation
occurs when the MMU is disabled. Consider the following code sequence:
MOV
MCR
R1, #0x1
15,0,R1,0,0
; Enable MMU
Fetch nontranslated
Fetch nontranslated
Fetch nontranslated
Fetch Translated
To disable the MMU:
1. Disable the WB by clearing bit 3 in the control register.
2. Disable the Dcache by clearing bit 2 in the control register.
3. Disable the Icache by clearing bit 12 in the control register.
4. Disable the MMU by clearing bit 0 in the control register.
Note: If the MMU is disabled and subsequently reenabled, the contents of the TB is preserved. If the
contents are now invalid, the TB should be flushed before reenabling the MMU.
7.5
Mini Data Cache
The mini data cache is a 16-entry, 2-way set-associative data cache. It is accessed in parallel with
the main data cache. A data reference is allocated into the mini data cache if the B and C bits in
the MMU are 0 and 1, respectively. A line of data can reside only in one of the two Dcaches at any
one time. Both Dcaches must be flushed prior to any page table manipulation that could change the
allocation policy.
SA-1100 Developer’s Manual
7-3
Clocks
8
This section describes the Intel® StrongARM® SA-1100 Microprocessor (SA-1100) clocks. The
following diagram shows the distribution of clocks in the SA-1100. The 3.6864-MHz oscillator
feeds both PLLs. The primary PLL provides clocks for the core logic and a 7.36-MHz clock for
several of the serial controllers. The core, Dcaches, and read and write buffers use either the
full-speed core clock or the divided-down clock. The LCD controller, DMA, memory controller,
and GPIO use the core clock divided by 2 (RCLK). The 32.768-kHz oscillator feeds the real-time
clock (RTC) and the power manager logic. The secondary PLL provides the clock for the UDC, the
ICP, and the MCP. The oscillators and PLLs are completely integrated with the SA-1100 and
require no external devices other than the crystals for operation.
ARM™
SA-1 Core
32.768-kHz
Oscillator
3.6864-MHz
Oscillator
Divide
by 2
Icache
Primary PLL
59 MHz – 200 MHz
RTC
and
Dcache
Power
Manager
7.36 MHz
Write
Buffer
Secondary PLL
48 MHz
Read
Buffer
Peripherals
SDLC UART – 7.36 MHz
ICP – 7.36 or 48 MHz
MCP/SSP – 7.36 or 12 MHz
PPC – 7.36 MHz
GPIO<27>
LCD
DMA
Memory
I/O
Controller Controller Controller
Control
UDC – 48 MHz
8.1
SA-1100 Crystal Oscillators
The SA-1100 clocks are derived from two crystals connected to onchip oscillators. The first clock
source is a 3.6864-MHz crystal that feeds the CPU PLL and the 48-MHz PLL. The CPU PLL
multiplies the oscillator output up to the core frequency. This frequency is then divided down to
generate baud rates for the serial ports. If the UARTs are not being used or do not need standard
baud rates, then the 3.6864 -Hz oscillator may be replaced with a 3.5795-MHz crystal to generate
The second oscillator is connected to a 32.768-kHz crystal. The output of this oscillator clocks the
power management controller and the real-time clock (RTC).
Oscillator Specifications” for detailed specifications of the crystal oscillators.
SA-1100 Developer’s Manual
8-1
Clocks
8.2
Core Clock Configuration Register
The core clock frequency is configured by software through the core clock configuration field
(CCF<4:0>) in the power manager phase-locked loop (PLL) configuration register (PPCR). This
field should be programmed during the boot sequence for the desired full-speed operation.
nRESET clears the field by selecting the lowest frequency operation.
register.
Table 8-1 shows the core clock frequency as a function of the CCF setting.
Table 8-1.
Core Clock Configurations
CCF<4:0>
Core Clock Frequency in MHz
3.6864-MHz Crystal Oscillator 3.5795-MHz Crystal Oscillator
00000
59.0
57.3
00001
00010
00011
73.7
71.6
88.5
85.9
103.2
118.0
132.7
147.5
162.2
176.9
191.7
206.4
221.2
Not supported.
100.2
114.5
128.9
143.2
157.5
171.8
186.1
200.5
214.8
—
00100
00101
00110
00111
01000
01001
01010
01011
01100– 11111
8.2.1
Restrictions on Changing the Core Clock Configuration
When the CPU writes to the PPCR, the core clock PLL and the 48-MHz PLL are stopped for a
period of time to allow the core clock PLL to relock to the new frequency. When these PLLs are
stopped, the core clock and all clocks derived from that clock are stopped. When this happens,
certain units within the SA-1100 (the LCD controller, all serial controllers, the DMA controller,
and the OS timer) will experience an interruption in operation for approximately 150 microseconds
after the PPCR is written.
Because of these restrictions, it is recommended that the user not change the PPCR except
immediately following a hard reset or immediately following wake-up from sleep mode. The LCD
controller, all serial controllers (except the UDC), the DMA controller, and the OS timer are
already disabled and are not affected by an interruption in their clock stream. In addition to these
restrictions, the PPCR must be written prior to enabling clock switching. Note that the 32.768-kHz
clock is not affected by any change in the PPCR and units using this clock (power management,
RTC) do not see any interruption in service during the 150 microsecond period.
8-2
SA-1100 Developer’s Manual
Clocks
8.3
Driving SA-1100 Crystal Pins from an External
Source
In most applications, a 3.6864-MHz crystal will be connected between the PXTAL and the
PEXTAL pins. Similarly, a 32.768-kHz crystal will be connected between the TXTAL and
TEXTAL pins. In some applications, supplying these clocks from an external source may be
preferred. This is accommodated in the SA-1100 design by:
• Supplying the 32.768-kHz clock from an external source
— Only the TXTAL pin is driven. The TEXTAL pin must be left floating.
— The peak-to-peak voltage swing on TXTAL must be at least 0.6 V and the voltage on the
pin must remain within the range of 0 V to 1 V, independent of the other power supply
voltages applied to the processor.
• Supplying a 3.6864-MHz clock from an external source
— Both PXTAL and PEXTAL are driven with complementary signals.
— The peak-to-peak voltage swing on PXTAL and PEXTAL must be at least 0.6 V and the
voltage on the pin must remain in the range of 0 V to 1 V, independent of the other power
supply voltages applied to the processor.†
— When an external clock is being used, the pull-down path in the internal 3.6864 MHz
oscillator is active. In order to limit the current into the internal oscillator, it is
recommended that the minimum impedance to the positive supply be controlled. The
maximum current sourced by the external clock source when the clock is at its maximum
positive voltage should be about 1 mA.†
— The maximum impedance of the external clock source is set by the minimum slew rate at
the PXTAL and PEXTAL pins, approximately 1 V per 100 ns.†
†These constraints can be satisfied by the following suggestions:
•
•
For applications in which a pulse generator is available, drive differential 1-V signals through
series 1-K resistors (after the usual 50-ohm terminators-to-ground).
To supply external clock signals from a 3.3-V supply, drive signals with open collector or
tristatable drivers. Set high level with 3.3 K from 3.3 V to the output and 1.3 K from the output
to ground.
•
To supply external clock signals from a 1.5-V supply, drive signals with open collector or
tristatable drivers. Set high level with 1.5 K from 1.5 V to the output and 2.7 K from output to
ground. This solution may be preferred in portable applications that turn off the 1.5-V supply
in sleep mode because this would eliminate the current through the resistors in sleep mode.
The two pairs of crystal pins are located close to each other on the processor. This arrangement is
advantageous when there are crystals connected to the pins because the low signal swings and slow
edges result in limited noise coupling between the pins. If one of the crystals is replaced by an
independent signal source and the other is not, some degradation of the remaining crystal oscillator
performance can result due to increased noise coupling. If only one crystal is being used, this effect
can be reduced by limiting the speed of the edge rate on the pin driven by the independent source.
SA-1100 Developer’s Manual
8-3
Clocks
If the PXTAL or TXTAL pin is driven above the voltage indicated, there will be no permanent
damage to the processor for pin voltages less than 2.5 V. However, ESD diodes on these pins will
attempt to clamp the voltage at approximately 1.5 V. The clamping action results in significant
noise injected into an internally generated supply used by several sensitive circuits on the
processor. Consequently, driving this pin higher than the 1 V limit can result in unpredictable
operation not obviously connected with the crystal pins. Users should refrain from driving the
crystal pins higher than 1 V even if there is no obvious side effect.
Note: In every system, there must be a provision for both a 3.6864-MHz and a 32.768-kHz source either
from an external oscillator or a crystal.
8.4
Clocking During Test
If TCK_BYP is high, then the PLLs and oscillators are not used and the high-speed core clock is
supplied externally on the TESTCLK pin. This mode is for testing only and is not supported for
standard operation.
8-4
SA-1100 Developer’s Manual
System Control Module
9
This chapter describes the system control module that controls several processor-wide system
functions. The units contained in the system control module are: the general-purpose I/O ports, the
interrupt controller, the real-time clock, the operating system timer, the power manager, and the
reset controller.
9.1
General-Purpose I/O
The Intel® StrongARM® SA-1100 Microprocessor (SA-1100) provides 28 general-purpose I/O
(GPIO) port pins for use in generating and capturing application-specific input and output signals.
Each pin is programmable as an input or output and as an interrupt source. All 28 pins are
configured as inputs during the assertion of reset, and remain inputs until they are configured
otherwise.
Each GPIO pin can be configured as an input or an output by programming the GPIO pin direction
register (GPDR). When programmed as an output, the pin can be controlled by writing to the GPIO
pin output set register (GPSR) and the GPIO pin output clear register (GPCR). Writing to these
registers controls the output data register, which is not directly readable or writable. The set and
clear registers can be written regardless of whether the pin is configured as an input or an output.
The programmed output state will take effect when the pin is reconfigured as an output.
When programmed as an input, the current state of each GPIO pin can be read through the GPIO
pin-level register (GPLR). This register can be read at any time and can be used to confirm the state
of the pin when it is configured as an output. In addition, each GPIO pin can be programmed to
detect a rising and/or falling edge through the GPIO rising-edge detect register (GRER) and GPIO
falling-edge detect register (GFER). The state of the edge detect can be read through the GPIO
edge detect status register (GEDR). These edge detects can be programmed to generate an interrupt
When the SA-1100 enters sleep mode, the contents of the power manager sleep state register
(PGSR) is loaded into the output data register. If the particular pin is programmed as an output,
then the state in the PGSR will be driven onto the pin before entering sleep. When the SA-1100
exits sleep mode, these values remain until reprogrammed by writing to the GPSR and GPCR.
Some GPIO pins can also serve an alternate function within the SA-1100. Certain modes within the
serial controllers and LCD controller require extra pins. These functions are hardwired into specific
GPIO pins and their use is described in the following sections. Even though a GPIO pin has been
taken over for an alternate function, the user must still program the proper direction of that pin
shows a block diagram of a single GPIO pin.
SA-1100 Developer’s Manual
9-1
System Control Module
Figure 9-1. General-Purpose I/O Block Diagram
Pin Direction
Register
Alternate Function
Register
Pin Set and
Clear Registers
0
1
GPIO Pin
Alternate Function
(Output)
Alternate Function
(Input)
Edge Detect
Status Register
Edge
Detect
Rising Edge Detect
Enable Register
Falling Edge Detect
Enable Register
Pin-Level
Register
9.1.1
GPIO Register Definitions
There are a total of eight registers within the GPIO control block: one is used to monitor pin state;
two are used to control pin state; one is used to control pin direction; two are used to specify a pin’s
edge type that should be detected; and one is used to flag when specified edge types are detected on
pins. The last register indicates whether a pin is used as normal GPIO or whether it is taken over by
the alternate function. Note that the pin direction register (GPDR) is the only register that is
initialized by reset. The values in all other GPIO registers are unknown following reset and must be
initialized by software.
9-2
SA-1100 Developer’s Manual
System Control Module
9.1.1.1
GPIO Pin-Level Register (GPLR)
The state of each of the GPIO port pins is visible through the GPIO pin-level register (GPLR).
Each bit number corresponds to the port pin number from bit 0 to bit 27. This is a read-only register
that is used to determine the current level of a particular pin (regardless of the programmed pin
direction).
The following table shows the locations of the 28 pin-level bits within the GPLR. This is a
read-only register. For reserved bits, reads return zero; a question mark indicates that the values are
unknown at reset.
Bit
Read
Reset
-
31
30
29
0
28
0
27
PL27
?
26
PL26
?
25
PL25
?
24
PL24
?
23
PL23
?
22
PL22
?
21
PL21
?
20
PL20
?
19
PL19
?
18
PL18
?
17
PL17
?
16
PL16
?
Reserved
0
-
0
Bit
15
14
13
PL13
?
12
PL12
?
11
PL11
?
10
PL10
?
9
PL9
?
8
PL8
?
7
PL7
?
6
PL6
?
5
PL5
?
4
PL4
?
3
PL3
?
2
PL2
?
1
PL1
?
0
PL0
?
Read PL15 PL14
Reset
?
?
Bit
Name
Description
{n}
PL{n}
GPIO port pin level n (where n = 0 through 27).
0 – Pin state is low.
1 – Pin state is high.
31.. 28
—
Reserved.
SA-1100 Developer’s Manual
9-3
System Control Module
9.1.1.2
GPIO Pin Direction Register (GPDR)
Pin direction is controlled by programming the GPIO pin direction register (GPDR). The GPDR
contains one direction control bit for each of the 28 port pins. If a direction bit is programmed to a
one, the port is an output. If it is programmed to a zero, it is an input. At hardware reset, all bits in
this register are cleared, configuring all GPIO pins as inputs. Soft resets and sleep reset have no
effect on this register. For reserved bits, writes are ignored and reads return zero. The following
table shows the location of each pin direction bit in the GPIO pin direction register.
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Bit
R/W
Reserved
PD27 PD26 PD25 PD24 PD23 PD22 PD21 PD20 PD19 PD18 PD17 PD16
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Reset
15
14
13
12
11
10
9
PD9
0
8
PD8
0
7
PD7
0
6
PD6
0
5
PD5
0
4
PD4
0
3
PD3
0
2
PD2
0
1
PD1
0
0
PD0
0
Bit
R/W
PD15 PD14 PD13 PD12 PD11 PD10
0
0
0
0
0
0
Reset
Bit
Name
Description
{n}
PD{n}
GPIO port pin direction n (where n = 0 through 27).
0 – Pin configured as an input.
1 – Pin configured as an output.
31..28
—
Reserved.
9-4
SA-1100 Developer’s Manual
System Control Module
9.1.1.3
GPIO Pin Output Set Register (GPSR) and Pin Output Clear Register
(GPCR)
When a port is configured as an output, the user controls the state of the pin by writing to either the
GPIO pin output set register (GPSR) or the GPIO pin output clear register (GPCR). An output pin
is set by writing a one to its corresponding bit within the GPSR. To clear an output pin, a one is
written to the corresponding bit within the GPCR. These are write-only registers. Reads return
unpredictable values. Writing a zero to any of the GPSR or GPCR bits has no effect. Writing a one
to a GPSR or GPCR bit corresponding to a pin that is configured as an input has no effect. For
reserved bits, writes are ignored. The following tables show the locations of the GPSR bits and the
locations of the GPCR bits. These are write-only registers and reset values do not apply.
Bit
Write
Reset
-
31
-
30
29
-
28
-
27
26
25
24
23
22
21
20
19
18
17
16
Reserved
PS27 PS26 PS25 PS24 PS23 PS22 PS21 PS20 PS19 PS18 PS17 PS16
-
-
-
-
-
-
-
-
-
-
-
-
-
Bit
15
14
13
12
11
10
9
PS9
-
8
PS8
-
7
PS7
-
6
PS6
-
5
PS5
-
4
PS4
-
3
PS3
-
2
PS2
-
1
PS1
-
0
PS0
-
Write PS15 PS14 PS13 PS12 PS11 PS10
Reset
-
-
-
-
-
-
Bit
Name
Description
{n}
PS{n}
GPIO output pin set n (where n = 0 through 27).
0 – Pin level unaffected.
1 – If pin configured as an output, set pin level high (one).
Reserved.
31..28
—
Bit
Write
Reset
31
30
29
-
28
-
27
26
25
24
23
22
21
20
19
18
17
16
Reserved
PC27 PC26 PC25 PC24 PC23 PC22 PC21 PC20 PC19 PC18 PC17 PC16
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Bit
15
14
13
12
11
10
9
PC9
-
8
PC8
-
7
PC7
-
6
PC6
-
5
PC5
-
4
PC4
-
3
PC3
-
2
PC2
-
1
PC1
-
0
PC0
-
Write PC15 PC14 PC13 PC12 PC11 PC10
Reset
-
-
-
-
-
-
Bit
Name
Description
{n}
PC{n}
GPIO output pin clear n (where n = 0 through 27).
0 – Pin level unaffected.
1 – If pin configured as an output, clear pin level low (zero).
Reserved.
31.. 28
—
The user can test a bit within the GPLR corresponding to a pin that is configured as an output after
having set or cleared the pin state to determine if there is an external conflict on the pin. For
example, if an off-chip device is driving a GPIO output pin high and the user has cleared the pin’s
state by writing a one to its GPCR bit, the user can read the GPLR, then compare the written value
(zero) to the actual value (one) to detect the conflict.
SA-1100 Developer’s Manual
9-5
System Control Module
9.1.1.4
GPIO Rising-Edge Detect Register (GRER) and Falling-Edge Detect
Register (GFER)
Each GPIO port can also be programmed to detect a rising-edge, falling-edge, or either transition
on a pin. When an edge is detected that matches the type of edge programmed for the pin, a status
bit is set. The interrupt controller can be programmed to signal an interrupt to the CPU or wake up
the SA-1100 from sleep mode when any one of these status bits is set.
The GPIO rising-edge and falling-edge detect registers (GRER and GFER, respectively) are used
to select the type of transition on a GPIO pin that causes a bit within the GPIO edge detect status
register (GEDR) to be set. For a given GPIO port pin, its corresponding GRER bit is set to cause a
GEDR status bit to be set when the pin transitions from logic level zero (0) to one (1). Likewise,
GFER is used to set the corresponding GEDR status bit when a transition from logic level one (1)
to zero (0) occurs. When the corresponding bits are set in both registers, either a falling- or a
rising-edge transition causes the corresponding GEDR status bit to be set.
The following table shows both the rising-edge and falling-edge enable bit locations corresponding
to all 28 port pins. For reserved bits, writes are ignored and reads return zero; a question mark
indicates that the values are unknown at reset.
GRER
Bit
R/W
31
0
30
29
0
28
0
27
26
25
24
23
22
21
20
19
18
17
16
Reserved
RE27 RE26 RE25 RE24 RE23 RE22 RE21 RE20 RE19 RE18 RE17 RE16
Reset
0
?
?
?
?
?
?
?
?
?
?
?
?
Bit
15
14
13
12
11
10
9
RE9
?
8
RE8
?
7
RE7
?
6
RE6
?
5
RE5
?
4
RE4
?
3
RE3
?
2
RE2
?
1
RE1
1
0
RE0
1
R/W RE15 RE14 RE13 RE12 RE11 RE10
Reset
?
?
?
?
?
?
Bit
Name
Description: GPIO Rising-Edge Detect Register (GRER)
{n}
RE{n}
GPIO pin n rising-edge detect (where n = 0 through 27).
0 – Disable rising-edge detect.
1 – Set corresponding GEDR status bit when a rising edge is detected on the GPIO pin.
31.. 28
—
Reserved.
GFER
Reset
Bit
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R/W
Reserved
FE27 FE26 FE25 FE24 FE23 FE22 FE21 FE20 FE19 FE18 FE17 FE16
Reset
0
0
0
0
?
?
?
?
?
?
?
?
?
?
?
?
Bit
15
14
13
12
11
10
9
FE9
?
8
FE8
?
7
FE7
?
6
FE6
?
5
FE5
?
4
FE4
?
3
FE3
?
2
FE2
?
1
FE1
1
0
FE0
1
R/W FE15 FE14 FE13 FE12 FE11 FE10
Reset
?
?
?
?
?
?
Bit
Name
Description: GPIO Falling-Edge Detect Register (GRER)
{n}
FE{n}
GPIO pin n falling-edge detect (where n = 0 through 27).
0 – Disable falling-edge detect.
1 – Set corresponding GEDR status bit when a falling edge is detected on the GPIO pin.
31..28
—
Reserved.
9-6
SA-1100 Developer’s Manual
System Control Module
9.1.1.5
GPIO Edge Detect Status Register (GEDR)
The GPIO edge detect status register (GEDR) contains 28 status bits that correspond to the 28
GPIO port pins. When an edge detect occurs on a pin that matches the type of edge programmed in
the GRER and/or GFER registers, the corresponding status bit is set in GEDR. Once a GEDR bit is
set, the CPU must clear it. GEDR status bits are cleared by writing a one to them. Writing a zero to
a GEDR status bit has no effect.
Each edge detect that sets the corresponding GEDR status bit for GPIO pins 0 – 27 can trigger an
interrupt request. Pins 27 – 11 together form a group that can cause one interrupt request to be
triggered when any one of the GEDR status bits 27 – 11 is set. Each of GPIO pins 10 – 0 causes an
description of the programming of GPIO interrupts. The following table shows a summary of
GEDR; a question mark indicates that the values are unknown at reset.
Bit
R/W
31
0
30
29
0
28
0
27
26
25
24
23
22
21
20
19
18
17
16
Reserved
ED27 ED26 ED25 ED24 ED23 ED22 ED21 ED20 ED19 ED18 ED17 ED16
Reset
0
?
?
?
?
?
?
?
?
?
?
?
?
Bit
15
14
13
12
11
10
9
ED9
?
8
ED8
?
7
ED7
?
6
ED6
?
5
ED5
?
4
ED4
?
3
ED3
?
2
ED2
?
1
ED1
?
0
ED0
?
R/W ED15 ED14 ED13 ED12 ED11 ED10
Reset
?
?
?
?
?
?
Bit
Name
Description
GPIO edge detect status n (where n = 0 through 27).
{n}
ED{n}
0 – No edge detect has occurred on pin as specified in GRER and/or GFER.
1 – Edge detect has occurred on pin as specified in GRER and/or GFER.
31..28
—
Reserved.
SA-1100 Developer’s Manual
9-7
System Control Module
9.1.1.6
GPIO Alternate Function Register (GAFR)
The GPIO alternate function register (GAFR) contains 28 control bits that correspond to the 28
GPIO port pins. When the processor sets a bit in the GAFR, the corresponding GPIO pin is
switched over to that pin’s alternate function. See the following section for details on alternate
functions. This register is cleared to all zeros on all reset conditions.
Bit
R/W
31
0
30
29
0
28
0
27
26
25
24
23
22
21
20
19
18
17
16
Reserved
AF27 AF26 AF25 AF24 AF23 AF22 AF21 AF20 AF19 AF18 AF17 AF16
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
10
9
AF9
0
8
AF8
0
7
AF7
0
6
AF6
0
5
AF5
0
4
AF4
0
3
AF3
0
2
AF2
0
1
AF1
0
0
AF0
0
R/W AF15 AF14 AF13 AF12 AF11 AF10
Reset
0
0
0
0
0
0
Bit
Name
Description
GPIO alternate function bits (where n = 0 through 27).
{n}
AF{n}
A bit set in this register indicates that the corresponding GPIO pin is to be used for its
alternate function. A zero in this register indicates that the corresponding GPIO pin is to
be used for its normal GPIO function.
31..28
—
Reserved.
9-8
SA-1100 Developer’s Manual
System Control Module
9.1.2
GPIO Alternate Functions
Most GPIO pins have an alternate function that can be invoked to enable additional functionality
within the SA-1100. If a GPIO is used for this alternate function, then it cannot be used as a GPIO
at the same time. Pins 0 and 1 are reserved because of their special use during sleep mode and are
not available for any alternate function. The following table shows each GPIO pin and its
corresponding alternate function. For more details on an alternate function, see the section that
corresponds to its name in the Unit column in the table.
Pin
Alternate Function
Direction
Output
Unit
Signal Description
GP<27>
GP<26>
GP<25>
GP<24>
GP<23>
GP<22>
32KHZ_OUT
RCLK_OUT
RTC clock
Clocks
Clocks
RTC
Raw 32.768-kHz oscillator output
Internal clock/2
Output
Output
—
Trimmed 1-Hz clock
—
Reserved
—
TREQB
Input
Input
Test controller
Test controller
TIC request B
TREQA/MBREQ
Either TIC request A or MBREQ
Either TIC acknowledge or
MBGNT
GP<21>
TIC_ACK/MBGNT
Output
Test controller
Serial port 4
GP<21>
GP<20>
GP<19>
GP<18>
GP<17>
GP<16>
GP<15>
GP<14>
GP<13>
GP<12>
GP<11>
GP<10>
MCP_CLK
Input
MCP clock in
UART_SCLK3
SSP_CLK
Input
Serial port 3:UART Sample clock input
Serial port 2:SSP Sample clock input
Input
UART_SCLK1
SDLC_AAF
SDLC_SCLK
UART_RXD
UART_TXD
SSP_SFRM
SSP_SCLK
SSP_RXD
Input
Serial port 1:UART Sample clock input
Serial port 1:SDLC Abort after frame control
Serial port 1:SDLC Geoport clock out
Serial port 1:UART UART receive
Output
I/O
Input
Output
Output
Output
Input
Serial port 1:UART UART transmit
Serial Port 4:SSP
Serial port 4:SSP
Serial port 4:SSP
Serial port 4:SSP
SSP frame clock
SSP serial clock
SSP receive
SSP_TXD
Output
SSP transmit
High-order data pins for
split-screen color LCD support
GP<2..9> LDD<8..15>
Output
LCD controller
GP<1>
GP<0>
Reserved
Reserved
—
—
—
No alternate function
No alternate function
—-
SA-1100 Developer’s Manual
9-9
System Control Module
9.1.3
GPIO Register Locations
The following table shows the registers associated with the GPIO block and the physical addresses
used to access them.
Address
0h 9004 0000
Name
GPLR
Description
GPIO pin-level register
0h 9004 0004
0h 9004 0008
0h 9004 000C
0h 9004 0010
0h 9004 0014
0h 9004 0018
0h 9004 001C
GPDR
GPSR
GPCR
GRER
GFER
GEDR
GAFR
GPIO pin direction register
GPIO pin output set register
GPIO pin output clear register
GPIO rising-edge detect register
GPIO falling-edge detect register
GPIO edge detect status register
GPIO alternate function register
9-10
SA-1100 Developer’s Manual
System Control Module
9.2
Interrupt Controller
The SA-1100 interrupt controller provides masking capability for all interrupt sources and
combines them into their final state, either an FIQ or IRQ processor interrupt. The interrupt
hierarchy of the SA-1100 is a two-level structure.
The first level of the structure, represented by the interrupt controller IRQ pending register (ICIP)
and the interrupt controller FIQ pending register (ICFP) contain the all-enabled and unmasked
interrupt sources. Interrupts are enabled at their source and unmasked in the interrupt controller
mask register (ICMR). The ICIP contains the interrupts that are programmed to generate an IRQ
interrupt. The ICFP contains all valid interrupts that are programmed to generate an FIQ interrupt.
This routing is programmed via the interrupt controller level register (ICLR).
The second level of the interrupt structure is represented by registers contained in the source device
(the device generating the first-level interrupt bit). Second-level interrupt status gives additional
information about the interrupt and is used inside the interrupt service routine. In general, multiple
second-level interrupts are OR’ed to produce a first- level interrupt bit. The enabling of interrupts
is performed inside the source device.
In most cases, the root source of an interrupt can be determined through reading two register
locations: the ICIP or ICFP (depending on which interrupt handler the software is in) to determine
the interrupting device, followed by the status register within that device to find the exact function
needing service. When the SA-1100 is in idle mode (see the Section 9.5, “Power Manager” on
page 9-26), any enabled interrupt causes it to resume operation. The interrupt mask register is
Figure 9-2. Interrupt Controller Block Diagram
All Other Qualified
Interrupt Bits
Interrupt Level
Register
31
31
Interrupt Mask
Register
FIQ
Interrupt
to
Processor
Interrupt Source
Bit
IRQ
Interrupt
to
Interrupt Pending
Register
Processor
IRQ Interrupt
Pending Register
FIQ Interrupt
Pending Register
9.2.1
Interrupt Controller Register Definitions
The interrupt controller contains four registers: the interrupt controller IRQ pending register
(ICIP), the interrupt controller FIQ pending register (ICFP), the interrupt controller mask register
(ICMR), and the interrupt controller level register (ICLR). Following reset, the FIQ and IRQ
interrupts are disabled within the CPU, and the states of all of the interrupt controller’s registers are
unknown and must be initialized by software before interrupts are enabled within the CPU.
SA-1100 Developer’s Manual
9-11
System Control Module
9.2.1.1
Interrupt Controller Pending Register (ICPR)
The ICPR is a 32-bit read-only register that shows all active interrupts in the system. These bits are
not affected by the state of the mask register (ICMR). The following table shows the pending
interrupt source assigned to each bit position in the ICPR. Also included in the table are the source
units for the interrupts and the number of second-level interrupts associated with each. For more
detail on the second-level interrupts, see the section describing that unit.
Bit Position
Unit
Source Module
# of Level 2 Sources
Bit Field Description
IP<31>
IP<30>
IP<29>
IP<28>
IP<27>
IP<26>
IP<25>
IP<24>
IP<23>
IP<22>
IP<21>
IP<20>
IP<19>
IP<18>
IP<17>
IP<16>
IP<15>
IP<14>
IP<13>
IP<12>
IP<11>
IP<10>
IP<9>
1
1
RTC equals alarm register.
One Hz clock TIC occurred.
OS timer equals match register 3.
OS timer equals match register 2.
OS timer equals match register 1.
OS timer equals match register 0.
Channel 5 service request.
Channel 4 service request.
Channel 3 service request.
Channel 2 service request.
Channel 1 service request.
Channel 0 service request.
SSP service request.
Real-time clock
1
System
1
Operating system timer
DMA controller
1
1
3
3
3
3
3
3
Serial port 4b
Serial port 4a
Serial port 3
3
Peripheral
8
MCP service request.
6
UART service request.
Serial port 2
6+6
6
UART/HSSP service request.
UART service request.
Serial port 1b
Serial port 1a
Serial port 0
5
SDLC service request.
6
UDC service request.
LCD controller
General-purpose I/O
12
17
1
LCD controller service request.
“OR” of GPIO edge detects 27-11.
GPIO<10> edge detect.
System
1
GPIO<9> edge detect.
IP<8>
1
GPIO<8> edge detect.
IP<7>
1
GPIO<7> edge detect.
IP<6>
1
GPIO<6> edge detect.
IP<5>
1
GPIO<5> edge detect.
IP<4>
1
GPIO<4> edge detect.
IP<3>
1
GPIO<3> edge detect.
IP<2>
1
GPIO<2> edge detect.
IP<1>
1
GPIO<1> edge detect.
IP<0>
1
GPIO<0> edge detect.
Total level 2 interrupt
sources
110
Several units have more than one source per interrupt signal. When an interrupt is signalled from
one of these units, the interrupt handler routine identifies which interrupt was signalled using the
interrupt controller’s flag register (this identifies the unit that made the request, but not the exact
source). The handler then reads the interrupting unit’s status register to identify which source
within the unit signalled the interrupt. For all interrupts that have one corresponding source, the
interrupt handler routine needs to use only the interrupt controller’s registers to identify the exact
cause of the interrupt.
9-12
SA-1100 Developer’s Manual
System Control Module
9.2.1.2
Interrupt Controller IRQ Pending Register (ICIP) and FIQ Pending
Register (ICFP)
The ICIP and the ICFP contain one flag per interrupt (32 total) that indicates an interrupt request
has been made by a unit. Inside the interrupt service routine, the ICIP and ICFP are read to
determine the interrupt source. In general, software then reads status registers within the
interrupting device to determine how to service the interrupt.
Bits within the ICPR are read only, and represent the logical OR of status bits for a given interrupt
within the source unit. Once an interrupt has been serviced, the handler clears the pending interrupt
at the source by writing a one to the necessary status bit. Clearing the interrupt status bit at the
source automatically clears the corresponding ICIP and ICFP flag provided there are no other
interrupt status bits set within the source unit.
All interrupt source status bits are cleared by writing a one to them. Writing a zero to an interrupt
status bit has no effect. The following table shows the bit locations corresponding to the 32
separate interrupt pending status flags in the ICIP. The next table shows the bit locations
corresponding to the 32 separate interrupt pending status flags in the ICFP. This is a read-only
register.
Bit
Read
Reset
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
IP31
IP30
IP29
IP28
IP27
IP26
IP25
IP24
IP23
IP22
IP21
IP20
IP19
IP18
IP17
IP16
These flags reflect the OR of the reset state of the individual interrupt status bits at the source unit.
Bit
Read
Reset
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
IP15
IP14
IP13
IP12
IP11
IP10
IP9
IP8
IP7
IP6
IP5
IP4
IP3
IP2
IP1
IP0
These flags reflect the OR of the reset state of the individual interrupt status bits at the source unit.
Bit
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Read FP31 FP30 FP29 FP28 FP27 FP26 FP25 FP24 FP23 FP22 FP21 FP20 FP19 FP18 FP17 FP16
Reset
These flags reflect the OR of the reset state of the individual interrupt status bits at the source unit.
Bit
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Read FP15 FP14 FP13 FP12 FP11 FP10
Reset
FP9
FP8
FP7
FP6
FP5
FP4
FP3
FP2
FP1
FP0
These flags reflect the OR of the reset state of the individual interrupt status bits at the source unit.
SA-1100 Developer’s Manual
9-13
System Control Module
9.2.1.3
Interrupt Controller Mask Register (ICMR)
The interrupt controller mask register (ICMR) contains one mask bit per pending interrupt bit (32
total). The mask bits control whether a pending interrupt bit will generate a processor interrupt
(IRQ or FIQ). When a pending interrupt becomes active, it is sent to the CPU only if its
corresponding ICMR mask bit is set to a one. Note that the mask bits are ignored when the
SA-1100 is in idle mode. While in idle, if any interrupt source makes a request, the corresponding
pending bit is set and the interrupt automatically becomes active, regardless of the state of its mask
bit.
Mask bits serve two purposes. First, they allow periodic software polling of interruptible sources
while preventing them from actually causing an interrupt. Second, they allow the interrupt handler
routine to prevent interrupts of lower priority from occurring while still maintaining a list of
pending interrupts that may have occurred previously (or during the servicing of another interrupt).
The ICMR is not initialized at reset; a question mark indicates that the values are unknown at reset.
The following table shows the bit locations corresponding to the 32 separate interrupt mask bits.
Bit
31
30
IM30
?
29
IM29
?
28
IM28
?
27
IM27
?
26
IM26
?
25
IM25
?
24
IM24
?
23
IM23
?
22
IM22
?
21
IM21
?
20
IM20
?
19
IM19
?
18
IM18
?
17
IM17
?
16
IM16
?
R/W IM31
Reset
?
Bit
15
14
IM14
?
13
IM13
?
12
IM12
?
11
IM11
?
10
IM10
?
9
IM9
?
8
IM8
?
7
IM7
?
6
IM6
?
5
IM5
?
4
IM4
?
3
IM3
?
2
IM2
?
1
IM1
?
0
IM0
?
R/W IM15
Reset
?
Bit
{n}
Name
IM{n}
Description
Interrupt mask n (where n = 0 through 31).
0 – Pending interrupt is masked from becoming active (interrupts not sent to CPU, Power
Manager).
1 – Pending interrupt is allowed to become active (interrupt sent to CPU, Power
Manager).
Note: IM bits are ignored during idle mode.
9-14
SA-1100 Developer’s Manual
System Control Module
9.2.1.4
Interrupt Controller Level Register (ICLR)
The interrupt controller level register (ICLR) controls whether a pending interrupt generates an
FIQ or an IRQ CPU interrupt. If a pending interrupt is unmasked, the corresponding ICLR bit field
is decoded to select which CPU interrupt should be asserted. If the interrupt is masked, then the
corresponding bit in the ICLR has no effect. The following table shows the location of all interrupt
level bits in the ICLR; question marks indicate that the values are unknown at reset.
Bit
R/W
31
IL31
?
30
IL30
?
29
IL29
?
28
IL28
?
27
IL27
?
26
IL26
?
25
IL25
?
24
IL24
?
23
IL23
?
22
IL22
?
21
IL21
?
20
IL20
?
19
IL19
?
18
IL18
?
17
IL17
?
16
IL16
?
Reset
Bit
R/W
15
IL15
?
14
IL14
?
13
IL13
?
12
IL12
?
11
IL11
?
10
IL10
?
9
IL9
?
8
IL8
?
7
IL7
?
6
IL6
?
5
IL5
?
4
IL4
?
3
IL3
?
2
IL2
?
1
IL1
?
0
IL0
?
Reset
Bit
Name
IL{n}
Description
{n}
Interrupt level n (where n = 0 through 31).
0 – Interrupt routed to CPU IRQ interrupt input.
1 – Interrupt routed to CPU FIQ interrupt input.
SA-1100 Developer’s Manual
9-15
System Control Module
9.2.1.5
Interrupt Controller Control Register (ICCR)
The interrupt controller control register (ICCR) contains a single control bit, the disable idle mask
bit (DIM). When set, this bit inhibits the idle mode operation where the output of the ICMR is
OR’ed to all ones. If this bit is set, then the interrupts that are capable of bringing the SA-1100 out
of idle mode are defined by the contents of the ICMR. The following table shows the location of all
interrupt level bits in the ICCR.
Bit
R/W
31
0
30
0
29
0
28
0
27
0
26
0
25
0
24
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
Reserved
Reset
0
Bit
R/W
15
0
14
0
13
0
12
0
11
0
10
0
9
8
Reserved
0
7
6
5
4
3
2
1
0
DIM
0
Reset
0
0
0
0
0
0
0
0
Bit
Name
Description
{0}
DIM
Disable idle mask.
0 – All enabled interrupts will bring the SA-1100 out of idle mode.
1 – Only enabled and unmasked (as defined in the ICMR) will bring the SA-1100 out of
idle mode. This bit is cleared during all resets.
1..31
—
Reserved.
9-16
SA-1100 Developer’s Manual
System Control Module
9.2.2
Interrupt Controller Register Locations
The following table shows the registers associated with the interrupt controller block and the
physical addresses used to access them.
Address
0h 9005 0000
Name
ICIP
Description
Interrupt controller IRQ pending register
Interrupt controller mask register
Interrupt controller level register
0h 9005 0004
0h 9005 0008
0h 9005 0010
0h 9005 0020
0h 9005 000C
ICMR
ICLR
ICFP
ICPR
ICCR
Interrupt controller FIQ pending register
Interrupt controller pending register
Interrupt controller control register
9.3
Real-Time Clock
The SA-1100 contains a real-time clock (RTC) that provides a general-purpose real-time reference
for use by the system. The RTC is uninitialized after a hardware reset (nRESET) and must be
written by the user to the desired value. Thereafter, the counter will remain valid until another
hardware reset (assumed to be infrequent). The value of the counter is unaffected by transitions
into and out of sleep, idle, software reset, or a watchdog reset. The counter is incremented on rising
edges of the 1-Hz clock.
In addition to the counter [ RTC counter register (RCNR) ], the RTC incorporates a 32-bit alarm
register (RTAR). The RTAR may be programmed with a value to be compared against the counter.
On each rising edge of the 1-Hz clock, the counter is incremented and then compared to the RTAR.
If the values match, then a status bit is set. This status bit is also routed to the interrupt controller
and may be programmed to generate a CPU interrupt.
Another interruptible status bit is available that is set whenever the 1 Hz clock ticks. Each status bit
may be cleared by writing a one to the status register in the desired bit position. The 1-Hz clock is
generated by dividing down the 32.768-kHz crystal oscillator output. This divider logic is
programmable to allow the user to “trim” the counter to adjust for inherent inaccuracies in the
crystal’s frequency. This trimming mechanism permits the user to adjust the RTC to an accuracy of
+/- 5 seconds per month. The trimming procedure is described later in this section.
9.3.1
RTC Counter Register (RCNR)
The RTC counter register (RCNR) is a read/write register and is not cleared by any reset source.
The counter may be written by the processor at any time although it is recommended that the
operating system prevent inadvertent writes to the RCNR through the use of the MMU protection
mechanisms.
Because of the asynchronous nature of the 1-Hz clock relative to the processor clock, writes to this
counter are controlled by a hardware mechanism that delays the actual write to the counter by up to
one 32-kHz-clock (~ 30 µs) after the processor store is performed.
After the processor writes to the RCNR, all other writes to this register location are ignored until
the new value is actually loaded into the counter. The RCNR may be read at any time. Reads reflect
the value in the counter immediately after it increments or loads.
SA-1100 Developer’s Manual
9-17
System Control Module
9.3.2
RTC Alarm Register (RTAR)
The real-time clock alarm register is a 32-bit register that is readable and writable by the processor.
Following each rising edge of the 1-Hz clock, this register is compared to the RCNR. If the two are
equal and the enable bit is set, then the alarm bit in the RTC status register is set. The value in this
register is undefined after the assertion of nRESET.
9.3.3
RTC Status Register (RTSR)
The following table shows the location of all bits in the RTSR. All reserved bits are read as zeros
and are unaffected by writes; a question mark indicates that the value is unknown at reset. The AL
and HZ bits in this register are routed to the interrupt controller where they may be enabled to
cause an interrupt. The AL and HZ bits are cleared by writing ones to them.
.
Bit
R/W
Reset
0
31
0
30
0
29
0
28
0
27
0
26
0
25
0
24
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
Reserved
0
8
0
Bit
15
0
14
0
13
0
12
0
11
0
10
9
7
6
5
4
3
HZE
?
2
ALE
?
1
HZ
?
0
AL
?
R/W
Reset
Reserved
0
0
0
0
0
0
Bit
Name
Description
0
1
2
3
AL
RTC alarm detected.
0 – No alarm has been detected.
1 – An alarm has been detected (RTNR matches RCAR).
HZ
1-Hz rising-edge detected.
0 – No rising edge has been detected.
1– A rising edge has been detected.
ALE
HZE
—
RTC alarm interrupt enable.
0 – The RTC alarm interrupt is not enabled.
1 – The RTC alarm interrupt is enabled.
1-Hz interrupt enable.
0 – The 1-Hz interrupt is not enabled.
1 – The 1-Hz interrupt is enabled.
31..4
Reserved.
9-18
SA-1100 Developer’s Manual
System Control Module
9.3.4
RTC Trim Register (RTTR)
The RTTR is programmed by the user to select the frequency of the 1-Hz clock. If this register is
not programmed and left at its reset value (all zeros), then the 1-Hz clock will actually be running
at 32.768 kHz. See the following section for details on how to calculate the value in this register.
The following table shows the location of all bits in the RTTR. All reserved bits are read as zeros
and are unaffected by writes.
.
Bit
R/W
Reset
0
31
0
30
0
29
28
0
27
0
26
0
25
D9
0
24
D8
0
23
D7
0
22
D6
0
21
D5
0
20
D4
0
19
D3
0
18
D2
0
17
D1
0
16
D0
0
Reserved
0
Bit
15
C15
0
14
C14
0
13
C13
0
12
C12
0
11
C11
0
10
C10
0
9
C9
0
8
C8
0
7
C7
0
6
C6
0
5
C5
0
4
C4
0
3
C3
0
2
C2
0
1
C1
0
0
C0
0
R/W
Reset
Bit
Name
C0-C15
Description
0..15
Clock divider count.
This value is the integer portion of the clock trim logic.
Trim delete count.
16..25 D0-9
This value represents the number of 32-kHz clocks to delete when clock trimming
begins.
26..31
—
Reserved.
9.3.5
Trim Procedure
The 1-Hz clock feeding the RTC is obtained by dividing the output of the 32.768-kHz oscillator
down. Since 32768 is a power of two, a 15-bit divider will generate a 1-Hz clock (given a perfect
crystal and perfect board environment). The inherent inaccuracies of crystals, aggravated by
varying capacitance of the board connections, and so on, cause the timebase to be somewhat
inaccurate, requiring a periodic adjustment in the 1 Hz clock period. The SA-1100, through the
RTTR, allows the user to adjust or "trim" the 1 Hz timebase to an accuracy of +/- 5 seconds per
month. At reset, the RTTR contains zeros that disable the trim circuitry. When the trim circuitry is
disabled, the 1-Hz clock feeding the RTC is the same frequency as the output of the 32.768-kHz
oscillator. The RTTR is reset to all zeros each time the nRESET signal is asserted.
9.3.5.1
Oscillator Frequency Calibration
To generate the value to be entered into the RTTR, the user must first measure the output frequency
of the 32.768-kHz oscillator using an accurate timebase, such as a frequency counter. This clock is
made externally visible by selecting the alternate function for GPIO<27>. To gain access to the
clock, this pin must be programmed as an output and then switched over to the alternate function.
access to the clock. The trim is accomplished by dividing the output of the oscillator by an integer
value and then doing fine-grain fractional adjustment by periodically deleting clocks from the
stream feeding this integer divider.
SA-1100 Developer’s Manual
9-19
System Control Module
9.3.5.2
RTTR Value Calculations
After the true frequency of the oscillator is known, it must be split into integer and fractional
portions. The integer portion of the value (minus one) is loaded into the C0-C15 field of the RTTR.
This value is compared against a 16-bit counter clocked by the output of the 32.768-kHz oscillator.
The counter resets and generates a pulse when the two values are equal. This pulse constitutes the
raw 1-Hz signal.
The fractional part of the adjustment is done by periodically deleting clocks from the clock stream
feeding the integer counter. The period, called the "trim interval," is hardwired to be 210 -1 seconds
(approximately 17 minutes). The number of clocks deleted, called the "trim delete value," is a
10-bit programmable counter allowing from 0 to 210 -1 32-kHz clocks to be deleted from the input
clock stream once per trim interval. D0-D9 represents the number of clocks deleted per trim
operation. In summary, every 210 -1 seconds, the integer counter stops clocking for a period equal
to the fractional error that has accumulated. If this counter is programmed to a zero (as it is at a
hard reset), then no trim operations will occur and the RTC will be clocked with the raw
32.768-kHz clock. The relationship between the nominal 1-Hz clock frequency and the nominal
32.768-kHz clock (f1 and f32K respectively) is shown in the following equation.
f32k
(2^10-1)*(C<15..0> +1) -D<9..0>
f1=
*
(C<15..0> +1)
(2^10-1)*(C<15..0> +1)
Trim Example #1 – Measured Value Has No Fractional Component
In this example, the oscillator output is measured to be 36045.000 cycles/s (Hz). This output is
exactly 3277 cycles over the nominal frequency of the crystal and has no fractional component. As
such, only the integer trim function is needed and no fractional trim is required. Accordingly, the
C0-C15 field of the RTTR is loaded with the binary equivalent of 36045-1, or 0x8CCC. The
D0-D9 field is left at zero (power-up state) to disable fractional trimming. This trim exercise leaves
an error of zero in trimming.
Trim Example #2 – Measured Value Has a Fractional Component
This example is a more common case in that the measured frequency of the oscillator has a
fractional component. If the oscillator output is measured to be 32768.92 cycles/s (Hz), an integer
trim is necessary so that the average number of cycles counted before generating one 1-Hz clock is
32768.92. Similar to the previous example, the integer field D0-D15 is loaded with the
hexadecimal equivalent of 32768-1 or 0x7FFF.
Because the actual clock frequency is 0.92 cycles per second faster than the integer value, the 1-Hz
clock generated by just the integer trimming is slightly faster than needed and must be slowed
down. Accordingly, the fractional trim must be programmed to delete 0.92 cycles per second on
average to bring the 1-Hz output frequency down to the proper value. Since the trimming
procedure is performed only every 210-1=1023 seconds, the trim must be set to delete (.92*1023)
= 941.16 clocks every 1023 seconds. The fractional component of this value cannot be trimmed
out and constitutes the error in trimming, described below. The counter should be loaded with the
hexadecimal equivalent of 941, or 0x3AD.
9-20
SA-1100 Developer’s Manual
System Control Module
This trim setting leaves an error of .16 cycles per 1023 seconds. The error calculation yields (in
parts-per-million or ppm):
0.16 cycles
1023 sec 32768 cycles
1 sec
Error = --------------------------X------------------------------ = 0 . 0 0 2 p p m
Maximum Error Calculation Versus Real-Time Clock Accuracy
As seen from trim example #2, the maximum possible error approaches 1 clock per 210-1 seconds.
Calculating the ppm error for this scenario yields:
1 cycle
1023 sec 32768 cycles
1 sec
Error (maximum) = --------------------X------------------------------ = 0 . 0 3 p p m
To maintain an accuracy of +/- 5 seconds per month, the required accuracy is calculated to be:
5 sec
1 month
Error = --------------X----------------------------- = 1.9 ppm
month 2592000 sec
This calculation indicates that the accuracy of the SA-1100 trim mechanism is more than adequate
to compensate for the static environmental and manufacturing variables, and still provides
acceptable accuracy.
9.3.6
Real-Time Clock Register Locations
The following table describes the real-time clock registers.
Address
0h 9001 0004
Name
RCNR
Description
RTC count register
RTC alarm register
RTC status register
RTC timer trim register
0h 9001 0000
0h 9001 0010
0h 9001 0008
RTAR
RTSR
RTTR
9.4
Operating System Timer
The SA-1100 contains a 32-bit operating system timer that is clocked by the 3.6864-MHz oscillator.
The operating system count register (OSCR) is a free-running up-counter that is not cleared during
any reset (contains unknown value after reset). The OS timer also contains four 32-bit match registers
(OSMR<3:0>). Each register can be written and read by the user. When the value in the OSCR
matches (is equal to) the value within any of the match registers, and the interrupt enable bit is set, the
corresponding bit in the OSSR is set. These bits are also routed to the interrupt controller where they
can be programmed to cause an interrupt. OSMR<3> also serves as a watchdog match register that
resets the SA-1100 when a match occurs. The only register that is reset to a known state is the
watchdog match enable register (WMER). The user must initialize all other registers and clear any set
status bits before the FIQ and IRQ interrupts are enabled within the CPU.
SA-1100 Developer’s Manual
9-21
System Control Module
9.4.1
9.4.2
OS Timer Count Register (OSCR)
The OS timer count register is a 32-bit counter that increments on rising edges of the 3.6864-MHz
clock. This counter can be read or written at any time. It is recommended that the system
write-protect this register through the MMU protection mechanisms.
OS Timer Match Registers 0–3 (OSMR<0>, OSMR<1>,
OSMR<2>, OSMR<3>)
These registers are 32 bits wide and are readable and writable by the processor. They are compared
against the OSCR following every rising edge of the 3.6864-MHz clock. If any of these registers
match the counter at this time, then the corresponding status bit in the OSSR is set. The status bits
are routed to the interrupt controller where they can be unmasked to cause a CPU interrupt.
OSMR<3> may also serve as a watchdog timer. See the Section 9.4.6, “Watchdog Timer” on
page 9-24 for operation information.
9.4.3
OS Timer Watchdog Match Enable Register (OWER)
The watchdog enable register contains a single control bit (bit 0) that enables the watchdog
function. This bit is set by writing a one to it. It can only be cleared by one of the reset functions
(hardware reset, software reset) and by entering sleep mode. A watchdog reset also clears the
watchdog enable bit. The format of this register follows:
.
Bit
R/W
31
0
30
0
29
0
28
0
27
0
26
0
25
0
24
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
Reserved
Reset
0
Bit
R/W
15
0
14
0
13
0
12
0
11
0
10
0
9
8
Reserved
0
7
6
5
4
3
2
1
0
WME
0
Reset
0
0
0
0
0
0
0
0
Bit
Name
Description
0
WME
Watchdog match enable.
0 – OS timer match register<3> matches cause an interrupt request.
1 – OS timer match register<3> matches cause a reset of the SA-1100.
Note: This is a write-once bit that once written, can only be changed after a hardware
(pin), software (SWR), or sleep mode reset.
31..1
—
Reserved.
9-22
SA-1100 Developer’s Manual
System Control Module
9.4.4
OS Timer Status Register (OSSR)
This status register contains status bits indicating whether a match has occurred on any of the four
match registers. These bits are set when the event occurs (following the rising edge of the
3.6864-MHz clock) and cleared by writing a one to the proper bit position. Writing zeros to this
register has no effect. All reserved bits read as zeros and are unaffected by writes; a question mark
indicates that the value is unknown at reset.
Bit
R/W
31
0
30
0
29
0
28
0
27
0
26
0
25
0
24
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
Reserved
Reset
0
8
0
Bit
R/W
15
0
14
0
13
0
12
0
11
0
10
9
7
6
5
4
3
M3
?
2
M2
?
1
M1
?
0
M0
?
Reserved
Reset
0
0
0
0
0
0
Bit
Name
Description
0
1
2
3
M0
M1
M2
M3
—
Match status channel 0.
0 – OS timer match register<0> has not matched the OS timer counter since the last
clear.
1 – OS timer match register<0> has matched the OS timer counter.
Match status channel 1.
0 – OS timer match register<1> has not matched the OS timer counter since the last
clear.
1 – OS timer match register<1> has matched the OS timer counter.
Match status channel 2.
0 – OS timer match register<2> has not matched the OS timer counter since the last
clear.
1 – OS timer match register<2> has matched the OS timer counter.
Match status channel 3.
0 – OS timer match register<3> has not matched the OS timer counter since the last
clear.
1 – OS timer match register<3> has matched the OS timer counter.
Reserved.
31..4
SA-1100 Developer’s Manual
9-23
System Control Module
9.4.5
OS Timer Interrupt Enable Register (OIER)
This register contains four enable bits indicating whether a match between one of the match
registers and the OS timer counter will set a status bit in the OSSR. Each match register has a
corresponding enable bit. Clearing an enable bit does not clear the corresponding interrupt status
bit if that bit is already set.
Bit
R/W
31
0
30
0
29
0
28
0
27
0
26
0
25
0
24
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
Reserved
Reset
0
8
0
Bit
R/W
15
0
14
0
13
0
12
0
11
0
10
9
7
6
5
4
3
E3
0
2
E2
0
1
E1
0
0
E0
0
Reserved
Reset
0
0
0
0
0
0
Bit
Name
Description
0
1
2
3
E0
E1
E2
E3
—
Interrupt enable channel 0.
This bit is set by software and allows a match between match register 0 and the OS timer
to assert interrupt bit M0 in the OSSR.
Interrupt enable channel 1.
This bit is set by software and allows a match between match register OSMR[1] and the
OS timer to assert interrupt bit M1 in the OSSR.
Interrupt enable channel 2.
This bit is set by software and allows a match between match register OSMR[2] and the
OS timer to assert interrupt bit M2 in the OSSR.
Interrupt enable channel 3.
This bit is set by software and allows a match between match register OSMR[3] and the
OS timer to assert interrupt bit M3 in the OSSR.
31..4
Reserved.
9.4.6
Watchdog Timer
OSMR<3> may also serve as a watchdog compare register. This function is enabled by setting bit 0
in the OWER. When a compare against this register occurs when the watchdog is enabled, reset is
applied to the SA-1100 and most internal states are cleared (with exceptions listed below). Internal
reset is asserted for 256 processor clocks and then removed, allowing the SA-1100 to boot. Units
that do not receive this internal reset are: the power manager, the refresh timer, and the PLL
configuration. Watchdog reset affects the SA-1100 similar to a software reset. See the Section 9.6,
“Reset Controller” on page 9-41 for details on what is affected by each kind of reset. When the
SA-1100 comes out of a watchdog reset, a bit is set in the reset controller status register (RCSR) to
indicate that the event happened.
The following procedure is suggested when using OSMR<3> as a watchdog: each time the
operating system services the register, the current value of the counter is read, and a number is then
added to the value read, corresponding to the amount of time before the next timeout (care must be
taken to account for counter wraparound). This number is then written back to OSMR<3>. The OS
code must repeat this procedure periodically before each match occurs. If the match occurs, the OS
timer will assert a reset.
9-24
SA-1100 Developer’s Manual
System Control Module
9.4.7
OS Timer Register Locations
Table 9-1 shows the registers associated with the OS timer and the physical addresses used to
access them.
Table 9-1.
OS Timer Register Locations
Address
Name
Description
OS timer match registers<3:0>
0h 9000 0000
0h 9000 0004
0h 9000 0008
OSMR<0>
OSMR<1>
OSMR<2>
0h 9000 000C
OSMR<3>
0h 9000 0010
0h 9000 0014
0h 9000 0018
0h 9000 001C
OSCR
OSSR
OWER
OIER
OS timer counter register
OS timer status register
OS timer watchdog enable register
OS timer interrupt enable register
SA-1100 Developer’s Manual
9-25
System Control Module
9.5
Power Manager
The SA-1100 contains power management logic that controls the transition between three different
modes of operation: run, idle, and sleep. These modes are used to reduce processor power
consumption at times when some functions are not needed, or when the system’s power supply is
low or out of regulation. Each of the respective modes is associated with a reduced level of power
consumption. Idle mode is entered via software. Sleep mode is entered either via software or by
asserting one of two input pins that indicate a power supply fault. Idle mode is exited through an
interrupt. Sleep mode is exited through a preprogrammed wake-up condition. Both modes may be
exited in extreme cases via hardware reset. If none of the power management modes is active and
the SA-1100 is out of reset, then it is said to be in run mode.
9.5.1
9.5.2
Run Mode
Run mode is the normal operating mode of the SA-1100: all power supplies are enabled, all clocks
are running, and every on-chip resource is functional. This is the normal state of operation for the
processor while it is executing code. Under usual conditions, the processor enters run mode after
successful power-up and reset of the part.
Idle Mode
Idle mode allows a software application to stop the CPU when not in use, while continuing to
monitor interrupt service requests both on or off-chip. When an interrupt occurs, the CPU is
reactivated. During idle mode, the SCM, PM, and MPCM are each fully operational.
In idle mode, the CPU clock is stopped. Since the SA-1100 is static, all CPU state information is
saved. This allows the part to be switched back to run mode, starting operation exactly where it left
off. During idle mode, all other on-chip resources are active, including: all system unit modules
(real-time clock, operating system timer, interrupt controller, general-purpose I/O, and power
manager); all peripheral unit modules (DMA controller, LCD controller, serial controller 0-4); and
all memory controller resources. The PLL also remains in lock so that the part can be brought out
of idle mode quickly when an interrupt occurs.
9.5.2.1
Entering Idle Mode
Idle mode is entered while in run mode by executing a three instruction sequence consisting of the
privileged on-chip coprocessor 15 instruction ‘disable clock switching’, a load from a
noncacheable memory location (C=B=0), and the privileged on-chip coprocessor 15 instruction
‘wait for interrupt’. This sequence must reside in the first three words of an instruction cache line,
which requires that the linker align the idle mode instruction sequence on an eight word boundary.
Idle mode is entered by following the exact code sequence:
AREA Idle$$Code , CODE, READONLY, ALIGN=5
;Aligned to 8 word boundary
;p15 = coprocessor 15
;r0 = register 0 (contents not used)
;c15 = test, clk, and idle cntl register
;c2 = CRm = 0b0010
mcr p15, 0, r0, c15, c2, 2
ldr r0, <r1>
;2 = OPC_2 = 0b010
;<r1> points to non-cachable mem loc
;c8 = CRm = 0b1000
mcr p15, 0, r0, c15, c8, 2
9-26
SA-1100 Developer’s Manual
System Control Module
9.5.2.2
Exiting Idle Mode
Any enabled interrupt from the system unit or peripheral unit will cause a transition from idle mode
back to run mode. Note that the interrupt controller (ICMR) mask register is ignored during idle
mode, meaning that an interrupt does not need to be unmasked to bring the SA-1100 out of idle.
When an interrupt occurs, the CPU clocks are reactivated, the wait for interrupt instruction is
completed, and run program flow resumes.
A transition from idle to run mode can also occur by asserting the nRESET pin or if OSMR<3> is
configured as a watchdog and a match occurs that causes the assertion of reset. Since the watchdog
timer (if enabled) is functional during idle, care must be taken to set the watchdog match register
far enough in advance to ensure that another interrupt is guaranteed to bring the SA-1100 out of
idle before the watchdog reset occurs. It is recommended that either an RTC alarm or another OS
timer channel be used for this purpose.
When in idle mode, if the BATT_FAULT and/or VDD_FAULT pins are asserted, the SA-1100
enters sleep mode.
9.5.3
Sleep Mode
Sleep mode offers the greatest power savings to the user and consequently the lowest level of
available functionality. In the transition from run or idle to sleep mode, the SA-1100 performs an
orderly shutdown of on-chip activity, applies an internal reset to the processor, and then negates the
PWR_EN pin indicating to the external system that the VDDI (1.5-V supply) should be driven to
zero volts. Internally, this switches off the power to the majority of the processor at this time. (The
VDDX I/O voltage supply must remain powered during sleep.) Running off the 32.768-kHz crystal
oscillator, the sleep state machine watches for a preprogrammed wake-up event to occur, after
which it asserts PWR_EN (to reestablish the VDDI power supply), and steps through an orderly
wake-up sequence. When the power supply and clocks are stable, the power manager brings the
SA-1100 out of reset. Status bits in the reset controller status register (RCSR) may be read to
indicate to software that the reset was due to sleep mode.
9.5.3.1
9.5.3.2
CPU Preparation for Sleep Mode
In preparation for sleep mode, software should initialize the power manager GPIO sleep state
register (PGSR) and the power manager wake-up enable register (PWER). Also, the GPIO
falling-edge detect and GPIO rising-edge detect enable registers (GFER and GRER) should be
written with the appropriate values. The OPDE bit in the power manager configuration register
(PCFR) should also be programmed with the desired value.
Events Causing Entry into Sleep Mode
Sleep mode can be entered in one of two ways: via software or a power supply fault. Entry into
sleep mode via software is accomplished by setting the force sleep bit in the power manager
control register (PMCR). This bit is set by software and cleared by hardware during sleep. When
the SA-1100 wakes up from sleep, this bit is already cleared.
Entry into sleep via a power supply fault is caused by the assertion of either the VDD_FAULT or
BATT_FAULT pins. The VDD_FAULT pin should be used to indicate that the main power supply
is out of regulation. The BATT_FAULT pin should be used to indicate that the battery has been
removed or is low. These pins have identical operation for the purpose of entering sleep mode.
They have different implications during the wake-up sequence as described in the following
section.
SA-1100 Developer’s Manual
9-27
System Control Module
9.5.3.3
The Sleep Shutdown Sequence
The sleep state machine begins the shutdown sequence. This sequence consists of three steps.
• In the first step, the following actions occur:
a. Power manager switches the GPIO output pins to their sleep state. This sleep state is
programmed in advance by loading the power manager GPIO sleep state register (PGSR)
into the GPIO output data register. (See the Section 9.1, “General-Purpose I/O” on
page 9-1.)
b. The DRAMs are placed into self-refresh mode. The memory controller finishes whatever
memory operation might be in progress and then drives the RAS<3:0> and CAS<3:0>
pins low.
c. If the sleep sequence was entered due to the assertion of VDD_FAULT or BATT_FAULT,
the possible wake-up sources are reset from what was programmed by software to their
"fault state". The fault state is to allow a transition only on GP<0> and GP<1> to act as a
wake-up event.
• In the second step of sleep shutdown, the following actions occur:
a. All potential wake-up sources are cleared. This involves clearing all the GPIO edge detect
status bits and clearing the RTC alarm interrupt bit. These bits are cleared to prevent latent
status bits from causing an immediate wake-up. This functionality is provided to cover the
situation of entering sleep due to a power fault because the CPU does not have the ability
to prepare for the entry into sleep.
b. An internal reset is applied to the SA-1100. All units are reset and the RESET_OUT pin is
asserted.
• In the third step of sleep shutdown, the following actions occur:
a. The 3.686-MHz oscillator is stopped. This action is dependent on the state of the
oscillator power-down enable bit (OPDE) in the power manager configuration register
(PCFR). If this bit is set, then the oscillator is stopped during sleep, resulting in greater
power savings. If the bit is cleared (the power-on reset state), then the oscillator continues
to run during sleep and results in a faster wake-up sequence.
b. The PWR_EN pin is negated. The external system must respond to this negation by
disabling the VDDI power supply. In contrast to the SA-110, the SA-1100 systems are not
required to drive VDDI to zero volts in sleep. However, the power supply should be
disabled to prevent power consumption.
Each step in the sleep shutdown sequence takes one cycle of the 32.768-kHz clock
(~30 microseconds).
9.5.3.4
9.5.3.5
During Sleep Mode
During sleep mode, the SA-1100 watches for preprogrammed wake-up events. These events are
either programmed by the CPU prior to setting the force sleep bit or by the power manager when a
fault condition is detected.
The Sleep Wake-Up Sequence
When a valid wake-up event is detected and there is no BATT_FAULT, the SA-1100 begins a
wake-up sequence. If BATT_FAULT is asserted, then the wake-up event is ignored. VDD_FAULT
is always ignored at this time because the VDDI supply is disabled at this time. The wake-up
sequence occurs in three steps.
9-28
SA-1100 Developer’s Manual
System Control Module
• In the first step of the wake-up sequence, the following actions occur:
a. The PWR_EN pin is asserted, indicating that the external supply must apply power on the
VDDI pins.
b. An internal timer begins to time the power ramp. This timer waits for approximately
10 ms.
c. The 3.686-MHz oscillator is enabled for operation if it was originally programmed to be
disabled.
d. If BATT_FAULT is asserted at any time during the sleep wake-up sequence, the power
manager transitions back to sleep mode through the fault state.
• In the second step of the wake-up sequence (after the power ramp timer has expired), the
following actions occur:
a. A second internal timer begins to time the 3.686-MHz oscillator as it begins to ramp up to
speed. This timer waits for 150 ms. If the OPDE bit in the PCFR is zero, then the
oscillator was never disabled and this timer is not used. In this case, the power manager
transitions to the third step directly without waiting for the oscillator timer to complete.
b. If BATT_FAULT or VDD_FAULT is asserted at any time during the oscillator ramp, the
power manager transitions back to sleep mode through the fault state.
• In the third step of the wake-up sequence (after the 3.6864-MHz oscillator is stabilized), the
following actions occur:
a. The SA-1100 internal reset is negated and the CPU begins a normal boot sequence.
b. The RESET_OUT pin is negated, indicating that the SA-1100 is about to perform a fetch
from the reset vector location.
During the fault state entered through the assertion of VDD_FAULT or BATT_FAULT, the
following actions occur:
• All potential wake-up sources are cleared (all GPIO edge detects and the RTC alarm interrupt).
• The power manager wake-up source register (PWER) is loaded with 0x0000 0003 and bits 0
are set. This limits the potential wake-up sources to a rising or falling edge on GP<0> or
GP<1>. This wake-up fault state is provided to prevent spurious events from causing an
unwanted wake-up during a low battery or shorted power supply situation. This fault state
setting of PWER, GRER, and GFER registers is also the default state of the registers after a
hardware reset.
9.5.3.6
Booting After Sleep Mode
When the SA-1100 boots after sleep mode (or at any other time), it must examine the reset
controller status register (RCSR) to determine why it just booted. This register has bits to indicate
sleep reset, software reset, watchdog reset, or hardware reset (assertion of nRESET). See the
Section 9.6, “Reset Controller” on page 9-41 for more details on reset.
Next, software should examine the power manager sleep status register (PSSR) to determine why it
was in sleep. This register has bits to indicate whether a VDD_FAULT, BATT_FAULT, or force
sleep bit has been asserted since the register was last cleared. It is possible for multiple bits to be set
in this register.
SA-1100 Developer’s Manual
9-29
System Control Module
Also, the SA-1100 provides the power manager scratchpad register (PSPR) for saving any general
processor state during sleep. This register may be written by the processor and the contents will
survive sleep mode. The bits in this register are not explicitly used by the SA-1100, but may be
used by software to index into ROM space to retrieve memory controller configuration, for
example.
Note: The nRESET pin must not be asserted during sleep mode if the DRAM contents are to be
preserved. The assertion and subsequent negation of nRESET during sleep mode causes the
SA-1100 to clear the FS bit in the force sleep register, assert PWR_EN, time the PLL lock
sequence, and subsequently negate the internal reset signal. This causes the SA-1100 to perform a
normal boot sequence because all information about the previous sleep state is lost.
9.5.3.7
Reviving the DRAMs from Self-Refresh Mode
Because the DRAMs are placed in self refresh prior to the sleep mode shutdown, their contents are
preserved during sleep. After exiting sleep, software must reconfigure the DRAM control registers,
which lost power during sleep mode, and then take the DRAMs out of self-refresh mode. Clearing
the DRAM hold (DH) bit in the power management status register (PMSR) will cause the
RAS<3:0> and CAS<3:0> pins to return to the negated state (high) in preparation for a DRAM
access.
9.5.4
9.5.5
Notes on Power Supply Sequencing
On the SA-1100, as on the SA-110, it is important that VDDX (3.3 V nominal) power-up occur
before VDDI (1.5 V nominal). One approach to ensuring this sequencing is to power the 1.5-V
supply using the 3.3-V supply. On the SA-1100, a second simple option is available. If the
PWR_EN output is used to enable the 1.5-V supply, the SA-1100 will enforce the required
sequencing by holding PWR_EN deasserted until the 3.3-V supply is sufficiently high.
Assumed Behavior of an SA-1100 System in Sleep Mode
The assumed model of an SA-1100 system in sleep mode is one in which the system is relatively
quiet. In particular, there should be no gratuitous switching on of the SA-1100 input pins. Although
there will be some switching in GPIOs to bring the processor out of sleep and potentially on the
VDD_FAULT and BATT_FAULT pins, the switching is a low-frequency activity and usually
brings the SA-1100 out of sleep mode.
The major concern is for power dissipation in sleep and requirements for the power supplies on the
processor during sleep. The SA-1100 generates these supplies using several on-chip regulators with
limited current capacity. Excessive activity on-chip pins might load these regulators beyond their
capacity and result in droop of the on-chip supplies. One example is that of a component tied to one
of the GPIO pins that constantly transmits to the processor. If the system design indicated that
activity from this detector should not bring the SA-1100 out of sleep, the transitions from this
GPIO might result in switching in the processor that would exceed the sleep current limit. This
concern exists regardless of whether the GPIO is enabled as a wake-up source.
Figure 9-3 shows the three power-related modes of the SA-1100 and the actions that cause
each module within the SA-1100, as well as the status of the power and clock supplies to each unit
during each of the three power-related modes.
9-30
SA-1100 Developer’s Manual
System Control Module
Figure 9-3. Transitions Between Modes of Operation
Power on, nRESET asserted
HARDWARE RESET
nRESET asserted
nRESET asserted
nRESET negated
RUN
Wait for interrupt
instruction
Force sleep bit set, or VDD or
battery fault pins asserted
System or
peripheral unit
interrupt
GPIO or RTC
alarm interrupt
IDLE
SLEEP
VDD or battery fault
pins asserted
CPU clock held low; all
other resources active, wait
for interrupt
Wait for wake-up
event
Table 9-2.
SA-1100 Power and Clock Supply Sources and States During Power-Down Modes
Power Management Mode
Supply Source
Run
Idle
Sleep
Module
Pwr
Clk
Pwr
Clk
Pwr
Clk
Pwr
Clk
CPU
MMUs (I&D)
Write buffer
Read buffer
JTAG
Stopped
VDD
Stopped
3.6864
MHz
Disabled
OS timer
LCD controller
Serial channel 0-4
On
Running
On
Memory and
PCMCIA
control
Running
Real-time clock
Interrupt
Running
controller
On
32.768
kHz
VDDX
Power manager
General-purpose I/O
Pin pads
SA-1100 Developer’s Manual
9-31
System Control Module
9.5.6
Pin Operation in Sleep Mode
The SA-1100 pins are categorized by the following types based on their behavior during sleep mode:
Type 1 – These pins are outputs and are driven low during sleep. These pins hold their state after
sleep mode is exited until the DRAM_control_hold bit in the PSSR is cleared.
Type 2 – These pins are outputs and are normally driven to a one in sleep. To support systems that
power down external devices, these pins can also be tristated in sleep through the use of the
Type 3 – These pins are I/Os. When programmed as outputs, they can be actively held high or low
during sleep. When programmed as inputs, they are actively sampled by the SA-1100.
Type 4 – These pins are I/Os but become inputs during sleep. They can be programmed to hold the pin
state at a zero or can be tristated. The receivers on these pins are disabled during sleep. These pins hold
their state after sleep mode is exited until the peripheral_control_hold bit in the PSSR is cleared.
Type 5 – These pins are outputs and are actively driven during sleep.
Type 6 – These pins are outputs and are tristated during sleep.
Type 7 – These pins are inputs and are actively sampled during sleep.
Type 8 – These pins are inputs and are not observed during sleep; the receiver is disabled.
Type 9 – These pins are analog inputs and outputs, and are always active.
Table 9-3.
Pin State During Step
Pin Name
A<25:0>
Type
Pin Name
nPREG
Type
Pin Name
RXD_2
Type
Pin Name
Type
1
1
4
nRESET_OUT
nTRST
TDI
1
D<31:0>
nCS<3:0>
nOE
1
2
2
2
1
1
2
2
2
2
2
1
L_DD<7:0>
L_FCLK
L_BIAS
TXD_C
RXD_C
SCLK_C
SFRM_C
UDC+
4
4
4
4
4
4
4
4
4
4
4
4
TXD_3
4
4
3
8
9
9
9
9
5
7
7
7
8
RXD_3
8
GP<27:0>
ROM_SEL
PXTAL
TDO
6
nWE
TMS
8
nRAS<3:0>
nCAS<3:0>
nPIOW
TCK
8
PEXTAL
TXTAL
TCK_BYP
TESTCLK
VDD
7
7
nPIOR
TEXTAL
—
—
—
—
—
nPCE<2:1>
nIOIS16
nPWAIT
PSKTSEL
UDC-
PWR_EN
BATT_FAULT
VDD_FAULT
nRESET
VDDX
VSS
TXD_1
RXD_1
TXD_2
VSSX
—
9-32
SA-1100 Developer’s Manual
System Control Module
9.5.7
Power Manager Registers
The power manager is controlled through eight 32-bit registers. The power manager control
register (PMCR) is used to allow software invocation of sleep mode. The sleep status register
(PSSR) contains status bits that indicate why sleep mode was invoked. The power manager
scratchpad register (PSPR) is a general-purpose register used to store processor data during sleep.
The power manager wake-up enable register (PWER) is used to program the desired wake-up
sources in the system. The power manager general configuration register (PCFR) contains bits
used to control various configurable functions within the SA-1100. The power manager PLL
configuration register (PPCR) allows the user to change the PLL operating frequency. The power
manager GPIO sleep state register (PGSR) is used to program the value loaded onto GPIO outputs
when the SA-1100 transitions into sleep mode. The power manager oscillator status register
(POSR) contains a single bit that indicates whether the 32.768-kHz oscillator has stabilized after a
hardware reset.
9.5.7.1
Power Manager Control Register (PMCR)
Sleep mode is invoked by setting the force bit within the power manager control register (PMCR).
The force bit is automatically cleared upon exiting sleep mode or when a hardware reset occurs.
Writing zero to the force bit has no effect. For reserved bits, writes are ignored and reads return
zero. This register should be protected by programming MMU permissions. The following table
shows the PMCR.
Bit
R/W
31
0
30
0
29
0
28
0
27
0
26
0
25
0
24
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
Reserved
Reset
0
Bit
R/W
15
0
14
0
13
0
12
0
11
0
10
0
9
8
Reserved
0
7
6
5
4
3
2
1
0
SF
0
Reset
0
0
0
0
0
0
0
0
Bit
Name
Description
0
SF
Sleep force.
0 - Do not force invocation of sleep mode.
1 - Force invocation of sleep mode.
Note: This bit is cleared on wake-up or a hardware reset.
31..1
—
Reserved.
SA-1100 Developer’s Manual
9-33
System Control Module
9.5.7.2
Power Manager General Configuration Register (PCFR)
The PCFR contains bits used to configure various functions within the SA-1100. The OPDE bit, if
set, allows the 3.6864-MHz oscillator to be disabled during sleep mode. This bit is cleared on the
assertion of nRESET. The FP and FS bits control the state of the PCMCIA control pins and the
static memory control pins during sleep. The following table shows the bit-field definitions for this
register. The FO bit forces the SA-1100 to assume that the 32-kHz oscillator is stable instead of
waiting for the requisite 2–10 seconds using an internal counter. This function is primarily useful
for "warm" hardware resets where the oscillator is already stable when the processor comes out of
reset.
Bit
R/W
31
0
30
0
29
0
28
0
27
0
26
0
25
0
24
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
Reserved
Reset
0
Bit
R/W
15
14
13
12
11
10
9
8
7
6
5
4
3
FO
0
2
FS
0
1
FP
0
0
OPD
E
Reserved
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit
Name
Description
3.6864-MHz oscillator power-down enable.
0
OPDE
0 – Do not stop the oscillator during sleep mode (reset condition).
1 – Stop the 3.6-MHz oscillator during sleep mode.
1
FP
Float PCMCIA controls during sleep mode.
This bit determines whether the PCMCIA control signals are driven to a high (negated)
state during sleep or not driven (floated). A zero indicates that the pins are driven low. A
one indicates that they will be floated. This bit is zero at hardware reset. The PCMCIA
signals affected by this bit are: nPOE, nPWE, nPIOW, nPIOR, nPCE<2:1>, nIOIS16,
and nPWAIT. PSKSEL and nPREG are derived from address signals and assume the
state of the address bus during sleep.
2
3
FS
FO
Float static chip selects during sleep mode.
This bit determines whether the static chip select control signals are driven to a high
during sleep or floated. A zero indicates that the pins are driven low. A one indicates that
they will be floated. The static chip select signals affected by this bit are: nCS<3:0>,
nOE, and nWE. This bit is zero at hardware reset.
Force 32-kHz oscillator enable on.
This bit is used to allow software to force the SA-1100 to use the 32-kHz oscillator for
internal clocking functions instead of waiting for it to stabilize in the normal way. This
function is
useful primarily to attain rapid functionality after a "warm" hardware reset when it is
known that the oscillator is stable. Use of this bit is intended for test purposes and some
customer use in special situations. It should be used with care, however, since setting
this bit when the 32-kHz oscillator is not stable will yield unpredictable results.
31..4
—
Reserved.
9-34
SA-1100 Developer’s Manual
System Control Module
9.5.7.3
Power Manager PLL Configuration Register (PPCR)
The PPCR contains bits used to configure the core operating frequency generated by the PLL. The
frequencies generated through settings in this register. Note that the contents of this register are
preserved during sleep mode and do not need to be re-initialized after a wake-up event. The PPCR
is only cleared upon the assertion of nRESET (hard reset).
Bit
R/W
31
0
30
0
29
0
28
0
27
0
26
0
25
0
24
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
Reserved
Reset
0
Bit
R/W
15
14
13
12
11
10
Reserved
0
9
8
7
6
5
4
3
2
1
0
CCF
4
CCF
3
CCF
2
CCF
1
CCF
0
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit
Name
Description
4-0
CCF<4:0>
Clock speed configuration.
31..5
—
Reserved.
SA-1100 Developer’s Manual
9-35
System Control Module
9.5.7.4
Power Manager Wake-Up Enable Register (PWER)
The following table shows the location of all wake-up interrupt enable bits in the PWER. For a
GPIO to serve as a wake-up source, it must be programmed as an input in the GPDR. When a fault
condition is detected in the VDD_FAULT or BATT_FAULT pins, this register is set to hexadecimal
0000 0003, enabling only GP<1,0> as wake-up sources. This register is also set to this value on
hard reset (nRESET asserted). For reserved bits, writes are ignored and reads return zero.
Bit
31
30
0
29
Reserved
0
28
0
27
26
25
WE25
0
24
23
22
WE22
0
21
20
19
WE19
0
18
17
16
WE16
0
R/W WE31
WE27 WE26
WE24 WE23
WE21 WE20
WE18 WE17
Reset
0
0
0
0
0
0
0
0
0
Bit
15
14
13
12
11
WE11
0
10
WE10
0
9
WE9
0
8
WE8
0
7
WE7
0
6
WE6
0
5
WE5
0
4
WE4
0
3
WE3
0
2
WE2
0
1
WE1
1
0
WE0
1
R/W WE15 WE14 WE13 WE12
Reset
0
0
0
0
Bit
Name
Description
{n}
WE{n}
Sleep wake-up enable n (where n = 0 through 27).
0 – Wake-up due to GPIO<n> edge detect disabled.
1 – Wake-up due to GPIO<n> edge detect enabled.
30..28
31
—
Reserved.
WE31
Sleep wake-up enable 31.
0 – Wake-up due to RTC alarm disabled.
1 – Wake-up due to RTC alarm enabled.
9-36
SA-1100 Developer’s Manual
System Control Module
9.5.7.5
Power Manager Sleep Status Register (PSSR)
PSSR contains five status flags. The software sleep status flag is set when sleep mode is entered as
a result of the force sleep (FS) control bit being set by the CPU. The battery fault status bit is set
any time the BATT_FAULT pin is asserted (even when the SA-1100 is already in sleep mode). The
VDD fault status bit is set only when the assertion of the VDD_FAULT pin causes sleep mode
invocation ( that is, if the force sleep bit is asserted and sleep mode is entered followed by the
assertion of the VDD_FAULT pin, the VDD fault status bit is not set). Hardware (power-on) reset
clears PSSR, but the sleep mode reset, software reset, and watchdog reset do not affect this register.
The peripheral hold and DRAM hold bits indicate that those two interfaces retain the same value as
during sleep until these bits are cleared.
The five status flags are cleared when a one is written to them. Writing zero to any status bit has no
effect. Reserved bits read as zeros and are unaffected by writes. The following table shows the
PSSR.
Bit
R/W
31
0
30
0
29
0
28
0
27
0
26
0
25
0
24
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
Reserved
Reset
0
Bit
R/W
15
14
13
12
11
10
Reserved
0
9
8
7
6
5
4
PH
0
3
DH
0
2
VFS
0
1
BFS
0
0
SWS
0
Reset
0
0
0
0
0
0
0
0
0
0
Bit
Name
Description
0
1
2
SS
Software sleep status.
0 – Chip has not been placed in sleep mode by setting the force sleep (FS) control bit since it
was last cleared by reset or by the CPU.
1– Chip was placed in sleep mode by setting the force sleep (FS) control bit.
Battery fault status.
BFS
VFS
0 – BATT_FAULT pin has not been asserted since it was last cleared by a hardware reset or
by the CPU.
1 – BATT_FAULT pin has been asserted.
VDD fault status.
0 – VDD_FAULT pin has not been asserted since it was last cleared by a hardware reset or
by the CPU.
1 – VDD_FAULT pin was asserted in run or idle mode and caused the chip to enter sleep
mode.
Note: This bit will not be set by the assertion of VDD_FAULT while the SA-1100 is in sleep
mode.
SA-1100 Developer’s Manual
9-37
System Control Module
Bit
Name
Description
3
4
DH
DRAM control hold.
This bit is set upon exit from sleep mode and indicates that the RAS<3:0> and CAS<3:0>
continue to be held low and that the DRAMs are still in self-refresh mode. This bit should be
cleared by the processor (by writing a one to it) after the DRAM interface has been configured
but before any DRAM access is attempted. The RAS and CAS lines are released when this
bit is cleared. This bit is cleared on hardware reset.
PH
Peripheral control hold.
This bit is set upon exit from sleep mode and indicates that the peripheral pins are being held in
their sleep state. This bit should be cleared by the processor (by writing a one to it) after the
peripheral interfaces have been configured but before they are actually used by the processor.
31..5
—
Reserved.
9-38
SA-1100 Developer’s Manual
System Control Module
9.5.7.6
Power Manager Scratch Pad Register (PSPR)
The power manager also contains a 32-bit register to save processor configuration information in
any format the user desires. The power manager scratch pad register (PSPR) is a holding register
that is powered by the VDDx power supply pins and is never reset (only configured via writes).
Any value can be written to it while in run mode. The value remains intact while in sleep mode,
and can be read once sleep mode is exited. The user may use the register value to represent
processor configuration prior to sleep mode invocation. (The 32 bits can represent encoded
configuration information or can act as a pointer to ROM where a configuration table is kept.) The
PSPR is a simple read/write register. See the Section 9.5.8, “Power Manager Register Locations”
on page 9-40 for its physical address.
9.5.7.7
Power Manager GPIO Sleep State Register (PGSR)
The GPIO sleep state register (PGSR) allows the user to select the output state of each GPIO pin
when the SA-1100 goes into sleep mode. When a transition to sleep is required (either through
software or through the assertion of the BATT_FAULT or VDD_FAULT pins), the contents of the
PGSR is loaded into the GPIO output data register. [This register is normally controlled by
software through the GPSR (set) and GPCR (clear) registers]. Only pins already configured as
outputs will reflect the new state; however, all 28 bits of the output register are loaded. After the
SA-1100 reenters the run mode from sleep, these GPIO pins retain their programmed sleep state
until changed by writing ones to the GPSR or GPCR registers; question marks indicate that the
values are unknown at reset. If a pin direction is switched from an input to an output, the last
contents of the register will be driven onto the pin.
Bit
R/W
31
0
30
29
0
28
0
27
26
25
24
23
22
21
20
19
18
17
16
Reserved
SS27 SS26 SS25 SS24 SS23 SS22 SS21 SS20 SS19 SS18 SS17 SS16
Reset
0
?
?
?
?
?
?
?
?
?
?
?
?
Bit
15
14
13
12
11
10
9
SS9
?
8
SS8
?
7
SS7
?
6
SS6
?
5
SS5
?
4
SS4
?
3
SS3
?
2
SS2
?
1
SS1
?
0
SS0
?
R/W SS15 SS14 SS13 SS12 SS11 SS10
Reset
?
?
?
?
?
?
Bit
Name
Description
Sleep state of GPIO n (where n = 0 through 27)
{n}
SS{n}
0 – This pin is driven to a zero during the transition to sleep (if programmed as an
output).
1 – This pin is driven to a one during the transition to sleep (if programmed as an
output).
31..28
—
Reserved
SA-1100 Developer’s Manual
9-39
System Control Module
9.5.7.8
Power Manager Oscillator Status Register (POSR)
The power manager oscillator status register (POSR) is a single-bit, read-only register that contains
a status bit indicating whether the 32.768-kHz oscillator is up to speed after a hardware reset. This
bit is set after the expiration of a timer that is clocked by a ring oscillator. This bit will be set within
2–10 seconds after the negation of nRESET.
Bit
R/W
31
0
30
0
29
0
28
0
27
0
26
0
25
0
24
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
Reserved
Reset
0
Bit
R/W
15
0
14
0
13
0
12
0
11
0
10
0
9
8
Reserved
0
7
6
5
4
3
2
1
0
OOK
0
Reset
0
0
0
0
0
0
0
0
Bit
Name
Description
0
OOK
Oscillator OK.
This bit is cleared on a hardware reset and set after the 32.768-kHz oscillator has
stabilized. This bit is read only.
31..28
—
Reserved.
9.5.8
Power Manager Register Locations
Table 9-4 shows the registers associated with the power manager and the physical addresses used
to access them
.
Table 9-4.
Power Manager Register Locations
Address
0h 9002 0000
Name
PMCR
Description
Power manager control register
0h 9002 0004
0h 9002 0008
0h 9002 000C
0h 9002 0010
0h 9002 0014
0h 9002 0018
0h 9002 001C
PSSR
PSPR
PWER
PCFR
PPCR
PGSR
POSR
Power manager sleep status register
Power manager scratch pad register
Power manager wake-up enable register
Power manager general configuration register
Power manager PLL configuration register
Power manager GPIO sleep state register
Power manager oscillator status register
9-40
SA-1100 Developer’s Manual
System Control Module
9.6
Reset Controller
The reset controller manages the various reset sources within the SA-1100. From a programmer’s
view, it is visible as two registers: one used to invoke software reset and one to read status after
booting to indicate why the processor was reset.
The four types of reset in the SA-1100 include:
• Hardware reset
Hardware reset is invoked when the nRESET pin is asserted and resets all units in the SA-1100
to a known state. Hardware reset is intended to be used for power-up only. Because the
memory controller receives a full reset, all DRAM contents will be lost during hardware reset.
The RESET_OUT pin is asserted during hardware reset.
• Software reset
Software reset is invoked when the software reset (SWR) bit in the RSRR is set by software.
Software reset applies reset to the majority of the SA-1100 as well as causing the assertion of
the RESET_OUT pin. During software reset, the DRAM refresh and configuration are not
cleared. This allows DRAM contents to survive a software reset. After the SWR bit is set, the
SA-1100 stays reset for 256 processor clocks and then is allowed to boot again.
• Watchdog reset
Watchdog reset is invoked when the watchdog enable bit (WE) in the OWER is set and the
OSMR3 matches the OS timer counter. When watchdog reset is invoked, the rest of the reset
sequence is identical to software reset. The watchdog enable bit cannot be cleared under
program control. Only one of the four reset types can clear it.
• Sleep reset
Sleep reset is invoked automatically when the SA-1100 enters sleep mode. During sleep mode,
the majority of the processor loses power and will receive reset prior to the negation of the
PWR_EN pin. Sleep reset does not affect the power manager, RTC, or GPIO wake-up register.
During sleep reset, although the memory controller is in reset, the RAS<3:0> and CAS<3:0>
pins are held in the self-refresh state required by the DRAMs.
After booting from a reset, software can examine the reset controller reset status register (RCSR)
to determine which types of reset caused the reset condition.
SA-1100 Developer’s Manual
9-41
System Control Module
9.6.1
Reset Controller Registers
The reset controller contains two registers, the reset controller software reset register (RSRR) and
the reset controller reset status register (RCSR).
9.6.1.1
Reset Controller Software Reset Register (RSRR)
The reset controller software reset register has a software reset bit, which when set, causes a reset
of the SA-1100. The software reset bit (SWR) is located within the least significant bit of the
write-only reset controller software reset register (RSRR). Writing a one to this bit causes all
on-chip resources to reset but does not cause the PLL to go out of lock. The software reset bit is
self-resetting. It is automatically cleared to zero several system clock cycles after a one is written to
it. Writing zero to the software reset bit has no effect. Care should be taken to restrict access to this
register by programming MMU permissions. For reserved bits, writes have no effect. Reading this
register returns zeros.
The following table shows the RSRR.
Bit
Write
Reset
31
0
30
0
29
0
28
0
27
0
26
0
25
0
24
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
Reserved
0
Bit
Write
Reset
15
0
14
0
13
0
12
0
11
0
10
0
9
8
Reserved
0
7
6
5
4
3
2
1
0
SWR
0
0
0
0
0
0
0
0
0
Bit
Name
Description
0
SWR
Software reset.
0 – Do not invoke a software reset of the chip.
1 – Invoke a software reset of the chip.
Note: This bit is self-resetting, and is automatically cleared several system clock cycles
after it has been set.
31..1
—
Reserved.
9-42
SA-1100 Developer’s Manual
System Control Module
9.6.1.2
Reset Controller Status Register (RCSR)
The reset controller reset status register (RCSR) is used by the CPU to determine the last cause or
causes of the reset. The SA-1100 has four sources of reset:
• Hardware reset
• Software reset
• Watchdog reset
• Sleep mode reset
Each RCSR status bit is set by a different source of reset, and can be cleared by writing a one back to that
bit. Note that the hardware reset state of software, watchdog, and sleep mode reset bits is zero. The table
below shows the status bits within RCSR. For reserved bits, writes are ignored and reads return zero.
Bit
R/W
31
0
30
0
29
0
28
0
27
0
26
0
25
0
24
23
0
22
0
21
0
20
0
19
0
18
0
17
0
16
0
Reserved
Reset
0
8
0
Bit
R/W
15
0
14
0
13
0
12
0
11
0
10
9
7
6
5
4
3
SMR
0
2
1
0
Reserved
WDR SWR HWR
Reset
0
0
0
0
0
0
0
0
1
Bit
Name
Description
0
1
2
3
HWR
SWR
WDR
SMR
Hardware reset.
0 – Hardware reset has not occurred since the last time the CPU cleared this bit.
1 – Hardware reset has occurred since the last time the CPU cleared this bit.
Software reset.
0 – Software reset has not occurred since the last time the CPU cleared this bit.
1 – Software reset has occurred since the last time the CPU cleared this bit.
Watchdog reset.
0 – Watchdog reset has not occurred since the last time the CPU cleared this bit.
1 – Watchdog reset has occurred since the last time the CPU cleared this bit.
Sleep mode reset.
0 – Sleep mode reset has not occurred since the last time the CPU cleared this bit.
1 – Sleep mode reset has occurred since the last time the CPU cleared this bit.
Note: Each status flag can be cleared only by reading a one and then writing a zero to it.
31..4
—
Reserved.
9.6.2
Reset Controller Register Locations
Table 9-5 shows the registers associated with the reset controller and the physical addresses used to
access them.
Table 9-5.
Reset Controller Register Locations
Address
Name
Description
0h 9003 0000
0h 9003 0004
RSRR
RCSR
Reset controller software reset register
Reset controller status register
SA-1100 Developer’s Manual
9-43
Memory and PCMCIA Control Module10
The external memory bus interface for the Intel® StrongARM® SA-1100 Microprocessor
(SA-1100) supports standard fast-page and EDO asynchronous DRAMs, burst and nonburst
ROMs, Flash EPROMs, SRAM, and PCMCIA expansion devices. It is programmable through the
configuration of the memory controller.
Figure 10-1. General Memory Interface Configuration
RAS3
DRAM Bank 3
RAS2
DRAM Bank 2
DRAM Bank 1
DRAM Bank 0
DRAM Memory Interface
Up to 4 banks of Standard, EDO,
or Burst EDO DRAM Memory
(32-bits wide)
RAS1
RAS0
Intel®
StrongARM®*
SA-1100
Memory
Controller
Interface
CAS<3:0>
Data Bus
Buffers
and
Transceivers
Socket 0
Socket 1
PCMCIA Interface
Up to 2-socket support.
Requires some
Address Bus
external buffering
PCMCIA Control
CS0
CS1
CS2
CS3
Static Bank 0
Static Bank 1
Static Bank 2
Static Bank 3
Static Memory Interface
Up to 4 banks of ROM, Flash, SRAM memory
(16-bit or 32-bit wide)**
** NOTE:
SRAM width is required to be 32 bits.
Static bank 0 must be populated by "bootable" memory
Static RAM support is available in nonRAM systems only.
* StrongARM is a registered trademark of ARM Limited..
A6841-01
10.1
Overview of Operation
The SA-1100 memory interface supports three interfaces:
• DRAM Memory Interface
The dynamic memory interface supports four 32-bit wide banks of fast-page or EDO asynchronous
DRAMs. Each bank is allocated 128 Mbyte of the internal memory map. However, the actual size
of each bank is dependent on the particular DRAM configuration used. If multiple banks are
populated, each must be identical in size and configuration. There are 4 bank selects, nRAS<3:0>,
SA-1100 Developer’s Manual
10-1
Memory and PCMCIA Control Module
4 byte selects, nCAS<3:0>, 12 bits of multiplexed row and column addresses, nWE, and nOE. The
SA-1100 performs CAS before RAS refresh (CBR) during normal operation and supports
self-refreshing DRAMs during power-down sleep mode.
• Static Memory Interface
The static memory interface has four chip selects, nCS<3:0>, and 26 bits of byte address, A<25:0>,
for access of up to 64 Mbyte of memory in each of four banks. Each chip select is individually
programmable for selecting nonburst ROM, burst ROM, Flash EPROM, or asynchronous SRAM.
Each may be individually configured to be 16 or 32 bits wide except SRAM, which, if used, must
be 32 bits. nOE is asserted on reads and nWE is asserted on writes. For SRAMs, nCAS<3:0> are
byte selects for both reads and writes. Because the nCAS<3:0> pins are used to control both
SRAM and DRAM, systems with both memory types are not supported.
When the SA-1100 comes out of reset, it begins fetching and executing instructions at address
0x00, which corresponds to memory selected by nCS0. This is where boot ROM is expected to be.
• PCMCIA Interface
The PCMCIA interface provides control signals to support a single PCMCIA card slot with
additional hooks to support two slots. It shares address and data pins with the memory devices. It
uses address lines, A<25:0>, and data lines, D<15:0>. nPREG is actually A<26> and selects
register space (I/O or attribute) versus memory space. nPOE and nPWE are provided for memory
and attribute reads and writes. nPIOR, nPIOW, and nIOIS16 control I/O reads and writes.
nPWAIT allows for extended access times. nPCE1 and nPCE2 are byte select low and high,
respectively. PSKTSEL selects between two card slots.
This interface also supports 32-bit accesses that are outside the PCMCIA specification. There are
several restrictions with respect to the use of this feature that are described later in this chapter.
10-2
SA-1100 Developer’s Manual
Memory and PCMCIA Control Module
10.1.1
Example Memory System
Figure 10-2 shows a system using 1M x 16 DRAMs for a total of 16 Mbyte of DRAM. Two banks
of ROM and two banks of Flash EPROM are shown, each on a 32-bitwide databus. The PCMCIA
interface is not shown.
Figure 10-2. Example Memory Configuration
DRAM
DRAM
DRAM
BANK 2
DRAM
BANK 0
BANK 1
BANK 3
nRAS<3:0>
RAS3
RAS
RAS2
RAS
RAS1
RAS0
RAS
RAS
DRAM
WE
WE
WE
nWE
WE
2 Mbyte
(x16)
nOE
OE
OE
OE
OE
UCAS
LCAS
A11-0 D15-0
UCAS
LCAS
A11-0 D15-0
UCAS
LCAS
A11-0 D15-0
UCAS
LCAS
A11-0 D15-0
D31-16
D31-0
CAS3
CAS2
CAS1
CAS0
RAS
WE
RAS
RAS
WE
RAS
WE
WE
OE
OE
OE
OE
UCAS
LCAS
UCAS
LCAS
A11-0 D15-0
UCAS
LCAS
UCAS
LCAS
A11-0 D15-0
D15-0
A11-0
D15-0
A11-0
D15-0
nCAS<3:0>
A21/DRA11-
A10/DRA0
DRA11-0
A24-2
16-bit ROM
CS3
A25-22,A9-0
nCS<3:0>
CS0
CS2
CS1
CE
WE
OE
A22-0
D15-0
16-bit
ROM
16-bit
16-bit
ROM
CE
OE
CE
CE
16-bit
FLASH
WE FLASH
OE
EPROM
EPROM
OE
A22-0
D15-0
A22-0
A22-0
D15-0
D15-0
D31-16
CE
WE
OE
A22-0
D15-0
16-bit
16-bit
ROM
CE
OE
CE
CE
16-bit
ROM
16-bit
FLASH
WE
OE
FLASH
OE
EPROM
EPROM
A22-0
D15-0
A22-0
A22-0
D15-0
D15-0
D15-0
ROM BANK 0
ROM BANK 1
FLASH BANK 1
FLASH BANK 0
SA-1100 Developer’s Manual
10-3
Memory and PCMCIA Control Module
10.1.2
Types of Memory Accesses
The SA-1100 performs memory accesses for the following operations:
Unbuffered write
Uncached read
Buffered write
Linefetch
Level 1 translation fetch
Level 2 translation fetch
Cache line copyback
Read-lock-write sequence
Internal DMA read
Read buffer fetch
Internal DMA write
SA-1100 will only generate a subset of all possible transactions on the bus. Many of these
transactions may be completed internal to the processor by accessing caches, the read buffer,
on-chip registers, or the memory space that returns zeroes for flushing the cache.
If a memory access is followed by an idle period on the bus, the control signals will return to their
inactive state and the address and data signals will remain at their previous values to avoid
unnecessary bus transitions and eliminating the need for many pull-up resistors.
10.1.3
10.1.4
Reads
Read bursts are generated by DMA requests, read buffer requests, and cache line fills. All cache
line fills are 8 words long. DMA and read buffer requests may be 1, 4, or 8 words long. All other
reads are single accesses.
Data and instruction cache line fills start on an 8-word boundary and will be 8 words long.
Writes
For single access writes, one byte, half-word, or word is written. The write burst sizes are 1, 2, 3, or
4 full words. A write burst size of 8 words may be generated by castouts and all 32 bytes are
written.
For stores to DRAM or SRAM memory spaces, the nCAS<3:0> lines enable a corresponding byte
of the data bus during a write transaction. Flash memory space stores must be the width of the
Flash data bus, either 16 or 32 bits.
10.1.5
Transaction Summary
Table 10-1 lists all the transactions that the SA-1100 can generate. No burst will cross an aligned
32-byte boundary. Note that on a 16-bit bus, the read single operation becomes a two half-word
burst with address bit 1 always starting at 0. Writes to Flash memory space will take place in one
single operation regardless of bus size.
10-4
SA-1100 Developer’s Manual
Memory and PCMCIA Control Module
Table 10-1. SA-1100 Transactions
Starting
Address
Bits <4:2>
Description
Burst
Size
Bus Operation
Read single
Read burst
1
4
Any
Generated by core, DMA, or read buffer request.
Generated by read buffer or DMA request.
0
4
Read burst
Write single
8
1
0
Generated by cacheline fills or read buffer request.
Any
1..4 bytes are written as specified by the byte mask.
Generated by write buffer or DMA request.
Write burst
Write burst
Write burst
Write burst
2
3
4
8
0, 1, 2
4, 5, 6
All 4 bytes of each word are written. Generated by
write buffer or DMA request.
0, 1
4, 5
All 4 bytes of each word are written. Generated by
write buffer or DMA request.
0
4
All 4 bytes of each word are written. Generated by
write buffer or DMA request.
0
Cacheline copyback. All 32 bytes are written.
Generated by write buffer.
10.1.6
10.1.7
Read-Lock-Write
The read-lock-write sequence is generated by an SWP instruction to a noncacheable/nonbufferable
location. Locked access to memory is ensured through internal arbitration of accesses to the
memory controller.
Aborts and Nonexistent Memory
Reads from reserved address locations (as specified in the memory map) will result in a data abort
exception. Writes to reserved address space will have no effect.
Reads and writes from or to nonexistent memory are not detected in hardware. In case no memory
is selected on a read, the value last driven on the data bus is returned.
A single access to a disabled DRAM bank (MDCNFG:DEx=0) will cause a CBR refresh cycle to
all banks. Zeros are returned to the register file on reads and writes are dropped. A burst read
access to a disabled DRAM bank will result in a data abort exception.
SA-1100 Developer’s Manual
10-5
Memory and PCMCIA Control Module
10.2
Memory Configuration Registers
The SA-1100 memory interface is programmed through a set of configuration registers that are
described in the following sections.
Table 10-2 shows the registers associated with the memory interface and the physical addresses
used to access them. All addressing is little endian. These registers are readable and writable only
as full words. They are grouped together within one page and thus all have the same memory
protections.
Table 10-2. Memory Interface Control Registers
Physical Address
0xA000 0000
Symbol
MDCNFG
Register Name
DRAM configuration register
0xA000 0004
0xA000 0008
0xA000 000C
0xA000 0010
0xA000 0014
0xA000 0018
MDCAS0
MDCAS1
MDCAS2
MSC0
DRAM CAS waveform shift register 0
DRAM CAS waveform shift register 1
DRAM CAS waveform shift register 2
Static memory control register 0
Static memory control register 1
Expansion bus configuration register
MSC1
MECR
10-6
SA-1100 Developer’s Manual
Memory and PCMCIA Control Module
10.2.1
DRAM Configuration Register (MDCNFG)
MDCNFG is a read/write register and contains control bits for configuring the DRAM. All DRAM
banks must be implemented with the same type of DRAM devices. Question marks indicate that
the values are unknown at reset.
Bit
31
30
29
DRI12
?
28
DRI11
?
27
DRI10
?
26
25
24
23
22
21
DRI4
?
20
19
18
17
16
Read DRI14 DRI13
DRI9 DRI8 DRI7 DRI6 DRI5
DRI3 DRI2 DRI1 DRI0 TDL1
Reset
?
?
?
?
?
9
?
8
?
7
?
6
?
4
?
3
?
2
?
1
?
0
-
Bit
15
14
13
12
11
10
5
Read TDL0 TRASR3 TRASR2 TRASR1 TRASR0 TRP3 TRP2 TRP1 TRP0 CDB2 DRAC1 DRAC0 DE3 DE2 DE1 DE0
Reset
?
?
?
?
?
?
?
?
?
?
?
?
0
0
0
0
Bit
Name
Description
3..0
DE<3:0>
DRAM enable bank 3-0.
For each DRAM bank, there is an enable bit. Reads or writes to a disabled DRAM
bank trigger a single CBR refresh cycle to all banks. When all banks are disabled,
the refresh counter is disabled.
0 – DRAM bank disabled.
1 – DRAM bank enabled.
These bits are cleared by hardware reset.
DRAM row address bit count.
5..4
DRAC<1:0>
00 – 9 row address bits. (Select this for support of 9x9 and 9x8 DRAMs.)
01 – 10 row address bits. (Select this for support of 10x10, 10x9, and 10x8 DRAMs.)
10 – 11 row address bits. (Select this for support of 11x11, 11x10, 11x9, and 11x8 DRAMs.)
11 – 12 row address bits. (Select this for support of 12x10, 12x9, and 12x8 DRAMs.)
6
CDB2
Clock divide by 2.
0 – CAS waveform shift register (MDCAS0, 1, 2) shifted every CPU clock.
1 – CAS waveform shift register shifted every memory clock. (CPU clock divided by 2.)
10..7
TRP<3:0>
RAS precharge.
Number of memory clocks nRAS deasserted before next assertion. Between any two
DRAM accesses, nRAS is high for TRP+1 or 2 memory cycles (whichever is greater).
Between a DRAM access and a refresh, both nRAS and nCAS are deasserted for
TRP+1 or 2 memory cycles (whichever is greater).
14..11 TRASR<3:0> RAS assertion during CBR.
Number of memory clocks (minus one) nRAS asserted during CAS before RAS
refresh.
16..15 TDL<1:0>
Data input latch after CAS deassertion.
00 – Read data is latched coincident with the deassertion of nCAS.
01 – Read data is latched one CPU clock cycle after the deassertion of nCAS (useful for
EDOs).
10 – 2 clocks later.
11 – 3 clocks later.
SA-1100 Developer’s Manual
10-7
Memory and PCMCIA Control Module
Bit
Name
Description
31..17 DRI<14:0>
DRAM refresh interval.
The number of memory clock cycles (divided by 4) between CAS before RAS (CBR)
refresh cycles. One row is refreshed in each DRAM bank during each CBR refresh
cycle.
The value that must be loaded into this register is calculated as follows:
DRI = Number of cycles/4 = ((Refresh time / rows) - (longest burst access time)) x
Mem clock frequency /4.
The longest burst access time to subtract must also take into consideration access to
ROM or Flash EPROM. (These may be interrupted to service a DRAM refresh cycle
after each 32-bit word. If there is a read on a 16-bit bus, a refresh cycle may be
inserted after 2 read cycles. If there is a read to a 32-bit bus, the refresh waits one
read cycle to be serviced. The DRAM interface inserts CBR refresh cycles between
bursts of up to 8 words. Because the address pins are ignored by the DRAMs during
CBR refresh cycles, PCMCIA transactions may be ongoing during a refresh cycle and
will not be interrupted.)
10-8
SA-1100 Developer’s Manual
Memory and PCMCIA Control Module
10.2.2
DRAM CAS Waveform Shift Registers (MDCAS0, MDCAS1,
MDCAS2)
MDCAS0, MDCAS1, and MDCAS2 are 32-bit read/write registers that contain the nCAS
waveform for a full 8-beat burst read or write to asynchronous DRAM. Each bit represents one
CPU cycle if MDCNFG:CDB2 is 0 and 2 CPU cycles (1 memory clock cycle) if MDCNFG:CDB2
is 1. The least significant bit of MDCAS0 goes out first and is the cycle coincident with the
assertion of nRAS. Bit 1 is one cycle after the assertion of nRAS, and so on. MDCAS1 is
appended after MDCAS0 and MDCAS2 is appended after MDCAS1. A 1 in any field causes
nCAS to be deasserted in that cycle; a 0 causes nCAS to be asserted in that cycle. The memory
controller counts nCAS pulses and deasserts nRAS in the cycle following the deassertion of the
final nCAS pulse of the burst. All eight nCAS pulses must be programmed or the processor will
hang. When MDCNFG:CDB2 is 0, the MDCAS0 must contain 1s in the lower 4 bits and each
transition of nCAS must be a minimum of 2 clocks (nCAS must be asserted for a minimum of
2 CPU clock cycles and deasserted for 2). When MDCNFG:CDB2 is 1, the MDCAS0 must contain
1s in the lower 2 bits and each transition of nCAS must be a minimum of 1 bit. These registers are
unaffected by reset.
SA-1100 Developer’s Manual
10-9
Memory and PCMCIA Control Module
10.2.3
Static Memory Control Registers (MSC1–0)
MSC1 and MSC0 are read/write registers and contain control bits for configuring static memory
selected by nCS<3:0>. Reset forces the values in these registers to the slowest possible nonburst
ROM timing. Timing fields are specified as numbers of memory clock cycles. The memory clock
cycle consists of two CPU cycles. Each register contains two identical fields, for a total of four
identical fields, each corresponding to the chip select, nCS<x>, of the same number. On hardware
reset, the MSC0:SMCNFG0 field is set to 0b 1111 1111 1111 1x00 (binary) where x represents the
inverse of the ROM_SEL pin. All other fields in MSC0 and MSC1 are unaffected by reset;
question marks indicate that the values are unknown at reset.
MSC0 Register Format
Bit
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Read RRR1_2 RRR1_1 RRR1_0 RDN1_4 RDN1_3 RDN1_2 RDN1_1 RDN1_0 RDF1_4 RDF1_3 RDF1_2 RDF1_1 RDF1_0 RBW1 RT1_1 RT1_0
Reset
?
?
?
?
?
?
?
?
9
?
8
?
7
?
6
?
5
?
4
?
3
?
2
?
1
?
0
-
Bit
15
14
13
12
11
10
Read RRR0_2 RRR0_1 RRR0_0 RDN0_4 RDN0_3 RDN0_2 RDN0_1 RDN0_0 RDF0_4 RDF0_3 RDF0_2 RDF0_1 RDF0_0 RBW0 RT0_1 RT0_0
Reset
1
1
1
1
1
1
1
1
1
1
1
1
1
x
0
0
MSC1 Register Format
Bit
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Read RRR3_2 RRR3_1 RRR3_0 RDN3_4 RDN3_3 RDN3_2 RDN3_1 RDN3_0 RDF3_4 RDF3_3 RDF3_2 RDF3_1 RDF3_0 RBW3 RT3_1 RT3_0
Reset
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
-
Bit
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Read RRR2_2 RRR2_1 RRR2_0 RDN2_4 RDN2_3 RDN2_2 RDN2_1 RDN2_0 RDF2_4 RDF2_3 RDF2_2 RDF2_1 RDF2_0 RBW2 RT2_1 RT2_0
Reset
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
Bit
Name
Description
1..0
RTx<1:0>
ROM type.
00 – Nonburst ROM or Flash EPROM.
1
01 – Nonburst ROM or SRAM.
10 – Burst-of-four ROM.
11 – Burst-of-eight ROM.
2
RBWx
ROM bus width.
0 – 32 bits
1 – 16 bits
On reset, the RBW field in SMCNFG0 is loaded with the inverse of the ROM_SEL
pin.
7..3
RDFx<4:0>
ROM delay first access.
Number of memory clock cycles (minus 1) from address to data valid for a nonburst
ROM or the first access of a burst ROM.
For Flash and SRAM, this determines the read access time.
One memory clock cycle is added to this value.
10-10
SA-1100 Developer’s Manual
Memory and PCMCIA Control Module
Bit
Name
Description
12..8
RDNx<4:0>
ROM delay next access.
Number of memory clock cycles (minus 1) from address to data valid for subsequent
accesses of a burst ROM.
For Flash and SRAM, this determines the write pulse width.
One memory clock cycle is added to this value.
15..13 RRRx<2:0>
ROM/SRAM recovery time.
Number of memory clock cycles (divided by 2) from chip select deasserted after a
read to next chip select (of a different memory bank) or nRAS asserted. nCS
negated to nRAS asserted is 2*RRR or 1 cycle (whichever is greater).
For Flash and SRAM, this field will also be used after writes to hold off subsequent
accesses.
This field should be programmed with the maximum of Toff, write pulse high time
(Flash/SRAM), and write recovery before read (Flash).
1
When SMCNFGx:RT=01, accesses to the selected bank will output a byte mask on nCAS<3:0> for both reads and writes. This
option should be selected only when there is no DRAM in the system.
SA-1100 Developer’s Manual
10-11
Memory and PCMCIA Control Module
10.2.4
Expansion Memory (PCMCIA) Configuration Register
(MECR)
MECR is a read/write register that contains control bits for configuring the timing of the PCMCIA
interface. This register is unaffected by reset; question marks indicate that the values are unknown
at reset.
Writes to the reserved fields have no effect and reads return zeros. The programming of each of the
six fields allows the user to individually select the duration of accesses to I/O, common memory,
and attribute memory for each of two PCMCIA card slots. Each field is identical and represents the
number of memory clocks per tick of an internal clock, referred to as BCLK. BCLK clocks the
diagram.
The BCLK_SEL field is designed to allow the user to program the speeds of the PCMCIA memory,
attribute, and I/O accesses. When an access to a PCMCIA address space is detected, the
appropriate BS_xx field is selected based on the memory map. Every (BS_xx + 1) memory clock
cycles, a BCLK tick is generated to advance the PCMCIA state machine. All signals (except
nPWAIT, which is asynchronous) on the PCMCIA bus are driven or sampled relative to this
each BS_xx setting given a processor core frequency of 160 MHz (6.25-ns cycle time).
Note: The BCLK speed for a given setting will change if the processor frequency changes.
Bit
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Read RES BSM2_4 BSM2_3 BSM2_2 BSM2_1 BSN2_0 BSA2_4 BSA2_3 BSA2_2 BSA2_1 BSA2_0 BSIO2_4 BSIO2_3 BSIO2_2 BSIO2_1 BSIO2_0
Reset
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
-
Bit
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Read RES BSM1_4 BSM1_3 BSM1_2 BSM1_1 BSN1_0 BSA1_4 BSA1_3 BSA1_2 BSA1_1 BSA1_0 BSIO1_4 BSIO1_3 BSIO1_2 BSIO1_1 BSIO1_0
Reset
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
Bit
Name
Description
4..0
9..5
BSIO1<4:0>
BSA1<4:0>
Clock count for accesses to PCMCIA card slot 1, I/O space.
Clock count for accesses to PCMCIA card slot 1, attribute space.
14..10 BSM1<4:0>
15
Clock count for accesses to PCMCIA card slot 1, common memory space.
Reserved.
—
20..16 BSIO2<4:0>
25..21 BSA2<4:0>
30..26 BSM2<4:0>
Clock count for accesses to PCMCIA card slot 2, I/O space.
Clock count for accesses to PCMCIA card slot 2, attribute space.
Clock count for accesses to PCMCIA card slot 2, common memory space.
Reserved.
31
—
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Memory and PCMCIA Control Module
Table 10-3. BS_xx Bit Encoding
Bit
4..0
Name
BS_xx
Description
0b00000 – BCLK= 2 processor clocks (clk/2)
0b00001 – BCLK= 4 processor clocks
0b00010 – BCLK= 6 processor clocks
....
0b11101 – BCLK= 60 processor clocks
0b11110 – BCLK= 62 processor clocks
0b11111 – BCLK= 64 processor clocks
Table 10-4. BCLK Speeds for 160-MHz Processor Core Frequency
BCLK_SEL
BCLK Cycle Time–ns
0b00000 – Every 2 processor clocks (clk/2).
0b00001 – Every 4 processor clocks.
0b00010 – Every 6 processor clocks.
0b00011 – Every 8 processor clocks.
...
12.5
25
37.5
50
0b11111 – Every 64 processor clocks.
400
To calculate the recommended BS_xx value for each address space: divide the command width
time (the greater of twIOWR and twIORD, or the greater of twWE and twOE) by processor cycle
time; divide by 2; divide again by 3 (number of BCLKs per command assertion); round up to the
next whole number; and subtract 1. For example, for a processor cycle time of 6.25 ns and an
nIOWR command assertion time of 165 ns, the recommended setting for BS_IO would be
(165 /(2 x 3 x 6.25)) - 1 = 3.4, or 4 after rounding up.
SA-1100 Developer’s Manual
10-13
Memory and PCMCIA Control Module
10.3
Dynamic Interface Operation
This section describes the dynamic memory interface.
10.3.1
DRAM Overview
The dynamic memory interface supports up to four banks of identical size and type dynamic
memory on a 32-bit bus. Initialization software must set up the memory interface configuration
registers with the DRAM size, type, number of row address bits, nCAS waveforms, and timing
parameters. The SA-1100 generates accesses of 1–8 words.
Table 10-5 shows some of the supported DRAM configurations.
Table 10-5. DRAM Memory Size Options
DRAM
Bank Size
Number
Chips /
Bank
MaxMemory
(4 Banks,
32-bit Bus)
Total
Number
of Chips
Row bits x
Col. Bits
Configuration
Chip Size
(Mbyte/Bank)
(Words x Bits)
1 Mbyte
2 Mbyte
2 Mbyte
4 Mbyte
4 Mbyte
8 Mbyte
16 Mbyte
256 K x 16
512 K x 8
512 K x 32
1 M x 4
4 Mbit
2
9 x 9
4 Mbyte
8 Mbyte
8 Mbyte
16 Mbyte
16 Mbyte
32 Mbyte
64 Mbyte
8
4 Mbit
4
1
8
2
4
2
10 x 9
16
4
16Mbit
4 Mbit
10 x 9
10 x 10
32
8
1 M x 16
2 M x 8
16 Mbit
16 Mbit
64 Mbit
10 x 10, 12 x 8
11 x 10, 12 x 9
12 x 10
16
8
4 M x 16
Table 10-6 shows the DRAM row and column address multiplexing. For each row address size specified,
column address sizes of 11, 10, 9, and 8 are supported wherever the row address is larger than or the same
size as the column address (12 rows x 11 columns are not supported). Connecting address lines to the
DRAM chips as shown allows the proper addressing without having to specify the column address size.
.
Table 10-6. DRAM Row/Column Address Multiplexing
Number of Row
Address Bits
(as specified in
MDCNFG:DRAC)
DRAM Address Pins at RAS Time
DRAM Address Pins at CAS Time
DRA10 DRA9 DRA8
IA23 IA22
DRA11
DRA10
DRA9
DRA8-0
DRA11
DRA7-0
12 bits
IA21
IA20
IA20
x
IA19
IA19
IA19
x
IA18-10
IA18-10
IA18-10
IA18-10
x
x
IA9-2
IA9-2
IA9-2
IA9-2
11 bits
DRAM:
x
x
x
x
x
x
IA23
IA22
IA21
x
IA21
IA20
IA19
10 bits
x
x
9 bits
x
DRAx = SA-1100 DRAM interface address pin, A(21:10) = DRA(11:0)
IAx = Internal address bit
Note: At RAS time, all address pins, A(25:0), are driven with the internal address that corresponds to the pin
of the same number. For example, a DRAM with 13 bits of row address can be accommodated by
hooking up the 13th row address line of the DRAM to SA-1100 address pin A22. (MDCNFG:DRAC is
a "don’t care".) The column address, in this case, will be limited to a maximum of 8 bits. In general,
DRAMs that utilize fewer than 8 column address bits can be used, but there will be holes in the memory
map due to no physical memory being addressed by the still significant internal address bit IA9.
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SA-1100 Developer’s Manual
Memory and PCMCIA Control Module
10.3.2
DRAM Timing
The DRAM nCAS timing is generated using shift registers. The rate at which these shift registers
are clocked is determined by MDCNFG:CDB2. The time at which to sample the read data is
programmable to coincide with the deassertion of nCAS or up to 3 CPU cycles later. This method
provides a way to take advantage of the EDO DRAMs while still supporting the fast-page-mode
DRAMs. A full 8-beat burst nCAS waveform is specified, and the memory interface controller
shifts the waveform shift register once every CPU clock cycle if MDCNFG:CDB2=0 and once
every 2 CPU clock cycles if MDCNFG:CDB2=1. The shifting continues until the number of nCAS
pulses have been generated that corresponds to the actual number of data words being accessed.
Registers MDCAS0, MDCAS1, and MDCAS2 contain the nCAS waveform for a full 8-beat burst
access to DRAM. To begin an access, the row address is output on DRA(11:0), which is A(21:10).
One CPU clock later (1/2 memory clock), nRAS is asserted and the nCAS waveform begins and is
shifted with each CPU clock, if MDCNFG:CDB2=0. A 1 in this shift register drives nCAS high
(deasserts) at the rising edge of the CPU clock cycle, and a 0 drives nCAS low (asserts). The
column address for the first beat of data will be valid 1 CPU cycle before nCAS transitions from
deasserted to asserted. During reads, a rising edge is detected on the nCAS waveform and input
data is latched MDCNFG:TDL cycles after the rising edge. The shift register continues to shift
until the number of nCAS pulses equals the burst size of the current transaction. For write
transactions, nRAS will be deasserted on the next rising memory clock edge after the last nCAS
rising edge (either 1 or 2 CPU clock cycles). For read transactions, nRAS will be deasserted on the
rising memory clock cycle edge that occurs either 2 or 3 CPU clock cycles after the input data is
latched. For each additional beat after the first, the column address will be updated coincident with
the deassertion of nCAS, or 1 CPU cycle later. For writes, the write data outputs will follow the
same timing as the column address. nWE and nOE, as appropriate, follow the same timing as
nRAS. After nRAS is deasserted, the timing parameter MDCNFG:TRP is used to determine the
wait before the next assertion of nRAS.
If MDCNFG:CDB2=1, the nCAS waveform will be shifted every memory clock, or every 2 CPU
cycles. The timing of the other signals remains the same relative to the nCAS waveform. For
MDCNFG:CDB2=0, there is a requirement that nCAS high and low times be programmed with a
minimum of 2 bits and the 4 least significant bits in MDCAS0 must be 1. For the
MDCNFG:CDB2=1 case, high and low nCAS pulse times may be 1 bit each and the least significant
2 bits of MDCAS0 must be 1. These requirements are necessary for the internal hardware to properly
generate addresses and write data, and for proper address and data setup times.
SA-1100 Developer’s Manual
10-15
Memory and PCMCIA Control Module
Figure 10-3 shows the rate of the shift registers during DRAM nCAS timing for a single-beat
transaction.
Figure 10-3. DRAM Single-Beat Transactions
CPU Clock
Memory Clock
nRAS
TRP
nCAS
ADDR
ROW
COL
ROW
Reads:
Latch Input Data
nOE
Input Data
DO
Writes:
nWE
Write Data
DO
Contents of DRAM register fields:
time
last
first
MDCAS1 = 11 0001 1000 11000 (binary) MDCAS0 = 0110 0011 0001 1000 1100 0110 0000 0111 (binary)
MDCNFG:TRP = 4 MDCNFG:CDB2 = 1 TDL = 00
A4777-01
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Memory and PCMCIA Control Module
Figure 10-4 shows the rate of the shift registers during DRAM nCAS timing for burst-of-eight
transactions.
Figure 10-4. DRAM Burst-of-Eight Transactions
Memory Clock
TRP
nRAS
nCAS
ADDR
COL
COL+4 COL+8 COL+12 COL+16 COL+20 COL+24
COL+28
ROW
Reads:
nOE
Input Data
D0
D1
D2
D3
D4
D5
D6
D7
Latch Input Data (internal):
Writes:
nWE
Write Data
D0
D1
D2
D3
D4
D5
D6
D7
Contents of DRAM register fields:
time
last
first
MDCAS1 = 11 0001 1000 1100 (binary) MDCAS0 = 0110 0011 0001 1000 1100 0110 0000 0111 (binary)
MDCNFG:TRP = 4 MDCNFG:CDB2 = 1 TDL = 00
A4778-01
Contents of DRAM register fields:
MDCAS1=11 0001 1000 1100(binary)
MDCNFG:TRP=4
time
MDCAS0= 0110 0011 0001 1000 1100 0110 0000 0111(binary)
last
TDL=00
MDCNFG:CDB2=1
first
SA-1100 Developer’s Manual
10-17
Memory and PCMCIA Control Module
10.3.3
DRAM Refresh
The SA-1100 provides support for CAS before RAS (CBR) refresh. When the DRAM interface is
enabled [by setting any of MDCNFG:DE(3-0) and setting MDCNFG:DRI greater than zero], the
refresh counter starts counting up every memory cycle (2 CPU cycles) from 0. When its value
reaches the value in MDCNFG:DRI times 4, the memory controller is notified that a refresh cycle
is due, then the counter is cleared and resumes counting. After the current transaction completes, a
refresh cycle is performed. All four nCAS lines are asserted. Two memory clock cycles later
(4 CPU cycles), the nRAS signals for all enabled banks are asserted and held low for
MDCNFG:TRASR+1 memory clock cycles. After that, all nRAS and nCAS signals are deasserted
and MDCNFG:TRP is used to hold off subsequent DRAM accesses to allow for row precharge
time. Hardware reset clears the refresh counter. Software reset does not affect it.
A read or write to any disabled DRAM bank will cause a refresh cycle to all banks to occur.
Figure 10-5 shows a timing diagram of a CBR refresh cycle.
Figure 10-5. DRAM Refresh Cycle
CPU Clock
Memory Clock
nCAS[3:0]
TRASR+1
nRAS[3:0]
A4779-01
10.3.4
DRAM Self-Refresh in Sleep Mode
The SA-1100 will put the DRAM into the self-refresh state prior to entering sleep mode by
asserting nCAS, then asserting nRAS (just as for a normal CBR refresh cycle), and maintaining
nCAS and nRAS low while power and clocks are turned off.
self-refresh mode. An access to a DRAM bank while the DRAM interface is in self-refresh mode
will have undefined results, but the DRAMs will remain in self-refresh mode.
10.4
Static Memory Interface
The static memory interface is comprised of four chip selects, nCS<3:0>, and are each configurable
for ROM, burst ROM, SRAM, or Flash EPROM. The data bus for each chip select region may be
programmed to be 16 or 32 bits wide, although if SRAM is selected, only a 32-bit bus is supported.
nOE is asserted for all reads. nWE is asserted for Flash and SRAM writes. For SRAM
implementations, nCAS<3:0> signals are used for the byte enables where nCAS<3> corresponds to
the MSB. The SA-1100 supplies 26 bits of byte address (A<25:0>) for access of up to 128 Mbyte per
chip select. A<0> is not used in 16-bitwide bus systems and <1:0> are not used in 32-bitwide
systems.
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SA-1100 Developer’s Manual
Memory and PCMCIA Control Module
The RT fields in the MSCx registers specify the type of memory (burst-of-four ROM, burst-of-eight
ROM, nonburst ROM, Flash, SRAM) and the RBW fields specify the bus width for the memory space
selected by nCS<3:0>. If a 16-bit bus width is specified, transactions take place across data pins
D<15:0>.
10.4.1
ROM Interface Overview
The SA-1100 provides programmable timing for both burst and nonburst ROMs. The RDF field in
MSCx is the latency (in memory clock cycles) for nonburst ROMs and the first data beat of a burst
ROM. RDN is the latency for the burst data beats after the first for burst ROMs. RRR delays the
following access to a different memory space to allow time for the current ROM to tristate the data
bus. This parameter should be programmed with the maximum tOFF value, as specified by the
ROM manufacturer. One memory clock cycle is added to each of these parameters. At power-on
reset, the SMCNFG0 field in the MSC0 register is initialized such that the RDF, RDN, and RRR
fields are set to their maximum values to accommodate the slowest ROMs at initial boot; RT is set
to be nonburst ROM; and RBW0 is loaded with the value of the inverse of the ROM_SEL pin. The
remaining fields in MSC0 and MSC1 are not initialized on power-on reset. MSC0:SMCNFG0 is
selected when the address space corresponding to nCS0 is accessed.
The SA-1100 supports a ROM burst size of 1, 4, or 8 words. A single DRAM CBR refresh cycle
may be inserted between word accesses within a transaction. nCS and nOE are deasserted during
the refresh cycle.
10.4.2
ROM Timing Diagrams and Parameters
SA-1100 Developer’s Manual
10-19
Memory and PCMCIA Control Module
Figure 10-6. Burst-of-Eight ROM Timing Diagram
Memory Clock
nCS0
A[25:5]
RDN+1 RDN+1 RDN+1 RDN+1 RDN+1 RDN+1 RDN+1
RDF+1.5
0
A[4:2]
nOE
1
2
3
4
5
6
7
D0
D1
D2
D4
D5
Input Data
Latch
Input Data
(2*RRR)+1
nCS1
Note: One extra CPU cycle (1/2 memory cycle) is added to the first access after nCS is asserted.
In this example, MSC0:SCNFG0:RDF = 12 (decimal), RDN = 4, RRR = 2.
A4780-01
Note: One extra CPU cycle (1/2 memory cycle) is added to the first access after nCS is as
In this example, MSC0:SCNFG0:RDF=12(decimal), RDN=4, RRR=2.
10-20
SA-1100 Developer’s Manual
Memory and PCMCIA Control Module
Figure 10-7. Eight Beat Burst Read from Burst-of-Four ROM
Memory Clock
nCS0
A[25:5]
A[4]
RDN+1 RDN+1 RDN+1
RDF+1.5
RDN+1 RDN+1 RDN+1
RDF+1
0
1
2
3
0
1
2
3
A[3:2]
nOE
D0
D1
D2
D3
D4
D5
D6
Input Data
Latch
Input Data
(2*RRR)+1
nCS1
A4781-01
Figure 10-8. Nonburst ROM, SRAM, or Flash Read Timing Diagram – Four Data Beats
Memory Clock
(2*RRR)+1
RDF+1.5
nCS0
nCAS[3:0]
(SRAM only)
nOE
RDF+1
A1
RDF+1
A2
RDF+1
A0
A3
D3
A[25:0]
D0
D1
D2
Read
(Input) Data
Latch
Read Data
nCS1
A4782-01
SA-1100 Developer’s Manual
10-21
Memory and PCMCIA Control Module
10.4.3
SRAM Interface Overview
The SA-1100 provides a 32-bit asynchronous SRAM interface that uses the nCAS pins for byte
selects on both reads and writes (nCS<3:0> selects the SRAM bank, nOE is asserted on reads, and
nWE is asserted on writes). Address bits A<25:2> provide addressability of up to 64 Mbyte of
SRAM per bank. Because the nCAS signals are used to access SRAM, a system with both SRAM
and DRAM is not supported.
The timing for a read access is identical to that for a nonburst ROM. (See section 10.4.2 on page
19.) The RDF fields in the MSCx registers are the latency for a read access. The MSCx:RDN field
controls the nWE low time during a write cycle. MSCx:RRR is the time from nCS deassertion after
a read to the start of an access from a different memory bank or after a write to any other memory
access. MSCx:RBW must be set to be a 32-bit bus and MSCx:RT must select SRAM.
10.4.4
SRAM Timing Diagrams and Parameters
are byte selects and are asserted with the same timing as nCS. When nCAS0 is low (asserted),
D<7:0> will be used to transfer data. When nCAS1 is low, D<15:8> is used, and so on. During
writes, all 32 data pins are actively driven by the SA-1100; they are not tristated regardless of the
state of the individual nCAS pins.
Figure 10-9 shows the timing for SRAM writes.
Figure 10-9. SRAM Write Timing Diagram (4–Beat Burst)
CPU Clock
Memory Clock
(2*RRR)+1
tCEH
tAS
nCS0
tAH
A0
tDSWH
A0+4
A0+8
A0+12
A[25:0]
tASW
tDH
tCES
RDN+1
RDN+1
RDN+1
RDN+1
tCES
nWE
nOE
D0
D1
D2
D3
D[31:0]
nCAS[3:0]
A4786-01
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Memory and PCMCIA Control Module
tAS = Address setup to nCS = 1 CPU cycle
tCES = nCS, nCAS setup to nWE = 2 memory clock cycles (4 CPU cycles)
tASW = Address setup to nWE low (asserted) = 1/2 memory cycle (1 CPU cycle)
[For A<25:5>, tASW=5 CPU cycles. For A<4:2>, tASW=1 CPU cycle for subsequent beats in a
burst]
tDSWH = Write data setup to nWE high (deasserted) = 1/2 memory cycle + (RDN+1) memory cycles
tDH = Data hold after nWE high (deasserted) = 1/2 memory cycle (1 CPU cycle)
tCEH = nCS, nCAS held asserted after nWE deasserted = 1 memory clock cycle (2 CPU cycles)
tAH = Address hold after nWE deasserted = 1/2 memory cycle (1 CPU cycle)
nWE high time between burst beats = 1 memory cycle (2 CPU cycles)
10.4.5
FLASH EPROM Interface Overview
The SA-1100 provides an SRAM-like interface for access of Flash EPROM. The RDF fields in the
MSCx registers are the latency for a read access. The RDN field controls the nWE low time during
a write cycle. RRR is the time from nCS deassertion after a read to the start of a read from a
different memory or after a write to another memory access. A single DRAM CBR refresh cycle
may be inserted between words of a burst read from Flash memory. During the refresh cycle, nCS
and nOE will be deasserted.
There are some requirements for writes to Flash memory. Flash memory space must be uncacheable
and unbuffered. Writes must be exactly the width of the populated Flash devices on the data bus (no
byte writes to a 32-bit bus or word writes to a 16-bit bus, and so on). Software is responsible for
partitioning commands and data, and writing them out to Flash in the appropriate sequence.
SA-1100 Developer’s Manual
10-23
Memory and PCMCIA Control Module
10.4.6
FLASH EPROM Timing Diagrams and Parameters
Flash reads have the same timing as nonburst ROMs as shown in the preceding figures.
Figure 10-10 shows the timing for Flash writes.
Figure 10-10. Flash Write Timing Diagram (2 Writes)
Write Command
Write Data
Possible Read or Write
CPU Clock
Memory Clock
(2*RRR)+1
tAS
(2*RRR)+1
tAS
tCEH
tCEH
tAS
nCS0
tASW
A0
tAH
tAH
A[25:0]
tCES
tDSWH
RDN+1
tCES
RDN+1
tCES
nWE
nOE
tDH
D[31:0]
CMD
DATA
A4787-01
tAS = Address setup to nCS = 1 CPU cycle
tCES = nCS setup to nWE = 2 memory clock cycles (4 CPU cycles)
tASW = Address setup to nWE low (asserted) = 2-1/2 memory cycles (5 CPU cycles)
tDSWH = Write data setup to nWE high (deasserted) = 1/2 memory cycle + (RDN+1) memory cycles
tDH = Data hold after nWE high = 1+1/2 memory cycle
tCEH = nCS held asserted after nWE deasserted = 1 memory clock cycle (2 CPU cycles)
tAH = Address hold after nWE deasserted = 1+1/2 memory cycle (3 CPU cycles)
10-24
SA-1100 Developer’s Manual
Memory and PCMCIA Control Module
10.5
General Memory BUS Timing
This section explains the boundary cases between DRAM, static, and refresh operations.
10.5.1
Static Access Followed by a DRAM Access
With a static memory access, nWE is deasserted 1 memory clock cycle prior to the deassertion of
nCS. Then memory control will wait 2*RRR memory clock cycles (or 1, whichever is greater)
before the assertion of nRAS for a DRAM access.
The SA-1100 always drives the data bus except while doing a read cycle (or while the alternate
master mode is active). The delay from nOE asserted to data bus high-Z is approximately 0 ns.
When nOE is deasserted, the data bus drives the same data that was already on the bus.
10.5.2
DRAM Access Followed by a Static Access
After a DRAM read cycle, the memory controller will wait TRP+1 memory cycles (or 2,
whichever is greater) before nCS is asserted for a static memory access. nWE will be asserted 2
memory clock cycles after that for a total of TRP+3 memory clock cycles. For a static memory
write after a DRAM write cycle, nWE will be asserted 3 memory clock cycles after nRAS is
deasserted.
When nOE and nRAS are deasserted at the end of a DRAM ready cycle, the SA-1100 nCS<x> and
nOE may be asserted for a static memory read, at which time the SA-1100 will stop driving in 0 ns.
If the subsequent access is a static memory write, new data will be driven out TRP+1.5 memory
clock cycles after the deassertion of nRAS and nOE. The minimum time between the end of a
DRAM refresh cycle and nWE asserted is 3 memory clock cycles.
10.5.3
DRAM Access Followed by a Refresh Operation
At the end of a DRAM read/write cycle, nCAS will go high 1/2 to 1 memory clock cycles before
nRAS goes high. For a subsequent refresh cycle, nCAS will go high TRP+1 memory clock cycles
after the nRAS goes high. After that, nRAS will go high 2 memory clock cycles. In this case, TRP
is used to hold off nCAS rather than just nRAS. There is no overlap (pipelining) between
successive memory accesses.
SA-1100 Developer’s Manual
10-25
Memory and PCMCIA Control Module
10.6
PCMCIA Overview
The SA-1100 PCMCIA interface provides controls for one PCMCIA card slot with a PSKTSEL
pin for support of a second slot. This 16-bit host interface supports 8- and 16-bit peripherals and
handles common memory, I/O, and attribute memory accesses. The interface does not support the
PCMCIA DMA protocol. The duration of each access is based on an internally generated clock that
the PCMCIA space.
Figure 10-11. PCMCIA Memory Map
Socket 2 Memory Space
Socket 2 Attribute Space
Reserved
0h3C00 0000
0h3800 0000
0h3400 0000
0h3000 0000
0h2C00 0000
0h2800 0000
0h2400 0000
0h2000 0000
Socket 2 I/O Space
Socket 1 Memory Space
Socket 1Attribute Space
Reserved
Socket 1 I/O Space
The PCMCIA memory space is divided into eight partitions, four for each card slot. The four
partitions for each card slot are common memory, I/O, attribute memory, and a reserved space.
Each partition starts on a 64 Mbyte boundary. Pins A<25:0>, nPREG, and PSKTSEL are driven at
the same time. nPCE1 and nPCE2 are driven at address time for memory and attribute accesses.
For I/O accesses, their value depends on the value of nIOIS16 and thus will be valid a finite time
after nIOIS16 is valid.
Common memory accesses assert the nPOE or nPWE control signals and are always 16-bit
accesses with nPCE1 asserted for low byte access and nPCE2 asserted for high byte access. I/O
accesses assert the nIOR or nIOW control signals and use the nIOIS16 input signal to determine
the bus width of the transfer (8 or 16 bit). The SA-1100 uses nPCE2 to indicate to the expansion
device that the upper half of the data bus, D<15:8>, will be used for the transfer and nPCE1 to
indicate that the lower half of the data bus, D<7:0>, will be used. When nPCE2 is low, A<0> is
ignored and an odd byte is transferred across D<15:8>. If nPCE2 is high and nPCE1 is low, then
A<0> is used to determine whether the byte being transferred across D<7:0> is the odd byte or
even byte. Transfers always start assuming a 16-bit bus. After the address is placed on the bus, an
I/O device may respond with nIOIS16 indicating that it can perform the transfer in a single 16-bit
transfer. If nIOIS16 is not asserted within the proper time, the address is assumed to be to two 8-bit
registers and the transfer is completed as two 8-bit transfers on the low byte lane, D<7:0>, with
nPCE2 deasserted, nPCE1 asserted, A<0> =0 for the first 8-bit transfer, and A<0> =1 for the
second 8-bit transfer.
10-26
SA-1100 Developer’s Manual
Memory and PCMCIA Control Module
10.6.1
32-Bit Data Bus Operation
The SA-1100 PCMCIA interface supports the use of a 32-bit data bus. Because the PCMCIA 2.0 is
8- or 16-bit only, the 32-bit operation is outside the scope of the PCMCIA specification. This 32-bit
mode is intended for use as a nonstandard expansion bus for communication with
customer-designed logic. The operation is fairly simple; if a word read or write is performed to
PCMCIA memory space, then the entire 32-bit bus is read or written. Normal PCMCIA operations
should be performed using byte or half-word accesses only. Thirty-two bit accesses should be word
aligned and only to "16-bit" space, as opposed to 8-bit space. Memory and attribute space is 16 bits
by definition. However, I/O space may be 8- or 16-bit depending upon the state of the nIOIS16
input pin. Thirty-two bit accesses to I/O space require that the target assert nIOIS16.
For 32-bit accesses, the only size information present on the bus is the assertion of the nPCE1 and
nPCE2 pins. This is the same information that is present during half-word accesses. As such, there
is no way by looking at the SA-1100 pins to determine whether the access is a half-word or word.
This information can be derived only though a user-defined address decode outside the SA-1100.
The following table shows the operation of the PCMCIA interface and its relation to data width.
Data Bus
Width
1 = 16 Bit
0 = 8 Bit
Access Type
Address (1:0)
Resulting Operation
Word
1
00
Word read or write, nPCE1 and nPCE2 asserted (low).
nIOIS16 must be asserted for I/O space.
1x
Undefined operation.
Undefined operation.
Undefined operation.
x1
0
1
xx
Half-word
x0 (even)
Single half-word access, nPCE1 and nPCE2 asserted
(low). nIOIS16 must be asserted for I/O space.
x1 (odd)
Undefined operation.
0
1
0
x0 (even)
Two-byte accesses, both on the lower byte lane. Even
access first (nPCE1 asserted and nPCE2 negated for
both).
x1 (odd)
Undefined operation.
Byte
x0 (even)
Load or store byte on the lower byte lane (nPCE1
asserted, nPCE2 negated).
x1 (odd)
Load or store byte on the upper byte lane (nPCE1
negated, nPCE2 asserted).
xx (even or odd)
Load or store byte on the low byte lane (nPCE2
negated and nPCE1 asserted).
SA-1100 Developer’s Manual
10-27
Memory and PCMCIA Control Module
10.6.2
External Logic for PCMCIA Implementation
a solution for the voltage-control circuit. These diagrams provide the logical connections necessary
for support of 3 V and 5 V PCMCIA cards as well as hot insertion capability. For dual-voltage
support, level shifting buffers are required for all signals. Hot insertion capability requires that each
socket be electrically isolated from the other. If one or both of these features is not required, then
some of the logic shown in these diagrams may be eliminated.
The pull-ups shown are included for compliance with the PCCARD xxx standard. Low power
systems should remove power from these pull-ups during sleep to avoid unnecessary power
consumption. The CD<2:1> signals have been “ORed” before being provided to the SA-1100. This
signal is then routed into a GPIO pin for interrupt capability. Similarly, RDY/BSY is routed to a
GPIO. The INPACK# signal is not used. In the data bus transceiver control logic, nCE1 should
control the enable for the low byte lane and nCE2 should control the enable for the high byte lane.
10-28
SA-1100 Developer’s Manual
Memory and PCMCIA Control Module
Figure 10-12. PCMCIA External Logic for a Two-Socket Configuration
®
Intel
®*
StrongARM
SA-1100
Socket 0
D<15:0>
D<15:0>
DIR OE#
nCEx
Socket 1
D<15:0>
DIR OE#
nPOE
nPIOR
nCEx
CD1#
CD2#
GPIO<w>
CD1#
CD2#
GPIO<x>
GPIO<y>
RDY/BSY#
GPIO(z)
RDY/BSY#
PSKTSEL
A<25:0>
nPREG
A<25:0>
REG#
A<25:0>
REG#
nPCE<1:2>
nPOE,
CE<1:2>#
OE#
WE#
IOR#
IOW#
6
6
6
nPWE
nPIOW,
nPIOR
CE<1:2>#
OE#
WE#
IOR#
IOW#
WAIT#
nPWAIT
WAIT#
IOIS1616#
nPIOIS16
IOIS1616#
* StrongARM is a registered trademark of ARM Limited.
A6840-01
SA-1100 Developer’s Manual
10-29
Memory and PCMCIA Control Module
Figure 10-13. PCMCIA External Logic for a One-Socket Configuration
Intel®
StrongARM®*
SA-1100
Socket 0
D<15:0>
D<15:0>
DIR OE#
nPOE
nPIOR
nPCEx
CD1#
CD2#
GPIO<y>
GPIO<z>
RDY/BSY#
PSKTSEL
NC
A<25:0>
nPREG
A<25:0>
REG
nPCE<1:2>
nPOE,
CE<1:2>#
OE#
WE#
6
6
nPWE
IOR#
IOW#
nPIOW,
nPIOR
WAIT#
nPWAIT
IOIS1616#
nPIOIS16
* StrongARM is a registered trademark of ARM Limited.
A6844-01
10-30
SA-1100 Developer’s Manual
Memory and PCMCIA Control Module
Figure 10-14. PCMCIA Voltage-Control Logic
Intel®
StrongARM®*
SA-1100
Socket x
2
D<15:0>
BVD 1,2
2
VSS 1,2
EN#
nCS<3>
nOE
Transparent
Latch
VPPEN
Voltage-Control
Circuit
3VEN
5VEN
WR
nWE
* StrongARM is a registered trademark of ARM Limited.
A6845-01
The PCMCIA card voltage may be controlled through a set of discrete registers mapped into a
10.6.3
PCMCIA Interface Timing Diagrams and Parameters
Figure 10-15 shows a 16-bit access to a 16-bit memory or I/O device. The parameter, BS, is
programmed in the MECR register. When common memory is accessed, the MECR:BSM1 or
MECR:BSM2 field is used, depending on whether card socket 0 or 1 is addressed.
MECR:BSIO1(2) is used for I/O accesses and MECR:BSA1(2) is used for access to attribute
SA-1100 Developer’s Manual
10-31
Memory and PCMCIA Control Module
Figure 10-15. PCMCIA Memory or I/O 16-Bit Access
CPU Clock
Memory Clock
BS_xx+1
BCLK
BS_xx+1
A, nPREG,
PSKTSEL
nPCE2, nPCE1
3*(BS_xxL+1)
BS_xx+2
3*(BS_xx+1)
nPWE, nPIOW,
nPOE, or nPIOR
nIOIS16
(for I/O only)
nPWAIT
Latch Read
Data
Read Data
[15:0]
Write Data
[15:0]
BS_xx = 1
A4788-01
10-32
SA-1100 Developer’s Manual
Memory and PCMCIA Control Module
Figure 10-16. PCMCIA I/O 16-Bit Access to 8-Bit Device
CPU Clock
Memory Clock
BS_xx+1
BCLK
A[25:1], nPREG,
PSKTSEL
BS_xx+1
2*(BS_xx+1)
A[0]
nPCE2
nPCE1
3*(BS_xx+1)
3*(BS_xx+1)
BS_xx+2
nPIOR, nPIOW
nIOIS16
nPWAIT
Latch Read
Data
Read Data
Low Byte
High Byte
D[7:0]
Write Data
D[7:0]
Low Byte
High Byte
BS_xx = 1
A4788-01
Timing parameters are in CPU clock cycle units. All are minimums except as noted:
Address access time: 6*(BS_xx+1)
Command (nPOE, nPWE, nPIOR, nPIOW) assertion time: 3*(BS_xx+1)
Address setup to command assert: 3*(BS_xx+1)
Address hold after command deassertion: BS_xx+1
nPWAIT valid after command assertion (max): 2*(BS_xx+1) -1
Chip enable (nPCE1,2) setup to nPOE, nPWE assert: 3*(BS_xx+1)
Chip enable (nPCE1,2) setup to nPIOR, nPIOW assert: 3*(BS_xx+1) - (nIOIS 16 delay from address)
Chip enabled hold from command deassert: BS_xx+1
SA-1100 Developer’s Manual
10-33
Memory and PCMCIA Control Module
10.7
Initialization of the Memory Interface
On power-on reset, the dynamic memory interface is disabled and the static interface for the boot
ROM, connected to nCS0, is configured for the slowest nonburst ROM/Flash EPROM. The
ROM_SEL pin determines the bus size of the boot ROM (nCS0).
Initialization software is responsible for setting up the memory interface configuration registers
before enabling the DRAM interface by setting MDCNFG:DE3-0.
Most DRAMs require a wait period followed by a series of refresh cycles before the first memory
access. The SA-1100 provides a mechanism for software to control these events. When a particular
DRAM bank (bank n, selected by nRAS) is disabled (MDCNFG:DEn=0), a read from any address
in that bank will trigger a CBR refresh cycle for all banks.
10.7.1
Flow of Events After Reset or Exiting Sleep Mode
On power-on reset, the memory controller is in the following state:
nRAS(3:0) = 0xF
nCAS(3:0) = 0xF
nCS(3:0) = 0xF
nOE = 1
nWE = 1
nPIOR = 1
nPIOW = 1
nPOE = 1
nPWE = 1
All DRAM banks disabled (MDCNFG:DE3:0 = 0).
Static interface set to slowest nonburst ROM/Flash timing.
(MSC0:SMCNFG0 field is initialized as follows:
RRR=0xF, RDN=0x1F, RDF=0x1F, RBW = not ROM_SEL, RT=0)
Upon exiting sleep mode, the memory controller is in a state similar to reset, except the nCAS and
nRAS pins remain asserted to ensure that the DRAMs remain in a self-refresh state until the
processor has been configured:
nRAS(3:0) = 0
nCAS(3:0) = 0
nCS(3:0) = 0xF
nOE = 1
nWE = 1
nPIOR = 1
nPIOW = 1
nPOE = 1
nPWE = 1
All DRAM banks disabled (MDCNFG:DE3:0 = 0).
Static interface set to slowest nonburst ROM/Flash timing.
(MSC0:SMCNFG0 field is initialized as follows:
RRR=0xF, RDN=0x1F, RDF=0x1F, RBW = not ROM_SEL, RT=0)
10-34
SA-1100 Developer’s Manual
Memory and PCMCIA Control Module
The following flow should be followed when coming out of reset, whether for sleep or power-up:
• Read boot ROM and write to memory configuration registers, but do not enable DRAM banks.
• If necessary, finish any DRAM power-up wait period (usually about 100 µs).
nCAS and nRAS pins from their self-refresh state.
• If coming out of sleep, wait the DRAM-specific post-self-refresh precharge period before
issuing a new DRAM transaction.
• If power-on reset, perform the number of initialization refreshes required by the specific
DRAM part by reading disabled banks. A read from any disabled bank will refresh all four
banks.
• Enable DRAM banks by setting MDCNFG:DE3:0.
10.8
Alternate Memory Bus Master Mode
The SA-1100 supports the existence of an alternate master on the memory bus. The alternate
master is given control of the memory bus (address, data, RAS, CAS, and static controls) using a
hardware handshake. This handshake is performed through MBREQ and MBGNT, which are
invoked through the alternate functions on GPIO<22> and GPIO<21> respectively. When the
alternate master wants to take control of the memory bus, it asserts MBREQ (GPIO<22>). The
SA-1100 will then complete any pending or in-progress memory operation and any outstanding
DRAM refresh cycle and then assert MBGNT (GPIO<21>). When the alternate master asserts
MBGNT, the SA-1100 will tristate the memory bus pins (A<25:0>, D<31:0>, nCS<3:0>, nOE,
NWE, nRAS<3:0>, nCAS<3:0> ).
During the tristate period, both MBREQ and MBGNT remain high and an external device may take
control of the tristated pins. It is recommended that the external device drive all the pins even if
some are not actually used. This will prevent floating inputs and the crossover current associated
with them. Note that during the tristate period, the SA-1100 is unable to perform DRAM refresh
cycles. The alternate master must assume the responsibility for DRAM integrity during this period.
It is recommended that the system be designed such that the period of alternate mastership is
limited to much less than the refresh period, or that the alternate master implement a refresh
counter making it capable of performing refresh at the proper intervals.
To give up the bus, the alternate master negates MBREQ. The SA-1100 will then negate MBGNT
and begin driving the bus. If the refresh counter inside the SA-1100 requested a refresh cycle
during the alternate master tenure, then that refresh cycle is run first, followed by any other bus
transactions that stalled during that period. This mode is set up by writing to the following
registers:
• GPIO pin direction register to program GIO<21> as an output and GPIO<22> as an input.
• GPIO alternate function register to program GPIO<21> and GPIO<22> to their alternate
function.
• Test unit control register (TUCR) to set bit 10.
SA-1100 Developer’s Manual
10-35
Peripheral Control Module
11
This chapter describes the peripheral control units that are integrated within the Intel®
StrongARM® SA-1100 Microprocessor (SA-1100) and the DMA controller that services them.
The peripheral units include one parallel data port to drive an LCD display, one synchronous serial
port, and four asynchronous serial ports that implement different serial protocol standards. Each
section includes a description of the unit’s operation and the control, data, and status registers used
to configure the unit. The DMA controller acts as the gateway to the peripheral units. It provides
DMA access to these units and control and address decode for programmed I/O accesses between
the processor and registers inside the units. Note that the LCD controller contains its own high
bandwidth DMA controller that is connected to the ARM™ system bus and is used to read pixel
and palette information from the off-chip frame buffer.
11.1
Read/Write Interface
the peripheral control module to the SA-1100 CPU and to the external memory controller. The
DMA connects the ARM system bus to the ARM peripheral bus. The ARM peripheral bus
implements a standard asynchronous protocol that is used by all peripherals designed for ARM
chips. This standard allows a single library of peripherals to be developed for the entire ARM
family of CPUs, providing a means to quickly spin off new chip implementations that contain
different peripheral mixes for target applications. Note that the LCD controller interfaces to the
ARM system bus because its throughput requirement is much higher than that of any other serial
peripheral. Placing the LCD on the ARM system bus allows faster synchronous transfers to be
made between the external frame buffer and the LCD controller. Additionally, the LCD controller
contains its own dual-channel DMA controller to supply frame buffer data to the unit.
Although the ARM peripheral bus supports 32 bits of data, the register size (width) implemented
for each peripheral is equal to the maximum data size that must be coherently read or written by the
CPU and DMA. This minimizes the size of the peripheral while providing the necessary memory
throughput for the unit. Although the peripherals’ register sizes vary, the ARM peripheral bus does
register width, DMA port size, and DMA burst size of each of the six peripherals (and the PPC)
implemented on the SA-1100.
SA-1100 Developer’s Manual
11-1
Peripheral Control Module
Figure 11-1. Peripheral Control Module Block Diagram
ARM™* System Bus
DMA
Controller
ARM™ Peripheral Bus
LCD
Controller
Serial Port 0
UDC
Serial Port 1
SDLC/UART
Serial Port 2
ICP
Serial Port 3
UART
Serial Port 4
MCP/SSP
L_PCLK
L_BIAS
UDC+
UDC-
TXD1
RXD1
TXD2
RXD2
TXD3
RXD3
TXD4
SCLK
* ARM is a trademark of ARM Limited.
A6833-01
Table 11-1.
Peripheral Control Modules’ Register Width and DMA Port Size
Register Width /
DMA Port Size
Peripheral
DMA Burst Size
LCD controller
32
8
4 words
8 bytes
4 bytes
4 bytes
4 bytes
8 bytes
4 bytes
8 bytes
8 bytes
N/A
Serial port 0: UDC
UART
SDLC
UART
HSSP
8
Serial port 1:
8
8
Serial port 2: ICP
Serial port 3: UART
Serial port 4:
8
8
MCP
SSP
16
16
32
Peripheral pin controller (PPC)
11.2
Memory Organization
Several of the serial ports contain more than one serial engine. Each individual engine is
self-contained (no shared logic or registers) and implements a separate serial protocol. Serial ports
1, 2, and 4 each contain two separate serial engines, totalling eight separate serial engines within all
five serial ports. Each of the eight serial engines, including the peripheral pin controller (PPC), has
been allocated a separate 64 Kbyte block on-chip memory space in which its registers reside.
Although the register width of individual units varies, each register is right justified on word
boundaries. All register accesses via the CPU must be performed using word reads and writes. This
chapter includes a summary of individual peripheral registers. See Appendix A, “Register
Summary” for a complete summary of all on-chip registers.
11-2
SA-1100 Developer’s Manual
Peripheral Control Module
Table 11-2 shows the base address for each of the peripheral control units.
Table 11-2. Peripheral Units’ Base Addresses
Peripheral
Serial Protocol
Base Address
LCD Controller
Serial Port 0
0h B010 0000
0h 8000 0000
0h 8001 0000
0h 8002 0000
0h 8003 0000
0h 8004 0000
0h 8005 0000
0h 8006 0000
0h 8007 0000
0h 9006 0000
USB
UART
SDLC
UART
HSSP
UART
MPC
Serial Port 1
Serial Port 2
(ICP)
Serial Port 3
Serial Port 4
SSP
1
Peripheral Pin Controller (PPC)
1 The PPC does not support DMA requests.
SA-1100 Developer’s Manual
11-3
Peripheral Control Module
11.3
Interrupts
Each peripheral unit interfaces to the interrupt controller within the system control module. The
interrupt controller contains a 32-bit interrupt pending register, which when read, informs the user
of all the units on the SA-1100 that are currently generating an unmasked interrupt. Once the user
determines which unit is causing the interrupt, the unit’s status registers can be read to determine
the exact cause of the interrupt. This mechanism provides a two-level approach to identify the
source of any interrupt from the hundreds of possible interrupt sources that exist on the SA-1100.
Each of the peripheral units generate either one or two interrupts that correspond to specific
interrupt pending bits within the interrupt controller. Serial ports 1 and 4 each contain two
independent serial engines. Although each peripheral uses only one set of pins for serial
communication, the user may choose to use both serial engines within serial ports 1 and 4 by
assigning one of the two protocols to communicate off-chip by taking control of GPIO pins.
Because the two engines within serial ports 1 and 4 can operate at the same time, these two units
are assigned two separate interrupt request numbers within the interrupt controller’s pending
Table 11-3. Peripheral Units’ Interrupt Numbers
Interrupt
Number
Peripheral
LCD controller
12
13
14
15
16
17
18
19
Serial port 0: USB
SDLC
Serial port 1:
UART
Serial port 2: ICP
Serial port 3: UART
MCP
Serial port 4:
SSP
11-4
SA-1100 Developer’s Manual
Peripheral Control Module
11.4
Peripheral Pins
Each peripheral has a number of dedicated pins with which to communicate to off-chip devices.
The six peripherals of the SA-1100 use a total of 24 pins: the LCD uses twelve pins; serial port 4
four pins; and serial port 0 through 3 each use two pins. Many applications may not require the use
of all six of the SA-1100’s peripherals. To provide maximum flexibility, the pins associated with
any unused peripheral (except serial port 0) can be used as general-purpose digital input/output
pins that are noninterruptible. When a peripheral is disabled, the peripheral pin controller (PPC)
automatically takes control of the peripheral’s pin direction and pin state. A user can sample input
pin state by reading the PPC pin state register (PPSR) and control the state of an output pin by
writing to it. Pin direction is established by configuring the PPC pin direction register (PPDR).
Table 11-4 shows a list of the pins associated with the peripheral units.
.
Table 11-4. Dedicated Peripheral Pins
Peripheral
GPIO Pin
Function
L_PCLK
L_LCLK
L_FCLK
L_BIAS
LDD<7:0>
UDC+
Pixel clock
Line clock/horizontal sync pulse
Frame clock/vertical sync pulse
A/C bias signal
LCD Controller
Pixel data
Positive differential receiver
Negative differential receiver
Serial transmit data
Serial receive data
Serial transmit data
Serial receive data
Serial transmit data
Serial receive data
Serial transmit data
Serial receive data
Serial clock
Serial port 0: USB
UDC-
TXD_1
RXD_1
TXD_2
RXD_2
TXD_3
RXD_3
TXD_C
RXD_C
SCLK_C
SFRM_
Serial port 1: SDLC/UART
Serial port 2: ICP
Serial port 3: UART
Serial port 4: MPC/SSP
Serial frame clock
SA-1100 Developer’s Manual
11-5
Peripheral Control Module
11.5
Use of the GPIO Pins for Alternate Functions
Each of the SA-1100’s six peripheral units has a number of dedicated pins that can be used to drive
an LCD display, communicate serially with off-chip devices, or be used as general-purpose digital
input/output pins. Each of the peripherals, except serial port 0 and 2, also has programming options
that allow the unit to take over control of one or more GPIO pins from the system control module
to be used for various special functions. Several control bits must be programmed to enable GPIO
use by peripheral units. First, the user must enable the special function either within the peripheral
unit or within the peripheral pin controller (PPC). Second, the user must enable the GPIO pin to
communicate to the peripheral and select the pin’s direction by programming the GPIO alternate
function register (GAFR) and GPIO pin direction register (GPDR), respectively. See Section 9.1,
GPIO pins that can be used for alternate peripheral pin functions.
Table 11-5. Peripheral Unit GPIO Pin Assignment
Peripheral
GPIO Pin
Function
LDD<8> pin for dual-panel color mode.
GPIO<2>
GPIO<3>
GPIO<4>
GPIO<5>
GPIO<6>
GPIO<7>
GPIO<8>
GPIO<9>
LDD<9> pin for dual-panel color mode.
LDD<10> pin for dual-panel color mode.
LDD<11> pin for dual-panel color mode.
LDD<12> pin for dual-panel color mode.
LDD<13> pin for dual-panel color mode.
LDD<14> pin for dual-panel color mode.
LDD<15> pin for dual-panel color mode.
LCD
Controller
Serial port 0:
USB
N/A
None.
GPIO<14> Transmit pin for UART when SDLC and UART both needed.
GPIO<15> Receive pin for UART when SDLC and UART both needed.
GPIO<16> Sample clock input/output to SDLC.
Serial port 1:
SDLC/UART
GPIO<17> Toggle to drive external tristate for SDLC transmit packets.
GPIO<18> Sample clock input to UART.
Serial port 2:
ICP
N/A
None.
Serial port 3:
UART
GPIO<20> Sample clock input to UART.
GPIO<10> Transmit pin for SSP when MCP and SSP both needed.
GPIO<11> Receive pin for SSP when MCP and SSP both needed.
GPIO<12> SCLK pin for SSP when MCP and SSP both needed.
GPIO<13> SFRM pin for SSP when MCP and SSP both needed.
Serial port 4:
MPC/SSP
Clock input pin for SSP to drive the frame and sample rates when other than
GPIO<19>
nonmultiple of 3.6864 MHz needed.
Clock input pin for MCP to drive the frame and sample rates when other than
12 Mbps needed.
GPIO<21>
11-6
SA-1100 Developer’s Manual
Peripheral Control Module
11.6
DMA Controller
The DMA controller consists of six independent DMA channels. Each channel can be configured
to service any of the serial controllers. Two channels are required to service a full-duplex serial
controller. The DMA controller is intended to relieve the processor of the interrupt overhead in
servicing these ports with programmed I/O. If desired, any or all peripherals (except the UDC) may
be serviced with programmed I/O instead of DMA. Each peripheral is capable of requesting
processor service through its own interrupt lines or through a DMA request.
The DMA controller consists of a set of configuration and control registers for each channel and a
common data transfer engine that services the active channel. Channels are serviced in a fixed
priority sequence if the DMA receives multiple requests. Each channel is serviced in increments of
that device’s burst size and delivered in the granularity of that device’s port width (byte or
half-word). The burst size and port width for each device is programmed in the channel registers
and is based on the device’s FIFO depth and bandwidth needs. When multiple channels are actively
executing, each channel is serviced with a burst of data after which the DMA controller may
perform a context switch to another active channel. The DMA controller performs context switches
based on whether a channel is active, whether its target device is currently requesting service (the
FIFO is half-empty), and where that channel lies in the priority scheme.
Data transfers are performed between a device (one of the serial controllers) and memory (ROM,
RAM, Flash, SRAM, or DRAM). DMA transfers to and from PCMCIA space are not permitted.
During a write, a burst of data is read from memory as words into a buffer inside the DMA
controller. That data is then written to the device according to the device’s port width and the state
of the endian bit (E). During a read, data is read from the device according to the device’s port
width and then sent to memory as words. The organization of the bytes inside that word is
determined again by the endian bit (E).
The control registers for each channel include two starting address registers and two transfer count
registers. These registers should be programmed by the system at the start of the transfer. The
registers control two rotating buffers for use during a transfer. These buffers, designated buffer A
and buffer B, can be chained together so that when a transfer to (or from) one buffer completes, the
transfer to (or from) the other begins immediately. By interrogating the status information in the
channel control/status register, the user can safely update the address pointer and transfer count of
the inactive buffer.
11.6.1
DMA Register Definitions
Each DMA channel is supported by six 32-bit registers as part of the DMA controller hardware.
These registers are the DMA device address register (DDARn), DMA control/status register
(DCSRn), DMA buffer A start address (DBSAn), DMA buffer B start address (DBSBn), DMA
buffer A transfer count (DBTAn), and DMA buffer B transfer count (DBTBn). (The n is a value
from 0 to 5 and is the channel number.) A register summary including physical addresses is
provided at the end of this section.
SA-1100 Developer’s Manual
11-7
Peripheral Control Module
11.6.1.1
DMA Device Address Register (DDARn)
The DDARn is a 32-bit read/write register containing channel information regarding the target
device. Writes to this register are blocked if the RUN bit in the DCSRn is one. The following figure
shows the format for this register; question marks indicate that the values are unknown at reset.
.
Bit
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
DA
31
DA
30
DA
29
DA
28
DA
27
DA
26
DA
25
DA
24
DA
23
DA
22
DA
21
DA
20
DA
19
DA
18
DA
17
DA
16
Read
Reset
0
0
0
0
?
?
?
?
?
?
?
?
?
?
?
?
-
Bit
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
DA
15
DA
14
DA
13
DA
12
DA
11
DA
10
DA
9
DA
8
DS
3
DS
2
DS
1
DS
0
DW
BS
E
RW
Read
Reset
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
Bit
Name
Description
0
1
2
3
RW
Device data transfer direction (read/write).
0 = Transfer is a write (memory to device).
1 = Transfer is a read (device to memory).
E
Device endianess.
0 = Byte ordering is little endian.
1 = Byte ordering is big endian.
BS
Device burst size.
0 = Four datums per burst.
1 = Eight datums per burst.
DW
Device datum width.
0 = Datum size is one byte.
1 = Datum size is one half-word.
7..4
DS<3:0>
Device select.
This field is programmed to point to the desired device.
DA<31:8> Device address field.
This field is a partial address of the data port of the device currently being serviced.
31..8
1
1
“Partial” means that certain bits in the address are assumed to be zero. The DA<31:8> field is constructed as follows:
DA<31:28> = Device port address 31:28.
Device port address 27:22 is assumed to be zero.
DA<27:8> = Device port address 21:2.
Device port address 1:0 is assumed to be zero.
11-8
SA-1100 Developer’s Manual
Peripheral Control Module
The value written to the device select DS<3:0> field specifies which DMA request this channel
responds to. The device datum width (DW) field value is fixed for each device type and indicates
whether the device’s data port is one or two bytes wide. If the datum width is programmed
incorrectly for a particular device select, then the results are unpredictable.
The device burst size (BS) field value is fixed for each device type. It indicates how many beats of
the datum width are transferred each time the device requests service. This value is chosen based
on the FIFO size of the particular device. If the burst size is programmed incorrectly for a particular
device select, then the results are unpredictable.
The device endianess E field value indicates the byte ordering within a word when data is read
from or written to memory. If the E bit is zero, then memory is assumed to be little endian. If the bit
is one, then memory is assumed to be big endian. The following figure shows big and little endian
DMA transfers.
Figure 11-2. Big and Little Endian DMA Transfers
Big Endian DMA Transfers
D<31> D<0>
Little Endian DMA Transfers
D<31>
3
D<0>
3
2
1
0
2
1
0
from memory
from memory
DMA
Controller
DMA
Controller
0
3
2
1
0
3
0
1
2
3
3
1
2
0
1
0
2
3
1
2
0
3
2
0
1
2
3
2
1
0
3
1
From
To
To From
From
To
To From
Half-word wide
Device
Byte-wide
Device
Half-word wide
Device
Byte-wide
Device
A6893-01
The device transfer direction (RW) field indicates the direction of the transfer. A zero indicates that
the transfer is a write (with respect to the device) and that the flow of data will be from memory to
the device. If the RW field is programmed to a one, then the transfer is a read and the flow of data
will be from the device to memory. The transfer direction is fixed for each device type. If the burst
size is programmed incorrectly for a particular device select, then the results are unpredictable.
SA-1100 Developer’s Manual
11-9
Peripheral Control Module
Table 11-6.
Valid Settings for the DDARn Register
DDAR Fields
DS<3:0> DW
Device
Address
Unit Name
Function
DA<31:8>
BS
E
RW
UDC transmit
UDC receive
SDLC transmit
SDLC receive
UART transmit
UART receive
0x 8000 0028
0x 8000 0028
0x 8002 0078
0x 8002 0078
0x 8001 0014
0x 8001 0014
0x 8004 006C
0x 8004 006C
0x80000A
0x80000A
0x80801E
0x80801E
0x804005
0x804005
0x801001B
0x801001B
0x80C005
0x80C005
0x814005
0x814005
0x818002
0000
0001
0010
0011
0100
0101
0110
0111
0110
0111
1000
1001
1010
0
1
1
0
0
0
0
1
1
0
0
0
0
0
0/1
0
Serial port 0
0
0
0
0
0
0
0
0
0
0
0
1
0/1
0/1
0/1
0/1
0/1
0/1
0/1
0/1
0/1
0/1
0/1
0/1
1
0
1
0
1
0
1
0
1
0
1
0
Serial port 1
Serial port 2 HSSP transmit
HSSP receive
UART transmit 0x 8003 0014
UART receive 0x 8003 0014
Serial port 3 UART transmit 0x 8005 0014
UART receive
0x 8005 0014
0x 8006 0008
Serial port 4 MCP transmit
(audio)
MCP receive
(audio)
0x 8006 0008
0x 8006 000C
0x 8006 000C
0x818002
0x818003
0x818003
1011
1100
1101
1
1
1
0
0
0
0/1
0/1
0/1
1
0
1
MCP transmit
(telecom)
MCP receive
(telecom)
SSP transmit
SSP receive
0x 8007 006C
0x 8007 006C
0x81C01B
0x81C01B
1110
1111
1
1
0
0
0/1
0/1
0
1
11-10
SA-1100 Developer’s Manual
Peripheral Control Module
11.6.1.2
DMA Control/Status Register (DCSRn)
The DCSRn is a 32-bit read/write register that contains control and status bits for the channel. The
following figure shows the format for this register; question marks indicate that the values are
unknown at reset.
Bit
Read
Reset
-
31
30
0
29
0
28
0
27
0
26
0
25
0
24
23
0
22
0
21
0
20
0
19
0
18
0
17
?0
16
0
Reserved
0
-
0
Bit
15
14
13
12
11
10
9
8
7
BIU
?
6
5
4
3
2
1
IE
?
0
RUN
?
STR
TB
DON
EB
STR
TA
DON
EA
ERR
OR
Read
Reset
Reserved
?
?
?
?
?
?
?
?
?
?
?
?
?
Bit
Name
Description
0
RUN
Run bit.
This is a control bit and is set by the user to indicate that the device address register has
been loaded. No transfer will occur on this channel unless this bit is set. Clearing the RUN
bit on an active channel acts as a pause to that channel. Operation can then be resumed
by again setting the RUN bit.
1
2
3
IE
Interrupt enable.
This bit enables interrupts to be passed onto the interrupt controller. An interrupt is the
“OR” of the DONEA, DONEB, and ERROR bits.
ERROR Transfer error bit.
ERROR is a status bit and is set to indicate that a memory error has occurred. It can generate
an interrupt if the IE bit is set. ERROR is cleared by software through setting the RUN bit.
DONEA Buffer A done.
This bit is a status bit and indicates that the transfer into or out of buffer A has completed.
It is cleared by writing a one to it or by setting the STRTA bit. DONEA can generate an
interrupt if IE is set.
4
STRTA
Buffer A transfer start.
This bit is a control bit and is written by the user. It causes the buffer A transfer to begin.
This bit is functional only if the RUN bit is set.
5
6
DONEB This bit is a status bit and indicates that the transfer into or out of buffer B has completed.
It is cleared by writing a one to it or by setting the STRTB bit. DONEB can generate an
interrupt if IE is set.
STRTB
Buffer B transfer start.
This bit is a control bit and is written by the processor. It causes the buffer B transfer to
begin. This bit is functional only if the RUN bit is set.
7
BIU
Buffer in use.
BIU is a status bit and may be read to indicate which buffer (A or B) is active . This bit is
toggled by the DMA controller when DONEA or DONEB are set. This bit is cleared by all
reset sources (hard, sleep, watchdog, or software).
8..31
—
Reserved.
These bits are reserved and read as zeros. Writes to this field have no effect.
The RUN bit is the channel enable. It should be written to a one when the channel is ready for a
transfer. It can also be used to pause the channel in the middle of a transfer; when it is set to a one
again, the channel will resume from the current pointer value using the current active buffer. If the
RUN bit is cleared in the middle of a burst, the burst will complete before the channel is paused.
The DDAR may be written only when RUN is zero.
SA-1100 Developer’s Manual
11-11
Peripheral Control Module
The IE bit is the interrupt enable for the channel. An interrupt is generated if the DONEA,
DONEB, or ERROR bits are set and the IE bit is set. The interrupt is negated when all of these
status bits are cleared.
The ERROR bit is set if the DMA controller is incorrectly programmed and points to reserved
memory space. No error is generated for references to nonexistent external memory. If enabled,
ERROR generates a channel interrupt.
The DONEA bit is a status bit set by the DMA controller to indicate that the transfer to or from
buffer A has completed. If enabled, DONEA causes a channel interrupt.
The STRTA bit is written by the user to start the channel transfer to or from buffer A. When
DONEA is set, STRTA is cleared. The immediate action resulting from setting STRTA is
dependent on the state of the BIU bit.
The DONEB bit is a status bit set by the DMA controller to indicate that the transfer to or from
buffer B has completed. If enabled, DONEB will cause a channel interrupt.
The STRTB bit is written by the user to start the channel transfer to or from buffer B. When
DONEB is set, STRTB is cleared. The immediate action resulting from setting STRTB is
dependent on the state of the BIU bit.
The BIU bit indicates the current buffer-in-use (A or B). If BIU is a zero, buffer A is in use. If BIU
is a one, buffer B is in use.The setting of DONEA or DONEB toggles the BIU bit. This bit is never
cleared except on reset (either hardware, software, or sleep). For this reason, the processor must
interrogate this bit before programming the channel for a new transfer. If both STRTA and STRTB
are set at the same time, the first buffer serviced depends on the state of BIU.
11.6.1.3
DMA Buffer A Start Address Register (DBSAn)
The DBSAn is a 32-bit read/write register that contains the starting memory address for buffer A.
This register may be written only when STRTA is zero.
11.6.1.4
DMA Buffer A Transfer Count Register (DBTAn)
The DBTAn is a 32-bit read/write register that contains the current transfer count in bytes for buffer
A. This register may be written only when the STRTA bit for this channel is a zero. The following
figure shows the format of this register; question marks indicate that the values are unknown at reset.
.
Bit
Read
Reset
31
0
30
0
29
0
28
0
27
0
26
0
25
0
24
23
0
22
0
21
0
20
0
19
0
18
0
17
?0
1
16
0
Reserved
0
Bit
Read
Reset
15
14
Reserved
?
13
12
11
10
9
8
7
6
5
4
3
2
0
TCA
12
TCA
11
TCA
10
TCA
9
TCA
8
TCA
7
TCA
6
TCA
5
TCA
4
TCA
3
TCA
2
TCA
1
TCA
0
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
Bit
Name
Description
Transfer count (buffer A).
0..12
13..31
TCA<12:0>
This field is a 13-bit value and contains the current transfer count (in bytes) for the transfer
to or from buffer A. The maximum value programmed via this transfer count is 8 Kbyte.
—
Reserved. These bits are reserved and read as zeros. Writes to this field have no effect.
11-12
SA-1100 Developer’s Manual
Peripheral Control Module
11.6.1.5
11.6.1.6
DMA Buffer B Start Address Register (DBSBn)
The DBSBn is a 32-bit read/write register that contains the starting memory address for buffer B.
This register may be written only while STRTB in the DCSR is zero.
DMA Buffer B Transfer Count Register (DBTBn)
The DBTBn is a 32-bit read/write register that contains the current transfer count in bytes for buffer
B. This register may be written only when the STRTB bit for this channel is a zero. The following
figure shows the format of this register; question marks indicate that the values are unknown at reset.
Bit
Read
Reset
31
0
30
0
29
0
28
0
27
0
26
0
25
0
24
23
0
22
0
21
0
20
0
19
0
18
0
17
?0
1
16
0
Reserved
0
Bit
Read
Reset
15
14
Reserved
?
13
12
11
10
9
8
7
6
5
4
3
2
0
TCB
12
TCB
11
TCB
10
TCB
9
TCB
8
TCB
7
STC
B6
TCB
5
TCB
4
TCB
3
TCB
2
TCB
1
TCB
0
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
Bit
Name
Description
0..12
TCB<12:0> Transfer count (buffer B).
This field is a 13-bit value and contains the current transfer count (in bytes) for the transfer
to or from buffer B. The maximum value programmed via this transfer count is 8 Kbyte.
13..31
—
Reserved.
These bits are reserved and read as zeros. Writes to this field have no effect.
11.6.2
DMA Operation
The DMA controller provides dynamic context switching between active channels on a demand
basis. A context switch may occur when a channel completes a command or when a particular burst
(portion of a transfer) has been completed. For example, if the FIFO in a particular transmit serial
controller is full and cannot accept more data, that channel may be switched out of the active
context in favor of another channel that is requesting service. An active channel may actually go
idle many times as the device is serviced. Channels are serviced in a fixed priority with channel 0
being the highest and channel 5 being the lowest.
SA-1100 Developer’s Manual
11-13
Peripheral Control Module
11.6.3
DMA Register List
The following table lists the registers contained within the DMA controller:
Physical Address
Register Name
Symbol
Channel 0 Registers
0h B000 0000
DMA device address register.
DDAR0
DMA control/status register 0.
Write ones to set.
0h B000 0004
DCSR0
0h B000 0008
0h B000 000C
0h B000 0010
0h B000 0014
0h B000 0018
0h B000 001C
Channel 1 Registers
0h B000 0020
Write ones to clear.
Read only.
DMA buffer A start address 0.
DMA buffer A transfer count 0.
DMA buffer B start address 0.
DMA buffer B transfer count 0.
DBSA0
DBTA0
DBSB0
DBTB0
DMA device address register 1.
DDAR1
DCSR1
DMA control/status register 1.
Write ones to set.
0h B000 0024
0h B000 0028
0h B000 002C
0h B000 0030
0h B000 0034
0h B000 0038
0h B000 003C
Channel 2 Registers
0h B000 0040
Write ones to clear.
Read only.
DMA buffer A start address 1.
DMA buffer A transfer count 1.
DMA buffer B start address 1.
DMA buffer B transfer count 1.
DBSA1
DBTA1
DBSB1
DBTB1
DMA device address register 2
DDAR2
DCSR2
DMA control/status register 2.
Write ones to set.
0h B000 0044
0h B000 0048
0h B000 004C
0h B000 0050
0h B000 0054
0h B000 0058
0h B000 005C
Channel 3 Registers
0h B000 0060
Write ones to clear.
Read only.
DMA buffer A start address 2.
DMA buffer A transfer count 2.
DMA buffer B start address 2.
DMA buffer B transfer count 2.
DBSA2
DBTA2
DBSB2
DBTB2
DMA device address register 3.
DDAR3
DCSR3
DMA control/status register 3.
Write ones to set.
0h B000 0064
0h B000 0068
0h B000 006C
Write ones to clear.
Read only.
11-14
SA-1100 Developer’s Manual
Peripheral Control Module
Physical Address
Register Name
DMA buffer A start address 3.
Symbol
0h B000 0070
0h B000 0074
0h B000 0078
0h B000 007C
Channel 4 Registers
0h B000 0080
DBSA3
DBTA3
DBSB3
DBTB3
DMA buffer A transfer count 3.
DMA buffer B start address 3.
DMA buffer B transfer count 3.
DMA device address register 4.
DDAR4
DCSR4
DMA control/status register 4.
Write ones to set.
0h B000 0084
0h B000 0088
0h B000 008C
0h B000 0090
0h B000 0094
0h B000 0098
0h B000 009C
Channel 5 Registers
0h B000 00A0
Write ones to clear.
Read only.
DMA buffer A start address 4.
DMA buffer A transfer count 4.
DMA buffer B start address 4.
DMA buffer B transfer count 4.
DBSA4
DBTA4
DBSB4
DBTB4
DMA device address register 5.
DDAR5
DCSR5
DMA control/status register 5.
Write ones to set.
0h B000 00A4
0h B000 00A8
0h B000 00AC
0h B000 00B0
0h B000 00B4
0h B000 00B8
0h B000 00BC
Write ones to clear.
Read only.
DMA buffer A start address 5.
DMA buffer A transfer count 5.
DMA buffer B start address 5.
DMA buffer B transfer count 5.
DBSA5
DBTA5
DBSB5
DBTB5
SA-1100 Developer’s Manual
11-15
Peripheral Control Module
11.7
LCD Controller
The SA-1100’s LCD controller has three types of displays:
Passive Color Mode
Supports a total of 3375 possible colors, allowing any 256 colors to be
displayed each frame.
Active Color Mode
Supports up to 65536 colors (16-bit).
Passive Monochrome ModeSupports 15 gray-scale levels.
Display sizes up to 1024 x 1024 pixels are supported. However, the size of encoded pixel data within
the frame buffer limits the maximum size screen the LCD can drive due to memory bus bandwidth.
The LCD controller also supports single- or dual-panel displays. Encoded pixel data is stored in
external memory in a frame buffer in 4-, 8-, 12-, or 16-bit increments and is loaded into a 5-entry
FIFO (32 bits per entry) on a demand basis using the LCD’s own dedicated dual-channel DMA
controller. One channel is used for single-panel displays and two are used for dual-panel displays.
Frame buffer data contains encoded pixel values that are used by the LCD controller as pointers to
index into a 256-entry x 12-bit wide palette. Monochrome palette entries are 4 bits wide; color
palette entries are 12 bits wide. Encoded pixel data from the frame buffer, which is 4 bits wide,
addresses the top 16 locations of the palette; 8-bit pixel data accesses any of the 256 entries within
the palette. When passive color 12-bit pixel mode is enabled, the color pixel values bypass the
palette and are fed directly to the LCD’s dither logic. When active color 16-bit pixel mode is
enabled, the pixel value not only bypasses the palette, but also bypasses the dither logic and is sent
directly to the LCD’s data pins.
Once the 4- or 8-bit encoded pixel value is used to select a palette entry, the value programmed
within the entry is transferred to the dither logic, which uses a patented space- and time-based
dithering algorithm to produce the pixel data that is output to the screen. Dithering causes
individual pixels to be turned off on each frame at varying rates to produce the 15 levels of gray for
monochrome screens and 15 levels each for the red, green, and blue pixel components for color
screens, providing a total of 3375 colors (256 colors are available on each frame). The data output
from the dither logic is placed in a 19-entry pin data FIFO before it is placed out on the LCD’s pins
and driven to the display using pixel clock.
Depending on the type of panel used, the LCD controller is programmed to use either 4-, 8-, or
16-pixel data output pins. Single-panel monochrome displays use either four or eight data pins to
output 4 or 8 pixels for each pixel clock; single-panel color displays use eight pins to output 2-2/3
pixels each pixel clock (8 pins / 3 colors/pixel = 2-2/3 pixels per clock). The LCD controller also
supports dual-panel mode, which causes the LCD controller’s data lines to be split into two groups,
one to drive the top half and one to drive the bottom half of the screen. For dual-panel displays, the
number of pixel data output pins is doubled, allowing twice as many pixels to be output each pixel
clock to the two halves of the screen.
In active color display mode, the LCD controller can drive TFT displays. The LCD’s line clock pin
functions as a horizontal sync (HSYNC) signal, the frame clock pin functions as a vertical sync
(VSYNC) signal, and the ac bias pin functions as an output enable (OE) signal. In TFT mode, the LCD’s
dither logic is bypassed, sending selected palette entries (12 bits each) directly to the LCD’s data output
pins. Additionally, 16-bit pixels can be used that bypass both the palette and the dither logic.
The LCD controller can be configured in active color display mode and used with an external DAC
(and optionally an external palette) to drive a video monitor. Note that only monitors that implement
the RGB data format can be used; the LCD controller does not support the NTSC standard.
11-16
SA-1100 Developer’s Manual
Peripheral Control Module
When the LCD controller is disabled, control of its pins is given to the peripheral pin controller
(PPC) to be used as general-purpose digital input/output pins that are noninterruptible. The LCD
controller’s pins include:
• LDD<7:0>
Data lines used to transmit either four or eight data values at a time to the LCD display. For
monochrome displays, each pin value represents a pixel; for passive color, groupings of three
pin values represent one pixel (red, green, and blue data values). In single-panel monochrome
mode, LDD<3:0> pins are used. For double-pixel data, single-panel monochrome, dual-panel
monochrome, single-panel color, and active color modes LDD<7:0> are used.
• GPIO<9:2>
When dual-panel color or 16-bit TFT operation is programmed, GPIO pins are used as the
additional, required LCD data lines to output pixel data to the screen.
• L_PCLK
Pixel clock used by the LCD display to clock the pixel data into the line shift register. In
passive mode, pixel clock transitions only when valid data is available on the data pins. In
active mode, pixel clock transitions continuously and the ac bias pin is used as an output to
signal when data is available on the LCD’s data pins.
• L_LCLK
Line clock used by the LCD display to signal the end of a line of pixels that transfers the line
data from the shift register to the screen and increment the line pointers. Also, it is used by
TFT displays as the horizontal synchronization signal.
• L_FCLK
Frame clock used by the LCD displays to signal the start of a new frame of pixels that resets
the line pointers to the top of the screen. Also, it is used by TFT displays as the vertical
synchronization signal.
• L_BIAS
AC bias used to signal the LCD display to switch the polarity of the power supplies to the row
and column axis of the screen to counteract DC offset. In TFT mode, it is used as the output
enable to signal when data should be latched from the data pins using the pixel clock.
The pixel clock frequency is derived from the output of the on-chip PLL that is used to clock the
CPU (CCLK) and is programmable from CCLK/6 to CCLK/514. Each time new data is supplied to
the LCD data pins, the pixel clock is toggled to latch the data into the LCD display’s serial shifter.
The line clock toggles after all pixels in a line have been transmitted to the LCD driver and a
programmable number of pixel clock wait states have elapsed both at the beginning and end of
each line. In passive mode, the frame clock is asserted during the first line of the screen. In active
mode, the frame clock is asserted at the beginning of each frame after a programmable number of
line clock wait states occur. In passive display mode, the pixel clock does not transition when the
line clock is asserted. However, in active display mode, the pixel clock transitions continuously
and the ac bias bin is used as an output enable to signal when valid pixels are present on the LCD’s
data lines. In passive mode, the ac bias pin can be configured to transition each time a
programmable number of line clocks have elapsed to signal the display to reverse the polarity of its
voltage to counteract DC offset in the screen.
SA-1100 Developer’s Manual
11-17
Peripheral Control Module
11.7.1
LCD Controller Operation
The LCD controller supports a variety of user-programmable options including display type and size,
frame buffer, encoded pixel size, and output data width. Although all programmable combinations are
possible, the selection of displays available within the market dictate which combinations of these
programmable options are practical. The type of external memory system implemented by the user
limits the bandwidth of the LCD’s DMA controller, which, in turn, limits the size and type of screen that
can be controlled. The user must also determine the maximum bandwidth of the SA-1100’s external bus
that the LCD is allowed to use without negatively affecting all other functions that the SA-1100 must
perform. Note that the LCD’s DMA engine has the highest priority on the SA-1100’s internal data bus
structure (ARM system bus) and can “starve” other masters on the bus, including the CPU.
The following sections describe individual functional blocks within the LCD controller, frame buffer and
palette memory organization, and the LCD’s DMA controller. The sections are arranged in order of data
flow, starting with the off-chip frame buffer and ending with the pins that interface to the LCD display.
11.7.1.1
DMA to Memory Interface
Palette RAM and encoded pixel data are stored in off-chip memory (usually DRAM) in the frame buffer
and are transferred to the LCD controller’s 5-entry x 32-bit wide input FIFO, on a demand basis, using
the LCD controller’s dedicated DMA controller. The LCD controller is on the ARM system bus (ASB)
rather than the ARM peripheral bus (APB), where all other peripherals are located, because it is a higher
speed synchronous bus that is able to maintain the data rate required for demanding displays, such as
dual-panel color. The LCD’s DMA contains two channels that transfer data from external memory to the
input FIFO. One channel is used for single-panel displays and two are used for dual-panel displays.
The LCD controller issues a service request to the DMA after it has been initialized and enabled.
The DMA automatically performs four word transfers, filling all but one entry of the FIFO. Values
are fetched from the bottom of the FIFO, one entry at a time, and each 32-bit value is unpacked into
individual pixel encodings, of 4, 8, 12, or 16 bits each. After the value is removed from the bottom
of the FIFO, the entry is invalidated and all data in the FIFO is transferred down one entry. When
four of the five entries are empty, a service request is issued to the DMA. If the DMA is not able to
keep the FIFO filled with enough pixel data due to insufficient external memory access speed and
the FIFO is emptied, the FIFO underrun status bit is set and an interrupt request is made.
11.7.1.2
Frame Buffer
The frame buffer is in an off-chip memory area used to supply enough encoded pixel values to fill the
entire screen one or more times. At the start or lowest order address of the LCD controller’s frame buffer
is either a 32- or 512-byte buffer used to store the lookup palette data for each frame. A 32-byte buffer is
used to load the top 16 entries of the palette for 4-, 12-, or 16-bit pixel encodings, and a 512-byte buffer
is used to load the entire 256-entry palette for 8-bit pixel encodings. Note that the LCD’s on-chip palette
is not used for 12- and 16-bit pixel encodings; the PBS field must be programmed to select 12- and
16-bit pixel mode and the remainder of the 32 bytes at the top of the frame buffer must be zero-filled
even though the data is not used.
Each time a new frame is fetched from the frame buffer, the LCD controller’s palette is first loaded with
the data contained within the palette buffer. Each of the 16 or 256 palette entries is stored in adjacent
organization. The user can select how the LCD views the ordering of frame buffer palette/pixel entries
by programming the big/little endian select (BLE) bit in LCD control register 0. In little endian mode,
palette entries are ordered starting with the least significant half-word, followed by the most significant.
In big endian mode, palette entries are ordered starting with the most significant half-word, followed by
the least significant. Note that the ordering of the 4-bit R, G, B, and monochrome pixel data (and the
PBS field) does not change between big and little endian modes; only the relative positioning of the
individual 16-bit palette entries changes.
11-18
SA-1100 Developer’s Manual
Peripheral Control Module
Figure 11-3. Palette Buffer Format
.
Individual Palette Entry
Bit 15
Color
Bit 15
Mono
14
14
13
12
12
11
11
10
Red (R)
10
9
8
7
6
5
4
4
3
3
2
1
0
0
Unused
PBS*
Green (G)
Blue (B)
13
9
8
7
6
5
2
1
Unused
PBS*
Unused
Monochrome (M)
*Note: Pixel bit size (PBS) is contained only within the first palette entry (palette entry 0).
16- or 256-Entry Palette Buffer
Bit
31
16
15
0
Base + 0x0
Base + 0x4
Palette entry 1
Palette entry 3
Palette entry 0
Palette entry 2
.
.
Base + 0x1C
Base + 0x20
Palette entry 15
Palette entry 17
Palette entry 14
Palette entry 16
.
Note: Entries 16 through 254 do not
.
.
exist for 4-, 12- and 16-bit/pixel modes.
Base +
0x1FC
Palette entry 255
Palette entry 254
Base +
0x200
Start of Encoded Pixel Data
Little Endian Palette Entry Ordering
16 15
Bit
31
0
Base + 0x0
Base + 0x4
Palette Entry 0
Palette Entry 2
Palette Entry 1
Palette Entry 3
.
.
Big Endian Palette Entry Ordering
SA-1100 Developer’s Manual
11-19
Peripheral Control Module
The first palette entry (palette entry 0) also contains an extra field that is used to synchronously
configure the LCD controller at the beginning of each frame. Bits 12 and 13 of the first palette
entry contain a field that is used to select the number of bits per pixel that is to be used in the next
unpack pixel data into nibbles, bytes, 12-bit values, or half-words, and by the palette to tell it how
many address bits are contained in the pixel data it is supplied, configuring the palette size to 16 or
256 entries. Note that 12/16-bit pixel mode bypasses the LCD palette and supplies 12-bit values
directly to the dither logic when passive mode is enabled, or 16-bit values directly to the output
FIFOs when active mode is enabled. The following table shows the encoding of the PBS bit field.
Bit
Name
PBS
Description
13..12
Pixel bit size.
0x – 4 bits per pixel, 16-entry palette, 32 bytes of palette buffer transferred each frame
to palette.
01 – 8 bits per pixel, 256-entry palette, 512 bytes of palette buffer transferred each
frame to palette.
10 – 12 bits per pixel in passive mode (PAS=0), 16 bits per pixel in active mode
(PAS=1). Palette unused, however, 32 bytes of “dummy” palette data is transferred
each frame to palette. Palette data must be zero-filled.
11 – Reserved.
Note: Two 4-bit pixels are packed into each byte, and 12-bit pixels are right justified on
half-word boundaries.
Following the palette buffer is the pixel data buffer that contains one encoded pixel value for each
of the pixels present on the display. The number of pixel data values depends on the size of the
memory organization within the frame buffer for each size pixel encoding. Note that for 4-bit
encodings, 2 pixels are placed into each byte, and for 12-bit encodings the value is right- justified
within a half-word. These figures show the encoded pixel organization for little endian memory
organization. The user can select how the LCD views the ordering of frame buffer pixel entries by
programming the big/little endian select (BLE) bit in LCD control register 0. In big endian mode,
pixel entries are ordered starting with the most significant nibble, byte, or half-word and ending
with the least significant.
Figure 11-4. 4 Bits Per Pixel Data Memory Organization (Little Endian)
Bit
3
2
1
0
4 bits/pixel
Encoded Pixel Data<3:0>
Bit
31
28
27
24
23
20
19
16
15
12
11
Pixel 2
8
7
4
3
0
Base +
0x20
Pixel 7
Pixel 6
Pixel 5
Pixel 4
Pixel 3
Pixel 1
Pixel 9
Pixel 0
Pixel 8
Base +
0x24
Pixel 15
Pixel 14
Pixel 13
Pixel 12
Pixel 11
Pixel 10
..
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SA-1100 Developer’s Manual
Peripheral Control Module
Figure 11-5. 8-Bits Per Pixel Data Memory Organization (Little Endian)
Bit
7
6
5
4
3
2
1
0
8 bits/pixel
Encoded Pixel Data<7:0>
Bit 31
24
23
16
15
8
7
0
Base +
0x200
Pixel 3
Pixel 7
Pixel 2
Pixel 6
Pixel 1
Pixel 5
Pixel 0
Pixel 4
Base +
0x204
..
Figure 11-6. 12-Bits Per Pixel Data Memory Organization (Passive Mode Only)
Bit 15 14 13 12
12 bits/pixel Unused
11 10
9
8
7
6
5
4
3
2
1
0
Red Data<3:0>
Green Data<3:0>
Blue Data<3:0>
Bit
31
16
15
0
Base + 0x20
Base + 0x24
Pixel 1
Pixel 3
Pixel 0
Pixel 2
..
Figure 11-7. 16-Bits Per Pixel Data Memory Organization (Active Mode Only)
)
15 14 13 12
11 10
9
8
7
6
5
4
3
2
1
0
Bit
Encoded Pixel Data<15:0>
16 bits/pixel
Bit
Base + 0x20
Base + 0x24
31
16
15
0
Pixel 1
Pixel 3
Pixel 0
Pixel 2
SA-1100 Developer’s Manual
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Peripheral Control Module
In dual-panel mode, pixels are presented to two halves of the screen at the same time (upper and lower).
A second DMA channel and input FIFO exist to support dual-panel operation. The DMA channels
alternate service requests when filling the two input FIFOs. The palette buffer is implemented in DMA
channel 1, but not channel 2; the base address points to the top of the encoded pixel values for channel 2.
The DMA controller contains a base and current address pointer register. The end address is calculated
automatically by the LCD using the display information such as pixels per line, lines per frame, single-
or dual-panel mode, color or monochrome mode, and bits per pixel, which are programmed by the user.
The base address of both DMA channels must be configured such that the least significant four
address bits are all zero (for example, address bits 3 through 0 must be zero). This requirement
limits the base address of the frame buffer to start at even 4-word (or 16-byte) intervals.
The frame buffer must contain an even multiple of 16 pixels for every line and must be aligned on
a quadword boundary. Many LCD displays are a multiple of 16 pixels wide; however, most
passive LCD displays are not and will ignore extra pixels at the end of each line. Thus for these
types of displays that do not use an even multiple of 16 encoded pixel values, the user must adjust
the start address for each line by adding between 1 and 15 “dummy” pixel values to the end of the
previous line. For example, if the screen that is being driven is 107 pixels wide, and 4-bits/pixel
mode is used, each line is 107 pixels or nibbles in length (53.5 bytes). The next nearest 16-pixel
boundary occurs at 112 pixels or nibbles (56 bytes). Thus, the user must start each new line in the
frame buffer at multiples of 56 bytes by adding an extra 5 “dummy” pixels per line (2.5 bytes). The
user must ensure that the panel being controlled does indeed ignore extra pixel clocks at the end of
each line when a panel with line widths that are non-multiple of 16 pixels are used.
The user must add extra space at the end of the frame buffer. The LCD’s DMA may overshoot the
end of the frame buffer by one burst cycle (4-word read). The LCD’s DMA reads these extra
values, but they are flushed from the input FIFO each time the frame clock is pulsed. The user must
ensure that the four words immediately following the end of the frame buffer reside in legal
memory space (do not cause a bus error if read). Since the LCD does not alter this memory (only
reads are performed), these locations can be used for data storage unrelated to the LCD.
The following equations are used to calculate the total frame buffer size in bytes that is accessed by
the DMA based on varying pixel size encodings and screen sizes. The first term in the equations
represents the size of the palette buffer, the second term is the add-on for the DMA overshoot at the
end of the frame buffer, and the third term is the size required for the encoded pixel values. Note
that for dual-panel mode, the frame buffer size is equally distributed between the two DMA
channels and that DMA channel 2’s buffer is either 32 or 512 bytes smaller (no palette buffer; that
is, the first term in the equations is deleted).
Line(sXColumns)
4 bits/pixel:
FrameBufferSize = 32 + 16 + --------------------------------------------------- + (2(nXLines))
2
8 bits/pixel:
FrameBufferSize = 512 + 16 + (Line(sXColumns)) + (nXLines)
12 or 16 bits/pixel:
FrameBufferSize = 32 + 16 + 2(Line(sXColumns))
Where n = 0 to 15 and is the number of extra “dummy” pixels required per line to make pixels/line
an even multiple of sixteen.
Note: The base address of the frame buffer must start on even 4-word boundaries (the four least
significant address bits <3:0> must be zero).
11-22
SA-1100 Developer’s Manual
Peripheral Control Module
11.7.1.3
Input FIFO
Data from the LCD’s DMA is directed either to the palette or the input FIFO. The direction of data
flow is switched whenever the LCD controller is first enabled and by each frame pulse. After the
LCD controller is configured and enabled, the first 32 (4-, 12-, and 16-bits/pixel) or 512
(8-bit/pixel) bytes supplied by the DMA are sent to the palette. All subsequent encoded pixel data
is sent to the FIFO. After an entire frame of pixels has been processed, the frame clock pin is
pulsed to denote the start of the next frame. This signal is also used to change the direction of DMA
input data from the FIFO back to the palette. A modulus of 8 (4-, 12-, and 16-bits/pixel) or 128
(8-bits/pixel) is used to count when loading the palette RAM, depending on the pixel bit size shown
above. A 7-bit counter is loaded each time a frame clock pulse occurs or the LCD is enabled, and is
decremented each time a word is stored to the palette (two palette entries). When the counter wraps
around to zero, the data input from the DMA is switched back to the FIFO.
The LCD controller contains a 5-entry x 32-bit wide input FIFO that is used to store encoded pixels
fetched from the frame buffer. The FIFO signals a service request to the DMA whenever four
entries of the FIFO are empty. In turn, the DMA automatically fills the FIFO with a 4-word burst.
Pixel data from the frame buffer remains packed within individual 32-bit words when it is loaded
into the FIFO. The LCD controller’s port size is 32 bits wide to accommodate the heavy data flow
from the frame buffer. Depending on the number of bits per pixel, as words are taken from the
bottom of the FIFO, they are unpacked and supplied to the lookup palette in nibbles (4 bits/pixel)
or bytes (8 bits/pixel) to the dither logic (12 bits/pixel), or directly to the pins in half-word
increments (16 bits/pixel).
Each time a word is taken from the bottom of the FIFO, the entry is invalidated and all data in the
FIFO moves down one position. When four entries are empty, a service request is issued to the DMA.
11.7.1.4
Lookup Palette
The encoded pixel data taken from the bottom entry of the input FIFO is used as an address to
index and select individual palette locations. Four-bit pixel encodings address 16 locations and
8-bit pixel encodings select any of the 256 palette entries. Note that the user may program 1, 2, and
3 bits/pixel as well by zeroing out the upper 3, 2 or 1 bits of each encoded pixel value in the frame
buffer, respectively. However, for 1, 2, and 3 bits/pixel, the encoded pixel size remains at 4 bits
within the frame buffer and within the LCD controller’s input FIFO.
Once a palette entry is selected by the encoded pixel value, the contents of the entry is sent to the
color/gray-scale space/time base dither circuit. In color mode, the value within the palette is made up
of three 4-bit fields, one for each color component – red, green, and blue. In monochrome mode, only
intensity levels. For color operation, an individual frame is limited to a selection of 256 colors (the
number of palette entries). However, the LCD controller is capable of generating a total of 3375
colors (15 levels per color ^ 3 colors = 3375). When 12 or 16 bits per pixel mode is enabled, the
palette is bypassed. For passive displays, 12-bit pixels are sent directly to the dither logic; for active
displays, 16-bit pixels are sent to the output FIFO to be driven directly to the LCD’s data pins.
SA-1100 Developer’s Manual
11-23
Peripheral Control Module
11.7.1.5
Color/Gray-Scale Dithering
For passive displays, entries selected from the lookup palette are sent to the color/gray-scale
space/time base dither generator. Each 4-bit value is used to select one of 15 intensity levels. Note
that two of the 16 dither values are identical (always high). The color/gray intensity is controlled by
turning individual pixels on and off at varying periodic rates. For some screens, more intense
colors/grays are produced by making the average time the pixel is high longer than the average
time it is low, while other screens produce more intense colors/grays when the average time the
pixel is low is longer. The user should program the palette appropriately depending on whether a
one on the pixel line turns the pixel on or off. The dither generator also uses the intensity of
adjacent pixels in its calculations to give the screen image a smooth appearance. The proprietary
dither algorithm is optimized to provide a range of intensity values that match the eye’s visual
perception of color/gray gradations. In color mode, three separate dither blocks are used to process
resultant intensity level for all 15 color/gray-scale levels.
Table 11-7. Color/Gray-Scale Intensities and Modulation Rates
Dither Value
Intensity
Modulation Rate
(4-Bit Value from Palette)
(0% Is Black)
(Ratio of ON to ON+OFF Pixels)
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
0.0%
11.1%
20.0%
26.7%
33.3%
40.0%
44.4%
50.0%
55.6%
60.0%
66.6%
73.3%
80.0%
88.9%
100.0%
100.0%
0
1/9
1/5
4/15
3/9
2/5
4/9
1/2
5/9
3/5
6/9
11/15
4/5
8/9
1
1
11.7.1.6
Output FIFO
The LCD controller contains a 19-entry x 16-bit wide output FIFO that is used to store pixel pin data
before it is driven out to the pins. Each time a modulated pixel value is output from the dither
generator, it is placed into a serial shifter. The size of the shifter is controlled by programming the
color/monochrome select and single- and dual-panel, double pixel data, and passive/active select bits
in the LCD’s control registers and the pixel bit size within palette entry 0 in the frame buffer. The
shifter can be configured to be 4, 8, or 16 bits wide. Four pins are used for single-panel monochrome
screens; 8 pins are used for single- and dual-panel monochrome screens as well as single-panel color
displays; 12 pins are used for active displays; and 16 pins are used for dual-panel color and active
displays. Once the correct number of pixels have been placed within the shifter (4-, 8-, or 16-pixel
values), the value is transferred to the top of the output FIFO. The value is then transferred down until
it reaches the last empty location within the FIFO. Each time a value is taken from the bottom of the
FIFO, the entry is invalidated and all data in the FIFO moves down one position.
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SA-1100 Developer’s Manual
Peripheral Control Module
11.7.1.7
LCD Controller Pins
Pixel data is removed from the bottom of the output FIFO and is driven in parallel onto the LCD’s
data lines on the edge selected by the pixel clock polarity (PCP) bit. For a 4-bit wide bus, data is
driven onto the LCD data lines LDD<3:0> starting with the most significant bit. For an 8-bit wide
bus, data is driven onto LDD<7:0>; for a 12-bit bus GPIO<5:2> and LDD<7:0>; and for a 16-bit
bus GPIO<9:2> and LDD<7:0>. In monochrome dual-panel mode, the pixels for the upper half of
the screen are driven onto LDD<3:0> and the lower half to LDD<7:4>. In color dual-panel mode,
the upper panel pixels are driven onto LDD<7:0> and the lower panel pixels to GPIO<9:2>. Note
that for a 4-bit wide bus, data is output via the LDD<3:0> pins and the LCD<7:4> pins are held low
by the LCD controller. The user cannot use this pins as GPIOs in this mode. However, for a 12-bit
wide bus, the user is free to use GPIO<9:6> as general- purpose I/O signals.
When an entire line of pixels has been output to the LCD controller screen, the line clock pin (L_LCLK)
is toggled. Likewise, when an entire frame of pixels has been output to the LCD controller screen, the
frame clock pin (L_FCLK) is toggled. To prevent a dc charge from building within a passive display, its
power and ground supplies must be switched periodically. The LCD controller signals the display to
switch the polarity by toggling the ac bias pin (L_BIAS). The user can control the frequency of the bias
pin by programming the number of line clock transitions between each toggle.
When active display mode is enabled, the timing of the pixel, line, and frame clocks and the ac bias
pin changes. The pixel clock transitions continuously in this mode as long as the LCD is enabled. The
ac bias pin functions as an output enable. When it is asserted, the display latches data from the LCD’s
pins using the pixel clock. The line clock pin is used as the horizontal synchronization signal
(HSYNC) and the frame clock as the vertical synchronization signal (VSYNC). The timing of the line
and frame clock pins is programmable to support both passive and active mode. Programming
options include: waitstate insertion both at the beginning and end of each line and frame; pixel clock;
line clock; frame clock; output enable signal polarity; and frame clock pulse width.
When the LCD controller is disabled, control of all 12 of its pins is relinquished to the peripheral pin
controller (PPC) unit to be used as general-purpose digital I/O pins that are noninterruptible. See the
section 11.13 on page 184 for a description of the programming and operation of the PPC unit.
11.7.2
LCD Controller Register Definitions
The LCD controller contains four control registers, four DMA address registers, and one status
register. The control registers contain bit fields to enable and disable the LCD controller; to define
the height and width of the screen being controlled; and to indicate single- versus dual-panel
display mode, color versus monochrome mode, passive versus active display, polarity of the
control pins, pulse width of the line and frame clocks, pixel clock and ac bias pin frequency. AC
bias pin toggles per interrupt the number of waitstates to insert before and after each line, after each
frame, and various interrupt masks. An additional control field exists to tune the DMA’s
performance based on the type of memory system in which the SA-1100 is used. This field controls
the placement of a minimum delay between each LCD DMA request to ensure enough bus
bandwidth is given to other ARM system bus masters for accesses.
The DMA address registers are used to define the base addresses of the off-chip frame buffers and to
which address the DMA is currently pointing. Both of these registers exist for DMA channels 1 and 2.
The status registers contain bits that signal input and output FIFO overrun and underrun errors,
DMA bus errors, when the DMA base address can be reprogrammed, when the last active frame
has completed after the LCD is disabled, and each time the ac bias pin has toggled a programmed
number of times. Each of these hardware-detected events signals an interrupt request to the
interrupt controller.
SA-1100 Developer’s Manual
11-25
Peripheral Control Module
11.7.3
LCD Controller Control Register 0
LCD controller control register 0 (LCCR0) contains 10 bit fields that are used to control various
functions within the LCD controller.
11.7.3.1
LCD Enable (LEN)
The LCD enable (LEN) bit is used to enable and disable all LCD controller operation. When
LEN=0, the LCD controller is disabled and control of all 12 of its pins is given to the peripheral pin
controller (PPC) unit to be used as general-purpose I/O (noninterruptible). When LEN=1, the LCD
controller is enabled. Note that all other control registers should be initialized before setting LEN.
The user can program LCCR0 last, and configure all 10 bit fields at the same time via a word write
to the register. If the user clears LEN while the LCD controller is enabled, it will complete
transmission of the current frame before being disabled. Completion of the current frame is
signalled by the LCD when it sets the LCD disable done flag (LDD) within the LCD status register
that generates an interrupt request. The user should use a read-modify-write procedure to clear
LEN because the other bit-fields within LCCR0 continue to be used by the LCD controller after
LEN is cleared until the frame that is currently in progress completes. When the LCD controller is
disabled, control of all 12 of its pins is given to the peripheral pin controller (PPC) so that they may
be used for general-purpose input and output (noninterruptible). See the Section 11.13, “Peripheral
Pin Controller (PPC)” on page 11-184 for a description of the PPC.
11.7.3.2
11.7.3.3
Color/Monochrome Select (CMS)
The color/monochrome select (CMS) bit selects whether the LCD controller operates in color or
monochrome mode. When CMS=0, color mode is selected, palette entries are 12 bits wide (4 bits
per color), 8 data pins are enabled for single-panel mode, 16 data pins are enabled for dual-panel
mode (GPIO pins 2..9 are used as the extra 8 data output pins), and all three dither blocks are used,
one each for the red, green, and blue pixel components. When CMS=1, monochrome mode is
selected, palette entries are 4 bits wide (15 levels of gray-scale), 4 or 8 data pins are enabled for
single-panel mode, and 8 data pins are enabled for dual-panel mode.
Single-/Dual-Panel Select (SDS)
In passive mode (PAS=0), the single-/dual-panel select (SDS) bit is used to select the type of
display control that is implemented by the LCD screen. When SDS=0, single-panel operation is
selected (pixels presented to screen a line at a time), and when SDS=1, dual-panel operation is
selected (pixels presented to screen two lines at a time). Single-panel LCD drivers have one
line/row shifter and driver for pixels, and one line pointer; dual-panel LCD controller drivers have
two line/row shifters (one for the top half of the screen, one for the bottom), and two line pointers
(one for the top half of the screen, one for the bottom). When dual-panel mode is programmed,
both of the LCD controller’s DMA channels are used. DMA channel 1 is used to load the palette
RAM from the frame buffer and to drive the upper half of the display, and DMA channel 2 drives
the lower half. The two channels alternate when fetching data for both halves of the screen, placing
encoded pixel values within the two separate input FIFOs. When programming dual-panel
operation, the user must perform the following sequence in order: disable the LCD (LEN=0),
program dual-panel mode (SDS=0->1), write the upper panel DMA base address, write the lower
panel DMA base address, and enable the LCD (LEN=0->1). When dual-panel operation is enabled,
the LCD controller doubles its pin uses; thus, for monochrome screens 8 pins are used, and for
color screens, 16 pins are used.
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SA-1100 Developer’s Manual
Peripheral Control Module
Table 11-8 shows the LCD data pins and GPIO pins used for each mode of operation and the
data pin pixel ordering. Note that when dual-panel color operation is enabled, the user must
configure GPIO pins 2 through 9 as outputs by setting bits 2..9 within the GPIO pin direction
register (GPDR) and GPIO alternate function register (GAFR). See the Section 9.1,
“General-Purpose I/O” on page 9-1 for configuration information. Also note that SDS is ignored in
active mode (PAS=1).
.
Table 11-8. LCD Controller Data Pin Utilization
Color/
Single/
Passive/
Active Panel
Monochrome
Dual Panel
Panel
Screen Portion
Pins
Monochrome
Monochrome
Monochrome
Single
Single
Dual
Passive
Whole
LDD<3:0>
1
Passive
Passive
Whole
Top
LDD<7:0>
LDD<3:0>
LDD<7:4>
LDD<7:0>
LDD<7:0>
Bottom
Whole
Top
Color
Color
Single
Dual
Passive
Passive
Bottom
Whole
GPIO<9:2>
Color
Single
Active
GPIO<9:2>,
LDD<7:0>
1
Double-pixel data mode (DPD) = 1.
SA-1100 Developer’s Manual
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Peripheral Control Module
Figure 11-8. LCD Data-Pin Pixel Ordering
Top Left Corner of Screen
Column 0 Column 1 Column 2 Column 3 Column 4 Column 5 Column 6 Column 7 Column 8
Row 0
Row 1
Row 2
Row 3
LDD<0> LDD<1> LDD<2> LDD<3> LDD<0> LDD<1> LDD<2> LDD<3> LDD<0>
LDD<0> LDD<1> LDD<2> LDD<3> LDD<0> LDD<1> LDD<2> LDD<3> LDD<0>
LDD<0> LDD<1> LDD<2> LDD<3> LDD<0> LDD<1> LDD<2> LDD<3> LDD<0>
LDD<0> LDD<1> LDD<2> LDD<3> LDD<0> LDD<1> LDD<2> LDD<3> LDD<0>
Passive Monochrome Single-Panel Display Pixel Ordering
Top Left Corner of Screen
Column 0 Column 1 Column 2 Column 3 Column 4 Column 5 Column 6 Column 7 Column 8
Row 0
Row 1
Row 2
Row 3
LDD<0> LDD<1> LDD<2> LDD<3> LDD<4> LDD<5> LDD<6> LDD<7> LDD<0>
LDD<0> LDD<1> LDD<2> LDD<3> LDD<4> LDD<5> LDD<6> LDD<7> LDD<0>
LD<0>
LDD<1> LDD<2> LDD<3> LDD<4> LDD<5> LDD<6> LDD<7> LDD<0>
LDD<0> LDD<1> LDD<2> LDD<3> LDD<4> LDD<5> LDD<6> LDD<7> LDD<0>
Passive Monochrome Single-Panel Double-Pixel Display Pixel Ordering
Top Left Corner of Screen
Column 0 Column 1 Column 2 Column 3 Column 4 Column 5 Column 6 Column 7 Column 8
Row 0
Row 1
LDD<0> LDD<1>
LDD<3>
LDD<2>
LDD<0>
LDD<2> LDD<3> LDD<0>
LDD<1>
LDD<0> LDD<1> LDD<2> LDD<3> LDD<0> LDD<1> LDD<2> LDD<3> LDD<0>
LDD<4> LDD<5>
LDD<7>
LDD<6>
LDD<4>
LDD<6> LDD<7> LDD<4>
Row n/2
LDD<5>
LDD<4> LDD<5> LDD<6> LDD<7> LDD<4> LDD<5> LDD<6> LDD<7> LDD<4>
Row n/2+1
Passive Monochrome Dual-Panel Display Pixel Ordering
n = # of rows
Top Left Corner of Screen
Column 0 Column 0 Column 0 Column 1 Column 1 Column 1 Column 2 Column 2 Column 2
Red Blue Red Blue
Red Blue Green Green
Green
Row 0
Row 1
Row 2
Row 3
LDD<7> LDD<6> LDD<5> LDD<4> LDD<3> LDD<2> LDD<1> LDD<0> LDD<7>
LDD<7> LDD<6> LDD<5> LDD<4> LDD<3> LDD<2> LDD<1> LDD<0> LDD<7>
LDD<7> LDD<6> LDD<5> LDD<4> LDD<3> LDD<2> LDD<1> LDD<0> LDD<7>
LDD<7> LDD<6> LDD<5> LDD<4> LDD<3> LDD<2> LDD<1> LDD<0> LDD<7>
Passive Color Single-Panel Display Pixel Ordering
Top Left Corner of Screen
Column 0 Column 0
Red
Green
Column 2 Column 2
Green
Blue
Column 4 Column 5 Column 5
Blue Red
Green
Row 0
LDD<7> LDD<6>
LDD<0> LDD<7>
LDD<1> LDD<0> LDD<7>
Row 1
LDD<7> LDD<6>
LDD<0> LDD<7>
LDD<1> LDD<0> LDD<7>
Row n/2
GPIO<9> GPIO<8>
GPIO<2> GPIO<9>
GPIO<2> GPIO<9>
GPIO<3> GPIO<2> GPIO<9>
GPIO<3> GPIO<2> GPIO<9>
Row n/2+1 GPIO<9> GPIO<8>
n = # of rows
Passive Color Dual-Panel Display Pixel Ordering
11-28
SA-1100 Developer’s Manual
Peripheral Control Module
11.7.3.4
LCD Disable Done Interrupt Mask (LDM)
The LCD disable done interrupt mask (LDM) bit is used to mask or enable interrupt requests that
are asserted after the LCD is disabled and the frame currently being output to the pins has
completed. When LDM=0, the interrupt is enabled, and whenever the LCD disable done (LDD)
status bit within the LCD status register (LCSR) is set (one), an interrupt request is made to the
interrupt controller. When LDM=1, the interrupt is masked and the state of the LDD status bit is
ignored by the interrupt controller. Note that programming LDM=1 does not affect the current state
of LDD or the LCD controller’s ability to set and clear LDD; it only blocks the generation of the
interrupt request. This interrupt is particularly useful when the user needs to ensure the LCD has
been disabled and the current frame that is being output to the pins has completed, before entering
sleep mode. If the user disables the LCD, but does not need to enter sleep mode, this interrupt can
be masked using LDM.
11.7.3.5
Base Address Update Interrupt Mask (BAM)
The base address update interrupt mask (BAM) bit is used to mask or enable interrupt requests that
are asserted at the beginning of each frame when the LCD’s base address pointer is transferred to
the current address pointer within the LCD’s DMA. When BAM=0, the interrupt is enabled, and
whenever the base address update (BAU) status bit within the LCD status register (LCSR) is set
(one) an interrupt request is made to the interrupt controller. When BAM=1, the interrupt is masked
and the state of the BAU status bit is ignored by the interrupt controller. Note that programming
BAM=1 does not affect the current state of BAU or the LCD controller’s ability to set and clear
BAU; it only blocks the generation of the interrupt request. Note that this interrupt mask is
particularly useful when the user wishes to enter idle mode to turn off the CPU and to display the
same image (the off-chip frame buffer data does not change). By masking the BAU interrupt, the
SA-1100 is not forced out of idle mode at the end of each frame.
11.7.3.6
Error Interrupt Mask (ERM)
The error interrupt mask (ERM) bit is used to mask or enable interrupt requests that are asserted
whenever a bus error or input/output FIFO over/underrun error occurs. When ERM=0, all error
interrupts are enabled, and whenever the bus error (BER) status bit or any of the input/output FIFO
over/underrun (IOL, IUL, IOU, IUU, OOL, OUL, OOU, OUU) status bits within the LCD status
register (LCSR) are set (one), an interrupt request is made to the interrupt controller. When
ERM=1, error interrupts are masked; the state of all of the error status bits (BER, IOL, IUL, IOU,
IUU, OOL, OUL, OOU, OUU) are ignored by the interrupt controller. Note that programming
ERM=1 does not affect the current state of these status bits or the LCD controller’s ability to set
and clear them; it only blocks the generation of the interrupt requests.
11.7.3.7
Passive/Active Display Select (PAS)
The passive/active display select (PAS) bit selects whether the LCD controller operates in passive
(STN) or active (TFT) display control mode. When PAS=0, passive or STN mode is selected, all
LCD data flow operates normally (including the use of the LCD’s dither logic), and all LCD
controller pin timing operates as described in the preceding sections.
When PAS=1, active or TFT mode is selected. For 4- and 8-bit per pixel modes, pixel data is
transferred via the DMA from off-chip memory to the input FIFO, is unpacked and used to select an
entry from the palette, just like passive mode. However, the value read from the palette bypasses the
LCD’s dither logic, and is sent directly to the output FIFO to be output on the LCD’s data pins. This
12-bit value output to the pins represents 4 bits of red, 4 bits of green, and 4 bits of blue data. For
12- and 16-bit pixel encoding mode, the pixel size within the frame buffer is increased to 16 bits.
SA-1100 Developer’s Manual
11-29
Peripheral Control Module
Thus two 16-bit values are packed into each word in the frame buffer. Each 16-bit value is transferred
via the DMA from off-chip memory to the input FIFO. Unlike 4- and 8-bit per pixel modes, the 16-bit
value bypasses both the palette and the dither logic, and is placed directly in the output FIFO to be
output on the LCD’s data pins. Increasing the size of the pixel representation allows a total of 64K
colors to be generated. This 16-bit value output to the pins can be organized into one of three RGB
color formats: 6 bits of red, 5 bits of green, and 5 bits of blue data; 5 bits of red, 6 bits of green, and 5
bits of blue data; 5 bits of red, 5 bits of green, and 6 bits of blue data, as specified by the user. Note
that the pin timing of the LCD changes when active mode is selected. Timing of each pin is described
in subsequent bit-field sections for both passive and active mode. Additionally, the LCD controller
can be configured in active color display mode and used with an external DAC and optionally an
external palette to drive a video monitor. Note that only monitors that implement the RGB data format
can be used; the LCD controller does not support the NTSC standard.
Figure 11-9 shows which bits within each frame buffer entry (for 16-bit/pixel mode) and which bits
within a selected palette entry (for 4- and 8-bit/pixel mode) are sent to the individual LCD data
pins. In active mode, GPIO pins 2..9 are also used. Note that the user must configure GPIO pins
2..5 as outputs (for 4- and 8-bit/pixel mode), and GPIO pins 2..9 as outputs (for 16-bit/pixel mode)
by setting the appropriate bits within the GPIO pin direction register (GPDR) and GPIO alternate
function register (GAFR). See the General-Purpose I/O section for configuration information. If
GPDR<6:9> = GAFR<6:9> = 4’hF in 4- or 8-bit/pixel mode, then GPIO<6:9> are pulled low
during LCD operation in active mode. However, the user is free to clear GAFR<6:9>, allowing the
GPIO unit to assume control of these pins to be used as normal digital I/Os. In general, the user
may clear any number of GAFR bits 2..9, to allow the GPIO unit to assume control of unused
GPIO pins for normal digital I/O depending on the required number of data pins.
If the panel that is being controlled contains more data pin inputs than 16, the user may still use the
SA-1100’s LCD controller, but the panel will be limited to a total of 64 K colors. If the user wishes
to maintain the panel’s full range of colors and increase the granularity of the spectrum, the LCD’s
16 data pins should be interfaced to the panel’s most significant R, G, and B pixel data input pins
and the least significant R, G, and B data pins should be tied either high or low. If instead, the user
wishes to maintain the granularity of the spectrum and limit the overall range of colors possible, the
LCD’s 16 data pins should be interfaced to the panel’s least significant R, G, and B pixel data input
pins and the most significant data pins should again be tied either high or low.
Figure 11-9. Frame Buffer/Palette Bits Output to LCD Data Pins in Active Mode
16-Bit/Pixel Mode
Frame Buffer Entry
R<5> R<4> R<3> R<2> R<1> R<0> G<4> G<3> G<2> G<1> G<0> B<4>
R<4> R<3> R<2> R<1> R<0> G<5> G<4> G<3> G<2> G<1> G<0> B<4>
B<3>
B<3>
B<3>
3
B<2> B<1>
B<2> B<1>
B<2> B<1>
B<0>
B<0>
B<0>
0
R<4> R<3> R<2> R<1> R<0> G<4> G<3> G<2> G<1> G<0> B<5>
B<4>
4
Bit
15
14
13
12
11
10
9
8
7
6
5
2
1
GPIO GPIO GPIO GPIO GPIO GPIO GPIO GPIO
LDD
<7>
LDD
<6>
LDD
<5>
LDD
<4>
LDD
<3>
LDD
<2>
LDD
<1>
LDD
<0>
Data
Pin
<9>
<8>
<7>
<6>
<5>
<4>
<3>
<2>
4- or 8-Bit/Pixel Mode
Selected Palette Entry
R<3> R<2> R<1> R<0> G<3> G<2> G<1> G<0> B<3>
B<2> B<1>
B<0>
0
1
Bit
VSS
VSS
VSS
VSS
11
10
9
8
7
6
5
4
3
2
1
GPIO GPIO GPIO GPIO GPIO GPIO GPIO GPIO
<9> <8> <7> <6> <5> <4> <3> <2>
LDD
<7>
LDD
<6>
LDD
<5>
LDD
<4>
LDD
<3>
LDD
<2>
LDD
<1>
LDD
<0>
Data
Pin
1 GPIO pins 6..0 are grounded by the LCD in this mode. However, if GAFR bit 6..9 are cleared within the system control module,
these pins can be used as normal GPIO pins.
11-30
SA-1100 Developer’s Manual
Peripheral Control Module
11.7.3.8
Big/Little Endian Select (BLE)
The big/little endian select (BLE) bit selects whether the LCD controller views external memory
organization of the frame buffer as big or little endian. When BLE=0, little endian mode is selected
Figure 11-7. Pixels are packed into words starting with the least-significant nibble, byte, or
half-word. When BLE=1, big endian mode is selected and pixel data is organized in memory
starting with the most significant nibble, byte, or half-word. When BLE=1, palette entries are
packed into half-words starting with the most significant half-word. Note that BLE does not affect
the ordering of the 4-bit red/green/blue bit fields, the 4-bit monochrome field within each 16-bit
palette entry, or the 2-bit pixel bit size (PBS) field contained with palette entry 0.
11.7.3.9
Double-Pixel Data (DPD) Pin Mode
The double-pixel data (DPD) pin mode bit selects whether four or eight data pins are used to output
pixel data to the LCD screen in single-panel monochrome mode. When DPD=0, LDD<3:0> pins
are used to output 4-pixel values each pixel clock transition; when DPD=1, LDD<7:0> pins are
used to output 8-pixel values each pixel clock. See the following table and figure for a comparison
of how the LCD’s data pins are used in each of its display modes. Note that DPD does not affect
dual-panel monochrome mode nor any of the color modes.
11.7.3.10 Palette DMA Request Delay (PDD)
The 8-bit palette DMA request delay (PDD) field is used to select the minimum number of memory
controller clock cycles (half the frequency of the CPU clock) to wait between the servicing of each
DMA request issued while the on-chip palette is loaded. When the palette is loaded at the beginning
of every frame, either 32 or 512 bytes of data must be accessed by the LCD’s DMA. Since the LCD’s
DMA is the highest priority master on the ARM system bus, other masters (such as the CPU) will be
denied access to the bus and may be starved. Using PDD allows other masters to gain access of the
bus in between palette DMA loads, so that they are not locked from accessing the bus for an
unacceptable period of time. Note that PDD does not apply to normal input FIFO DMA requests for
frame buffer information since these DMA requests do not occur back-to-back. The input FIFO DMA
request rate is a function of the rate at which pixels are displayed on the screen.
After a palette DMA burst cycle has completed, the value contained within PDD is loaded to a
down counter that disables the palette from issuing another DMA request until the counter
decrements to zero. This counter ensures that the LCD’s DMA does not fully consume the
bandwidth of the SA-1100’s system bus. Once the counter reaches zero, any pending or future
DMA requests by the palette cause the DMA to arbitrate for the ARM system bus (ASB). Once the
DMA burst cycle has completed, the process starts over and the value in PDD is loaded to the
counter to create another waitstate period, which disables the palette from issuing a DMA request.
PDD can be programmed with a value that causes the FIFO to wait between 0 to 255 memory clock
cycles after the completion of one DMA request to the start of the next request. When PDD=8’h00,
the FIFO DMA request delay function is disabled. Note that waitstates are not inserted between
DMA burst cycles that are used to fill the input FIFO with pixel data.
SA-1100 Developer’s Manual
11-31
Peripheral Control Module
The following table shows the location of all 10 bit-fields located in LCD control register 0
(LCCR0). The user must program the control bits within all other control registers before setting
LEN=1 (a word write can be used to configure LCCR0 while setting LEN after all other control
registers have been programmed), and also must disable the LCD controller when changing the
state of any control bit within the LCD controller. Note that writes to reserved bits are ignored and
reads return zeros.
Address: 0h B010 0000
LCCR0: LCD Control Register 0
Read/Write
18 17
PDD<7:4>
Bit
Reset
Bit
31
30
29
0
28
0
27
0
26
25
24
23
22
21
0
20
0
19
0
16
0
Reserved
0
0
0
10
0
0
0
0
0
0
0
15
0
14
13
12
0
11
9
DPD
0
8
BLE
0
7
PAS
0
6
Res.
0
5
ERM
0
4
BAM
0
3
LDM
0
2
SDS
0
1
CMS
0
0
LEN
0
PDD<3:0>
Reserved
Reset
0
0
0
Bit
Name
LEN
Description
0
LCD controller enable.
0 – LCD controller disabled. Control of L_PCLK, L_LCLK, L_FCLK, L_BIAS, and the
LDD<7:0> pins is given to the PPC unit to be used as general-purpose I/O pins.
1 – LCD controller enabled.
1
2
CMS
SDS
Color/monochrome select.
0 – Color operation enabled.
1 – Monochrome operation enabled.
Single-/dual-panel display select.
0 – Single-panel display enabled. LDD<3:0> used for monochrome, LDD<7:0> used for
color.
1 – Dual-panel display enabled. LDD<7:0> used for monochrome, LDD<7:0> and
GPIO<9:2> used for color (user must also program GPDR and GAFR registers within
the GPIO unit).
Note: SDS is ignored in active mode (PAS=1). For dual-panel operation, the user must
disable the LCD, set SDS, program the upper panel DMA base address, program the
lower panel DMA base address, and enable the LCD.
3
4
LDM
BAM
LCD disable done mask.
0 – LCD disable done condition generates an interrupt (state of LDD status sent to the
interrupt controller).
1 – LCD disable done condition does not generate an interrupt (LDD status bit ignored).
Base address update mask.
0 – Base address update condition generates an interrupt (state of BAU status sent to
the interrupt controller).
1 – Base address update condition does not generate an interrupt (BAU status bit
ignored).
5
6
ERM
—
Error mask.
0 – Bus error and FIFO over/underrun errors generate an interrupt (state of BER, IOL,
IUL, IOU, IUU, OOL, OUL, OUU status sent to the interrupt controller).
1 – Bus error and FIFO over/underrun errors do not generate an interrupt (BER, IOL,
IUL, IOU, IUU, OOL, OUL, OOU, OUU status bits ignored).
Reserved.
11-32
SA-1100 Developer’s Manual
Peripheral Control Module
Bit
Name
PAS
Description
7
Passive/active display select.
0 – Passive or STN display operation enabled. Dither logic is enabled.
1 – Active or TFT display operation enable. Dither logic bypassed, pin timing changes to
support continuous pixel clock, output enable, VSYNC, HSYNC signals.
8
BLE
Big/little endian select.
0 – Little endian operation is selected, half-word palette buffer data is packed into
individual words of memory starting with the least significant half-word, and frame buffer
pixel data is packed into individual words of memory starting with the least significant
nibble, byte, or half-word.
1 – Big endian operation is selected, half-word palette buffer data is packed into
individual words of memory starting with the most significant half-word, and frame buffer
pixel data is packed into individual words of memory starting with the most significant
nibble, byte, or half-word.
9
DPD
Double-pixel data pin mode.
0 – In single-panel monochrome operation, four pixels are presented to LDD<3:0> each
pixel clock.
1 – In single-panel monochrome operation, eight pixels are presented to LDD<7:0>
each pixel clock.
Note: This bit is ignored in all other modes of operation except for single-panel
monochrome.
11..10
—
Reserved.
19..12 PDD
Palette DMA request delay.
Value (from 0 to 255) used to specify the number of memory controller clocks (half the
speed of the CPU clock). The on-chip palette DMA request should be disabled after
each DMA transfer to the palette. The clock count starts after the last write of each burst
cycle. While the counter is decrementing, all DMA requests from the palette are masked.
When the counter reaches zero, any pending or subsequent DMA requests are allowed
to generate a 4-word burst. Programming PDD=8h’00 disables this function.
31..20
—
Reserved.
SA-1100 Developer’s Manual
11-33
Peripheral Control Module
11.7.4
LCD Controller Control Register 1
LCD controller control register 1 (LCCR1) contains four bit fields that are used as modulus values
for a collection of down counters, each of which performs a different function to control the timing
of several of the LCD’s pins.
11.7.4.1
Pixels Per Line (PPL)
The pixels per line (PPL) bit-field is used to specify the number of pixels in each line or row on the
screen. PPL is a 10-bit value that represents between 16 and 1024 pixels per line. PPL is used to
count the correct number of pixel clocks that must occur before the line clock can be asserted. The
user should program PPL with the desired number of pixels per line minus 16. Note that the bottom
four bits of PPL are not implemented and therefore are not writable. Reads of these bits return
zeros because the LCD controller only supports displays that are a multiple of 16 pixels wide.
Many displays exist that are not a multiple of 16, but are able to ignore added pixels at the end of
each line. For example, if the display being controlled is 250 pixels wide, the nearest greater
multiple of 16 is 256. The user should program PPL to 256-16 = 240 (10’h0F0). In this case, the
user must also add the appropriate number of “dummy” pixel values (between 1 and 15) to the
frame buffer. Again, for a 250 pixel wide display, and if 4-bit/pixel mode is used, each line is 250
nibbles or 125 bytes in length. The next nearest pixel boundary occurs at 256 pixels or nibbles (128
bytes). Thus the user must start each new line in the frame buffer at multiples of 128 bytes by
adding an extra 6 “dummy” pixels per line (3 bytes). Note that the user must also ensure that the
display that is being controlled will ignore any additional pixel clocks at the end of each line
because these “dummy” pixel values will be output to the display and the pixel clock will continue
to transition until the PPL+16 value is reached.
11.7.4.2
Horizontal Sync Pulse Width (HSW)
The 6-bit horizontal sync pulse width (HSW) field is used to specify the pulse width of the line
clock in passive mode or horizontal synchronization pulse in active mode. L_LCLK is asserted
each time a line or row of pixels is output to the display and a programmable number of pixel clock
waitstates have elapsed. When line clock is asserted, the value in HSW is transferred to a 6-bit
down counter, which uses the programmed pixel clock frequency to decrement. When the counter
reaches zero, the line clock is negated. HSW can be programmed to generate a line clock pulse
width ranging from 1 to 64 pixel clock periods. The user should program HSW with the desired
number of pixel clocks minus one. Note that the pixel clock does not transition during the line
clock pulse in passive display mode, but does transition in active display mode. Also note that the
polarity (active and inactive state) of the line clock pin is programmed using the horizontal sync
polarity (HSP) bit in LCCR3.
11.7.4.3
End-of-Line Pixel Clock Wait Count (ELW)
The 8-bit end-of-line pixel clock wait count (ELW) field is used to specify the number of “dummy”
pixel clocks to insert at the end of each line or row of pixels before pulsing the line clock pin. Once
a complete line of pixels is transmitted to the LCD driver, the value in ELW is used to count the
number of pixel clocks to wait before pulsing the line clock. ELW generates a wait period ranging
from 1 to 256 pixel clock cycles. The user should program ELW with the desired number of pixel
clocks minus one. Note that the pixel clock pin, L_PCLK, does not transition during the these
“dummy” pixel clock cycles in passive display mode (pixel clock transitions continuously in active
display mode).
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SA-1100 Developer’s Manual
Peripheral Control Module
11.7.4.4
Beginning-of-Line Pixel Clock Wait Count (BLW)
The 8-bit beginning-of-line pixel clock wait count (BLW) field is used to specify the number of
“dummy” pixel clocks to insert at the beginning of each line or row of pixels. After the line clock
for the previous line has been negated, the value in BLW is used to count the number of pixel
clocks to wait before starting to output the first set of pixels in the next line. BLW generates a wait
period ranging from 1 to 256 pixel clock cycles. The user should program BLW with the desired
number of pixel clocks minus one. Note that the pixel clock pin, L_PCLK, does not transition
during these “dummy” pixel clock cycles in passive display mode (pixel clock transitions
continuously in active display mode).
The following table shows the location of the four bit fields located in LCD control register 1
(LCCR1). The LCD controller must be disabled (LEN=0) when changing the state of any field
within this register.
Address: 0h B010 0020
LCCR1: LCD Controller Control Register 1
Read/Write
Bit
Reset
Bit
31
30
29
28
0
27
0
26
25
24
23
22
21
0
20
0
19
0
18
17
16
0
BLW
ELW
0
0
0
0
0
0
0
0
0
0
15
0
14
0
13
0
12
0
11
0
10
0
9
8
7
6
5
4
3
2
1
0
HSW
PPL<9:4>
PPL<3:0>
Reset
0
0
0
0
0
0
0
0
0
0
Bit
Name
Description
9..0
PPL
Pixels per line.
Value (from 1 to 1024). Used to specify number of pixels contained within each line on
the LCD display. Pixels/line = (PPL+16).
Note that PPL<3:0> are not implemented but return zeros when read.
15..10
HSW
ELW
BLW
Horizontal sync pulse width.
Value (from 1 to 64). Used to specify number of pixel clock periods to pulse the line
clock at the end of each line. HSYNC pulse width = (HSW+1).
Note that pixel clock is held in its inactive state during the generation of the line clock in
passive display mode and is permitted to transition in active display mode.
23..16
31..24
End-of-line pixel clock wait count.
Value (from 1 to 256). Used to specify number of pixel clock periods to add to the end of
a line transmission before line clock is asserted. EOL = (ELW+1).
Note that pixel clock is held in its inactive state during the end-of-line wait period in
passive display mode and is permitted to transition in active display mode.
Beginning-of-line pixel clock wait count.
Value (from 1 to 256). Used to specify number of pixel clock periods to add to the
beginning of a line transmission before the first set of pixels is output to the display.
BOL wait = (BLW+1).
Note that pixel clock is held in its inactive state during the beginning-of-line wait period
in passive display mode and is permitted to transition in active display mode.
SA-1100 Developer’s Manual
11-35
Peripheral Control Module
11.7.5
LCD Controller Control Register 2
LCD controller control register 2 (LCCR2) contains four bit fields that are used as modulus values
for a collection of down counters, each of which performs a different function to control the timing
of several of the LCD’s pins.
11.7.5.1
Lines Per Panel (LPP)
The lines per panel (LPP) bit field is used to specify the number of lines or rows present on the LCD
panel being controlled. In single-panel mode, it represents the total number of lines for the entire LCD
display. In dual-panel mode, it represents half the number of lines of the entire LCD display because
it is split into two panels. LPP is a 10-bit value that represents between 1 and 1024 lines per screen.
The user should program LPP with the desired height of the display minus one. LPP is used to count
the correct number of line clocks that must occur before the frame clock can be pulsed.
The LCD’s DMA may overshoot the end of frame buffer by one burst cycle (4-word read). The LCD’s
DMA reads these extra values but they are flushed from the input FIFO each time the frame clock is
pulsed. The user must ensure that the four words immediately following the end of the frame buffer
reside in legal memory space (do not cause a bus error if read). Because the LCD does not alter this
memory (only reads are performed), these locations can be used for data storage unrelated to the LCD.
11.7.5.2
Vertical Sync Pulse Width (VSW)
The 6-bit vertical sync pulse width (VSW) field is used to specify the pulse width of the vertical
synchronization pulse in active mode, or is used to add extra “dummy” line clock waitstates
between the end and beginning of frame in passive mode.
In active mode (PAS=1), L_FCLK is used to generate the vertical sync signal and is asserted each
time the last line or row of pixels for a frame is output to the display and a programmable number
of line clock waitstates have elapsed as specified by ELW. When L_FCLK is asserted, the value in
VSW is transferred to a 6-bit down counter, which uses the line clock frequency to decrement.
When the counter reaches zero, L_FCLK is negated. VSW can be programmed to generate a
vertical sync pulse width ranging from 1 to 64 line clock periods. The user should program VSW
with the desired number of line clocks minus one. Note that the line clock does not transition
during generation of the vertical sync pulse. Also note that the polarity (active and inactive state) of
the L_FCLK pin is programmed using the frame clock polarity (FCP) bit in LCCR3.
In passive mode (PAS=0), VSW does not affect the timing of the L_FCLK pin, but rather can be
used to add extra line clock waitstates between the end of each frame and the beginning of the next
frame. When the last line clock of a frame is negated, the value in VSW is transferred to a 6-bit
down counter that uses the line clock frequency to decrement. When the counter reaches zero, the
next frame is permitted to begin. VSW can be programmed to generate from 1 to 64 dummy line
clock periods between each frame in passive mode. The user should program VSW properly to
ensure that enough waitstates occur between frames such that the LCD’s DMA is able to fully load
the on-chip palette, as well as allowing a sufficient number of encoded pixel values to be input
from the frame buffer, to be processed by the dither logic, and placed in the output FIFO, ready to
be output to the LCD’s data pins. The number of waitstates required is system dependent. The
factors that determine the number of waitstates include: palette buffer size (32 or 512 bytes),
memory system speed (number of waitstates, burst speed, number of beats), and what value is
programmed in the palette DMA request delay (PDD) bit-field in LCCR0. Note that the line clock
pin does transition during the insertion of the line clock waitstate periods.
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SA-1100 Developer’s Manual
Peripheral Control Module
VSW does not affect generation of the frame clock signal in passive mode. Passive LCD displays
require that the frame clock is active on the rising edge of the first line clock pulse of each frame,
with adequate setup and hold time. To meet this requirement, the LCD controller’s frame clock pin
is asserted on the rising edge of the first pixel clock for each frame. The frame clock remains
asserted for the remainder of the first line as pixels are output to the display and it is then negated
on the rising edge of the first pixel clock of the second line of each frame.
11.7.5.3
End-of-Frame Line Clock Wait Count (EFW)
The 8-bit end-of-frame line clock wait count (EFW) field is used in active mode (PAS=1) to
specify the number of line clocks to insert at the end of each frame. Once a complete frame of
pixels is transmitted to the LCD display, the value in EFW is used to count the number of line clock
periods to wait. After the count has elapsed, the VSYNC (L_FCLK) signal is pulsed. EFW
generates a wait period ranging from 0 to 255 line clock cycles (setting EFW=8’h00 disables the
EOF wait count). Note that the line clock pin, L_LCLK, does not transition during the generation
of the EFW line clock periods.
In passive mode, EFW should be set to zero such that no end-of-frame waitstates are generated.
VSW should be used exclusively in passive mode to insert line clock waitstates to allow the LCD’s
DMA to fill the palette and process a number of pixels before the start of the next frame.
11.7.5.4
Beginning-of-Frame Line Clock Wait Count (BFW)
The 8-bit beginning-of-frame line clock wait count (BFW) field is used in active mode (PAS + 1) to
specify the number of line clocks to insert at the beginning of each frame. The BFW count starts
just after the VSYNC signal for the previous frame has been negated. After this has occurred, the
value in BFW is used to count the number of line clock periods to insert before starting to output
pixels in the next frame. BFW generates a wait period ranging from 0 to 255 extra line clock cycles
(BFW=8’h00 disables the BOF wait count). Note that the line clock pin, L_LCLK, does transition
during the generation of the BFW line clock wait periods.
In passive mode, BFW should be set to zero such that no beginning-of-frame waitstates are
generated. VSW should be used exclusively in passive mode to insert line clock waitstates to allow
the LCD’s DMA to fill the palette and process a number of pixels before the start of the next frame.
SA-1100 Developer’s Manual
11-37
Peripheral Control Module
The following table shows the location of the four bit fields located in LCD control register 2
(LCCR2). The LCD controller must be disabled (LEN=0) when changing the state of any field
within this register.
Address: 0h B010 0024
LCCR2: LCD Controller Control Register 2
Read/Write
Bit
31
30
29
28
0
27
0
26
25
24
23
22
21
0
20
0
19
0
18
17
16
0
BFW
EFW
Reset
0
-
0
14
0
0
0
0
0
0
0
0
-
Bit
15
13
0
12
0
11
0
10
0
9
8
7
6
5
4
3
2
1
0
VSW
LPP
Reset
0
0
0
0
0
0
0
0
0
0
0
0
Bit
Name
Description
9..0
LPP
Lines per panel.
Value (from 1 to 1024). Used to specify number of lines per panel. For single-panel
mode, this represents the total number of lines on the LCD display; for dual-panel
mode, this represents half the number of lines on the whole LCD display.
Lines/panel = (LPP+1).
15..10
VSW
Vertical sync pulse width.
In active mode (PAS=1), value (from 1 to 64). Used to specify number of line clock
periods to pulse the L_FCLK pin at the end of each frame after the end-of-frame wait
(EFW) period elapses. Frame clock used as VSYNC signal in active mode.
In passive mode (PAS=0), value (from 1 to 64). Used to specify number of extra line
clock
periods to insert after the end-of-frame. Note that the width of L_FCLK is not affected
by VSW in passive mode and that line clock does not transition during the insertion of
the extra line clock periods. Also note that both EFW and BFW should be set to zero in
passive mode.
VSYNC width = (VSW+1).
23..16
31..24
EFW
BFW
End-of-frame line clock wait count.
In active mode (PAS=1), value (from 0 to 255). Used to specify number of line clock
periods to add to the end of each frame. Note that line clock does transition during the
insertion of the extra line clock periods. EFW should be cleared to zero (disabled) in
passive mode.
Beginning-of-frame line clock wait count.
In active mode (PAS=1), value (from 0 to 255). Used to specify number of line clock
periods to add to the beginning of a frame before the first set of pixels is output to the
display. Note that line clock does transition during the insertion of the extra line clock
periods. BFW should be cleared to zero (disabled) in passive mode.
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SA-1100 Developer’s Manual
Peripheral Control Module
11.7.6
LCD Controller Control Register 3
LCD controller control register 3 (LCCR3) contains seven different bit fields that are used to
control various functions within the LCD controller.
11.7.6.1
Pixel Clock Divider (PCD)
The 8-bit pixel clock divider (PCD) field is used to select the frequency of the pixel clock. PCD can
be any value from 1 to 225 (0 is illegal) and is used to generate a range of pixel clock frequencies
from CCLK/6 to CCLK/514 (where CCLK is the programmed frequency of the CPU clock). The
pixel clock frequency should be adjusted to meet the required screen refresh rate. The refresh rate
depends on: the number of pixels for the target display; whether single- or dual-panel mode is
selected; whether monochrome or color mode is selected; the number of pixel clock waitstates
programmed at the beginning and end of each line; the number of line clocks inserted at the
beginning and end of each frame; the width of the VSYNC signal in active mode or VSW line
clocks inserted in passive mode; and the width of the frame clock or HSYNC signal. All of these
factors alter the time duration from one frame transmission to the next. Different display
manufacturers require different frame refresh rates depending on the physical characteristics of the
display. PCD is used to alter the pixel clock frequency in order to meet these requirements. The
frequency of the pixel clock for a set PCD value or the required PCD value to yield a target pixel
clock frequency can be calculated using the two following equations. Note that programming PCD
= 8’h00 is illegal.:
CCLK
PixelClock = -----------------------------
2(PCD + 2)
CCLK
PCD = ------------------------------------- – 2
2(PixelClock)
11.7.6.2
AC Bias Pin Frequency (ACB)
The 8-bit ac bias frequency (ACB) field is used to specify the number of line clock periods to count
between each toggle of the ac bias pin (L_BIAS). In passive mode, after the LCD controller is
enabled, the value in ACB is loaded to an 8-bit down counter and the counter begins to decrement
using the line clock. When the counter reaches zero, it stops, the state of L_BIAS is reversed, and the
whole procedure starts again. The number of line clocks between each ac bias pin transition ranges
from 1 to 256. The user should program ACB with the desired number of line clocks minus one.
This pin is used by the LCD display to periodically reverse the polarity of the power supplied to the
screen to eliminate dc offset. If the LCD display being controlled has its own internal means of
switching its power supply, ACB should be set to its maximum value to reduce power consumption
(8’hFF). Note that the ACB bit field has no effect on L_BIAS in active mode. Because the pixel
clock transitions continuously in active mode, the ac bias pin is used as an output enable signal. It
is asserted automatically by the LCD controller in active mode whenever pixel data is driven out to
the data pins to signal the display when it may latch pixels using the pixel clock.
SA-1100 Developer’s Manual
11-39
Peripheral Control Module
11.7.6.3
AC Bias Pin Transitions Per Interrupt (API)
The 4-bit ac bias pin transitions per interrupt (API) field is used to specify the number of L_BIAS
pin transitions to count before setting the ac bias count status (ACS) bit in the LCD controller
status register that signals an interrupt request. After the LCD controller is enabled, the value in
API is loaded to a 4-bit down counter and the counter decrements each time the ac bias pin is
inverted. When the counter reaches zero, it stops and the ac bias count (ABC) bit is set in the status
register. Once ABC is set, the 4-bit down counter is reloaded with the value in API, and is disabled
until ABC is cleared. When ABC is cleared by the CPU, the down counter is enabled and again
decrements each time the ac bias pin is inverted. The number of ac bias pin transitions between
each interrupt request ranges from 0 to 15. Note that programming API=4’h0 disables the ac bias
pin transitions per interrupt function.
In active mode, L_BIAS is used as an output enable signal. However, signalling of the API interrupt
may still occur. The ACB bit field can be used to count line clock pulses in active mode. When the
programmed number of line clock pulses occurs, an internal signal is transitioned that is used to
decrement the 4-bit counter used by the API interrupt logic. Once this internal signal transitions the
programmed number of times, as specified by API, an interrupt is generated. The user should
program API to zero if the API interrupt function is not required in active mode (PAS = 1).
11.7.6.4
Vertical Sync Polarity (VSP)
The vertical sync polarity (VSP) bit is used to select the active and inactive states of the vertical sync
signal in active display mode (PAS = 1), and the frame clock signal in passive display mode. When
VSP=0, the L_FCLK pin is active high and inactive low. When VSP=1, the L_FCLK pin is active
low and inactive high. In active display mode, the L_FCLK pin is forced to its inactive state while
pixels are transmitted during the frame. After the end of the frame and a programmable number of
line clocks periods occur (controlled by EFW), the L_FCLK pin is forced to its active state for a
programmable number of line clocks (controlled by VSW), and is then again forced to its inactive
state. In passive display mode, the L_FCLK pin is forced to its inactive state during the transmission
of the second line of each frame through to the end of the frame. Frame clock is then forced to its
active state on the rising edge of the first pixel clock of each frame. Frame clock remains active
during the transmission of the entire first line of pixels in the frame and is then forced back to its
inactive state on the rising edge of the first pixel clock of the second line of the frame.
11.7.6.5
Horizontal Sync Polarity (HSP)
The horizontal sync polarity (HSP) bit is used to select the active and inactive states of the
horizontal sync signal in active display mode, and the line clock signal in passive display mode.
When HSP=0, the L_LCLK pin is active high and inactive low. When HSP=1, the L_LCLK pin is
active low and inactive high. Both in active and passive display modes, the L_FCLK pin is forced
to its inactive state whenever pixels are transmitted After the end of each line and a programmable
number of pixel clock periods occur (controlled by ELW), the L_FCLK pin is forced to its active
state for a programmable number of line clocks (controlled by HSW), and is then again forced to its
inactive state.
11.7.6.6
Pixel Clock Polarity (PCP)
The pixel clock polarity (PCP) bit is used to select which edge of the pixel clock data is driven out
onto the LCD’s data pins. When PCP=0, data is driven onto the LCD’s data pins on the rising edge
of the L_PCLK pin. When PCP=1, data is driven onto the LCD’s data pins on the falling edge of
the L_PCLK pin.
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SA-1100 Developer’s Manual
Peripheral Control Module
11.7.6.7
Output Enable Polarity (OEP)
The output enable polarity (OEP) bit is used to select the active and inactive states of the output
enable signal in active display mode. In this mode, the ac bias pin is used as an enable that signals the
off-chip device when data is actively being driven out using the pixel clock. The pixel clock
continuously toggles during operation of active mode (PAS=1). When OEP=0, the L_BIAS pin is
active high and inactive low. When OEP=1, the L_BIAS pin is active low and inactive high. In active
display mode, data is driven onto the LCD’s data pins on the programmed edge of the L_PCLK pin
when L_BIAS is in its active state. Note that OEP does not affect L_BIAS in passive display mode.
The following table shows the location of the seven different bit fields located in LCD controller
control register 3 (LCCR3). The LCD controller must be disabled (LEN=0) when changing the state
of any field within this register. Note that writes to reserved bits are ignored and reads return zeros.
Address: 0h B010 0028
LCCR3: LCD Controller Control Register 3
Read/Write
Bit
31
30
29
28
27
26
25
24
23
OEP
0
22
PCP
0
21
HSP
0
20
VSP
0
19
0
18
17
16
0
Reserved
API
Reset
0
-
0
0
0
12
0
0
0
0
0
0
0
-
Bit
15
14
0
13
0
11
0
10
0
9
8
7
0
6
0
5
0
4
3
2
1
0
ACB
PCD
Reset
0
0
0
0
0
0
0
0
Bit
Name
Description
7..0
PCD
Pixel clock divisor.
Value (from 0 to 255). Used to specify the frequency of the pixel clock based on the
CPU clock (CCLK) frequency. Pixel clock frequency can range from CCLK/6 to
CCLK/514.
Pixel Clock Frequency = CCLK/2(PCD+2).
Note that PCD must be programmed with a value of 1 or greater (PCD = 8’h00 is illegal).
AC bias pin frequency.
15..8
ACB
Value (from 1 to 256). Used to specify the number of line clocks to count before
transitioning the ac bias pin in passive mode (PAS=0). This pin is used to periodically
invert the polarity of the power supply to prevent dc charge buildup within the display. If
the passive display that is being controlled does not need to use L_BIAS, the user
should program ACB to its maximum value (8’hFF) to conserve power. Note that ACB
is ignored in active mode (PAS = 1).
Number of line clocks/toggle of the L_BIAS pin = (ACB+1).
AC bias pin transitions per interrupt.
19..16
API
Value (from 0 to 15). Used to specify the number of ac bias pin transitions to count
before setting the line count status (ABC) bit, signalling an interrupt request. Counter
frozen when ABC is set and is restarted when ABC is cleared by software. This
function is disabled when API=4’h0.
20
VSP
Vertical sync polarity.
0 – L_FCLK pin is active high and inactive low.
1 – L_FCLK pin is active low and inactive high.
Active mode: Vertical sync pulse active between frames, after end-of-frame wait period.
Passive mode: Frame clock active during first line of each frame.
SA-1100 Developer’s Manual
11-41
Peripheral Control Module
Bit
Name
Description
21
HSP
Horizontal sync polarity.
0 – L_LCLK pin is active high and inactive low.
1 – L_LCLK pin is active low and inactive high.
Active and passive mode: horizontal sync pulse/line clock active between lines, after
end-of-line wait period.
22
23
PCP
OEP
Pixel clock polarity.
0 – Data is driven on the LCD’s data pins on the rising edge of L_PCLK.
1 – Data is driven on the LCD’s data pins on the falling edge of L_PCLK.
Output enable polarity.
0 – L_BIAS pin is active high and inactive low in active display mode and parallel data
input mode.
1 – L_BIAS pin is active low and inactive high in active display mode and parallel data
input mode.
In active display mode, data is driven out to the LCD’s data pins on programmed pixel
clock edge when ac bias pin is active. Note that OEP is ignored in passive display
mode.
31..24
—
Reserved.
11.7.7
LCD Controller DMA Registers
The LCD controller has two fully independent DMA channels used to transfer frame buffer data for
each frame displayed from off-chip memory to the LCD’s palette RAM and the input FIFO. DMA
channel 1 is used for single-panel display mode and the upper screen in dual-panel mode. DMA
channel 2 is used exclusively for the lower screen in dual-panel mode. Both DMA channels contain
a base address pointer and current address pointer register. The LCD’s DMA engine has the highest
priority to gain mastership of the SA-1100’s internal ARM system bus. The LCD is given highest
priority to prevent other masters from starving the LCD screen (including the CPU).
The two DMA channels use a separate set of base address and current address pointers. The user
must initialize the base address pointer registers before enabling the LCD. Once enabled, the base
address is transferred to the current address pointer.
After the LCD is enabled, the input FIFO requests a DMA transfer and the DMA makes a 4-word
burst access from off-chip memory using the address contained within the current address pointer.
The pointer is incremented by 4 (bytes) each time a word is read from memory (bit 2 of the pointer
is incremented). Each of the 4 words from the burst is loaded into the top of the input FIFO. The
LCD then takes one value at a time from the bottom of the FIFO, unpacks it into individual
encoded pixel values, and uses the values to index into the palette. Each time the input FIFO
contains four empty entries, another DMA request is made and another 4-word burst is performed.
To calculate the frame buffer end address, the DMA controller uses the values programmed in the
pixels per line (PPL), lines per panel (LPP), single/dual screen select (SDS), color/monochrome
select (CMS) bit fields, and double pixel data (DPD) bit fields within the control registers as well
as the pixel bit size (PBS) field contained within the first entry of the palette buffer from the
off-chip frame buffer. When the current address pointer reaches the calculated end of buffer
address, the value in the base address pointer is again transferred to the current address pointer.
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SA-1100 Developer’s Manual
Peripheral Control Module
11.7.8
DMA Channel 1 Base Address Register
DMA channel 1 base address register (DBAR1) is a 32-bit register that is used to specify the base
address of the off-chip frame buffer for DMA channel 1. The base address pointer register can be
both read and written. Addresses programmed in the base address register must be aligned on
quadword boundaries; the least significant four bits (DBAR1<3:0>) must always be written with
zeros. The user must initialize the base address register before enabling the LCD, and can also
write a new value to it while the LCD is enabled to allow a new frame buffer to be used for the next
frame. The user can change the state of DBAR1 while the LCD controller is active just after the
base address update (BAU) status bit is set with the LCD’s status register, which generates an
interrupt request. This status bit indicates that the value in the base address pointer has transferred
to the current address pointer register and that it is safe to write a new base address value. DMA
channel 1 is used to transfer frame buffer data from off-chip memory to the LCD’s input FIFO and
the palette RAM for single-panel mode, and for the top half of the screen in dual-panel mode. For
dual-panel operation, the user must perform the following sequence in order: disable the LCD
(LEN=0), program dual panel mode (SDS= 0 → 1), write the upper panel DMA base address,
write the lower panel DMA base address, enable the LCD (LEN= 0 → 1). Note that DBAR1 is not
reset and must be initialized before enabling the LCD; question marks indicate that the values are
unknown at reset.
Address: 0h B010 0010
DBAR1: DMA Channel 1 Base Address Register
Read/Write
Bit
31
30
29
28
?
27
26
25
24
23
22
21
20
?
19
?
18
17
16
?
DMA Channel 1 Base Address Pointer
Reset
?
-
?
14
?
?
?
?
9
?
8
?
7
?
6
?
?
?
-
Bit
15
13
?
12
?
11
?
10
?
5
4
3
2
1
0
DMA Channel 1 Base Address Pointer
Reset
?
?
?
?
?
?
?
?
?
?
?
?
Bit
Name
Description
31..0
DBAR1
DMA channel 1 base address pointer.
Used to specify the base address of the frame buffer within off-chip memory. Value in
DBAR1 is transferred to current address pointer register 1 when LCD is first enabled
(LEN= 0 → 1) and when the current address pointer value equals the end-of-frame
buffer. DBAR1 should be written only when the LCD is disabled or immediately after an
interrupt is generated by the setting of the base address update (BAU) status bit. The
base address must be on a quadword boundary; the user must always write bits 0
through 3 to zero.
SA-1100 Developer’s Manual
11-43
Peripheral Control Module
11.7.9
DMA Channel 1 Current Address Register
DMA channel 1 current address register (DCAR1) is a 32-bit read-only register that is used by
DMA channel 1 to keep track of the address of the DMA transfer currently in progress or the
address of the next DMA transfer. Any time the LCD is first enabled (LEN= 0 → 1) or the value in
the current address pointer register equals the calculated end address value, the contents of the base
address pointer register is transferred to the current address pointer. This register can be read to
determine the approximate line that the LCD controller is currently processing and driving out to
the display. It is also useful to read this register just before writing the DMA’s base address pointer
to ensure that the end of frame is not about to occur, which means that the base address pointer is
about to be transferred to the current address pointer. Note that DCAR1 is a read-only register that
is not reset and is not initialized until the LCD is first enabled, causing the contents of the base
address register to be transferred to it; question marks indicate that the values are unknown at reset.
.
Address: 0h B010 0014
DCAR1: DMA Channel 1 Current Address Register
Read-Only
Bit
31
30
29
?
28
?
27
?
26
25
24
23
22
21
20
?
19
?
18
?
17
16
?
DMA Channel 1 Current Address Pointer
Reset
?
-
?
?
?
9
?
8
?
7
?
6
?
?
1
?
-
Bit
15
14
?
13
?
12
?
11
?
10
?
5
4
3
2
0
DMA Channel 1 Current Address Pointer
Reset
?
?
?
?
?
?
?
?
?
?
Bit
Name
DCAR1
Description
31..0
DMA channel 1 current address pointer.
Read-only register. Continuously reflects the current address that DMA channel 1 is
transferring from or will use in the next transfer. Base address register is transferred to
this register whenever the LCD is enabled (LEN= 0 → 1) and when the current address is
equal to the calculated end address of the buffer.
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SA-1100 Developer’s Manual
Peripheral Control Module
11.7.10 DMA Channel 2 Base and Current Address Registers
DMA channel 2’s base and current address registers (DBAR2 and DCAR2) function exactly like
DMA channel 1’s except that they are used exclusively for dual-panel operation. (See the preceding
sections.) When SDS=1, DMA channel 2 is used to supply frame buffer data to the lower half of the
display. Note that the palette buffer, which resides within the first 16 or 256 entries of the frame buffer,
is utilized only by DMA channel 1. The user should not place palette entries into the frame buffer for
DMA channel 2. The base address for channel 2 points to the first encoded pixel values for the lower
half of the display. For dual-panel operation, the user must perform the following sequence in order:
disable the LCD (LEN=0), program dual-panel mode (SDS= 0 → 1), write the upper panel DMA base
address, write the lower DMA base address and enable the LCD (LEN= 0 → 1). The following figures
show the format of these registers; question marks indicate that the values are unknown at reset.
Address: 0h B010 0018
DBAR2: DMA Channel 2 Base Address Register
Read/Write
Bit
Reset
Bit
31
30
29
?
28
?
27
26
25
24
23
22
21
20
?
19
?
18
17
16
?
DMA Channel 2 Base Address Pointer
?
?
?
?
?
9
?
?
?
?
?
?
15
?
14
?
13
?
12
?
11
?
10
?
8
7
6
5
4
3
2
1
0
DMA Channel 2 Base Address Pointer
Reset
?
?
?
?
?
?
?
?
?
?
Bit
Name
DBAR2
Description
31..0
DMA channel 2 base address pointer.
Used to specify the base address of the frame buffer within off-chip memory for the lower
half of the display in dual-panel operation. Value in DBAR2 is transferred to current
address pointer register 2 when LCD is first enabled (LEN= 0 → 1) and when the current
address pointer value reaches the end-of-frame buffer. DBAR2 should be written only
when the LCD is disabled or immediately after an interrupt is generated by setting the
base address update status (BAU) bit. The base address must be on a quadword
boundary. The user must always write bits 0 through 3 to zero.
Address: 0h B010 001C
DCAR2: DMA Channel 2 Current Address Register
Read-Only
Bit
Reset
Bit
31
30
29
28
?
27
?
26
25
24
23
22
21
20
?
19
?
18
?
17
16
?
DMA Channel 2 Current Address Pointer
?
?
?
?
?
9
?
8
?
7
?
6
?
?
1
?
15
?
14
?
13
?
12
?
11
?
10
?
5
4
3
2
0
DMA Channel 2 Current Address Pointer
Reset
?
?
?
?
?
?
?
?
?
Bit
Name
Description
DMA channel 2 current address pointer.
Read-only register. Continuously reflects the current address that DMA channel 2 is
31..0
DCAR2
transferring from or will use in the next transfer. Base address register is transferred to
this register whenever the LCD is first enabled and when the current address is equal to
the calculated end address of the buffer.
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Peripheral Control Module
11.7.11 LCD Controller Status Register
The LCD controller status register (LCSR) contains bits that signal overrun and underrun errors for
both the input and output FIFOs, ac bias pin transition count, LCD disabled, DMA base update
ready, and DMA transfer bus error conditions. Each of these hardware-detected events signal an
interrupt request to the interrupt controller.
Each of the LCD’s status bits signal an interrupt request as long as the bit is set. Once the bit is
cleared, the interrupt is cleared. Read/write bits are called status bits (read-only bits are called
flags). Status bits are referred to as “sticky” (once set by hardware, they must be cleared by
software). Writing a one to a sticky status bit clears it; writing a zero has no effect. Read-only flags
are set and cleared by hardware; writes have no effect. The user has the ability to mask all LCD
interrupts by clearing bit 12 within the interrupt controller mask register (ICMR). See the
11.7.11.1 LCD Disable Done Flag (LDD) (read/write, maskable interrupt)
The LCD disable done flag (LDD) is set after the LCD has been disabled and the frame that is
active finishes being output to the LCD’s data pins. When the LCD is disabled by clearing the LCD
enable bit (LEN= 0 → 1) in LCCR0, the LCD allows the current frame to complete before it is
disabled. After the last set of pixels is clocked out onto the LCD’s data pins by the pixel clock, the
LCD is disabled, LDD is set, and an interrupt request is made to the interrupt controller if it is
unmasked (LDM=0). This interrupt is useful to allow an orderly shutdown of the LCD controller
before the user places the SA-1100 into sleep mode.
11.7.11.2 Base Address Update Flag (BAU) (read-only, maskable interrupt)
The base address update flag (BAU) is a read-only bit that is set after the contents of the DMA base
address register 1 are transferred to the DMA current address register 1 and is cleared when DMA
base address register 1 is written. The value in the base address register is transferred to the current
address register when the LCD is first enabled by writing a one to LEN (LEN= 0 → 1) and when the
current address pointer equals the end address value calculated by the LCD controller. When BAU
is set, an interrupt request is made to the interrupt controller if it is unmasked (BAM = 0). This
interrupt allows the user to program the DMA with a new base address value to alternate between
two or more frame buffer locations. When dual-panel mode is enabled (SDS=1), both DMA
channels are enabled, and BAU is set only after both channels’ base address registers are
transferred to their corresponding current address registers (1 and 2) and is cleared when DMA
base address register 2 (lower panel) is written. Therefore, the user must always update the DMA
base address register 1 (upper panel) first in dual-panel mode.
11.7.11.3 Bus Error Status (BER) (read/write, maskable interrupt)
The bus error status (BER) bit is set when a DMA transfer causes a bus error to occur on the ARM
system bus. A bus error is signalled when the DMA controller attempts to access a reserved or
nonexistent memory space. When this occurs, the SA-1100’s memory controller returns zeros for
the read. It asserts the bus error signal to the LCD’s DMA, which in turn, causes the BER bit to be
set and an interrupt request is made to the interrupt controller if it is unmasked (ERM = 0). The
DMA is not disabled as a result of the bus error and operation continues as normal. If a DMA
access causes a bus error, zeros are returned by the memory controller, which causes a palette entry
to be filled with zeros (highest intensity color or black), or if pixel data is being DMAed, the LCD
accesses the first location of the palette RAM one or more times.
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11.7.11.4 AC Bias Count Status (ABC) (read/write, nonmaskable interrupt)
The ac bias count status (ABC) bit it set each time the ac bias pin (L_BIAS) transitions a particular
number of times as specified by the ac bias pin transitions per interrupt (API) field in LCCR3. If
API is programmed with a nonzero value, a counter is loaded with the value in API and is
decremented each time the L_BIAS pin reverses state. When the counter reaches zero, the ABC bit
is set, which signals an interrupt request to the interrupt controller. The counter reloads using the
value in API, but does not start to decrement again until ABC is cleared by the user.
11.7.11.5 Input FIFO Overrun Lower Panel Status (IOL) (read/write, maskable
interrupt)
The input FIFO overrun lower panel status (IOL) bit is set when the LCD’s DMA channel 2
attempts to place data into the lower panel’s input FIFO after it has been completely filled. It is
cleared by writing a one to the bit. This bit is used only in dual-panel mode (SDS=1). When this bit
is set, an interrupt request is made to the interrupt controller if it is unmasked (ERM=0).
11.7.11.6 Input FIFO Underrun Lower Panel Status (IUL) (read/write, maskable
interrupt)
The input FIFO underrun lower panel status (IUL) bit is set when the lower panel’s input FIFO is
completely empty and the LCD’s pixel unpacking logic attempts to fetch data from the FIFO. It is
cleared by writing a one to the bit. This bit is used only in dual-panel mode (SDS=1). When this bit
is set, an interrupt request is made to the interrupt controller if it is unmasked (ERM=0).
11.7.11.7 Input FIFO Overrun Upper Panel Status (IOU) (read/write, maskable
interrupt)
The input FIFO overrun upper panel status (IOU) bit is set when the LCD’s DMA channel 1
attempts to place data into the upper panel’s input FIFO after it has been completely filled. It is
cleared by writing a one to the bit. This bit is used in single-panel mode (SDS=0) and dual-panel
mode (SDS=1). When this bit is set, an interrupt request is made to the interrupt controller if it is
unmasked (ERM=0).
11.7.11.8 Input FIFO Underrun Upper Panel Status (IUU) (read/write, maskable
interrupt)
The input FIFO underrun upper panel status (IUU) bit is set when the upper panel’s input FIFO is
completely empty and the LCD’s pixel unpacking logic attempts to fetch data from the FIFO. It is
cleared by writing a one to the bit. This bit is used in single-panel mode (SDS=0) and dual-panel
mode (SDS=1). When this bit is set, an interrupt request is made to the interrupt controller if it is
unmasked (ERM=0).
11.7.11.9 Output FIFO Overrun Lower Panel Status (OOL) (read/write, maskable
interrupt)
The output FIFO overrun lower panel status (OOL) bit is set when the LCD’s dither logic attempts
to place data into the lower panel’s output FIFO after it has been completely filled. It is cleared by
writing a one to the bit. This bit is used only in dual-panel mode (SDS=1). When this bit is set, an
interrupt request is made to the interrupt controller if it is unmasked (ERM = 0).
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Peripheral Control Module
11.7.11.10 Output FIFO Underrun Lower Panel Status (OUL) (read/write,
maskable interrupt)
The output FIFO underrun lower panel status (OUL) bit is set when the lower panel’s output FIFO
is completely empty and the LCD’s data pin driver logic attempts to fetch data from the FIFO. It is
cleared by writing a one to the bit. This bit is used only in dual-panel mode (SDS=1). When this bit
is set, an interrupt request is made to the interrupt controller if it is unmasked (ERM=0).
11.7.11.11 Output FIFO Overrun Upper Panel Status (OOU) (read/write,
maskable interrupt)
The output FIFO overrun upper panel status (OOU) bit is set when the LCD’s dither logic attempts
to place data into the upper panel’s output FIFO after it has been completely filled. It is cleared by
writing a one to the bit. This bit is used in single-panel mode (SDS=0) and dual-panel mode
(SDS=1). When this bit is set, an interrupt request is made to the interrupt controller if it is
unmasked (ERM=0).
11.7.11.12 Output FIFO Underrun Upper Panel Status (OUU) (read/write,
maskable interrupt)
The output FIFO underrun upper panel status (OUU) bit is set when the upper panel’s output FIFO
is completely empty and the LCD’s data pin driver logic attempts to fetch data from the FIFO. It is
cleared by writing a one to the bit. This bit is used in single-panel mode (SDS=0) and dual-panel
mode (SDS=1). When this bit is set, an interrupt request is made to the interrupt controller if it is
unmasked (ERM=0).
The following table shows the location of the status and flag bits in LCSR. For reserved bits, writes
are ignored and reads return zero. Set status bits should be cleared by software before enabling
both the LCD controller and interrupt controller.
Read/Write &
Address: 0h B010 0004
LCSR: LCD Status Register
Read-Only
Bit
Reset
Bit
31
30
29
28
0
27
0
26
0
25
24
23
22
21
0
20
0
19
0
18
0
17
16
0
Reserved
0
0
0
0
0
0
0
0
15
0
14
13
0
12
0
11
OUU
0
10
OOU
0
9
OUL
0
8
OOL
0
7
IUU
0
6
IOU
0
5
IUL
0
4
IOL
0
3
ABC
0
2
BER
0
1
BAU
0
0
LFD
1
Reserved
Reset
0
Bit
Name
Description
0
LDD
LCD disable done flag.
0 – LCD has not been disabled and the last active frame completed.
1 – LCD has been disabled and the last active frame has just completed.
1
BAU
Base address update flag (read-only).
0 – Base address has been written and has not yet been transferred to the current
address register.
1 – Base address has been transferred to the current address register, triggered either
by enabling the LCD or when the current address pointer equals the end address value
calculated by the LCD.
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Bit
Name
BER
Description
2
Bus error status.
0 – DMA has not attempted an access to reserved/nonexistent memory space.
1 – DMA has attempted an access to a reserved/nonexistent location in external
memory. The errant DMA read returns zeros.
3
ABC
AC bias count status.
0 – AC bias transition counter has not decremented to zero, or API is programmed to all
zeros.
1 – AC bias transition counter has decremented to zero, indicating that the L_BIAS pin
has transitioned the number of times specified by the API control bit field. Counter is
reloaded with the value in API but is disabled until the user clears ABC.
4
5
IOL
IUL
Input FIFO overrun lower panel status.
0 – Input FIFO for the lower panel display has not overrun.
1 – DMA attempted to place data into the input FIFO for the lower panel after it has been
filled.
Input FIFO underrun lower panel status.
0 – Input FIFO for the lower panel display has not underrun.
1 – DMA not supplying data to input FIFO for the lower panel at a sufficient rate. FIFO
has completely emptied; pixel unpacking logic has attempted to take added data from
the FIFO.
6
7
IOU
IUU
Input FIFO overrun upper panel status.
0 - Input FIFO for the upper or whole panel display has not overrun.
1 - DMA attempted to place data into the input FIFO for the upper or whole panel after it
has been filled.
Input FIFO underrun upper panel status.
0 – Input FIFO for the upper or whole panel display has not underrun.
1 – DMA not supplying data to input FIFO for the upper or whole panel at a sufficient
rate. FIFO has completely emptied; pixel unpacking logic has attempted to take added
data from the FIFO.
8
9
OOL
OUL
Output FIFO overrun lower panel status.
0 – Output FIFO for the lower panel display has not overrun.
1 – Dither logic attempted to place data into the output FIFO for the lower panel after it
had been filled.
Output FIFO underrun lower panel status.
0 – Output FIFO for the lower panel display has not underrun.
1 – LCD dither logic not supplying data to output FIFO for the lower panel at a sufficient
rate. FIFO has completely emptied and data pin driver logic has attempted to take
added data from the FIFO.
10
11
OOU
OUU
Output FIFO overrun upper panel status.
0 – Output FIFO for the upper or whole panel display has not overrun.
1 – Dither logic attempted to place data into the output FIFO for the upper or whole
panel after it had been filled.
Output FIFO underrun upper panel status.
0 – Output FIFO for the upper or whole panel display has not underrun.
1 – LCD dither logic not supplying data to output FIFO for the upper or whole panel at a
sufficient rate. FIFO has completely emptied and data pin driver logic has attempted to
take added data from the FIFO.
31..12
—
Reserved.
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11.7.12 LCD Controller Register Locations
Table 11-9 shows the registers associated with the LCD controller and the physical addresses used
to access them.
Table 11-9. LCD Controller Control, DMA, and Status Register Locations
Address
0hB010 0000
Name
LCCR0
Description
LCD controller control register 0
LCD controller status register 1
Reserved
0hB010 0004
LCSR
—
0hB010 0008 – 0h B010 000C
0hB010 0010
DBAR1
DCAR1
DBAR2
DCAR2
LCCR1
LCCR2
LCCR3
—
DMA channel 1 base address register
DMA channel 1 current address register
DMA channel 2 base address register
DMA channel 2 current address register
LCD controller control register 1
LCD controller control register 2
LCD controller control register 3
Reserved
0hB010 0014
0hB010 0018
0hB010 001C
0hB010 0020
0hB010 0024
0hB010 0028
0hB010 002C – 0hB010 FFFF
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11.7.13 LCD Controller Pin Timing Diagrams
Figure 11-10. Passive Mode Beginning-of-Frame Timing
VSP = 0
L_FCLK
L_LCLK
LEN set to 1
HSP = 0
L_PCLK
VSW = 1
ELW = 2
HSW = 6
BLW = 2
LDD[x:0]
Line 0 Data
PPL = 16
Line 1 Data
Line 2 Data
Notes:
LEN - LCD enable:
0 - LCD is disabled.
1 - LCD is enabled.
VSP - Vertical sync polarity:
0 - Frame clock is active high, inactive low.
1 - Frame clock is active low, inactive high.
VSW - Vertical Sync Pulse Width:
1 to 64 horizontal sync clock periods to assert the vertical sync signal (hsync transitions).
HSP - Horizontal sync polarity:
0 - Line clock is active high, inactive low.
1 - Line clock is active low, inactive high.
ELW - End-of-line pixel clock wait count:
1 to 256 "dummy" pixel clock periods to wait after last pixel in line before asserting line clock
(pixel clock does not transition).
BLW - Beginning-of-line pixel clock wait count:
1 to 256 "dummy" pixel clock periods to wait after line clock negated before asserting pixel clocks
(pixel clock does not transition).
HSW - Horizontal sync pulse width:
0 to 64 "dummy" pixel clock periods to assert the line clock (pixel clock does not transition).
PPL - Pixels per line:
16 to 1024 pixels per line on the screen (must be programmed on 16 pixel multiples).
Frame clock asserted on first pixel clock of each frame, and is negated one "dummy" pixel clock
period before the first pixel clock of the 2nd line.
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Figure 11-11. Passive Mode End-of-Frame Timing
L_FCLK
L_LCLK
L_PCLK
ELW = 1
VSW = 2
BLW = 1
LDD[x:0]
Line 479 Data
LPP = 480
Line 0 Data
Notes:
BLW - Beginning-of-line pixel clock wait count:
0 to 256 "dummy" pixel clock periods to wait after line clock is negated before asserting pixel
clocks (pixel clock does not transition).
VSW - Vertical sync pulse width:
In passive mode, 1 to 64 line clock periods to wait between the end of one frame and the
beginning of the next frame (line clock transitions).
ELW - End-of-line pixel clock wait count:
1 to 256 "dummy" pixel clock periods to wait after last pixel in line before asserting line clock
(pixel clock does not transition).
LPP - Lines per panel:
1 to 1024 lines per panel.
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Figure 11-12. Passive Mode Pixel Clock and Data Pin Timing
L_FCLK
L_LCLK
PCP = 0
L_PCLK
Data Pins Sampled
by the Display
Data Pins Change
Pixels 8 through 11 Pixels 12 through 15
LDD[3:0]*
*DPD = 0
Pixels 0 through 3
Pixels 4 through 7
Notes:
PCP - Pixel clock polarity:
0 - Pixels sampled from data pins on rising edge of pixel clock.
1 - Pixels sampled from data pins on falling edge of pixel clock.
DPD - Dual pixel data mode:
0 - 4 data pins are used in single-panel monochrome mode.
1 - 8 data pins are used in single-panel monochrome mode.
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Figure 11-13. Active Mode Timing
VSP = 0
VSW = 0
LEN set to 1
L_FCLK
(VSYNC)
HSW = 4
HSP = 0
L_LCLK
(HSYNC)
L_BIAS
(OE)
L_PCLK
BFW = 1
BFW = 2
ELW = 1
BLW = 1
LDD[7:0],
GPIO[9:2]
Line 0 Data
PPL = 16
Line 1 Data
Notes:
LEN - LCD enable:
0 - LCD is disabled.
1 - LCD is enabled.
VSP - Vertical sync polarity:
0 - Vertical sync clock is active high, inactive low.
1 - Vertical sync clock is active low, inactive high.
VSW - Vertical sync width:
1 to 64 horizontal sync clock periods to assert the vertical sync signal (hsync transitions).
HSW - Horizontal sync pulse width:
1 to 64 pixel clock periods to assert the line clock (pixel clock transitions).
HSP - Horizontal sync polarity:
0 - Horizontal sync clock is active high, inactive low.
1 - Horizontal sync clock is active low, inactive high.
BFW - Beginning-of-frame horizontal sync clock wait count:
0 to 255 horizontal sync clock periods to wait at the beginning of each frame (hsync transitions).
BLW - Beginning-of-line pixel clock wait count:
1 to 256 pixel clock periods to wait after line clock negated before asserting pixel clocks
(pixel clock transitions).
ELW - End-of-line pixel clock wait count:
1 to 256 pixel clock periods to wait after last pixel in line before asserting line clock (pixel clock
transitions).
PPL - Pixels per line:
1 to 1024 pixels per line on screen.
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Figure 11-14. Active Mode Pixel Clock and Data Pin Timing
L_FCLK
(VSYNC)
L_BIAS
OE)
L_LCLK
(HSYNC)
PCP = 0
L_PCLK
Data Pins Sampled
by the Display
Data Pins Change
LDD[7:0],
GPIO[9:2]
Pixels 0 through 15
Pixels 16 through 31 Pixels 32 through 47
Pixels 48 through 63
Notes:
PCP - Pixel clock polarity:
0 - Pixels sampled from data pins on rising edge of pixel clock.
1 - Pixels sampled from data pins on falling edge of pixel clock.
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11.8
Serial Port 0 – USB Device Controller
This section describes the implementation-specific options of the USB protocol for a device
controller as it applies to serial port 0, such as number, type, and function of the endpoints,
interrupts to the CPU, transmit/receive FIFO interface, and so on. It is assumed that the user has a
working knowledge of the USB standard. The UDC is USB-compliant and supports all standard
device requests issued by the host. For programmer convenience, summaries of UDC operation are
provided as well as quick reference tables. However, the user should refer to the Universal Serial
Bus Specification, Revision 1.01 for a full description of the USB protocol and its operation.
Serial port 0 is a universal serial bus device controller (UDC) that supports three endpoints and can
operate half-duplex at a baud rate of 12 Mbps (slave only, not a host or hub controller).
The serial information transmitted by the UDC contains layers of communication protocols, the most
basic of which are fields. UDC fields include: sync, packet identifier, address, endpoint, frame number,
data, and CRC fields. Fields are used to produce packets. Depending on the function of a packet, a
different combination and number of fields are used. Packet types include: token, start of frame, data,
and handshake packets. Packets are then assembled into groups to produce frames. These frames or
transactions fall into four groups: bulk, control, interrupt, and isochronous. (The UDC supports only
bulk and control.) Endpoint 0, by default, is used only to communicate control transactions to configure
the UDC after it is reset or hooked up (physically connected to an active USB host or hub). Endpoint 0’s
responsibilities include: connection, address assignment, endpoint configuration, bus enumeration, and
disconnect. Endpoint 1 is used to perform bulk OUT data transactions and receiving data from the USB
host; endpoint 2 is used to perform bulk IN data transactions and transmitting data to the USB host.
The UDC uses two separate FIFOs to buffer incoming and outgoing data to or from the host
(16-entry x 8-bit for transmitting, and 20-entry x 8-bit for receiving). The FIFOs can be filled or
emptied either by the DMA or the CPU, with service requests being signalled when either FIFO is
half-full or empty. Interrupts are signalled when the receive FIFO experiences an overrun and the
transmit FIFO experiences an underrun. The control endpoint 0 has an additional 8-entry x 8-bit
FIFO that can only be read or written by processor reads and writes.
The external pins dedicated to this interface are UDC+ and UDC-. The USB protocol uses
differential signalling between the two pins for half-duplex data transmission. A 1.5-Kohm pull-up
resistor is required to be connected to the USB cable’s D+ signal to pull the UDC+ pin high when
not driven. This signifies the UDC is a high-speed, 12-Mbps device and provides the correct
polarity for data transmission. Using differential signalling allows multiple states to be transmitted
on the serial bus. These states are combined to transmit data as well as various bus conditions,
including: idle, resume, start of packet, end of packet, disconnect, connect, and reset.
11.8.1
USB Operation
Following a reset of the SA-1100 or whenever the UDC is attached to a USB bus, all endpoints are
automatically configured by the UDC and the UDC is forced to use the USB default address of
zero. The host then assigns the UDC a unique address. At this point, the UDC is under the host’s
control and responds to its commands that are transmitted to endpoint 0 using control transactions.
Endpoint 1 is used to perform bulk OUT data transactions, receiving data from the USB host, and
endpoint 2 bulk IN data transactions, transmitting data to the USB host.
The following sections provide details of the USB protocol in a bottom-up fashion starting with
signalling levels.
1. The latest revision of the Universal Serial Bus Specification Revision 1.0 can be accessed via the World Wide Web Internet site at:
http://www.teleport.com/~usb/
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11.8.1.1
Signalling Levels
USB uses differential signalling to encode data and to communicate various bus conditions. The
USB specification refers to the J and K data states to differentiate between high- and low-speed
transmission. Because the UDC supports only 12-Mbps transmission, references are made only to
actual data state 0 and actual data state 1.
Four distinct states are represented using differential data by decoding the polarity of the UDC+
and UDC- pins. Two of the four states are used to represent data. A one is represented when UDC+
is high and UDC- is low; a zero is represented when UDC+ is low and UDC- is high. The
remaining two states and pairings of the four encodings are further decoded to represent the current
differential signalling.
Table 11-10. USB Bus States
Bus State
UDC+/UDC- Pin Levels
UDC+ high, UDC- low (same as a 1).
Idle
Resume
UDC+ low, UDC- high (same as a 0).
Start of Packet
End of Packet
Disconnect
Transition from idle to resume.
UDC+ AND UDC- low for 2-bit times followed by an idle for 1-bit time.
UDC+ AND UDC- below single-ended low threshold for more than 2.5 µs.
(Disconnect is the static bus condition that results when no device is plugged into a hub
port.)
Connect
Reset
UDC+ OR UDC- high for more than 2.5 µs.
UDC+ AND UDC- low for more than 2.5 µs. (Reset is driven by the host controller and
sensed by a device controller.)
Hosts and hubs have pull-down resistors on both the D+ and D- lines. When a device is not attached
to the cable, the pull-down resistors cause D+ and D- to be pulled down below the single-ended low
threshold of the host or hub. This creates a state called single-ended zero (SE0). A disconnect is
detected by the host when an SE0 persists for more than 2.5 µs (30-bit times). When the UDC is
connected to the USB cable, the pull-up resistor on the UDC+ pin causes D+ to be pulled above the
single-ended high threshold level. After 2.5 µs elapse, the host detects a connect.
After this point, the bus is in the idle state because UDC+ is high and UDC- is low. A start of
packet is signalled by transitioning the bus from the idle to the resume state (a 1 to 0 transition).
The beginning of each USB packet begins with a sync field, which starts with the 1-to-0 transition
transferred, an end of packet is signalled by pulling both UDC+ and UDC- low for 2-bit times,
followed by an idle for 1-bit time. If the idle persists for more than 3 ms, the UDC enters suspend
mode and it is placed in low-power mode. The UDC can be awakened from the suspend state by
the host by switching the bus to the resume state via normal bus activity, or by signalling a reset.
Under normal operating conditions, the host ensures that devices do not enter the suspend state by
periodically signalling an end of packet (EOP).
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11.8.1.2
Bit Encoding
USB uses nonreturn to zero inverted (NRZI) to encode individual bits. Both the clock and the data
are encoded and transmitted within the same signal. Instead of representing data by controlling the
state of the signal, transitions are used. A zero is represented by a transition, and a one is
represented by no transition (this produces the data). Each time a zero occurs, the receiver logic
synchronized the baud clock to the incoming data (this produces the clock). To ensure the receiver
is periodically synchronized, any time six consecutive ones are detected in the serial bit stream, a
zero is automatically inserted by the transmitter. This procedure is known as “bit stuffing”. The
receiver logic, in turn, automatically detects stuffed bits and removes them from the incoming data.
Bit stuffing causes a transition on the incoming signal at least once every seven bit-times to
guarantee baud clock lock. Bit stuffing is enabled for an entire packet beginning when the start of
packet is detected until the end of packet is detected (enabled during the sync field all the way
Figure 11-15. NRZI Bit Encoding Example
Bit
Value
1
1
0
1
0
0
1
0
Digital
Data
NRZI
Data
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11.8.1.3
Field Formats
Individual bits are assembled into groups called fields. Fields are used to construct packets and
packets are used to construct frames or transactions. The seven USB field types include: sync,
packet identifier, address, endpoint, frame number, data, and CRC fields.
A sync is preceded by the idle state on the USB bus and is always the first field of every packet.
The first bit of a sync field signals the start of packet (SOP) to the UDC or host. A sync is 8 bits
wide and consists of seven zeros followed by a one (0x80).
The packet identifier (PID) is 1 byte wide and always follows the sync field. The first 4 bits contain
an encoded value that represents packet type (token, data, handshake, special), packet format, and
type of error detection. The last four bits contain a check field that ensures the PID is transmitted
without errors. The check field is generated by performing a ones complement of the PID. The UDC
automatically XORs the PID and check field and takes the appropriate action (as prescribed by the
USB standard) if the result does not contain all ones, indicating an error has occurred in transmission.
The UDC’s three endpoints are accessed using the address and endpoint fields. The address field
contains 7 bits and permits 128 unique devices to be placed on the USB. After the SA-1100 is reset,
or a reset is signalled via the USB bus, the UDC (and all other 127 possible devices) is assigned the
default address of zero. The host is then responsible for assigning unique addresses for each device
on the bus. This is performed in the enumeration process one device at a time. Once the host
assigns the UDC an address, it responds only to transactions addressed to it. The address field is
transmitted in every packet and follows the PID field.
When the UDC detects that a packet is addressed to it, the endpoint field is used to determine
which of the UDC’s three endpoints are being addressed. The endpoint field is 4 bits. However,
only the encodings for endpoints 0 through 2 are allowed. The endpoint field follows the address
.
Table 11-11. Endpoint Field Addressing
Endpoint Field Value
UDC Endpoint Selected
0000
0001
0010
0011
01xx
10xx
11xx
Endpoint 0
Endpoint 1
Endpoint 2
Invalid
Invalid
Invalid
Invalid
The frame number is an 11-bit field that is incremented by the host each time a frame is
transmitted. When it reaches its maximum value of 2047 (0x7FF), it rolls over. It is transmitted in
the start of frame (SOF) packet, which is output by the host in 1 ms intervals. The frame number
field is used only by device controllers to control isochronous transfers, and therefore, does not
affect the UDC. Data fields are used to transmit the bulk data between the host and the UDC. A
data field is made up of 0 to 1023 bytes. Each byte is transmitted LSB first.
Cyclic redundancy check fields are used to detect errors introduced during transmission of token
and data packets, and is applied to all the fields in the packet except the PID field (recall the PID
contains its own 4-bit ones complement check field for error detection). Token packets use a 5-bit
CRC (x5+x2+1) and data packets use a 16-bit CRC (x16+x15+x2+1). For both CRCs, the checker is
reset to all ones at the start of each packet.
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11.8.1.4
Packet Formats
USB supports four packet types: token, data, handshake, and special. A token packet is placed at
the beginning of a frame and is used to identify OUT, IN, SOF, and SETUP transactions. OUT and
IN frames are used to transfer data, SOF packets are used to time isochronous transactions, and
SETUP packets are used for control transfers to configure endpoints. A token packet consists of a
transactions, the address and endpoint fields are used to select which UDC endpoint is to receive
the data, and for an IN transaction, which endpoint must transmit data.
Figure 11-16. IN, OUT, and SETUP Token Packet Format
8 bits
Sync
8 bits
PID
7 bits
4 bits
5 bits
Address
Endpoint
CRC5
A start of frame (SOP) is a special type of token packet that is issued by the host once every 1 ms.
SOF packets consist of a sync, a PID, a frame number (which is incremented after each frame is
does not make use of the frame number field, the presence of SOF packets every 1ms will prevent
the UDC from going into suspend mode.
Figure 11-17. SOF Token Packet Format
8 bits
Sync
8 bits
PID
11 bits
5 bits
Frame Number
CRC5
Data packets follow token packets, and are used to transmit data between the host and UDC. There
are two types of data packets as specified by the PID: DATA0 and DATA1. These two types are
used to provide a mechanism to guarantee data sequence synchronization between the transmitter
and receiver across multiple transactions. During the handshake phase, both communicate and
agree which data token type to transmit first. For each subsequent packet transmitted, the data
packet type is toggled ( DATA0, DATA1, DATA0, and so on). A data packet consists of a sync, a
Figure 11-18. Data Packet Format
8 bits
Sync
8 bits
PID
0–1023 bytes
Data
16 bits
CRC16
Handshake packets consist of only a sync and a PID. Handshake packets do not contain a CRC
because the PID contains its own check field. They are used to report data transaction status,
including whether data was successfully received, flow control, and stall conditions. Only
transactions that support flow control can return handshakes. The three types of handshake packets
are: ACK, NAK, and STALL. ACK indicates that a data packet was received without bit stuffing,
CRC, or PID check errors. NAK indicates that the UDC was unable to accept data from the host or
it has no data to transmit. NAK is also used by endpoint 1 to indicate no interrupts are pending.
STALL indicates that the UDC is unable to transmit or receive data, and requires host intervention
to clear the stall condition. Bit stuffing, CRC, and PID errors are signalled by the receiving unit by
Figure 11-19. Handshake Packet Format
8 bits
Sync
8 bits
PID
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11.8.1.5
Transaction Formats
Packets are assembled into groups to form transactions. Four different transaction formats are used
in the USB protocol. Each is specific to a particular endpoint type: bulk, control, interrupt, and
isochronous. Note that isochronous and interrupt transactions are not supported by the UDC and
are not described in this section. Endpoint 0, by default, is a control endpoint and receives only
control transactions; both endpoints 1 and 2 use bulk transactions. Note that all USB bus
transactions are initiated by the host controller and that transmission takes place between the host
and UDC one direction at a time (half-duplex).
Bulk transactions guarantee error-free transmission of data between the host and UDC by using
packet error detection and retry. The three packet types used to construct bulk transactions are:
token, data, and handshake. The eight possible types of bulk transactions based on data direction,
host are highlighted in boldface type, and packets sent by the host to the UDC are not.
Figure 11-20. Bulk Transaction Formats
Action
Token Packet
Data Packet
Handshake Packet
ACK
Host successfully received data from UDC
IN
DATA0/DATA1
UDC temporarily unable to transmit data
UDC endpoint needs host intervention
Host detected PID, CRC, or bit stuff error
UDC successfully received data from host
UDC temporarily unable to receive data
UDC endpoint needs host intervention
UDC detected PID, CRC, or bit stuff error
IN
None
NAK
STALL
None
ACK
IN
None
IN
DATA0/DATA1
DATA0/DATA1
DATA0/DATA1
DATA0/DATA1
DATA0/DATA1
OUT
OUT
OUT
OUT
NAK
STALL
none
Packets from UDC to host are boldface
Control transactions are used by the host to configure endpoints and query their status. Like bulk
transactions, control transactions begin with a setup packet, followed by an optional data packet,
then a handshake packet. Note that control transactions, by default, use DATA0 type transfers.
Figure 11-21 shows the four possible types of control transactions. Note that packets sent by the
UDC to the host are highlighted in boldface type, and packets sent by the host to the UDC are not.
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Figure 11-21. Control Transaction Formats
Action
Token Packet
Data Packet
Handshake Packet
ACK
UDC successfully received control from host
SETUP
DATA0
UDC temporarily unable to receive data
UDC endpoint needs host intervention
UDC detected PID, CRC, or bit stuff error
SETUP
SETUP
SETUP
DATA0
DATA0
DATA0
NAK
STALL
None
Packets from UDC to host are boldface
Control transfers are assembled by the host by first sending a control transaction to tell the UDC
what type of control transfer is taking place (control read or control write), followed by two or
more bulk data transactions. The control transaction, by default, uses a DATA0 transfer, and each
subsequent bulk data transaction toggles between DATA1 and DATA0 transfers. For a control write
to an endpoint, OUT transactions are used. For control reads, IN transactions are used. The transfer
direction of the last bulk data transaction is reversed. It is used to report status and functions as a
handshake. The last bulk data transaction always uses a DATA1 transfer by default (even if the
previous bulk transaction used DATA1). For a control write, the last transaction is an IN from the
UDC to the host, and for a control read, the last transaction is an OUT from the host to the UDC.
11.8.1.6
UDC Device Requests
The UDC’s control, status, and data registers are used only to control and monitor the transmit and
receive FIFOs for endpoints 1 and 2. All other UDC configuration and status reporting is controlled
by the host via the USB bus using device requests that are sent as control transactions to endpoint
0. Each setup packet to endpoint 0 is 8 bytes long and specifies:
• Data transfer direction: host to device, device to host
• Data transfer type: standard, class, vendor
• Data recipient: device, interface, endpoint, other
• Number of bytes to transfer
• Index or offset
• Value: used to pass a variable-sized data parameter
• Device request
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Specification Revision 1.0 for a full description of host device requests.
Table 11-12. Host Device Request Summary
Request
Name
SET_FEATURE
Used to enable a specific feature such as device remote wake-up and
endpoint stalls.
CLEAR_FEATURE
Used to clear or disable a specific feature.
SET_CONFIGURATION
Configures the UDC for operation. Used following a reset of the SA-1100 or
after a reset has been signalled via the USB bus.
GET_CONFIGURATION
SET_DESCRIPTOR
Returns the current UDC configuration to the host.
Used to set existing descriptors or add new descriptors. Existing descriptors
include: device, configuration, string, interface, and endpoint.
GET_DESCRIPTOR
SET_INTERFACE
GET_INTERFACE
GET_STATUS
Returns the specified descriptor if it exists.
Used to select an alternate setting for the UDC’s interface.
Returns the selected alternate setting for the specified interface.
Returns the UDC’s status including: remote wake-up, self-powered, data
direction,
endpoint number, and stall status.
SET_ADDRESS
SYNCH_FRAME
Sets the UDC’s 7-bit address value for all future device accesses.
Used to set and then report an endpoint’s synchronization frame.
11.8.2
UDC Register Definitions
All configuration, request/service, and status reporting is controlled by the USB host controller and
is communicated to the UDC via the USB bus. Several registers are available to the programmer to
control the interfacing of the UDC to software. A control register is used to enable the UDC and to
mask the various interrupt sources that exist within the UDC. A status register is used to indicate
the state of the various interrupt sources. The device address register is available, which software
writes when parsing a SET_ADDRESS command from the USB host controller. There is a register
for each of the OUT and IN endpoints’ maximum packet size. All three endpoints (control, OUT,
and IN) have a control/status register. Endpoint 0 (control) has an address for the 8 x 8 data FIFO
used for both transmitting and receiving data, as well as a write count register used to determine
how many bytes the USB host controller has sent to the endpoint 0. Both endpoints 1 and 2 (OUT
and IN, respectively) share a data register address that contains an 8-bit field, which addresses the
top of the transmit FIFO and bottom of the receive FIFO. When it is read, the receive FIFO is
accessed, and when it is written, the transmit FIFO is accessed.
Note: Due to the internal synchronization required by the UDC’s configuration registers, it is possible for
the processor to write the UDC registers and FIFOs too fast. It is required that all writes to the UDC
be complete before another write may take place. In order to guarantee that a write is complete, it is
necessary to observe the effect of a write before another write may take place. For example, when
writing a UDC register followed by an immediate read to verify data in the same register, the first
read will be invalid and the second read will have correct data.
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11.8.3
UDC Control Register
The UDC control register (UDCR) contains seven control bits: two to enable or disable the UDC
and five to mask the transmit and receive FIFO service requests.
11.8.3.1
UDC Disable (UDD)
The UDC disable (UDD) bit is used to enable and disable the UDC. When UDD=0, the UDC is
enabled for serial transmission or reception. When UDC=1, it is disabled and the UDC+ and UDC-
pins are tristated.
If UDD is written to one the entire UDC design is reset. If this is done while the UDC is actively
transmitting or receiving data, it stops immediately and the remaining bits within the transmit or
receive serial shifter are reset. In addition, all entries within the transmit and receive FIFO ar reset.
11.8.3.2
11.8.3.3
UDC Active (UDA)
This read-only bit can be read to determine if the UDC is currently active. A one indicates that the
UDC is currently involved in a transaction.
Bit 2 Reserved
Bit 2 is reserved and should always be written to a zero to ensure compatibility with future
revisions of this design. This bit also will be set if the UDC detects that the data toggle mechanism
did not occur.
11.8.3.4
11.8.3.5
11.8.3.6
Endpoint 0 Interrupt Mask (EIM)
The endpoint 0 interrupt mask (EIM) bit is used to mask or enable the endpoint 0 interrupt request.
When EIM=1, the interrupt is masked and the EIR bit in the status/interrupt register is not allowed
to be set. When EIM=0, the interrupt is enabled, and whenever an interruptible condition occurs in
the receiver, the EIR bit is set. Note that programming EIM=1 does not affect the current state of
EIR; it only blocks future zero to one transitions of EIR.
Receive Interrupt Mask (RIM)
The receive interrupt mask (RIM) bit is used to mask or enable the receive FIFO service request
interrupt. When RIM=1, the interrupt is masked and the RIR bit in the status/interrupt register is
not allowed to be set. When RIM=0, the interrupt is enabled, and whenever an interruptible
condition occurs in the receiver, the RIR bit is set. Note that programming RIM=1 does not affect
the current state of RIR; it only blocks future zero to one transitions of RIR.
Transmit Interrupt Mask (TIM)
The transmit interrupt mask (TIM) bit is used to mask or enable the transmit endpoint 2 interrupt
request. When TIM=1, the interrupt is masked and the TIR bit in the status/interrupt register is not
allowed to be set. When TIM=0, the interrupt is enabled, and whenever an interruptible condition
occurs in the transmitter, the TIR bit is set. Note that programming TIM=1 does not affect the
current state of TIR; it only blocks future zero to one transitions of TIR.
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11.8.3.7
11.8.3.8
Suspend/Resume Interrupt Mask (SRM)
The suspend/resume interrupt mask (SRM) bit is used to mask or enable the suspend/resume
interrupt request. When SRM=1, the interrupt is masked, and the SUSIR/RESIR bits in the
status/interrupt register are not allowed to be set. When SRM=0, the interrupt is enabled, and
whenever a suspend or resume condition occurs, the SUSIR or RESIR bit is set. Note that
programming SRM=1 does not affect the current state of SUSIR/RESIR; it only blocks future zero
to one transitions of SUSIR/RESIR.
Reset Interrupt Mask (REM)
The reset interrupt mask (REM) bit is used to mask or enable the reset interrupt request. When
REM=1, the interrupt is masked, and the RSTIR bit in the status/interrupt register is not allowed to
be set. When REM=0, the interrupt is enabled, and whenever the USB host controller issues a reset
to the UDC, the RSTIR bit is set. Note that programming REM=1 does not affect the current state
of RSTIR; it only blocks future zero to one transitions of RSTIR.
The following table shows the location of the UDE, RIM, and TIM bits in UDC control register
(UDCR). The state of RIM and TIM are unknown and must be initialized before enabling the
UDC. The UDE bit is cleared to zero, disabling the UDC following a reset of the SA-1100. This
gives control of the UDC’s pins to the PPC unit that configures them as inputs. Writes to reserved
bits are ignored and reads return zeros.
Address: 0h 8000 0000
UDCCR
Read/Write & Read Only
Bit
7
REM
0
6
SRM
1
5
TIM
0
4
3
EIM
0
2
Res.
0
1
UDA
0
0
UDD
1
RIM
0
Reset
Bit
Name
Description
0
UDD
UDD disable.
0 – UDD disabled.
1 – UDD enabled, UDC+ and UDC- used for USB serial transmission/reception.
1
UDA
UDC active (read-only).
0 – UDC currently inactive.
1 – UDC currently active.
2
3
—
Reserved.
EIM
Endpoint zero interrupt mask.
0 – Endpoint zero interrupt enabled.
1 – Endpoint zero interrupt disabled.
4
5
6
7
RIM
TIM
Receive interrupt mask.
0 – Receive interrupt enabled.
1 – Receive interrupt disabled.
Transmit interrupt mask.
0 – Transmit interrupt enabled.
1 – Transmit interrupt disabled.
SRM
REM
Suspend/resume interrupt mask.
0 – Suspend/resume interrupt enabled.
1 – Suspend/resume interrupt disabled.
Reset interrupt mask.
0 – Reset interrupt enabled.
1 – Reset interrupt disabled.
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11.8.4
UDC Address Register
The UDC address register contains a 7-bit field that holds the device address. After a reset of the
UDC core, the value of this register is zero. The CPU writes an address to this register when it
receives a SET_ADDRESS from the USB host controller. It extracts the address assigned to the
UDC from the SET_ADDRESS command and writes the value into the UDC address register. The
new address is not propagated to the rest of the UDC core until the SET_ADDRESS command is
completed with an acknowledged handshake from the UDC.
Address: 0h 8000 0004
UDCAR
Read/Write
Bit
7
Res
0
6
5
4
3
2
1
0
0
7-bit Function Address
Reset
0
0
0
0
0
0
Bit
Name
Description
7
—
Reserved.
Always read zero.
Function address field
7-bit function address. Reset to all zero.
6..0
Address
11.8.5
UDC OUT Max Packet Register
The UDC OUT max packet register holds the value of the maximum packet size the UDC core will
accept minus one. This is done in order to accommodate maximum packets of 256 bytes, without
going to a max packet field of more than 8 bits. In order to accept packets up to 256 bytes, a value
of 0xff (255) should be written into the OUT max packet register. At reset the OUT max packet
register contains 0x08, and will therefore accept packets of length 9 bits or less.
Address: 0h 8000 0008
UDCOMP
Read/Write
Bit
7
6
5
0
4
3
2
0
1
0
0
Max Packet Size - 1
Reset
0
0
0
1
0
Bit
Name
Description
7..0
OUT
MaxP
OUT max packet size.
8-bit field containing the value of the maximum packet size minus one.
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11.8.6
UDC IN Max Packet Register
The UDC IN max packet register holds the value of the number of bytes the UDC core is to
transmit minus one. This is done in order to accommodate maximum packets of 256 bytes, without
going to a max packet field of more than 8 bits. In order to transmit packets of 256 bytes, a value of
0xff (255) should be written into the IN max packet register. At reset the IN max packet register
contains 0x08, and will therefore transmit packets of length 9 bits.
Address: 0h 8000 000C
UDCIMP
Read/Write
Bit
7
6
5
0
4
3
2
0
1
0
0
Max Packet Size - 1
Reset
0
0
0
1
0
Bit
Name
Description
7..0
IN MaxP
IN max packet size.
8-bit field containing the value of the number of bytes to transmit minus one.
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11.8.7
UDC Endpoint 0 Control/Status Register
The UDC endpoint zero control/status register contains 8 bits that are used to operate endpoint zero
(control endpoint).
11.8.7.1
OUT Packet Ready (OPR)
The OUT packet ready bit is set by the UDC when it receives a valid token to endpoint zero. When
this bit is set, the EIR bit will be set in the UDC status/interrupt register if endpoint zero interrupts
are enabled. This bit is cleared by writing a one to the serviced out packet ready bit (6). The UDC
is not allowed to enter the data phase of a transaction until this bit is cleared. If there is no data
phase, then the CPU should set the data end bit (4) at the same time it clears this bit.
11.8.7.2
11.8.7.3
IN Packet Ready (IPR)
The IN packet ready bit is set by the CPU after it has written a packet to the endpoint zero FIFO to
be transmitted. The UDC will automatically clear this bit when the packet has been successfully
transmitted. When this bit is cleared, the EIR bit in the UDC status/interrupt register will be set if
endpoint zero interrupts are enabled. The CPU will not be able to clear this bit.
Sent Stall (SST)
The sent stall bit is set by the UDC when it must abort the current control transfer by issuing a
STALL handshake due to a protocol violation. When this bit is set, the EIR bit in the UDC
status/interrupt register will be set if endpoint zero interrupts are enabled. The CPU clears this bit
by writing a one to it.
11.8.7.4
11.8.7.5
Force Stall (FST)
The force stall bit can be set by the UDC to force the UDC to issue a STALL handshake. The UDC
issues a STALL handshake for the current setup control transfer and the bit is cleared by the UDC
because endpoint zero cannot remain in a stalled condition.
Data End (DE)
The data end bit is set by the UDC after it writes the last packet for the current descriptor. Once the
current setup transfer has ended, the UDC clears this bit. When this bit is cleared the EIR bit in the
UDC status/interrupt register will be set if endpoint zero interrupts are enabled. If there is no data
phase, the CPU should set this bit at the same time it clears the OPR bit (0).
11.8.7.6
Setup End (SE)
The setup end bit is set by the UDC when a control transfer ends before the DE bit (4) gets set.
When this bit is set the EIR bit in the UDC status/interrupt register will be set if endpoint zero
interrupts are enabled. This bit is cleared by writing a one to the serviced setup end bit (7). When
the CPU detects this bit being set (if the OPR bit (0) is also set), then it should unload the new setup
packet after it clears setup end.
11.8.7.7
Serviced OPR (SO)
The serviced bit will clear the OPR bit (0) when writing a one.
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11.8.7.8
Serviced Setup End (SSE)
The serviced setup end bit will clear the SE bit (5) when writing a one.
Address: 0h 8000 0010
UDCCS0
Read/Write
Bit
7
SSE
0
6
SO
0
5
SE
0
4
3
FST
0
2
SST
0
1
IPR
0
0
OPR
0
DE
0
Reset
Bit
Name
Description
0
1
2
3
4
5
6
7
OPR
OUT packet ready (read-only).
1 – OUT packet ready.
IPR
SST
FST
DE
IN packet ready (read/write 1 to set).
1 – IN packet ready.
Sent stall (read/write 1 to clear).
1 – UDC sent stall handshake.
Force stall (read/write 1 to set).
1 – Force stall handshake.
Data end (read/write 1 to set).
1 – The last byte of the data phase has been written.
SE
Setup end (read-only).
1 – Control transfer ended before data end got set.
SO
Serviced OPR (write-only).
1 – Clear OPR, bit 0.
SSE
Serviced setup end (write-only).
1 – Clear SE, bit 5.
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11.8.8
UDC Endpoint 1 Control/Status Register
The UDC endpoint 1 control/status register contains 6 bits that are used to operate endpoint 1
(OUT endpoint).
11.8.8.1
Receive FIFO Service (RFS)
The receive FIFO service bit will be set if the receive FIFO has between 8 and 12 or more bytes
(out of 20) in it. Because the FIFOs are asynchronous, the exact threshold cannot be determined,
but is guaranteed to be in this range. This signal is also used as a DMA request signal to trigger the
DMA unit to service the FIFO.
11.8.8.2
Receive Packet Complete (RPC)
The receive packet complete bit gets set by the UDC when an OUT packet has been received.
When this bit is set the RIR bit in the UDC status/interrupt register will be set if receive interrupts
are enabled. This bit can be used to validate the other status/error bits in the endpoint 1
control/status register. The RPC bit gets cleared by writing a one to it. The UDC will issue NAK
handshakes to all OUT tokens while this bit is set.
11.8.8.3
11.8.8.4
Receive Packet Error (RPE)
The receive packet error bit will be set if a CRC, bit stuffing, or FIFO overrun error occurs. It is
only valid if the RPC bit (1) is set and gets cleared when the RPC bit gets cleared.
Sent Stall (SST)
The sent stall bit is set by the UDC when it must abort the current transfer by issuing a STALL
handshake due to a protocol violation (the host sends more data than the maximum packet size).
The CPU clears this bit by writing a one to it.
11.8.8.5
11.8.8.6
Force Stall (FST)
The force stall bit can be set by the UDC to force the UDC to issue a STALL handshake to all OUT
tokens. STALL handshakes will continue to be sent until the CPU clears this bit. The sent stall bit
(3) will be set when the STALL state is actually entered (this may be delayed if the UDC is active
when the FST bit is set), and the STALL state will not be exited until both the FST and SST bits are
cleared.
Receive FIFO Not Empty (RNE)
The receive FIFO not empty bit indicates that there is unread data in the receive FIFO. This bit
must be polled when the RPC bit is set to determine if there is any data in the FIFO that DMA did
not read. The receive FIFO must continue to be read until this bit clears or data will be lost.
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11.8.8.7
Bits 7..6 Reserved
Bits 7..6 are reserved for future use.
Address: 0h 8000 0014
UDCCS1
Read/Write
Bit
7
6
5
RNE
0
4
3
SST
0
2
RPE
0
1
RPC
0
0
RFS
0
Res.
FST
0
Reset
0
0
Bit
Name
Description
Receive FIFO service (read-only).
0
1
2
RFS
0 – Receive FIFO has less than 12 bytes.
1 – Receive FIFO has 12 bytes or more.
Receive packet complete (read/write 1 to clear).
0 – Error/status bits invalid.
RPC
RPE
1 – Receive packet has been received and error/status bits are valid.
Receive packet error (read-only).
0 – Receive packet has no errors.
1 – Receive packet has errors; valid only when RPC is set.
Sent stall (read/write 1 to clear).
3
4
SST
FST
1 – STALL handshake was sent; valid only when RPC is set.
Force stall (read/write).
1 – Issue STALL handshakes to OUT tokens.
Receive FIFO not empty (read-only).
0 – Receive FIFO empty.
5
RNE
—
1 – Receive FIFO not empty.
Reserved.
7..6
Always reads zero.
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11.8.9
UDC Endpoint 2 Control/Status Register
The UDC endpoint 2 control status register contains 6 bits that are used to operate endpoint 2
(IN endpoint).
11.8.9.1
Transmit FIFO Service (TFS)
The transmit FIFO service bit will be active if there are 8 or less (out of 16) bytes remaining in the
transmit FIFO. This bit will be used as a DMA request to trigger the DMA unit to service the
transmit FIFO.
11.8.9.2
Transmit Packet Complete (TPC)
The transmit packet complete bit will be set by the UDC when an entire packet has been sent to the
host. When this bit is set, the TIR bit in the UDC status/interrupt register will be set if transmit
interrupts are enabled. This bit can be used to validate the other status/error bits in the endpoint 2
control/status register. The TPC bit gets cleared by writing a one to it. The UDC will issue NAK
handshakes to all IN tokens while this bit is set.
11.8.9.3
11.8.9.4
Transmit Packet Error (TPE)
The transmit packet error bit acts as a status bit and will be valid while TPC is set. The TPE bit
being set will indicate that the host did not issue an ACK handshake to the current packet. The TPE
bit will be cleared when the TPC bit is cleared.
Transmit Underrun (TUR)
The transmit underrun bit will be set if the transmit FIFO experiences an underrun. This bit will be
valid when the TPC bit is set. When the UDC experiences an underrun, the packet is shortened and
the CRC is corrupted to ensure that the host discards the packet. The TUR bit will be cleared when
the TPC bit is cleared.
11.8.9.5
11.8.9.6
Sent STALL (SST)
The sent stall bit indicates that a STALL handshake was issued to the host. The CPU writes a one to
this bit to clear it. When this bit is cleared the transmit FIFO is flushed.
Force STALL (FST)
The CPU can set the force stall bit to force the UDC to issue a STALL handshake to all IN tokens.
STALL handshakes will continue to be sent until the CPU clears this bit. The sent stall bit (4) will
be set when the STALL state is actually entered (this may be delayed if the UDC is active when the
FST bit is set), and the STALL state will not be exited until both the FST and SST bits are cleared.
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11.8.9.7
Bits 7..6 Reserved
Bits 7..6 are reserved for future use.
Address: 0h 8000 0018
UDCCS2
Read/Write
Bit
7
6
5
FST
0
4
3
TUR
0
2
TPE
0
1
TPC
0
0
TFS
0
Res.
SST
0
Reset
0
0
Bit
Name
Description
0
1
2
TFS
Transmit FIFO service (read-only).
0 – Transmit FIFO has more than 8 bytes.
1 – Transmit FIFO has 8 bytes or less.
TPC
TPE
Transmit packet complete (read/write 1 to clear).
0 – Error/status bits invalid.
1 – Transmit packet has been sent and error/status bits are valid.
Transmit packet error (read-only).
0 – Transmit packet was received with no errors.
1 – Transmit packet has errors and the host did not issue ACK. Valid only when RPC is
set.
3
4
5
TUR
SST
FST
—
Transmit FIFO underrun.
1 – Transmit FIFO experienced an underrun. Valid only when TPC is set.
Sent STALL (read/write 1 to clear).
1 – STALL handshake was sent. Valid only when TPC is set.
Force STALL (read/write).
1 – Issue STALL handshakes to IN tokens.
7..6
Reserved.
Always reads zero.
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11.8.10 UDC Endpoint 0 Data Register
The UDC endpoint 0 data register is actually an 8-bit x 8-entry bidirectional FIFO. When the host
transmits data to the UDC endpoint 0, the CPU reads the UDC endpoint 0 register to access the
data. When the UDC is sending data to the host, the CPU writes the data to be sent into the UDC
endpoint 0 register. Although the same FIFO can be read and written by the CPU during various
points in a control sequence, the CPU may not read and write the FIFO at the same time. The
direction that the FIFO is flowing is controlled by the UDC. Normally, the UDC will be in an idle
state, waiting for the host to send commands. When this happens, the UDC fills the FIFO with the
command from the host and the CPU reads the command from the FIFO once it has arrived. The
UDC will do a partial decode of the command to determine if the CPU is going to be filling the
FIFO with data to send to the host. If so, the direction is turned around to accept data from the CPU
and have the UDC transmit the data. If the command is such that no data will be required from the
UDC, then this will not happen. The only time the CPU may write the endpoint 0 FIFO is when a
valid command from the host has been received which requires a transmission in response, that is,
a GET_DESCRIPTOR command.
Address: 0h 8000 001C
UDCD0
Read/Write
Bit
Reset
Bit
7
0
7
0
6
0
6
0
5
0
5
0
4
3
2
0
2
0
1
0
0
0
0
Bottom of Endpoint 0 FIFO
0
0
3
0
1
0
Read Access
4
Top of Endpoint 0 FIFO
Reset
0
0
Write Access
Bit
Name
DATA
Description
7..0
Top/bottom of endpoint 0 FIFO data.
Read – Bottom of endpoint 0 FIFO data.
Write – Top of endpoint 0 FIFO data.
11.8.11 UDC Endpoint 0 Write Count Register
The UDC endpoint 0 write count register can be read when a packet has been received by the
endpoint 0 to determine how many bytes to read out of the UDC endpoint 0 data register. When
data is present in the FIFO, this 4-bit field should read between 1 and 8.
Address: 0h 8000 0020
UDCWC
Read-Only
Bit
Reset
Bit
7
6
5
0
4
0
3
0
2
1
0
0
Reserved
Write Count
0
0
0
0
Name
Description
3..0
WC
Endpoint 0 write count (read-only).
4-bit field representing the number of bytes in the endpoint 0 FIFO.
7..4
—
Reserved.
Always reads zero.
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11.8.12 UDC Data Register
The UDC data register (UDDR) is an 8-bit register corresponding to both the top and bottom
entries of the transmit and receive FIFOs, respectively. Data is placed by the UDC’s receive logic
into the top of the receive FIFO. The data is transferred down the FIFO to the lowest location that
is empty. When UDDR is read, the bottom entry of the 8-bit receive FIFO is accessed. After the
read, the bottom FIFO entry is invalidated, which causes all data in the FIFO to automatically
transfer down one location.
When UDDR is written, the topmost FIFO entry of the 8-bit transmit FIFO is accessed. After a
write, the data is automatically transferred down the FIFO to the lowest location that is empty. The
UDC’s transmit logic takes 8-bit values from the bottom of the transmit FIFO one at a time, places
the data into a serial shifter, and transmits the value out onto the UDC pins. Each time a value is
taken from the bottom entry, the location is invalidated, which causes all data in the FIFO to
automatically transfer down one location.
The following table shows the location of the top/bottom of the transmit/receive FIFOs in the UDC
data register (UDDR). Note that both FIFOs are cleared when the SA-1100 is reset and when UDE
is written to zero. After either of these actions takes place, the user may prime the transmit FIFO by
writing up to sixteen 8-bit values to UDDR before enabling the UDC.
Address: 0h 8000 0008
UDDR
Read/Write
Bit
Reset
Bit
7
0
7
0
6
0
6
0
5
0
5
0
4
3
2
0
2
0
1
0
0
0
0
Bottom of receive FIFO
0
0
0
1
0
Read Access
4
3
Top of transmit FIFO
Reset
0
0
Write Access
Bit
7..0
Name
DATA
Description
Top/bottom of transmit/receive FIFO data.
Read – Bottom of receive FIFO data.
Write – Top of transmit FIFO data.
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11.8.13 UDC Status/Interrupt Register
The UDC status/interrupt register (UDCSR) contains bits that are used to generate the UDC’s
interrupt request. Each bit in the UDC status/interrupt register is logically ORed together to
produce one interrupt request. When the ISR for the UDC is executed, it must read the UDC
status/interrupt register to determine why the interrupt occurred.
Every bit in the UDCSR is controlled by a mask bit in the UDC control register. The mask bits,
when set, will prevent a status bit in the UDCSR from being set. If the mask bit for a particular
status bit is cleared and an interruptible condition occurs, the status bit will be set. In order to clear
status bits, the CPU must write a one into the position that it wishes to clear. The interrupt request
for the UDC will remain active as long as the value of the UDCSR is non-zero.
11.8.13.1 Endpoint 0 Interrupt Request (EIR)
The endpoint 0 interrupt request will be set if the EIM bit in the UDC control register is cleared,
and in the UDC endpoint 0 control/status register, the OUT packet ready bit gets set, the IN packet
ready bit gets cleared, the data end bit gets cleared, the setup end bit gets set, or the sent STALL bit
gets set. The EIR bit is cleared by writing a one to it.
11.8.13.2 Receive Interrupt Request (RIR)
The receive interrupt request bit gets set if the RIM bit in the UDC control register is cleared and
the Receive Packet Complete bit in the UDC endpoint 1 control/status register gets set. The RIR bit
is cleared by writing a one to it.
11.8.13.3 Transmit Interrupt Request (TIR)
The transmit interrupt request bit gets set if the TIM bit in the UDC control register is cleared and
the Transmit Packet Complete bit in the UDC endpoint 2 control/status register gets set. The RIR
bit is cleared by writing a one to it.
11.8.13.4 Suspend Interrupt Request (SUSIR)
The suspend interrupt request bit will be set if the SRM bit in the UDC control register is cleared and
the USB bus remains idle for more than 3 ms. The SUSIR bit gets cleared by writing a one to it.
11.8.13.5 Resume Interrupt Request (RESIR)
The resume interrupt request bit will be set if the SRM bit in the UDC control register is cleared,
the UDC is currently in the suspended state, and the USB bus is driven with resume signalling.
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11.8.13.6
Reset Interrupt Request (RSTIR)
The reset interrupt request register will be set if the REM bit in the UDC control register is cleared
and the host issues a reset. When the host issues a reset, the entire UDC is reset. The RSTIR bit
retains its state so software can determine that the design was reset.
Address: 0h 8000 0030
UDCSR
Read/Write (Clear)
Bit
7
6
5
RSTIR
0
4
3
SUSIR
0
2
1
RIR
0
0
Res.
RESIR
0
TIR
0
EIR
0
Reset
0
0
Bit
Name
Description
0
1
2
3
4
5
EIR
Endpoint 0 interrupt request (read/write clear).
1 – Endpoint 0 needs service.
RIR
Receive interrupt request (read/write clear).
1 – Receive endpoint (1) needs service.
TIR
Transmit interrupt request (read/write clear).
1 – Transmit endpoint (2) needs service.
SUSIR
RESIR
RSTIR
—
Suspend interrupt request (read/write clear).
1 – UDC received suspend signalling from the host.
Resume interrupt request (read/write clear).
1 – UDC received resume signalling from the host.
Reset interrupt request (read/write clear).
1 – UDC was reset by the host.
7..6
Reserved.
Always reads zero.
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11.8.14 UDC Register Locations
Table 11-13 shows the registers associated with the UDC and the physical addresses used to access them.
Table 11-13. UDC Control, Data, and Status Register Locations
Address
0h8000 0000
Name
UDCCR
Description
UDC control register
UDC address register
0h8000 0004
0h8000 0008
0h8000 000C
0h8000 0010
0h8000 0014
0h8000 0018
0h8000 001c
0h8000 0020
0h8000 0024
0h8000 0028
0h8000 002c
0h8000 0030
UDCAR
UDCOMP
UDCIMP
UDCCS0
UDCCS1
UDCCS2
UDCD0
UDCWC
—
UDC OUT max packet register
UDC IN max packet register
UDC endpoint 0 control/status register
UDC endpoint 1 (OUT) control/status register
UDC endpoint 2 (IN) control/status register
UDC endpoint 0 data register
UDC endpoint 0 write count register
Reserved
UDCDR
—
UDC transmit/receive data register (FIFOs)
Reserved
UDCSR
UDC status/interrupt register
11.9
Serial Port 1 – SDLC/UART
Serial port 1 is a combination synchronous data link controller (SDLC) and universal asynchronous
receiver/transmitter (UART) serial controller. The user can configure it to perform one of the two
functions, but operation of both modes using serial port 1’s pins cannot occur simultaneously
(SDLC transmit and UART receive). However, the peripheral pin control (PPC) unit can be
configured to take control of two GPIO pins and use them for UART transmission, while serial
port 1’s pins are used for SDLC operation. See the Section 11.13, “Peripheral Pin Controller
(PPC)” on page 11-184 for a description of how the PPC is configured to allow use of both the
SDLC and UART.
For both protocols, serial port 1 can operate at baud rates from 56.24 bps to 230.4 Kbps. Both also
contain an 11-bit wide by 12-entry deep receive FIFO and an 8-bit wide by 8-entry deep transmit
FIFO to buffer incoming and outgoing data, respectively. The FIFOs can be filled or emptied either
by the DMA or the CPU, with service requests being signalled when the transmit FIFO is
half-empty and the receive FIFO is one- to two-thirds full.
Used as an SDLC controller, serial port 1 supports much of the functionality found in commercial
serial communications controllers, such as the 85C30. Frames contain an 8-bit address, an optional
control field, a data field of any size that is a multiple of 8 bits, and a 16-bit CRC-CCITT. The start
and stop flags and CRC generation and checking are handled automatically. Data can be selectively
saved in the receive FIFO by programming an address with which to compare against all incoming
frames. Interrupts are signalled when CRC checks performed on received data indicate an error,
when a receiver abort occurs, when the transmit or receive FIFO needs to be filled or emptied,
when the transmit FIFO underruns during an active frame and is aborted, when the receive FIFO
overruns and data is lost, and when the last byte of data within a frame is contained within the
bottom four entries of the receive FIFO.
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Used as a UART, serial port 1 is identical to serial port 3. It supports most of the functionality of
the 16C550 protocol including 7 and 8 bits of data (odd, even, or no parity), one start bit, either one
or two stop bits, and transmits a continuous break signal. An interrupt is generated when a
framing, parity, or receiver overrun error is present within the bottom four entries of the receive
FIFO, when the transmit FIFO is half-empty or the receive FIFO is one- to two-thirds full, when a
begin and end of break is detected on the receiver, and when the receive FIFO is partially full and
the receiver is idle for three or more frame periods. Because programming and operation of serial
port 1 as a UART is identical to serial port 3, see the Section 11.9, “Serial Port 1 – SDLC/UART”
on page 11-78 for a complete description of using serial port 1 in UART mode.
The external pins dedicated to this interface are TXD1 and RXD1. If serial transmission is not
required and both the SDLC and UART are disabled, control of these pins is given to the peripheral
pin control (PPC) unit for use as general- purpose input/output pins (noninterruptible). See the
Modem control signals (RTS, CTS, DTR, and DSR) are not provided in this block but can be
implemented using the general-purpose I/O port (GPIO) pins described in the Chapter 9, “System
11.9.1
SDLC Operation
Following reset, both the SDLC and UART are disabled, which causes the peripheral pin controller
(PPC) to assume control of the port’s pins. Reset causes the PPC to configure all of the peripheral
pins as inputs, including serial port 1’s transmit (TXD1) and receive (RXD1) pins. Reset also
causes the SDLC’s transmit and receive FIFOs to be flushed (all entries invalidated). Before
enabling the SDLC, the user must first clear any writable or “sticky” status bits that are set by
writing a one to each bit. Next, the desired mode of operation is programmed in the control
registers. At this point, the user can “prime” the transmit FIFO by writing up to eight values, or the
FIFO can remain empty and either programmed I/O or the DMA can be used to service it after the
SDLC is enabled. Once the SDLC is enabled, transmission and reception of data can begin on the
transmit (TXD1) and receive (RXD1) pins.
11.9.1.1
Bit Encoding
SDLC uses frequency modulation zero (FM0) to encode individual bits. Both the clock and the
data are encoded and transmitted on the same line. Instead of representing data by controlling the
state of the line, its frequency is used. The line transitions at a frequency that represents the serial
stream’s bit rate (this produces the clock). Individual bits are separated by each transition. A zero is
encoded by placing an extra transition at the middle of its bit period. A one is represented by no
added transitions within its bit period (this produces the data). Note that nonreturn to zero (NRZ)
bit encoding can also be programmed in the SDLC. In NRZ encoding, a one is represented when
and FM0 encoding of the data byte 8b 0100 1011. Note that the byte’s LSB is transmitted first.
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Figure 11-22. FM0/NRZ Bit Encoding Example (0100 1011)
LSB
Bit
MSB
0
1
1
0
1
0
0
1
Value
NRZ
Data
FM0
Data
11.9.1.2
Frame Format
SDLC uses a flag (reserved bit pattern) to denote the beginning of a frame of information and to
synchronize frame transmission. The flag contains eight bits that start and end with a zero, and
contains six sequential ones in the middle (01111110). This sequence of six ones is unique because
all data between the start and stop flags is prohibited from having more than five consecutive ones.
Data that violates this rule is altered before transmission by automatically inserting a zero after five
consecutive ones are detected in the transmitted bit stream. This technique is commonly referred to
as “bit stuffing” and is transparent to the user. The information field within an SDLC frame is
placed between two flags and consists of an 8-bit address, an optional 8-bit control field, a data
field containing any multiple of 8 bits, and a 16-bit cyclic redundancy check (CRC-CCITT). The
user can also program the SDLC to insert an optional second start flag. Note that each byte within
the address, control, and data fields is transmitted and received LSB first, ending with the byte’s
frame format.
Figure 11-23. SDLC Frame Format
8 Bits
8 Bits
8 Bits
Any Multiple
of 8 Bits
8 Bits
16 Bits
8 Bits
(optional)
(optional)
Start Flag
0111 1110
Start Flag
0111 1110
Stop Flag
0111 1110
Address
Control
Data
CRC-CCITT
11.9.1.3
Address Field
The 8-bit address field is used by a transmitter to target a select group of receivers when multiple
stations are connected to the same set of serial lines. The address allows up to 255 stations to be
uniquely addressed (00000000 to 11111110). The global address (11111111) is used to broadcast
messages to all stations. Serial port 1 contains an 8-bit register that is used to program a unique
address for broadcast recognition. It also contains a control bit to enable or disable the address
match function. Note that the address of received frames is stored in the receive FIFO along with
normal data; it is transmitted and received starting with its LSB and ending with its MSB.
11.9.1.4
Control Field
The SDLC control field is typically 8 bits, but can be any length. Serial port 1 does not provide any
hardware decode support for the control byte; it treats all bytes between the address and the CRC as data.
Note that the control field is transmitted and received starting with its LSB and ending with its MSB.
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11.9.1.5
Data Field
The data field can be any length that is a multiple of 8 bits, including zero. The user determines the
data field length according to the application requirements and transmission characteristics of the
target system. Usually a length is selected that maximizes the amount of data that can be
transmitted per frame to allow the CRC checker to consistently detect all errors during
transmission. Note that serial port 1 does not support residue coding found in common SCCs; all
data fields must be a multiple of 8 bits. If a data field that is not a multiple of 8 bits is received, an
abort is signalled and the end of frame tag is set within the receive FIFO. Also note that each byte
within the data field is transmitted and received starting with its LSB and ending with its MSB.
11.9.1.6
CRC Field
SDLC uses the established CCITT cyclic redundancy check (CRC) to detect bit errors that occur
during transmission. A 16-bit CRC-CCITT is computed using the address, control, and data fields,
and is included in each frame. A separate CRC generator is implemented in both the transmit and
receive logic. The transmitter calculates a CRC while data is actively transmitted, and places the
16-bit value at the end of each frame before the flag is transmitted. The receiver calculates a CRC
for each received data frame, and compares the calculated CRC to the expected CRC value
contained within the end of each received frame. If the calculated value does not match the
expected value, an interrupt is signalled. The CRC computation logic is preset to all ones before
reception or transmission of each frame. Note that, unlike all other fields within the frame, the
CRC is transmitted and received starting with its MSB and ending with its LSB. The CRC logic
uses the following four-term polynomial in the implementation of its linear feedback shift register.
16
12
5
CRC(x)= (X + X + X + 1)
11.9.1.7
Baud Rate Generation
The baud or bit rate is derived by dividing down the 3.6864-MHz clock generated by the on-chip
PLL. The clock is first divided by a programmable number between 1 and 4096, and then by a
fixed value of 16. The receive baud clock is synchronized with the data steam each time a transition
is detected on the receive data line at a bit’s boundary. For FM0 encoding, zeros and ones are
decoded within the incoming data stream by detecting whether a transition occurs between the
boundaries of a bit time. If the receive line transitions, a zero is decoded; otherwise, a one is
decoded. The baud synchronizer differentiates a transition of the receive line at the bit boundary
from a transition caused by a zero by first establishing the bit boundary during reception of the
string of ones within the flag (01111110). A counter is then used to cause the synchronizer to ignore
transitions that occur during mid-bit. This is accomplished by using the clock produced before the
fixed divide by 16 takes place. This clock is used to increment a counter that is reset at the
boundary of each bit. Transitions that take place at any time before the counter reaches the value 12
(3/4 of a total bit time) are ignored. This function effectively masks a transition, which occurs
during reception of a zero, excluding it from the bit synchronization process. When NRZ encoding
is used, each bit of received data is sampled at its midpoint by using the clock that is generated
before the fixed divide by 16 takes place. A sample rate counter is used that is reset at the boundary
of each bit and is incremented using this clock. When it reaches a value of 8 (halfway through the
bit period), the receive data pin is sampled.
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11.9.1.8
Receive Operation
Once the SDLC receiver is enabled, it enters hunt mode, searching the incoming data stream for the
flag (01111110). The flag serves to achieve bit synchronization, denotes the beginning of a frame,
and delineates the boundaries of individual bytes of data. The end of the flag denotes the beginning
of the address byte. Once the flag is found, the receiver is synchronized to incoming data and hunt
mode is exited.
After each bit is decoded, a serial shifter is used to receive the incoming data a byte at a time. Once
the flag is recognized, each subsequent byte of data is decoded and placed within a 2-byte
temporary FIFO. A temporary FIFO is used to prevent the CRC from being placed within the
receive FIFO. When the temporary FIFO is filled, data values are pushed out one by one to the
receive FIFO. The first byte of a frame is the address. If receiver address matching is enabled, the
received address is compared to the address programmed in the address match value field in a
control register. If the two values are equal or if the incoming address contains all ones, all
subsequent data bytes including the address byte are stored in the receive FIFO. If the values do not
match, the receive logic does not store any data in the receive FIFO, ignores the remainder of the
frame, and begins to search for the stop flag. The second byte of the frame can contain an optional
control field, which must be decoded in software (no hardware support within the SDLC). Use of a
control byte is determined by the user.
When the receive FIFO is one- to two-thirds full, an interrupt and/or DMA request is signalled. If
the data is not removed soon enough, and the FIFO is completely filled, an overrun error is
generated when the receive logic attempts to place additional data into the full FIFO. Once the
FIFO is full, all subsequent data bytes received are lost while all FIFO contents remain intact.
Frames can contain any amount of data in multiples of 8 bits. Although the SDLC protocol does
not limit frame size, in practice they tend to be implemented in numbers ranging from hundreds to
thousands of bytes.
The receive logic continuously searches for the stop flag at the end of the frame. Once it is
recognized, the last byte that was placed within the receive FIFO is flagged as the last byte of the
frame, and the two bytes remaining within the temporary FIFO are removed and used as the 16-bit
CRC value for the frame. Instead of placing this in the receive FIFO, the receive logic compares it
to the CRC-CCITT value, which is continuously calculated using the incoming data stream. If they
do not match, the last byte that was placed within the receive FIFO is also flagged with a CRC
error. The CRC value is not placed in the receive FIFO.
The SDLC protocol permits back-to-back frames to be received. When this occurs, the flag at the
end of the first frame also serves as the flag to denote the beginning of the next frame (only one
flag separates the two). Most commercial SCCs continuously transmit flags between frames when
they do not occur back-to-back. To support both of these cases, the receive logic allows one or
more flags to separate frames. When the use of two start flags is programmed by the user, two flags
always separate back-to-back frames that are transmitted.
Most commercial SCCs can generate an abort (7 to 13 ones) when their transmit FIFO underruns.
The receive logic contains a counter that increments each time a one is decoded before entering the
serial shifter and is reset any time a zero is decoded. When seven or more ones are detected, a
receiver abort occurs. Note that data is moved from the serial shifter to the temporary FIFO a byte
at a time, and seven consecutive ones may bridge two bytes. For this reason, after an abort is
detected, the remaining data in the serial shifter is discarded along with the most recent byte of data
placed in the temporary FIFO. After this data is discarded, the oldest byte of data in the temporary
FIFO is placed in the receive FIFO, the EOF tag is set within the top entry of the FIFO (next to the
byte transferred from the temporary FIFO), the receiver abort interrupt is signalled, and the
receiver logic enters hunt mode until it recognizes the next flag.
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If the user disables the receiver during operation, reception of the current data byte is stopped
immediately, the serial shifter and receive FIFO are cleared, control of the RXD1 pin is given to
the peripheral pin control (PPC) unit, and all clocks used by the receive logic are automatically shut
off to conserve power. However, the transmitter continues to function as normal.
11.9.1.9
Transmit Operation
The SDLC transmit logic can operate at the same time as the receive logic (full-duplex). The user
may either “prime” the transmit FIFO by filling it with data or allow service requests to cause the
CPU or DMA to fill the FIFO once the SDLC transmitter is enabled. Once enabled, the transmit
logic issues a service request if its FIFO is empty. Flags are transmitted continuously until valid
data resides within the FIFO. Once a byte of data resides at the bottom of the transmit FIFO, it is
transferred to the serial shifter. It is encoded and shifted out onto the TXD1 pin clocked by the
programmed baud rate clock. Note that the flag and CRC value are automatically transmitted and
need not be placed in the transmit FIFO.
When the transmit FIFO is emptied halfway, an interrupt and/or DMA service request is signalled. If
new data is not supplied soon enough, the FIFO is completely emptied and the transmit logic attempts
to take additional data from the empty FIFO. The user can program one of two actions: an underrun to
signal the normal completion of a frame or an unexpected termination of a frame in progress.
When normal frame completion is selected and an underrun occurs, the transmit logic transmits the
16-bit CRC value calculated during the transmission of all data within the frame (including the
address and control bytes), followed by a flag to denote the end of the frame. The transmitter then
continuously transmits flags until data is once again available within the FIFO. Once data is
available, the transmitter begins transmission of the next frame.
When unexpected frame termination is selected and an underrun occurs, the transmit logic outputs
an abort and interrupts the CPU. An abort continues to be transmitted until data is once again
available in the transmit FIFO. The SDLC then transmits a flag and starts the new frame. The
off-chip receiver can choose to ignore the abort and continue to receive data, or to signal serial port
1 to retry transmission of the aborted frame.
If the user disables the transmitter during operation, transmission of the current data byte is stopped
immediately, the serial shifter and transmit FIFO are cleared, control of the TXD1 pin is given to
the peripheral pin control (PPC) unit, and all clocks used by the transmit logic are automatically
shut off to conserve power. However, the receiver continues to function as normal.
11.9.1.10 Simultaneous Use of the UART and SDLC
Serial port 1 contains a control bit to select which serial protocol to use: SDLC or UART. Note that
the two protocols cannot be combined at the same time (SDLC transmit and UART receive).
However, since the SDLC and UART are fully independent blocks, a mode is supported that allows
the user to enable the SDLC using serial port 1’s pins (TXD1 and RXD1) while the UART is
enabled using two GPIO pins (GPIO<14> for transmit and GPIO<15> for receive operation). This
mode is enabled by setting the UART pin reassignment (UPR) control bit within the peripheral pin
that when this mode is enabled, serial port 1’s control bit, which selects SDLC versus UART
operation, is ignored and serial port 1 defaults to SDLC mode.
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11.9.1.11 Transmit and Receive FIFOs
To reduce chip size and power consumption, the SDLC’s FIFOs use self-timed logic (they are not
clocked). Because of process and environmental variations, the depth at which a service request is
triggered to empty the receive FIFO is variable. This variation spans a maximum of four FIFO
entries; the receive FIFO service request can be made at four different FIFO depths. To
compensate for this variability and guarantee that at least four valid entries of data exist within the
FIFO before generating a service request, an extra four entries have been added to the receive FIFO
(four entries more than the transmit FIFO). The transmit FIFO is 8 entries deep and the receive
FIFO is 12 entries deep. The point at which the receive FIFO service request is triggered spans the
middle third of the 12-entry FIFO. The service request is signalled at a depth from one-third full to
two-thirds full or when the FIFO contains five, six, seven, or eight entries of data.
This service request variation applies only to an empty FIFO that is filled (receive FIFO). It does
not apply to a full FIFO that is emptied (transmit FIFO). The transmit FIFO is guaranteed to signal
a service request when it has four or more empty entries and negate the request when the FIFO
contains five or more entries that are filled.
If the DMA is used to service either one or both of the SDLC’s FIFOs, the burst size must be set to
4 words, even though more than four entries of data may exist within the receive FIFO. If
programmed I/O is used to service the FIFOs, a maximum of 4 words may be added to the transmit
FIFO without checking if more space is available. Likewise, a maximum of 4 words may be
removed from the receive FIFO without checking if more data is available. After this point, the
user must poll a set of status bits that indicate if any data remains in the receive FIFO or if space is
available in the transmit FIFO before emptying or filling the FIFOs any further.
11.9.1.12 CPU and DMA Register Access Sizes
Bit positioning, byte ordering, and addressing of the SDLC is described in terms of little endian
ordering. All SDLC registers are 8 bits wide and are located in the least significant byte of
individual words. The ARM peripheral bus does not support byte or half-word operations. All
reads and writes of the SDLC by the CPU should be wordwide. Two separate dedicated DMA
requests exist for both the transmit and the receive FIFOs. If the DMA controller is used to service
the transmit and/or receive FIFOs, the user must ensure that the DMA is properly configured to
perform byte-wide accesses, using 4 bytes per burst (half the size of the FIFOs). Note that a
separate set of registers also exist to configure UART operation.
programming and the operation of serial port 1 as a UART.
11.9.2
SDLC Register Definitions
There are eight registers within serial port 1: five control registers, one data register, and two status
registers. The control registers are used to select UART or SDLC mode, baud rate, number of start
flags, bit modulation mode, and address match value. They are used to select whether an abort or
end of frame occurs when the transmit FIFO underruns, whether the sample clock is an input or
output, and which edge of the sample clock is used to sample receive data and drive transmit data.
Also they are used to enable or disable the FIFO interrupt service request, sample clock
input/output operation, aborts after frames, receive operation, transmit operation, receive address
matching, and loopback mode. See the Section 11.9, “Serial Port 1 – SDLC/UART” on page 11-78
for a full description of UART programming and operation.
The data register addresses the top location of the transmit FIFO and bottom location of the receive FIFO.
When it is read, the receive FIFO is accessed, and when it is written, the transmit FIFO is accessed.
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The status registers contain bits that signal CRC, overrun, underrun, and receiver abort errors, and
the transmit FIFO service request, receive FIFO service request, and end-of-frame conditions. Each
of these hardware-detected events signals an interrupt request to the interrupt controller. The status
registers also contains flags for transmitter busy, receiver synchronized, receive FIFO not empty,
transmit FIFO not full, and receive transition detect (no interrupt generated).
11.9.3
SDLC Control Register 0
SDLC control register 0 (SDCR0) contains 8 bit fields that control various functions within the SDLC.
11.9.3.1
SDLC/UART Select (SUS)
The SDLC/UART select (SUS) bit is used to select whether serial port 1 is used for SDLC or
UART operation. When SUS=0, SDLC operation is selected. The receiver and transmitter logic is
then enabled individually by programming the transmitter and receiver enable bits (TXE, RXE).
When SUS=0 and TXE=0, control of the transmit pin (TXD1) is given to the PPC unit; when
SUS=0 and RXE=0, control of the receive pin (RXD1) is given to the PPC unit. When SUS=1,
UART operation is selected and the state of all remaining SDLC register bits is ignored (remaining
unchanged) and control of the TXD1 and RXD1 pins is given to the UART. See the Section 11.9,
“Serial Port 1 – SDLC/UART” on page 11-78 for a description of the programming and operation
of serial port 1 as a UART. SUS, TXE, and RXE are the only bits within the control register that are
reset placing serial port 1 into SDLC mode while disabling the transmitter and receiver.
The user also has the ability to take control of two GPIO pins and use them for UART serial
transmission while the SDLC makes use of serial port 1’s transmit and receive pins to allow both
units to be used at the same time. The peripheral pin control (PPC) unit can be programmed to
connect the UART’s transmit and receive lines to GPIO pins 14 and 15. When the UART pin
reassignment (UPR) bit is set in the PPC pin assignment register (PPAR), the UART transmits using
the GPIO<14> pin and receives using the GPIO<15> pin. The SUS bit is ignored in this case and
serial port 1 operation defaults to SDLC mode. Note that the user must set bits 14 and 15 in the GPIO
alternate function register (GAFR), and set bit 14 and clear bit 15 in the GPIO pin direction register
program the GPIO unit for this mode of operation.
11.9.3.2
11.9.3.3
Single/Double Flag Select (SDF)
The single/double flag select (SDF) bit is used to select whether one or two flags (01111110) are
transmitted at the start of each frame. When SDF=0, the transmit logic uses one flag. When
SDF=1, the transmit logic uses two flags. Note that SDF does not affect the number of flags that
are transmitted at the end each frame (one flag is always used). Normally, when back-to-back
transmissions are made, only one flag is inserted between the two frames (one flag serves as both
the frame’s start and end flag). However, when SDF=1, two flags are inserted between each frame.
SDF does not affect SDLC receive operation.
Loopback Mode (LBM)
The loopback mode (LBM) bit is used to enable and disable the ability of the SDLC transmit and
receive logic to communicate. When LBM=0, the SDLC operates normally. The transmit and receive
data paths are independent and communicate via their respective pins. When LBM=1, the output of
the transmit serial shifter is directly connected to the input of the receive serial shifter internally, and
control of the TXD1 and RXD1 pins are given to the peripheral pin control (PPC) unit.
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11.9.3.4
Bit Modulation Select (BMS)
The bit modulation select (BMS) bit selects whether the SDLC uses NRZ or FM0 bit encoding for
both transmit and receive data. When BMS=0, FM0 encoding is selected and when BMS=1, NRZ
encoding is selected. In frequency modulation zero (FM0) encoding, a transition occurs on every
bit boundary. Zeros are represented by an additional transition in the middle of the bit period, and
ones are represented by the lack of an additional transition in the middle of the bit period. In
nonreturn to zero (NRZ) encoding, a one is represented when the pin is high, and a zero when the
pin is low. Note that bit-stuffing/bit-extraction (the insertion/deletion of a zero after five ones are
encountered) is not affected by BMS. Also note that NRZ encoding must be selected (BMS=1)
when sample clock operation is enabled (SCE=1).
11.9.3.5
11.9.3.6
Sample Clock Enable (SCE)
The sample clock enable (SCE) bit is used to enable or disable driving or receiving a clock using
GPIO pin 16 for synchronous transmission/reception of data. When SCE=0, the on-chip
3.6864-MHz PLL, the SDLC’s programmable baud rate generator, and the receive logic’s digital
PLL are used. When SCE=1, the sample clock direction (SCD) bit is decoded to determine the
direction of the clock used on GPIO pin 16.
Sample Clock Direction (SCD)
When the sample clock function is enabled (SCE=1), the sample clock direction (SCD) bit is used
to select whether the sample clock is an input from or an output to GPIO pin 16.
When SCD=0, the sample clock is input using GPIO pin 16 and is used to synchronously drive both
the transmit and receive logic. For the receive logic, the RCE bit is decoded to select which edge of
the input clock is used to latch each bit of the incoming frame. Note that the clock is not embedded
within the data stream, and the digital PLL is shut down to conserve power. For the transmit logic, the
TCE bit is decoded to select which edge of the input clock is used to drive each bit of the outgoing
frame. The on-chip clock used to drive the programmable baud rate generator is shut down to
conserve power. Note that input clock frequency to GPIO<16> cannot exceed 3.6864 MHz.
When SCD=1, the sample clock, which is generated within the SDLC unit (the clock that is output
after dividing the 3.6864-MHz reference by the programmable BCD field, but before the fixed
divide by 16), is output to GPIO pin 16, and again the RCE and TCE bits are decoded to determine
which edge of this clock output is used to sample receive data and drive transmit data. Because the
baud clock that is generated before the fixed divide by 16 is used to synchronously drive the SDLC,
the effective baud rate is 16 times greater, allowing the SDLC to operate at speeds ranging from
899.78 bps to 3.6864 Mbps.
When the sample clock function is enabled (SCE=1), the user must program the SDLC bit
modulation select (BMS) control bit to select NRZ encoding (BMS=1). Unpredictable results occur
when FM0 encoding is selected during sample clock operation. Note that the SDLC frame format
is not affected during sample clock operation, only the sampling and driving of individual data bits.
Bit stuff (insertion of a zero after five consecutive ones) still occurs during NRZ encoding.
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11.9.3.7
11.9.3.8
Receive Clock Edge Select (RCE)
When sample clock operation is enabled (SCE=1), the receive clock edge select (RCE) bit is used
to select which edge of the clock input from or output to GPIO pin 16 to use (rising or falling) to
synchronously sample data from the receive pin. When RCE=0, each bit received is sampled on the
rising edge of the sample clock; when RCE=1, bits are sampled on the clock’s falling edge. Note
that the internal baud rate generator and receive logic’s digital PLL are not used in this mode.
Transmit Clock Edge Select (TCE)
When sample clock operation is enabled (SCE=1), the transmit clock edge select (TCE) bit is used
to select which edge of the clock input from or output to GPIO pin 16 to use (rising or falling) to
synchronously drive data onto the transmit pin. When TCE=0, each bit transmitted is driven on the
rising edge of the sample clock; when TCE=1, bits are driven on the clock’s falling edge. Note that
the internal baud rate generator is not used in this mode.
The following table shows the location of all bit fields located in SDLC control register 0
(SDCR0). The SDLC must be disabled (SUS=RXE=TXE=0) when changing the state of any bit
within this register. The reset state of all control bits except SUS is unknown (indicated by question
marks) and must be initialized before enabling the SDLC.
.
Address: 0h 8002 0060
SDCR0
Read/Write
Bit
7
TCE
?
6
5
4
3
BMS
?
2
LBM
?
1
SDF
?
0
SUS
0
RCE SCD
SCE
?
Reset
?
?
Bit
Name
Description
0
SUS
SDLC/UART select.
0 – SDLC mode selected.
1 – UART mode selected.
Note: For SUS=0, if TXE=0, TXD1 control is given to PPC unit; if RXE=0, RXD1 control is
given to PPC unit. If UPR is set in the PPC unit, SUS is ignored, the UART uses
GPIO<14> to transmit and GPIO<15> to receive data, and serial port 1 defaults to SDLC
mode. The user must also program the GAFR and GPDR registers appropriately in the
GPIO unit.
1
SDF
Single/double flag select.
0 – One flag generated at start of each transmit frame.
1 – Two flags generated at start of each transmit frame.
Note: SDF does not affect receive operation.
2
3
LBM
BMS
Loopback mode.
0 – Normal serial port operation enabled.
1 – Output of transmit serial shifter is connected to input of receive serial shifter internally
and control of TXD1 and RXD1 pins is given to the PPC unit.
Bit modulation select.
0 – FM0 bit encoding/decoding selected.
1 – NRZ bit encoding/decoding selected.
Note: BMS must be programmed to select NRZ (BMS=1) encoding when sample clock
operation is enabled (SCE=1).
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4
SCE
Sample clock enable.
0 – On-chip baud rate generator and digital PLL used to transmit and receive SDLC data.
1 – A clock is input or output via GPIO pin 16 and is used to synchronously sample
receive data and drive transmit data.
Note: BMS must be programmed to select NRZ encoding when sample clock operation is
enabled (BMS=1).
5
SCD
Sample clock direction.
0 – If sample clock enabled, it is input using GPIO pin 16.
1 – If sample clock enabled, the sample clock generated by the programmable baud rate
generator but before the fixed divide by 16 is output using GPIO pin 16.
Note: For both directions, the sample clock is used to synchronously sample receive data
and drive transmit data on the edges selected using RCE and TCE. A maximum of
3.6864-MHz clock allowed.
6
7
RCE
TCE
Receive clock edge select.
0 – Rising edge of clock input/output on GPIO pin 16 used to latch data from the receive pin.
1 – Falling edge of clock input/output on GPIO pin 16 used to latch data from the receive pin.
Transmit clock edge select.
0 – Rising edge of clock input/output on GPIO pin 16 used to drive data onto the transmit pin.
1 – Falling edge of clock input/output on GPIO pin 16 used to drive data onto the transmit pin.
11.9.4
SDLC Control Register 1
SDLC control register 1 (SDCR1) contains eight bit fields that control various functions within the
SDLC.
11.9.4.1
Abort After Frame (AAF)
The abort after frame (AAF) bit controls whether or not the SDLC transmits an abort at the end of
each frame transmitted, and also controls the state of GPIO pin 17. When the AAF bit is set, each
time the SDLC completes transmission of the flag at the end of a frame, the transmit logic signals
an abort by transmitting 12 sequential ones on the transmit pin (TXD1). Additionally, any time the
transmitter is idle (not sending a frame or the abort at the end of the frame), the SDLC forces GPIO
pin 17 high. Likewise, when the SDLC is actively transmitting a frame (including the start and stop
flags, and the abort at the end of the frame), it forces GPIO pin 17 low. If the transmit FIFO is
emptied at the end of a frame, the abort is signalled followed by the continuous transmission of
flags. If there is data present within the FIFO (indicating a new frame is available), the abort is
followed by the programmed number of start flags, then data transmission begins again. For this
case, GPIO<17> is not asserted because the two frames occur back-to-back (no idle time between
the two frames). Note that the user must configure GPIO<17> as an output by setting the pin
direction bit for pin 17 within GPDR. When AAF=1, the state of GPIO<17> is controlled solely by
serial port 1. Writing to the pin set (GPSR) or pin clear (GPCR) registers for pin 17 has no effect.
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11.9.4.2
Transmit Enable (TXE)
The transmit enable (TXE) bit is used to enable and disable SDLC transmit operation. When
TXE=0, the transmit logic is disabled and its clocks are turned off to conserve power. When
TXE=1, the SDLC transmitter logic is enabled for serial transmission. It is required that the user
first program all other control bits before setting TXE. If the TXE bit is cleared to zero while the
SDLC is actively transmitting data, transmission is stopped immediately, all data within the
transmit FIFO and serial output shifter is cleared, and control of the TXD1 pin is given to the
peripheral pin control (PPC) unit. Note that SUS, TXE, and RXE are the only control bits within
the SDLC that are initialized when a hardware reset occurs. Clearing TXE to zero ensures the
SDLC transmitter is disabled, giving control of the transmit pin to the PPC unit, which configures
TXD1 as an input following a reset of the SA-1100. Note that TXE is ignored when SUS=1
(enables UART operation).
11.9.4.3
Receive Enable (RXE)
The receive enable (RXE) bit is used to enable or disable SDLC receive operation. When RXE=0,
the receive logic is disabled and its clocks are turned off to conserve power. When RXE=1, the
SDLC receiver logic is enabled for serial reception. It is required that the user first program all
other control bits before setting RXE. If the RXE bit is cleared to zero while the SDLC is actively
receiving data, reception is stopped immediately, all data within the receive FIFO and serial input
shifter is cleared, and control of the RXD1 pin is given to the peripheral pin control (PPC) unit.
Note that SUS, TXE, and RXE are the only control bits within the SDLC that are initialized when a
hardware reset occurs. Clearing RXE to zero ensures the SDLC receiver is disabled, giving control
of the receive pin to the PPC unit, which configures RXD1 as an input following a reset of the
SA-1100. Note that RXE is ignored when SUS=1 (enables UART operation).
11.9.4.4
Receive FIFO Interrupt Enable (RIE)
The receive FIFO interrupt enable (RIE) bit is used to mask or enable the receive FIFO service
request interrupt. When RIE=0, the interrupt is masked and the state of the receive FIFO service
request (RFS) bit within SDLC status register 0 is ignored by the interrupt controller. When RIE=1,
the interrupt is enabled and whenever RFS is set (one), an interrupt request is made to the interrupt
controller. Note that programming RIE=0 does not affect the current state of RFS or the receive
FIFO logic’s ability to set and clear RFS; it only blocks the generation of the interrupt request. Also
note that RIE does not affect generation of the receive FIFO DMA request, which is asserted
whenever RFS=1.
11.9.4.5
Transmit FIFO Interrupt Enable (TIE)
The transmit FIFO interrupt enable (TIE) bit is used to mask or enable the transmit FIFO service
request interrupt. When TIE=0, the interrupt is masked and the state of the transmit FIFO service
request (TFS) bit within SDLC status register 0 is ignored by the interrupt controller. When TIE=1,
the interrupt is enabled, and whenever TFS is set (one), an interrupt request is made to the interrupt
controller. Note that programming TIE=0 does not affect the current state of TFS or the transmit
FIFO logic’s ability to set and clear TFS; it only blocks the generation of the interrupt request. Also
note that TIE does not affect generation of the transmit FIFO DMA request, which is asserted
whenever TFS=1.
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11.9.4.6
Address Match Enable (AME)
The address match enable (AME) bit is used to enable or disable the receive logic from comparing
the address programmed in the address match value (AMV) bit field to the address of all incoming
frames. When AME=1, data is stored in the receive FIFO for only those frames that have
addresses that match AMV, and for any frame that contains an address that contains all ones
(11111111), denoting a global address. For frames in which the address does not match, the data
and CRC are ignored and the receiver begins to search for the next flag. When AME=0, address
values are not compared and the data in every frame is stored in the receive FIFO.
11.9.4.7
Transmit FIFO Underrun Select (TUS)
The transmit FIFO underrun select (TUS) bit is used to select what action to take as a result of a
transmit FIFO underrun and to mask or enable the transmit FIFO underrun interrupt.
When TUS=0, transmit FIFO underruns are used to signal the transmit logic that the end of the
frame has been reached. When the transmit FIFO experiences an underrun, the CRC value, which
is calculated continuously on outgoing data, is loaded to the serial shifter and transmitted, followed
by a flag. Also when TUS=0, the transmit FIFO interrupt is masked and the state of the transmit
FIFO underrun (TUR) status bit is ignored by the interrupt controller.
When TUS=1, transmit FIFO underruns are used to signal the transmit logic that the end of the
frame has not yet been reached and that the rate in which data is supplied to the transmit FIFO is
not sufficient. When the transmit FIFO experiences an underrun, ones are continuously output by
the transmitter to signal an abort condition until data is once again available within the transmit
FIFO, and the CRC value is discarded. Additionally, when TUS=1, the transmit FIFO underrun
interrupt is enabled, and whenever TUR is set (one), an interrupt request is made to the interrupt
controller. To change the state of this bit during operation, the user should fill the transmit FIFO to
ensure TUS is not written at the same time the transmit FIFO underruns. Note that programming
TUS=0 does not affect the current state of TUR or the transmit FIFO logic’s ability to set and clear
TUR; it only blocks the generation of the interrupt request.
TUS is useful for ensuring that frames are not prematurely ended due to an unexpected transmit FIFO
underrun. At the start of a frame, the user can configure TUS=1 so that any underrun signals an abort
to the off-chip receiver. Just before the end of the frame, the user can then configure TUS=0 (the last
time the transmit FIFO is filled, for example), allowing the remaining data to be output by the
transmit logic. The FIFO then underruns, causing the CRC and end flag to be transmitted.
11.9.4.8
Receiver Abort Interrupt Enable(RAE)
The receiver abort interrupt enable (RAE) bit is used to mask or enable whether or not an abort
sequence, which is detected by the receive logic, generates an interrupt to the CPU. When RAE=0,
the interrupt is masked and the state of the receiver abort status (RAS) bit is ignored by the
interrupt controller. When RAE=1, the interrupt is enabled and whenever RAS is set (one), an
interrupt request is made to the interrupt controller. Note that programming RAE=0 does not affect
the current state of RAS or the receive logic’s ability to set and clear RAS as the result of an abort
detect; it only blocks the generation of the interrupt request.
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The following table shows the location of the bits within SDLC control register 1. RXE and TXE are
the only control bits in this register that are reset to a known state to ensure the SDLC is disabled
following a reset of the SA-1100. The reset state of all other control bits is unknown (indicated by
question marks) and must be initialized before enabling the SDLC. Note that SDCR1 may be written
while the SDLC is enabled to allow various modes to be changed during active operation.
Address: 0h 8002 0064
SDCR1
Read/Write
Bit
7
6
5
4
3
2
1
0
RAE
?
TUS
?
AME
?
TIE
?
RIE
RXE
0
TXE
0
AAF
?
Reset
?
Bit
Name
Description
0
AAF
Abort after frame.
0 – Aborts not signalled following transmission of a frame. GPIO<17> controlled by system
unit.
1 – Abort is signalled after the end flag of a frame by transmitting 12 ones. GPIO<17> pin
forced high during idle; forced low during transmission of a frame or the abort.
Note: The user must configure GPIO<17> as an output within GPDR in the system
control
module.
1
2
3
TXE
RXE
RIE
Transmit enable.
0 – SDLC transmit logic disabled. Control of the TXD1 pin is given to the PPC unit if SUS=0.
1 – SDLC transmit logic enabled if SUS=0.
Receive enable.
0 – SDLC receive logic disabled. Control of the RXD1 pin is given to the PPC unit if SUS =0.
1 – SDLC receive logic enabled if SUS=0.
Receive FIFO interrupt enable.
0 – Receive FIFO one- to two-thirds full or more condition does not generate an interrupt
(RFS bit ignored).
1 – Receive FIFO one- to two-thirds full or more condition generates an interrupt (state of
RFS sent to interrupt controller).
4
5
TIE
Transmit FIFO interrupt enable.
0 – Transmit FIFO half-full or less condition does not generate an interrupt (TFS bit ignored).
1 – Transmit FIFO half-full or less condition generates an interrupt (state of TFS sent to
interrupt controller).
AME
Address match enable.
0 – Disable receiver address match function. Stores data from all incoming frames in
receive FIFO.
1 – Enable receiver address match function. Do not FIFO data unless address
recognized or incoming address contains all ones (0hFF).
6
7
TUS
RAE
Transmit FIFO underrun select.
0 – Transmit FIFO underrun. Causes CRC and a flag to be transmitted, and masks
interrupt generation (TUR ignored).
1 – Transmit FIFO underrun. Causes an abort to be transmitted, and generates an
interrupt (state of TUR sent to interrupt controller).
Receiver abort interrupt enable.
0 – Abort detected by the receiver. Does not generate an interrupt (RAS bit ignored).
1 – Abort detected by the receiver. Generates an interrupt (state of RAS sent to interrupt
controller).
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11.9.5
SDLC Control Register 2
SDLC control register 2 (SDCR2) contains the 8-bit address match value field that is used by the
SDLC to selectively receive frames.
11.9.5.1
Address Match Value (AMV)
The 8-bit address match value (AMV) field is programmed with an address value that is used to
selectively store only the data within receive frames that have the same address value. The address
match enable (AME) bit must be set to enable this function. For incoming frames, which have the
same address value as the AMV field, the frame’s address, control, and data are stored in the
receive FIFO. For those that do not, the remainder of the frame is ignored, and the receive logic
looks for the next start flag in the incoming data stream. One special address exists that is always
matched by the address match logic regardless of the value programmed in AMV. When address
matching is enabled, whenever a frame is received with an address containing all ones (11111111),
the value programmed in AMV is ignored and the frame data is automatically stored in the receive
FIFO. The address value is contained within the first byte of data in a frame following the flag.
AMV can be written at any time, and is used for comparison for the next frame that occurs
following its update.
The following table shows the address match value field within SDLC control register 2. The reset
state of AMV is unknown (indicated by question marks) and must be initialized before enabling the
SDLC. Note that SDCR2 may be written while the SDLC is enabled to allow the address match
value to be changed during active receive operation.
Address: 0h 8002 0068
SDCR2
Read/Write
Bit
7
6
5
?
4
?
3
?
2
1
0
?
AMV
Reset
?
?
?
?
Bit
7..0
Name
AMV
Description
Address match value.
The 8-bit value used by receiver logic to compare to address of incoming frames. If
address matches, store frame address, control, and data in receive FIFO; if address
does not match, ignore frame and search for next flag.
Note: An address of 0hFF (all ones) in the incoming frame automatically generates a
match (AMV is ignored).
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11.9.6
SDLC Control Registers 3 and 4
SDLC control register 3 (SDCR3) contains the upper 4 bits and SDLC control register 4 (SDCR4)
the lower 8 bits of the baud rate divisor field.
11.9.6.1
Baud Rate Divisor (BRD)
The 12-bit baud rate divisor (BRD) field is used to select the baud or bit rate of the SDLC. A total
of 4096 different baud rates can be selected, ranging from a minimum of 56.24 bps to a maximum
of 230.4 Kbps. The baud rate generator uses the 3.6864-MHz clock generated by the on-chip PLL
and first divides it by the programmable baud rate using BRD. The resultant clock (called the
sample clock) is then divided by 16 to generate the bit clock. The receive baud clock is
synchronized with the data steam each time a transition is detected on the receive data line at a bit’s
boundary. The resultant baud rate given a specific BRD value, or required BRD value given a
desired baud rate, can be calculated using the following two respective equations, where BRD is
the decimal equivalent of the unsigned binary value programmed within the bit field:
6
3.6864×10
BaudRate = ---------------------------------------
16x(BRD + 1)
6
3.6864×10
BRD = ---------------------------------------- – 1
16BaudRate
The following tables show the bit locations corresponding to the baud rate divisor field that is split
between two 8-bit registers. The upper 4 bits of BRD reside within SDCR3 and the lower 8 bits
reside within SDCR4. The SDLC must be disabled (SUS=RXE=TXE=0) whenever these registers
are written. Note that writes to reserved bits are ignored and reads return zeros; question marks
indicate that the values are unknown at reset.
Address: 0h 8002 006C
SDCR3
Read/Write
Bit
7
6
5
0
4
0
3
?
2
1
0
?
Reserved
BRD<11:8>
Reset
0
0
?
?
Bit
3..0
Name
Description
BRD<11:8 Baud rate divisor.
>
Encoded value (from 0 to 4096). Used to generate the baud rate of the SDLC.
6
Baud Rate = 3.6864x10 /(16x(BRD+1)), where BRD is a decimal value.
7..4
—
Reserved.
Address: 0h 8002 0070
SDCR4
Read/Write
Bit
Reset
7
6
5
?
4
3
2
?
1
0
?
BRD<7:0>
?
?
?
?
?
Bit
7..0
Name
Description
BRD<7:0>
Baud rate divisor.
Encoded value (from 0 to 4096). Used to generate the baud rate of the SDLC.
6
Baud Rate = 3.6864x10 /(16x(BRD+1)), where BRD is a decimal value.
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11.9.7
SDLC Data Register
The SDLC data register (SDDR) is an 8-bit register corresponding to both the top and bottom
entries of the transmit and receive FIFOs, respectively.
When SDDR is read, the lower 8 bits of the bottom entry of the 11-bit receive FIFO is accessed. As
data enters the top of the receive FIFO, bits 8..10 are used as tags to indicate various conditions that
occur during reception of each piece of data. The tag bits are transferred down the FIFO along with
the data byte that encountered the condition. When data reaches the bottom, bit 8 of the bottom
FIFO entry is automatically transferred to the end of frame (EOF) flag, bit 9 to the CRC error
(CRE) flag, and bit 10 to the receiver overrun (ROR) flag, all within SDLC status register 1. The
user can read these flags to determine if the value at the bottom of the FIFO represents the last byte
within the packet and/or encountered an error during reception. After checking the flags, the FIFO
value can then be read, which causes the data in the next location of the receive FIFO to
automatically transfer down to the bottom entry and its EOF/CRE/ROR bits to be transferred to the
status register.
The end/error in FIFO (EIF) status bit is set within status register 0 whenever one or more of the
tag bits (8..10) are set within any of the bottom four entries of the receive FIFO and is cleared when
no error bits are set in the bottom four entries of the FIFO. When EIF is set, an interrupt is
generated and receive FIFO DMA requests are disabled so that the user can manually empty FIFO,
always checking the end of frame, CRC error, and overrun error flags in status register 1 first
before removing each data value from the FIFO. After each entry is removed, the user should
check the EIF bit to see if any errors remain, and repeat the procedure until all errors are flushed
from the FIFO. Once EIF is cleared, servicing of the receive FIFO by the DMA controller is
automatically reenabled.
When SDDR is written, the topmost entry of the 8-bit transmit FIFO is accessed. After a write, data
is automatically transferred down to the lowest location within the transmit FIFO, which does not
already contain valid data. Data is removed from the bottom of the FIFO one piece at a time by the
transmit logic, is loaded into the transmit serial shifter, and is then serially shifted out onto the
TXD1 pin at the programmed baud rate.
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The following table shows the bit locations corresponding to the data field and end-of-frame bit as
well as the cyclic redundancy check and receiver overrun error bits within the SDLC data register.
Note that both FIFOs are cleared when the SA-1100 is reset, the transmit FIFO is cleared when
writing TXE=0, and the receive FIFO is cleared when writing RXE=0.
Address: 0h 8002 0078
SDDR
Read/Write
Bit
10
ROR
0
9
CRE
0
8
EOF
0
7
0
6
0
5
4
3
2
1
0
0
Bottom of Receive FIFO Data
Reset
0
0
0
0
0
Read Access
Note: ROR, CRE, EOF are not read, but rather are transferred to corresponding status bits in SDSR1
each time a new data value is transferred to SDDR.
Bit
7
0
6
0
5
4
3
2
1
0
0
0
Top of Transmit FIFO Data
Reset
0
0
0
0
Write Access
Bit
7..0
Name
DATA
Description
Top/bottom of transmit/receive FIFO data.
Read – Bottom of receive FIFO.
Write – Top of transmit FIFO.
8
EOF
End of frame.
0 – The last byte of the frame has not been encountered.
1– The data value at the bottom of the receive FIFO represents the last byte of the frame.
Note: Each time an 11-bit value reaches the bottom of the receive FIFO, bit 8 from the
last FIFO entry is transferred to the EOF bit in SDSR1.
9
CRE
CRC error.
0 – CRC not encountered yet, or the CRC value calculated on the incoming data
matched the received CRC value.
1 – The CRC value calculated on the incoming data did not match the received CRC
value.
Note: Each time an 11-bit value reaches the bottom of the receive FIFO, bit 9 from the
last FIFO entry is transferred to the CRE bit in SDSR1.
10
ROR
Receiver overrun.
0 – No receiver overrun has been detected.
1 – Receive logic attempted to place data into receive FIFO while it was full; one or more
data values after the data value at the bottom of the receive FIFO were lost.
Note: Each time an 11-bit value reaches the bottom of the receive FIFO, bit 10 from the
last FIFO entry is transferred to the ROR bit in SDSR1.
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11.9.8
SDLC Status Register 0
SDLC status register 0 (SDSR0) contains bits that signal the transmit FIFO service request, receive
FIFO service request, receiver abort, transmit FIFO underrun, and the end/error in receive FIFO
condition. Each of these hardware-detected events signal an interrupt request to the interrupt controller.
A bit that can cause an interrupt signals the interrupt request as long as the bit is set. Once the bit is
cleared, the interrupt is cleared. Read/write bits are called status bits; read-only bits are called flags.
Status bits are referred to as “sticky” (once set by hardware, must be cleared by software). Writing
a one to a sticky status bit clears it; writing a zero has no effect. Read-only flags are set and cleared
by hardware; writes have no effect. Additionally, some bits that cause interrupts have
corresponding enable/mask bits in the control registers and are indicated in the following section
headings. Note that the user has the ability to mask all SDLC interrupts by clearing bit 14 within
the interrupt controller mask register (ICMR). See the Section 9.2, “Interrupt Controller” on
11.9.8.1
End/Error in FIFO Status (EIF) (read-only, nonmaskable interrupt)
The end/error in FIFO flag (EIF) is a read-only bit that is set when any tag bits (8 through 10) are set
within the bottom four entries of the receive FIFO and is cleared when no error bits are set within the
bottom four entries of the FIFO. When EIF is set, an interrupt is signalled and DMA requests to
empty the receive FIFO are disabled until EIF is cleared. To discover which FIFO entry contains the
end of frame or an error condition, the user should check the state of the EOF, CRE, and ROR bits and
read the corresponding value from the SDDR. This procedure should be repeated until EIF is cleared
because set tag bits that are present within any of the four lowest entries in the receive FIFO can set
EIF. Once all set tags bits are cleared from the bottom half of the receive FIFO, EIF is automatically
cleared, which in turn, clears the interrupt and reenables the receive FIFO DMA request.
11.9.8.2
Transmit Underrun Status (TUR) (read/write, maskable interrupt)
The transmit underrun status bit (TUR) is set when the transmit logic attempts to fetch data from the
transmit FIFO after it has been completely emptied. When an underrun occurs, the transmitter takes
one of two actions. When the transmit underrun select bit is clear (TUS=0), the transmitter ends the
frame by shifting out the CRC that is calculated continuously on outgoing data, followed by a flag.
When TUS=1, the transmitter is forced to transmit an abort and continues to transmit ones until valid
data is again available within the FIFO. Once data resides within the bottom entry of the transmit
FIFO, a new data frame is initiated by transmitting a start flag followed by the transmission of data
from the FIFO. When the TUR bit is set, an interrupt request is made unless it is masked. When
TUS=0, the interrupt is masked; when TUS=1 it is enabled. Note that underruns are not generated
when the SDLC transmitter is first enabled and is in the idle state (continuously transmits flags).
11.9.8.3
Receiver Abort Status (RAB) (read/write, maskable interrupt)
The receiver abort status bit (RAB) is set for three different cases:
• when an abort is detected during receipt of an incoming frame
• if the receive carrier is lost during active operation
• if the stop flag is not received on a byte boundary.
An abort is signalled when seven or more consecutive ones are detected on the RXD1 pin. An abort
is also signalled if the receive pin is held high or low for more than six bit periods, which indicates
a loss of carrier. It is also generated when the end flag is received and it is not on a byte boundary,
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which indicates that the address, control, and data fields did not add up to an even multiple of 8
bits. When an abort is received, the current data byte within the serial shifter is discarded, the least
recent byte (the oldest of the two bytes) of data in the temporary FIFO is moved to the receive
FIFO (the other byte is discarded), and the EOF tag is set in the FIFO entry that corresponds to the
last piece of data that was received before the frame was aborted. The receiver then enters hunt
mode, searching for a flag. When the RAB bit is set, an interrupt request is made unless the
receiver abort enable (RAE) bit is cleared.
11.9.8.4
Transmit FIFO Service Request Flag (TFS) (read-only, maskable
interrupt)
The transmit FIFO service request flag (TFS) is a read-only bit that is set when the transmit FIFO is
nearly empty and requires service to prevent an underrun. TFS is set whenever the transmit FIFO
has four or fewer entries of valid data (half-full or less), and is cleared when it has five or more
entries of valid data. When the TFS bit is set, an interrupt request is made unless the transmit FIFO
interrupt request enable (TIE) bit is cleared. The state of TFS is also sent to the DMA controller,
and can be used to signal a DMA service request. Note that TIM has no effect on the generation of
the DMA service request. After the DMA or CPU fills the FIFO such that five or more locations
are filled within the transmit FIFO, the TFS flag (and the service request and/or interrupt) is
automatically cleared.
11.9.8.5
Receive FIFO Service Request Flag (RFS) (read-only, maskable
interrupt)
The receive FIFO service request flag (RFS) is a read-only bit that is set when the receive FIFO is
nearly filled and requires service to prevent an overrun. The amount of data that causes RFS to be
set is nondeterministic. However, the range in which RFS will be set is guaranteed. RFS is set at
some point when the receive FIFO is one- to two-thirds full (or more). The UART’s FIFOs are
self-timed to reduce cost and save power. As a result, the depth at which the receive FIFO service
request is generated is variable. This is the reason the receive FIFO is twelve entries deep instead of
eight like the transmit FIFO. At which entry in the FIFO the request is actually triggered is
dependent on IC process, operating temperature, and so on. The receive FIFO is designed to signal
the RFS bit to be set when it contains eight entries of valid data. However, because of the
variability of the self-timed logic, RFS may also be set when seven, six, or five entries of valid data
are present within the FIFO. Likewise, under normal circumstances, RFS is cleared when the
receive FIFO has seven remaining entries of valid data. However, again due to variations, RFS may
be cleared when six or five entries of data remain.
When the RFS bit is set, a DMA service request is made. An interrupt request is also made unless
the receive FIFO interrupt request enable (RIE) bit is cleared. Even though more than four entries
of data may exist within the receive FIFO, the user must configure the DMA burst size to four
words. If programmed I/O is used to service the receive FIFO, a maximum of 4 words may be
removed without checking if data is valid. After this point, the receive FIFO not empty (RNE) flag
must be polled before each read to see if more data remains. After the DMA or CPU empties the
FIFO such that five or more empty locations are available within the receive FIFO, the RFS flag (as
well as the DMA and interrupt request) is automatically cleared.
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The following table shows the bit locations corresponding to the status and flag bits within SDLC
status register 0. Note that the reset state of all writable status bits is unknown (indicated by
question marks) and must be cleared (by writing a one to them) before enabling the SDLC. Also
note that writes to reserved bits are ignored and reads return zeros.
Address: 0h 8002 0080
SDSR0
Read/Write & Read-Only
Bit
7
6
Reserved
0
5
0
4
RFS
0
3
TFS
0
2
RAB
?
1
TUR
?
0
EIF
?
Reset
0
Bit
Name
EIF
Description
0
Error in FIFO (read-only).
0 – Bits 8..10 are not set within any of the four bottom entries of the receive FIFO;
receive FIFO DMA service requests are enabled.
1 – One or more tag bits (8..10) are set within one or more of the bottom four entries of
the receive FIFO; request interrupt, disable receive FIFO DMA service requests.
1
2
TUR
RAB
Transmit FIFO underrun.
0 –Transmit FIFO has not experienced an underrun.
1 – Transmit logic attempted to fetch data from transmit FIFO while it was empty;
interrupt request signalled if not masked (if TUS=1).
Receiver abort.
0 – No abort has been detected for the incoming frame.
1 – Abort detected during receipt of incoming frame, seven or more ones detected on
receive pin, EOF bit set in receive FIFO next to last piece of “good” data received before
the abort, interrupt requested if it is enabled (if RAE=1).
3
4
TFS
Transmit FIFO service request (read-only).
0 – Transmit FIFO is more than half-full (five or more entries filled) or transmitter
disabled.
1 – Transmit FIFO is half-full or less (four or fewer entries filled) and transmitter operation
is enabled. DMA service request signalled, interrupt request signalled if it is enabled (if
TIE=1).
RFS
Receive FIFO service request (read-only).
0 – Receive FIFO contains seven or fewer entries of data or receiver disabled.
1 – Receive FIFO is one- to two-thirds full (contains 5, 6, 7, or 8 entries of data) or more,
receiver operation is enabled, DMA service request signalled, and interrupt request
signalled if it is enabled (if RIE=1).
7..5
—
Reserved.
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11.9.9
SDLC Status Register 1
SDLC status register 1 (SDSR1) contains flags and status bits that indicate when the receiver is
synchronized, the transmitter is active, that the transmit FIFO is not full, that the receive FIFO is
not empty, a transition has been detected on the receive line, and when an end of frame, CRC error,
or underrun error has occurred. All bits within SDSR1 are noninterruptible.
11.9.9.1
11.9.9.2
11.9.9.3
Receiver Synchronized Flag (RSY) (read-only, noninterruptible)
The receiver synchronized (RSY) flag is a read-only bit that is set when the receiver is synchronized
with the incoming data stream and is cleared when the receiver logic is in hunt mode (looking for a
flag to achieve bit and frame synchronization) or the receiver is disabled (RXE=0). This bit does not
request an interrupt.
Transmitter Busy Flag (TBY) (read-only, noninterruptible)
The transmitter busy (TBY) flag is a read-only bit that is set when the transmitter is actively
transmitting a frame (address, control, data, CRC, start, or stop flag) or an abort, and is cleared when
the transmitter is idle (transmitting flags that are not part of a frame) or the transmitter is disabled
(TXE=0). This bit does not request an interrupt.
Receive FIFO Not Empty Flag (RNE) (read-only, noninterruptible)
The receive FIFO not empty flag (RNE) is a read-only bit that is set whenever the receive FIFO
contains one or more bytes of valid data and is cleared when it no longer contains any valid data. This
bit can be polled when using programmed I/O to remove remaining bytes of data from the receive
FIFO because DMA service and CPU interrupt requests are made only when 8, 7, 6, or 5 bytes reside
within the FIFO. Data remains after each service request as well as at the end of a frame. This bit does
not request an interrupt.
11.9.9.4
Transmit FIFO Not Full Flag (TNF) (read-only, noninterruptible)
The transmit FIFO not full flag (TNF) is a read-only bit that is set whenever the transmit FIFO
contains one or more entries that do not contain valid data and is cleared when the FIFO is
completely full. This bit can be polled when using programmed I/O to fill the transmit FIFO over
its halfway mark. This bit does not request an interrupt.
11.9.9.5
11.9.9.6
Receive Transition Detect Status (RTD) (read/write, noninterruptible)
The receive transition detect (RTD) status bit is set whenever the receiver is enabled (RXE=1) and a
transition is detected on the RXD1 pin (either rising or falling). This bit does not request an interrupt.
End of Frame Flag (EOF) (read-only, noninterruptible)
The end of frame flag (EOF) is set when the last byte of data within a frame (including aborted
frames) resides within the bottom entry of the receive FIFO.
The receive FIFO contains three tag bits (8, 9, and 10) that are not directly readable. The 8th bit is
set at the top of the FIFO whenever the last byte within a frame is moved from the receive serial
shifter to the top of the receive FIFO. This tag travels along with the last data value as it moves
down the FIFO. Each time a data value is transferred to the bottom of the FIFO (caused by a read of
the previous value), the state of the tag bit is moved from the FIFO to the EOF bit in the status
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register. After the error in FIFO (EIF) status bit is set, the user should always read SDSR1 first to
check EOF before reading the data value from SDDR because EOF corresponds to the current data
byte at the bottom of the receive FIFO and is updated each time data is removed from the FIFO.
11.9.9.7
CRC Error Status (CRE) (read-only, noninterruptible)
The CRC error flag (CRE) is set when the CRC value calculated by the receive logic does not
match the CRC value contained within the incoming serial data stream.
The receive FIFO contains 3 tag bits (8, 9, and 10) that are not directly readable. Whenever a CRC
error is detected, the 9th bit is set within the top entry of the receive FIFO, corresponding to the last
byte of data within the frame. This tag travels along with the last piece of data from the frame as it
moves down the FIFO. Each time a data value is transferred to the bottom of the FIFO (caused by a
read of the previous value), the state of the tag bit is moved from the FIFO to the CRE bit in the
status register, indicating whether or not the frame has encountered a CRC error. After the error in
the FIFO (EIF) status bit is set, the user should always read SDSR1 first to check CRE before
reading the data value from SDDR because CRE corresponds to the current data byte at the bottom
of the receive FIFO and is updated each time data is removed from the FIFO.
11.9.9.8
Receiver Overrun Status (ROR) (read-only, noninterruptible)
The receiver overrun flag (ROR) is set when the receive logic attempts to place data into the
receive FIFO after it has been completely filled.
The receive FIFO contains 3 tag bits (8, 9, and 10) that are not directly readable. The 10th bit is set
within the top entry of the receive FIFO whenever an overrun occurs. This tag travels along with
the last “good” data value before the overflow occurred as it moves down the FIFO. Each time a
data value is transferred to the bottom of the FIFO (caused by a read of the previous value), the
state of the tag bit is moved from the FIFO to the ROR bit in the status register, indicating that the
next value in the FIFO is the last “good” piece of data before the overflow occurred. After the error
in the FIFO (EIF) status bit is set, the user should always read SDSR1 first to check CRE before
reading the data value from SDDR because CRE corresponds to the current data byte at the bottom
of the receive FIFO and is updated each time data is removed from the FIFO.
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The following table shows the location of the flag and status bits within SDLC status register 1.
The bits within this register do not produce interrupt requests. Note that the reset value of RTD is
unknown (indicated by question marks) and must be cleared if set following a reset of the
SA-1100. The remainder of SDSR1 is read-only (writes are ignored).
.
Address: 0h 8002 0084
SDSR1
Read/Write & Read-Only
Bit
7
ROR
0
6
CRE
0
5
EOF
0
4
3
TNF
1
2
RNE
0
1
TBY
0
0
RSY
0
RTD
?
Reset
Bit
Name
RSY
Description
0
Receiver synchronized flag (read-only).
0 – Receiver is in hunt mode or is disabled.
1 – Receiver logic is synchronized with the incoming data (no interrupt generated).
1
TBY
Transmitter busy flag (read-only).
0 – Transmitter is idle (continuous flags) or disabled.
1– Transmit logic is currently transmitting a frame (address, control, data, CRC, or
start/stop flag) or an abort (no interrupt generated).
2
3
RNE
TNF
Receive FIFO not empty (read-only).
0 – Receive FIFO is empty.
1 – Receive FIFO is not empty (no interrupt generated).
Transmit FIFO not full (read-only).
0 – Transmit FIFO is full.
1 – Transmit FIFO is not full (no interrupt generated).
4
5
RTD
EOF
Receive transition detect.
0 – No transition detected on RXD1 pin since the last time software cleared this bit.
1 – Rising and/or falling edge detected on RXD1 pin (no interrupt generated).
End of frame (read-only).
0 – Current frame has not completed.
1 – The value at the bottom of the receive FIFO is the last byte of data within the frame.
6
7
CRE
ROR
CRC error (read-only).
0 – No CRC check errors encountered in the receipt of data.
1 – CRC calculated on the incoming data does not match CRC value contained within
the received frame.
Receive FIFO overrun (read-only).
0 – Receive FIFO has not experienced an overrun.
1 – Receive logic attempted to place data into receive FIFO while it was full; the next
data value in the FIFO is the last piece of “good” data before the FIFO was overrun.
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11.9.10 UART Register Locations
Table 11-14 shows the registers associated with the UART and the physical addresses used to
of the programming and operation of the UART (serial port 1’s UART is identical to serial port 3’s
UART).
Table 11-14. UART Control, Data, and Status Register Locations
Address
0h 8001 0000
Name
UTCR0
Description
UART control register 0
0h 8001 0004
0h 8001 0008
0h 8001 000C
0h 8001 0010
0h 8001 0014
0h 8001 0018
0h 8001 001C
0h 8001 0020
UTCR1
UTCR2
UTCR3
—
UART control register 1
UART control register 2
UART control register 3
Reserved
UTDR
—
UART data register
Reserved
UTSR0
UTSR1
UART status register 0
UART status register 1
0h 8001 0024 –
0h 8001 005C
—
Reserved
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11.9.11 SDLC Register Locations
Table 11-15 shows the registers associated with the SDLC and the physical addresses used to
access them.
Table 11-15. SDLC Control, Data, and Status Register Locations
Address
Name
SDCR0
Description
SDLC control register 0
0h 8002 0060
0h 8002 0064
0h 8002 0068
0h 8002 006C
0h 8002 0070
0h 8002 0074
0h 8002 0078
0h 8002 007C
0h 8002 0080
0h 8002 0084
SDCR1
SDCR2
SDCR3
SDCR4
—
SDLC control register 1
SDLC control register 2
SDLC control register 3
SDLC control register 4
Reserved
SDDR
—
SDLC data register
Reserved
SDSR0
SDSR1
SDLC status register 0
SDLC status register 1
0h 8002 0088 –
0h 8002 FFFF
—
Reserved
11.10
Serial Port 2 – Infrared Communications Port (ICP)
The infrared communications port (ICP) operates at half-duplex and provides direct connection to
commercially available Infrared Data Association (IrDA) compliant LED transceivers. The ICP
supports both the original IrDA standard with speeds up to 115.2 Kbps as well as the newer
4-Mbps standard. Both standards use different bit encoding techniques and serial packet formats.
Low-speed IrDA transmission uses the Hewlett-Packard Serial Infrared standard (HP-SIR) for bit
encoding and a universal asynchronous receiver-transmitter (UART) as the serial engine;
high-speed uses four-position pulse modulation (4PPM) and a specialized serial packet protocol
developed expressly for IrDA transmission. To support these two standards, the ICP contains two
separate blocks, each comprised of a bit encoder/decoder and serial-to-parallel data engine. The
engine within the ICP that implements the special 4-Mbps protocol is called the high-speed serial
to parallel (HSSP) receiver-transmitter. Only one of the two standards can be enabled at a time (the
user cannot enable low-speed transmit and high-speed receive at the same time). To support a
variety of IrDA transceivers, both the transmit and receive data pins can be individually configured
to communicate either using normal or inverted data. Additionally, if IrDA transmission is not
needed, the ICP’s UART can be enabled while disabling the HP-SIR bit encoder for use as a
general-purpose serial port.
Note: Programming and operation of serial port 2’s UART is identical to serial port 3. See Section 11.11,
“Serial Port 3 - UART” on page 11-128 for a complete description of using the ICP for low-speed
IrDA operation.
The external pins dedicated to the ICP are TXD2 and RXD2. If serial transmission is not required
and the ICP is disabled, control of these pins is given to the peripheral pin control (PPC) unit for
use as general-purpose input/output pins (noninterruptible). See Section 11.13, “Peripheral Pin
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11.10.1 Low-Speed ICP Operation
Following reset, both the UART and HSSP are disabled, which causes the peripheral pin controller
(PPC) to assume control of the port’s pins. Reset causes the PPC to configure all of the peripheral
pins as inputs, including serial port 2’s transmit (TXD2) and receive (RXD2) pins. Reset also
causes the UART’s transmit and receive FIFOs to be flushed (all entries invalidated). Before
enabling the ICP for low-speed operation, the user must first clear any writable or “sticky” status
bits, which are set by writing a one to each bit. Next, the desired mode of operation is programmed
in the control registers. At this point the user may “prime” the UART’s transmit FIFO by writing up
to eight values, or the FIFO can remain empty and either programmed I/O or the DMA can be used
to service it after the ICP is enabled. Once the ICP is enabled, transmission/reception of data can
begin on the transmit (TXD2) and receive (RXD2) pins.
For low-speed operation, all serial data that is transferred between the TXD2/RXD2 pins and the
ICP’s UART is modulated/demodulated according to the HP-SIR IrDA standard. The IrDA
standard also specifies the frame format that must be used by the UART.
*
11.10.1.1 HP-SIR Modulation
Hewlett-Packard Serial Infrared* (SIR) modulation is used for low-speed transmission up to
115.2 Kbps. Logic zero is represented by a pulse of light that is either 3/16 of the bit time wide, or
1.6 µs wide (1.6 µs is 3/16 of the bit time for the highest bit rate of 115.2 Kbps). The rising edge of
the pulse corresponds to the start of the zero bit time. Logic one is represented by the absence of
Note that the byte is transmitted starting with the LSB first.
Figure 11-24. HP-SIR Modulation Example
LSB
1
MSB
0
Bit
Value
0
0
1
1
0
1
Digital
Data
3/16 of the Bit Time
HP-SIR*
Data
11.10.1.2
UART Frame Format
For transmission rates up to 115.2 Kbps, the ICP’s UART is used. The user must program it to
produce a frame that produces 8 bits of data, one stop bit, and no parity, as shown in Figure 11-25.
Note that PE=1, SBS=1, DSS=0, SCE=1, BRK=1, RXE=0, TXE=0, and BRD=0x000 are illegal
programming modes for IrDA operation and will produce unpredictable results. See Section 11.11,
the ICP’s UART.
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Figure 11-25. UART Frame Format for IrDA Transmission (<= 115.2 Kbps)
Start Bit
Data<7>
Data<6>
Data<5>
Data<4>
Data<3>
Data<2>
Data<1>
Data<0>
Stop Bit
UTCR0-2 Programming:
PE=0
DSS = 1
SCE = 0
RCE = don’t care
TCE = don’t care
RXE = 1
TXE = 1
BRK = 0
RIE = 0 or 1
TIE = 0 or 1
OES = don’t care
SBS = 0
BRD = 0x001 to
0xFFF
11.10.2 High-Speed ICP Operation
Before enabling the ICP for high-speed operation, the user must first clear any writable or “sticky”
status bits that are set by writing a one to each bit. Next, the desired mode of operation is
programmed in the control registers. At this point the user can “prime” the HSSP’s transmit FIFO
by writing up to 16 values, or the FIFO can remain empty and either programmed I/O or the DMA
can be used to service it after the HSSP is enabled. Once the HSSP is enabled,
transmission/reception of data can begin on the transmit (TXD2) and receive (RXD2) pins.
For high-speed operation, all serial data, which is transferred between the TXD2/RXD2 pins and
the ICP’s HSSP, is modulated/demodulated according to the 4PPM IrDA standard. Additionally,
the HSSP uses a frame format that is very similar to the SDLC’s. For high-speed transmission, both
the modulation technique and the HSSP’s frame format are discussed in the following sections.
11.10.2.1 4PPM Modulation
Four-position pulse modulation (4PPM) is used for the high-speed transmission rate of 4.0 Mbps.
Two data bits are encoded at a time by placing a single 125 ns light pulse within one of four
timeslots. The four timeslots are collectively termed a “chip.” Bytes are encoded one at a time.
They are divided into four individual nibbles (2-bit pairings) and the least significant nibble is
constructed using four chips. Note that bits within each nibble are not reordered, but nibble 0 (least
significant) is transmitted first, ending with nibble 3 (most significant).
Figure 11-26. 4PPM Modulation Encodings
Chip
Timeslots
1
2
3
4
Data = 00
Data = 01
Data = 10
Data = 11
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Peripheral Control Module
Figure 11-27. 4PPM Modulation Example
Nibble 3
1
Nibble 2
1
Nibble 1
0
Nibble 0
0
Original
0
1
1
0
0
1
1
0
Byte Order
Reordered
Nibbles
0
0
1
1
Nibble 0
Nibble 1
Nibble 2
Nibble 3
Chips
1
3
4
2
Timeslots
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
125ns
4PPM
Data
Receive data sample counter frequency = 6X pulse width; each timeslot sampled on third clock.
11.10.2.2 HSSP Frame Format
When the 4-Mbps transmission rate is used, the high-speed serial/parallel (HSSP) interface within
the ICP is used along with the 4PPM bit encoding. The high-speed frame format shown in
Figure 11-28 is similar to serial port 1’s SDLC format with several minor modifications: the
start/stop flags and CRC are twice as long, and instead of one start flag, a preamble and start flag of
differing lengths are used.
Figure 11-28. High-Speed Serial Frame Format for IrDA Transmission (4.0 Mbps)
8180 chips
max
(2045 bytes)
4 chips
(8 bits)
4 chips
(8 bits)
16 chips
(32 bits)
64 chips
8 chips
8 chips
Control
Preamble
Start Flag
Start Flag
Address
Data
CRC-32
Stop Flag
(optional)
|0000|1100|0000|1100|0110|0000|0110|0000|
|0000|1100|0000|1100|0000|0110|0000|0110|
|1000|0000|1010|1000|... repeated 16 times
Stop Flag
Preamble
The preamble, start, and stop flags are a mixture of chips that contain either 0, 1, or 2 pulses within
the four timeslots. Chips with 0 and 2 pulses are used to construct flags because they represent invalid
data bit pairings (one pulse required per chip to represent one of four bit pairs). The preamble
contains 16 repeated transmissions of the four chips: 1000 0000 1010 1000; the start flag contains one
transmission of eight chips: 0000 1100 0000 1100 0110 0000 0110 0000; and the stop flag contains
one transmission of eight chips: 0000 1100 0000 1100 0000 0110 0000 0110. The address, control,
data, and CRC-32 use the standard 4PPM chip encoding to represent 2 bits per chip.
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11.10.2.3 Address Field
The 8-bit address field is used by a transmitter to target a select group of receivers when multiple
stations are connected to the same set of serial lines. The address allows up to 255 stations to be
uniquely addressed (00000000 to 11111110). The global address (11111111) is used to broadcast
messages to all stations. Serial port 1 contains an 8-bit register, which is used to program a unique
address for broadcast recognition, as well as a control bit to enable/disable the address match
function. Note that the address of received frames is stored in the receive FIFO along with normal
data and that it is transmitted and received starting with its LSB and ending with its MSB.
11.10.2.4 Control Field
The IPC control field is 8 bits and is optional (as defined by the user). Serial port 2 does not
provide any hardware decode support for the control byte, but instead treats all bytes between the
address and the CRC as data. Note that the control field is transmitted and received starting with its
LSB and ending with its MSB.
11.10.2.5 Data Field
The data field can be any length that is a multiple of 8 bits from 0 to 2045 bytes. The user
determines the data field length according to the application requirements and transmission
characteristics of the target system. Usually a length is selected that maximizes the amount of data
that can be transmitted per frame while allowing the CRC checker to be able to consistently detect
all errors during transmission. Note that serial port 2 does not contain any hardware that restricts
the maximum amount of data transmitted or received. It is up to the user to maintain these limits. If
a data field that is not a multiple of 8 bits is received, an abort is signalled. Also note that each byte
within the data field is transmitted and received starting with its LSB and ending with its MSB.
11.10.2.6 CRC Field
The HSSP uses the established 32-bit cyclic redundancy check (CRC-32) to detect bit errors that
occur during transmission. A 32-bit CRC is computed using the address, control, and data fields,
and is included in each frame. A separate CRC generator is implemented in both the transmit and
receive logic. The transmitter calculates a CRC, and while data is actively transmitted, places the
inverse of the resultant 32-bit value at the end of each frame before the flag is transmitted. In a
similar manner, the receiver also calculates a CRC for each received data frame and compares the
calculated CRC to the expected CRC value contained within the end of each received frame. If the
calculated value does not match the expected value, an interrupt is signalled. The CRC
computation logic is preset to all ones before reception or transmission of each frame and the result
is inverted before it is used for comparison or transmission. Note that unlike the address, control,
and data fields, the 32-bit inverted CRC value is transmitted and received from least significant
byte to most significant, and within each byte the least significant nibble or chip is encoded or
decoded first. The cyclic redundancy checker uses the 32-term polynomial:
32
26
23
22
16
12
11
10
8
7
5
4
2
CRC(x)= (x + x + x + x + x + x + x + x + x + x + x + x + x + x + 1)
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11.10.2.7 Baud Rate Generation
The baud rate is derived by dividing down a fixed 48-MHz clock generated by one of the two
on-chip PLLs by six. The 8-MHz baud (or timeslot) clock for the receive logic is synchronized
with the 4PPM data stream each time a transition is detected on the receive data line using a digital
PLL. To encode a 4-Mbps data stream, the required “chip” frequency is 2.0 MHz, with four
timeslots per chip at a frequency of 8.0 MHz. Receive data is sampled halfway through each
time-slot period by counting three out of the six 48-MHz clock periods that make up each timeslot
(four chips repeated 16 times) is used to identify the first timeslot or beginning of a chip and resets
the 2-bit time-slot counter logic, such that the 4PPM data is properly decoded.
11.10.2.8 Receive Operation
The IrDA standard specifies that all transmission occurs at half-duplex. This restriction forces the
user to enable one direction at a given time: either the transmit or receive logic, but not both.
However, the HSSP’s hardware does not impose such a restriction.The user may enable both the
transmitter and receiver at the same time. Although forbidden by the IrDA standard, this feature is
particularly useful when using the ICP’s loopback mode, which internally connects the output of
the transmit serial shifter to the input of the receive serial shifter.
After the ICP is enabled for 4-Mbps transmission, the receiver logic begins by selecting an
arbitrary chip boundary, receives four incoming 4PPM chips from the RXD2 pin using a serial
shifter, and latches and decodes the chips one at a time. If the chips do not decode to the correct
preamble, the time-slot counter’s clock is forced to skip one 8-MHz period, effectively delaying the
time-slot count by one. This process is repeated until the preamble is recognized, signifying that
the time-slot counter is synchronized. The preamble can be repeated as few as 16 times or may be
continuously repeated to indicate an idle receive line.
At any time after the transmission of 16 preambles, the start flag can be received. The start flag is
eight chips long. If any portion of the start flag does not match the standard encoding, the receive
logic signals a framing error and the receive logic once again begins to look for the frame
preamble.
Once the correct start flag is recognized, each subsequent grouping of four chips is decoded into a
data byte and placed within a 5-byte temporary FIFO, which is used to prevent the CRC from being
placed within the receive FIFO. When the temporary FIFO is filled, data values are pushed out one
by one to the receive FIFO. The first data byte of a frame is the address. If receiver address
matching is enabled, the received address is compared to the address programmed in the address
match value field in one of the control registers. If the two values are equal or if the incoming
address contains all ones, all subsequent data bytes, including the address byte, are stored in the
receive FIFO. If the values do not match, the receiver logic does not store any data in the receive
FIFO, ignores the remainder of the frame, and begins to search for the next preamble. The second
data byte of the frame can contain an optional control field as defined by the user and must be
decoded in software (no hardware support within the HSSP).
Frames can contain any amount of data in multiples of 8 bits up to a maximum of 2047 bytes
(including the address and control bytes). The HSSP does not limit frame size; it is the
responsibility of the user to check that the size of each incoming frame does not exceed the IrDA
protocol’s maximum allowed frame size.
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When the receive FIFO is one- to two-thirds full, an interrupt or DMA transfer is signalled. If the
data is not removed soon enough and the FIFO is completely filled, an overrun error is signalled
when the receive logic attempts to place additional data into the full FIFO. Once the FIFO is full,
all subsequent data bytes received are lost while all FIFO contents remain intact.
If any two sequential chips within the data field do not contain pulses (are 0000), the frame is
aborted, the least recent or oldest byte within the temporary FIFO is moved to the receive FIFO
(the remaining four FIFO entries are discarded), the end-of-frame (EOF) tag is set within the same
FIFO entry where the last “good” byte of data resides, and the receiver logic begins to search for
the preamble. An abort also occurs if any data chip containing 0011, 1010, 0101, or 1001 occurs
(invalid chips that do not occur in the stop flag).
The receive logic continuously searches for the 8-chip stop flag. Once it is recognized, the last byte
that was placed within the receive FIFO is flagged as the last byte of the frame and the data in the
temporary FIFO is removed and used as the 32-bit CRC value for the frame. Instead of placing this
in the receive FIFO, the receive logic compares it to the CRC-32 value, which is continuously
calculated using the incoming data stream. If they do not match, the last byte that was placed
within the receive FIFO is also tagged with a CRC error. The CRC value is not placed in the
receive FIFO.
If the user disables the HSSP’s receiver during operation, reception of the current data byte is
stopped immediately, the serial shifter and receive FIFO are cleared, control of the RXD2 pin is
given to the peripheral pin control (PPC) unit, and all clocks used by the receive logic are
automatically shut off to conserve power. The user should ensure that the polarity of the RXD2
input is reprogrammed properly if this pin is to be used as a GPIO input.
11.10.2.9 Transmit Operation
Before enabling the HSSP for transmission, the user may either “prime” the transmit FIFO by
filling it with data or allow service requests to cause the CPU or DMA to fill the FIFO once the
HSSP is enabled. Once enabled, the transmit logic issues a service request if its FIFO is empty. For
each frame output, a minimum of 16 preambles are transmitted. If data is not available after the
sixteenth preamble, additional preambles are output until a byte of valid data resides within the
bottom of the transmit FIFO. The preambles are then followed by the start flag and then the data
from the transmit FIFO. Four chips (8 bits) are encoded at a time and then loaded into a serial shift
register. The contents are shifted out onto the TXD2 pin clocked by the 8-MHz baud clock. Note
that the preamble, start and stop flags, and CRC value are automatically transmitted and need not
be placed in the transmit FIFO.
When the transmit FIFO is emptied halfway, an interrupt and/or DMA service request is signalled.
If new data is not supplied soon enough, the FIFO is completely emptied, and the transmit logic
attempts to take additional data from the empty FIFO (one of two actions can be taken as
programmed by the user). An underrun can either signal the normal completion of a frame or an
unexpected termination of a frame in progress.
When normal frame completion is selected and an underrun occurs, the transmit logic transmits the
32-bit CRC value calculated during the transmission of all data within the frame (including the
address and control bytes), followed by the stop flag to denote the end of the frame. The transmitter
then continuously transmits preambles until data is once again available within the FIFO. Once
data is available, the transmitter begins transmission of the next frame.
When unexpected frame termination is selected and an underrun occurs, the transmit logic outputs
an abort and interrupts the CPU. An abort continues to be transmitted until data is once again
available in the transmit FIFO. The HSSP then transmits 16 preambles, a start flag, and starts the
new frame. The off-chip receiver can choose to ignore the abort and continue to receive data or
signal the HSSP to retry transmission of the aborted frame.
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At the end of each frame transmitted, the HSSP outputs a pulse called the serial infrared interaction
pulse (SIP). A SIP is required at least every 500 ms to keep slower speed devices (115.2 Kbps and
slower) from colliding with the higher speed transmission. The SIP simulates a start bit that causes
all low-speed devices to stay off the bus for at least another 500 ms. Transmission of the SIP pulse
causes the TXD2 pin to be forced high for a duration of 1.625 µs and low for 7.375 µs (total SIP
period = 9.0 µs). After the 9.0 µs elapses, the preamble is then transmitted continuously to indicate
to the off-chip receiver that the HSSP’s transmitter is in the idle state. The preamble continues to be
transmitted until new data is available within the transmit FIFO, or the HSSP’s transmitter is
disabled. Note that it is the responsibility of the user to ensure that a frame completes once every
500 ms such that a SIP pulse is produced, keeping all low-speed devices from interrupting
transmission. Because most IrDA compatible devices produce a SIP after each frame transmitted,
the user only needs to ensure that a frame is either transmitted or received by the ICP every 500 ms.
Note that frame length does not represent a significant portion of the 500 ms timeframe in which a
SIP must be produced. At 4.0 Mbps, the longest frame allowed is 16,568 bits, which takes just over
4 ms to transmit. Also note that the HSSP issues a SIP when the transmitter is first enabled to
ensure all low-speed devices are silenced before transmitting its first frame.
If the user disables the HSSP’s transmitter during operation, transmission of the current data byte is
stopped immediately, the serial shifter and transmit FIFO are cleared, control of the TXD2 pin is
given to the peripheral pin control (PPC) unit, and all clocks used by the transmit logic are
automatically shut off to conserve power. The user should ensure that the polarity of the TXD2
output is reprogrammed properly if this pin is to be used as a GPIO output.
11.10.2.10 Transmit and Receive FIFOs
To reduce chip size and power consumption, the HSSP’s FIFOs use self-timed logic (they are not
clocked). Because of process and environmental variations, the depth at which a service request is
triggered to empty the receive FIFO is variable. This variation spans a maximum of four FIFO
entries; the receive FIFO service request can be made at four different FIFO depths.To compensate
for this variability and guarantee that at least eight valid entries of data exist within the FIFO before
generating a service request, an extra four entries have been added to the receive FIFO ( four
entries more than the transmit FIFO). The transmit FIFO is 16 entries deep and the receive FIFO is
20 entries deep. The point at which the receive FIFO service request is triggered spans one fifth
(four entries) of the 20-entry FIFO. The service request is signalled at a depth from two-fifths full
to three-fifths full (when the FIFO contains nine, ten, eleven, or twelve entries of data).
This service request variation applies only to an empty FIFO that is filled (receive FIFO). It does
not apply to a full FIFO that is emptied (transmit FIFO). The transmit FIFO is guaranteed to signal
a service request when it has eight or more empty entries and negate the request when the FIFO
contains nine or more entries that are filled.
If the DMA is used to service either one or both of the HSSP’s FIFOs, the burst size must be set to
eight words, even though more than eight entries of data may exist within the receive FIFO. If
programmed I/O is used to service the FIFOs, a maximum of 8 words may be added to the transmit
FIFO without checking if more space is available. Likewise, a maximum of 8 words may be
removed from the receive FIFO without checking if more data is available. After this point, the
user must poll a set of status bits that indicate if any data remains in the receive FIFO or if space is
available in the transmit FIFO before emptying or filling the FIFOs any further.
11.10.2.11 CPU and DMA Register Access Sizes
Bit positioning, byte ordering, and addressing of the SDLC is described in terms of little endian
ordering. All ICP (HSSP and UART) registers are 8 bits wide and are located in the least
significant byte of individual words. The ARM peripheral bus does not support byte or half-word
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operations. All reads and writes of the ICP by the CPU should be wordwide. Two separate,
dedicated DMA requests exist for both the transmit and the receive FIFOs. If the DMA controller is
used to service the transmit and/or receive FIFOs, the user must ensure the DMA is properly
configured to perform bytewide accesses, using 8 bytes per burst for the HSSP and 4 bytes per
burst for the UART. See later sections in this chapter for summaries of the ICP’s UART registers
and HSSP registers.
11.10.3 UART Register Definition
The ICP’s UART is the same as serial port 3’s UART except that one additional register exists to
control HP-SIR modulation for low-speed operation. See Section 11.11, “Serial Port 3 - UART” on
page 11-128 for a description of the programming and operation of all other features of the ICP’s
UART. Note that the user must ensure that the UART is programmed to yield the frame format
11.10.4 UART Control Register 4
UART control register 4 (UTCR4) contains two different bit fields that control various functions
for 115.2-Kbps (low-speed) IrDA transmission.
11.10.4.1 HP-SIR Enable (HSE)
The HP-SIR enable (HSE) bit controls whether the HP-SIR bit modulation logic is enabled or
disabled. When HSE=0, HP-SIR modulation is disabled, and if UART operation is enabled
(ITR=0), it is used for normal serial transmission (NRZ encoding only) rather than IrDA
communication. When HSE=1, HP-SIR modulation is enabled for low-speed IrDA
communication; zeros are represented by pulses that are 3/16 of the programmed bit width, while
ones are represented by no pulses.
11.10.4.2 Low-Power Mode (LPM)
The low-power mode (LPM) bit controls whether the HP-SIR bit modulation logic represents zeros
using a pulse that is 3/16 of the chosen bit width or a fixed 1.6 µs pulse width. When LPM=0, zeros
are encoded as a pulse, which is 3/16 of the bit width programmed within the UART’s baud rate
divisor (BRD) bit field. When LPM=1, the UART’s programmed bit length is ignored and zeros are
represented by pulses that are 1.6 µs in duration. Programming LPM=1 minimizes the time that the
off-chip LED transceiver is turned on to the minimum pulse width specified by the IrDA low-speed
standard, which in turn, minimizes power consumption.
The following table shows the location of the bits within UART control register 4; question marks
indicate that the values are unknown at reset. Both bits are reset to zero. Note that the UART must
be disabled (RXE=TXE=0) when changing the state of either of these two bits. Also note that
writes to reserved bits are ignored and reads return zeros.
Address: 0h 8003 0010
UTCR4
Read/Write
Bit
7
6
5
0
4
0
3
0
2
0
1
LPM
?
0
HSE
?
Reserved
Reset
0
0
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Bit
Name
Description
0
HSE
LPM
—
HP-SIR enable.
0 – HP-SIR modulation disabled; ICP functions as normal UART if ITR=0.
1 – HP-SIR modulation enabled; ICP functions as low-speed IrDA port if ITR=0.
1
Low-power mode.
0 – Each zero encoded as a pulse that is 3/16 of the programmed bit time if ITR=0.
1 – Each zero encoded as a pulse that is 1.6 µs wide if ITR=0.
7..2
Reserved.
11.10.5 HSSP Register Definitions
There are six registers within the HSSP: three control registers, one data register, and two status
registers. The control registers are used to select IrDA transmission rate, address match value,
whether an abort or end of frame occurs when the transmit FIFO underruns, and true or
complemented transmit and receive data; to enable or disable transmit and receive operation, the
FIFO interrupt service requests, receive address matching, and loopback mode.
The data register addresses the top location of the transmit FIFO and bottom location of the receive
FIFO. When it is read, the receive FIFO is accessed, and when it is written, the transmit FIFO is
accessed.
The status registers contain bits that signal CRC, overrun, underrun, framing, and receiver abort
errors as well as the transmit FIFO service request, receive FIFO service request, and end-of-frame
conditions. Each of these hardware-detected events signals an interrupt request to the interrupt
controller. The status registers also contain flags for transmitter busy, receiver synchronized,
receive FIFO not empty, and transmit FIFO not full (no interrupt generated).
11.10.6 HSSP Control Register 0
The HSSP control register 0 (HSCR0) contains eight different bit fields that control various
functions for 4 Mbps IrDA transmission.
11.10.6.1 IrDA Transmission Rate (ITR)
The IrDA transmission rate (ITR) bit is used to select the transmission speed of the ICP. ITR selects
the correct type of IrDA bit modulation to use (HP-SIR or 4PPM), and enables the correct
serial-to-parallel engine (UART or HSSP). When ITR=0, the HP-SIR modulator is enabled along
with serial port 2’s UART. When ITR=1, the 4PPM modulator is enabled as well as the HSSP. Note
that ITR is the only control bit that affects both the UART and HSSP. Once one of the two speeds is
selected, all further programming is controlled by the individual units (UART or HSSP).
11.10.6.2 Loopback Mode (LBM)
The loopback mode (LBM) bit is used to enable and disable the ability of the HSSP’s transmit and
receive logic to communicate. When LBM=0, the HSSP operates normally. The transmit and
receive data paths are independent and communicate via their respective pins. When LBM=1, the
output of the transmit serial shifter is directly connected to the input of the receive serial shifter
internally, and control of the TXD2 and RXD2 pins is given to the peripheral pin control (PPC)
unit. Note that even though the IrDA standard permits only half-duplex operation, the HSSP does
not restrict the user from transmitting and receiving data at the same time; both are fully
independent units. This function is essential when using the HSSP in loopback mode.
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11.10.6.3 Transmit FIFO Underrun Select (TUS)
The transmit FIFO underrun select (TUS) bit is used both to select what action to take as a result of
a transmit FIFO underrun as well as mask or enable the transmit FIFO underrun interrupt.
When TUS=0, transmit FIFO underruns are used to signal the transmit logic that the end of the
frame has been reached. When the transmit FIFO experiences an underrun, the CRC value, which
is calculated continuously on outgoing data, is loaded to the serial shifter and transmitted, followed
by the stop flag and SIP pulse. Also when TUS=0, the transmit FIFO interrupt is masked and the
state of the transmit FIFO underrun (TUR) status bit is ignored by the interrupt controller.
When TUS=1, transmit FIFO underruns are used to signal the transmit logic that the end of the
frame has not yet been reached. When the transmit FIFO experiences an underrun, the CRC value,
which is calculated continuously on outgoing data, is loaded to the serial shifter and transmitted,
followed by the stop flag and SIP pulse. Additionally, when TUS=0, the transmit FIFO underrun
interrupt is masked, causing the state of the transmit FIFO underrun (TUR) status bit to be ignored
by the interrupt controller. Note that programming TUS=0 does not affect the current state of TUR
or the transmit FIFO logic’s ability to set and clear TUR; it only blocks the generation of the
interrupt request.
When TUS=1, transmit FIFO underruns are used to signal the transmit logic that the end of the
frame has not yet been reached and that the rate in which data is supplied to the transmit FIFO is
not sufficient. When the transmit FIFO experiences an underrun, two sequential chips, each
containing zeros (0000), are output by the transmitter to signal an abort condition; next a SIP pulse
is output, followed by a minimum of 16 preambles. Preambles continue to be output until data is
once again available within the transmit FIFO. Additionally, when TUS=1, the transmit FIFO
underrun interrupt is enabled, and whenever TUR is set (one), an interrupt request is made to the
interrupt controller. To change the state of TUS during operation, the user should fill the transmit
FIFO to ensure TUS is not written at the same time that the transmit FIFO underruns.
TUS is useful for ensuring that frames are not prematurely ended due to an unexpected transmit
FIFO underrun. At the start of a frame, the user can configure TUS=1 such that any underrun
signals an abort to the off-chip receiver. Just before the end of the frame, the user can then
configure TUS=0, allowing the remaining data to be output by the transmit logic. The FIFO then
underruns, causing the CRC, stop flag, and SIP to be transmitted.
11.10.6.4 Transmit Enable (TXE)
The transmit enable (TXE) bit is used to enable and disable HSSP transmit operation. When
TXE=0, the transmit logic is disabled and its clocks are turned off to conserve power. When
TXE=1, the HSSP transmitter logic is enabled for IrDA transmission. It is required that the user
first program all other control bits before setting TXE. If the TXE bit is cleared to zero while the
HSSP is actively transmitting data, transmission is stopped immediately, all data within the
transmit FIFO and serial output shifter is cleared, and control of the TXD2 pin is given to the
peripheral pin control (PPC) unit. When the transmitter is turned on (TXE=0→1), a SIP pulse is
transmitted before transmission of data. A SIP pulse is used to prevent slower devices (115.2 Kbps)
from attempting to take control of infrared transmission. See the previous sections for further
timing details of the SIP pulse.
TXE and RXE are the only control bits within the HSSP that are initialized when a hardware reset
occurs. Clearing TXE to zero ensures the HSSP transmitter is disabled, giving control of the
transmit pin to the PPC unit that configures TXD1 as an input following a reset of the SA-1100.
Note that TXE is ignored when ITR=0 (enables UART operation). Also note that even though the
IrDA standard permits only half-duplex operation, the HSSP does not restrict the user from
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transmitting and receiving data at the same time; both are fully independent units. This function is
particularly useful when using the HSSP in loopback mode. See the Section 11.10.6.2, “Loopback
11.10.6.5 Receive Enable (RXE)
The receive enable (RXE) bit is used to enable or disable HSSP receive operation. When RXE=0, the
receive logic is disabled and its clocks are turned off to conserve power. When RXE=1, the HSSP
receiver logic is enabled for IrDA reception. It is required that the user first program all other control
bits before setting RXE. If the RXE bit is cleared to zero while the HSSP is actively receiving data,
reception is stopped immediately, all data within the receive FIFO and serial input shifter is cleared,
and control of the RXD2 pin is given to the peripheral pin control (PPC) unit. Note that TXE and
RXE are the only control bits within the HSSP that are initialized when a hardware reset occurs.
Clearing RXE to zero ensures the HSSP receiver is disabled, giving control of the receive pin to the
PPC unit, which configures RXD2 as an input following a reset of the SA-1100. Note that RXE is
ignored when ITR=0, which enables UART operation. Also note that even though the IrDA standard
permits only half-duplex operation, the HSSP does not restrict the user from transmitting and
receiving data at the same time; both are fully independent units. This function is particularly useful
when using the HSSP in loopback mode. See the Section 11.10.6.2, “Loopback Mode (LBM)” on
11.10.6.6 Receive FIFO Interrupt Enable (RIE)
The receive FIFO interrupt mask (RIE) bit is used to mask or enable the receive FIFO service
request interrupt. When RIE=0, the interrupt is masked, and the state of the receive FIFO service
request (RFS) bit within HSSP status register 0 is ignored by the interrupt controller. When RIE=1,
the interrupt is enabled, and whenever RFS is set (one), an interrupt request is made to the interrupt
controller. Note that programming RIE=0 does not affect the current state of RFS or the receive
FIFO logic’s ability to set and clear RFS; it only blocks the generation of the interrupt request.
Also note that RIE does not affect generation of the receive FIFO DMA request , which is asserted
whenever RFS=1.
11.10.6.7 Transmit FIFO Interrupt Enable (TIE)
The transmit FIFO interrupt mask (TIE) bit is used to mask or enable the transmit FIFO service
request interrupt. When TIE=0, the interrupt is masked and the state of the transmit FIFO service
request (TFS) bit within HSSP status register 0 is ignored by the interrupt controller. When TIE=1,
the interrupt is enabled, and whenever TFS is set (one), an interrupt request is made to the interrupt
controller. Note that programming TIE=0 does not affect the current state of TFS or the transmit
FIFO logic’s ability to set and clear TFS; it only blocks the generation of the interrupt request.
Also note that TIE does not affect generation of the transmit FIFO DMA request, which is asserted
whenever TFS=1.
11.10.6.8 Address Match Enable (AME)
The address match enable (AME) bit is used to enable or disable the receive logic from comparing
the address programmed in the address match value (AMV) bit field to the address of all incoming
frames. When AME=1, data is stored in the receive FIFO only for those frames that have addresses
that match AMV and for any frame that contains an address containing all ones (11111111),
denoting a global address. For frames in which the address does not match, the data and CRC are
ignored and the receiver resumes hunting for a preamble. When AME=0, address values are not
compared and the data in every frame is stored in the receive FIFO.
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The following table shows the location of the bits within HSSP control register 0. RXE and TXE
are the only control bits that are reset to a known state to ensure the HSSP is disabled following a
reset of the SA-1100. The reset state of all other control bits is unknown (indicated by question
marks) and must be initialized before enabling the HSSP. Note that the HSSP must be disabled
(RXE=TXE=0) when changing the state of bits 0 and 1, and bits 2 through 7 may be written while
the HSSP is enabled to allow various modes to be changed during active operation.
Address: 0h 8004 0060
HSCR0
Read/Write
Bit
7
AME
?
6
TIM
?
5
RIM
?
4
3
TXE
0
2
TUS
?
1
LBM
?
0
ITR
?
RXE
0
Reset
Bit
Name
ITR
Description
0
IrDA transmission rate.
0 – 115.2 Kbps (selects HP-SIR modulation, enables the ICP’s UART engine).
1 – 4.0 Mbps (selects 4PPM modulation, enables the ICP’s HSSP engine).
1
LBM
TUS
Loopback mode.
0 – Normal serial port operation enabled.
1 – Output of HSSP’s transmit serial shifter is connected to input of receive serial shifter
internally. Control of TXD2 and RXD2 pins is given to the PPC unit if ITR=1.
2
3
Transmit FIFO underrun select.
0 – Transmit FIFO underrun causes CRC, stop flag, and SIP to be transmitted, and
masks transmit underrun interrupt generation (TUR ignored).
1 –Transmit FIFO underrun causes an abort to be transmitted, and generates an interrupt
(state of TUR sent to interrupt controller).
TXE
Transmit enable.
0 – HSSP transmit logic disabled; control of the TXD2 pin is given to the PPC unit if ITR=1.
1 – HSSP transmit logic enabled if ITR=1.
Note: A SIP is transmitted immediately after the transmitter is enabled (TXE = 0 → 1).
4
5
RXE
RIE
Receive enable.
0 – HSSP receive logic disabled; control of the RXD2 pin is given to the PPC unit if ITR =1.
1 – HSSP receive logic enabled if ITR=1.
Receive FIFO interrupt enable.
0 – Receive FIFO two- or three-fifths full or more condition does not generate an
interrupt (RFS bit ignored).
1 – Receive FIFO two- or three-fifths full or more condition generates an interrupt (state
of RFS sent to interrupt controller).
6
7
TIE
Transmit FIFO interrupt enable.
0 – Transmit FIFO half-full or less condition does not generate an interrupt (TFS bit ignored).
1 – Transmit FIFO half-full or less condition generates an interrupt (state of TFS sent to
interrupt controller).
AME
Address match enable.
0 – Disable receiver address match function, store data from all incoming frames in
receive FIFO.
1 – Enable receiver address match function; do not FIFO data unless address
recognized or incoming address contains all ones (0hFF).
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11.10.7 HSSP Control Register 1
HSSP control register 1 (HSCR1) contains the 8-bit address match value field that is used by the
HSSP to selectively receive frames.
11.10.7.1 Address Match Value (AMV)
The 8-bit address match value (AMV) field is programmed with an address value that is used to
selectively store only the data within receive frames that have the same address value. The address
match enable (AME) bit must be set to enable this function. For incoming frames, which have the
same address value as the AMV field, the frame’s address, control, and data are stored in the
receive FIFO. For those that do not, the remainder of the frame is ignored and the receive logic
switches to hunt mode, looking for the preamble in the incoming data stream. One special address
exists, which is always matched by the address match logic regardless of the value programmed in
AMV. When address matching is enabled, whenever a frame is received with an address containing
all ones (11111111), the value programmed in AMV is ignored and the frame data is automatically
stored in the receive FIFO. The address value is contained within the first byte of data in a frame
following the flag. AMV can be written at any time and is used for comparison with the next frame,
which occurs following its update.
The following table shows the address match value field within HSSP control register 1. The reset
state of AMV is unknown (indicated by question marks) and must be initialized before enabling the
HSSP. Note that HSCR1 may be written while the HSSP is enabled to allow the address match
value to be changed during active receive operation.
Address: 0h 8004 0064
HSCR1
Read/Write
Bit
7
6
5
?
4
?
3
?
2
?
1
0
?
AMV
Reset
?
?
?
Bit
7..0
Name
AMV
Description
Address match value.
The 8-bit value used by receiver logic to compare to address of incoming frames. If
AME=1 and AVM matches the address of the incoming frame, store the frame address,
control, and data in receive FIFO; if address does not match, ignore the frame and
search for the next preamble.
Note: An address of 0hFF (all ones) in the incoming frame automatically generates a
match (AMV is ignored).
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11.10.8 HSSP Control Register 2
The HSSP control register 2 (HSCR2) contains two bit-fields that control the polarity of the
transmit and receive data pins. Note that unlike the rest of the HSSP’s registers, its bits are located
in byte 2 of the addressed word (bits 23..16). Word reads or writes should be used to access this
register. Also note that this register resides within the PPC’s address space.
11.10.8.1 Transmit Pin Polarity Select (TXP)
The transmit pin polarity select (TXP) bit is used to select whether data output to the ICP’s transmit
pin (TXD2) is true or complemented. When TXP=0, data output from the UART (low-speed
mode), HSSP (high-speed mode), or PPC (GPIO output mode) is inverted first before being output
to the TXD2 pin. When TXP=1, data output from either the UART, HSSP, or PPC to the TXD2 pin
is true or noninverted. TXP is initialized to 1 following reset such that output pin data defaults to
true data.
Note that TXP affects the TXD2 pin during all modes of operation including HSSP, UART, and
PCC. The user should ensure that this bit is properly programmed when using serial port 2 for high-
or low-speed IrDA, normal UART, or GPIO operation. Note that for GPIO mode, the user needs to
configure TXP only when the pin is to be used as an output (PPDR<14>=1). When used as a GPIO
input, TXP has no effect on the state of TXD2. See the Peripheral Pin Controller chapter.
Additionally, the user must ensure that the PPC sleep state direction bit for TXD2 is inverted from
its normal value, if TXP=0 indicating inverted data. Thus if the user wishes to make TXD2 an
output in sleep mode, but TXP=0 indicating the output is inverted, the PPC should be programmed
such that PSDR<14>=1. Likewise, if TXP=0 and the user wishes to make TXD2 an input in sleep
mode, the PPC should be programmed such that PSDR<14>=0. If TXP=1 indicating true data,
PSDR should be programmed normally.
11.10.8.2 Receive Pin Polarity Select (RXP)
The receive pin polarity select (RXP) bit is used to select whether data input to the ICP’s receive
pin (RXD2) is viewed by the ICP as true or complemented. When RXP=0, data input from the
RXD2 pin is first inverted before being sent to either the UART (low-speed mode), HSSP
(high-speed mode), or PPC (GPIO input mode). When RXP=1, data input from the RXD2 pin is
treated as true data and is not inverted before being sent to either the UART, HSSP, or PPC. RXP is
initialized to 1 following reset such that input pin data defaults to true data.
Note that RXP affects the RXD2 pin during all modes of operation including HSSP, UART, and
PCC. The user should ensure that this bit is properly programmed when using serial port 2 for high-
or low-speed IrDA, normal UART, or GPIO operation. Note that for GPIO mode, the user needs to
configure RXP only when the pin is to be used as an input (PPDR<15>=0). When used as a GPIO
output, RXP has no effect on the state of RXD2.
Also note that, unlike the TXP bit, RXP has no effect on the PPC sleep state direction bit for
RXD2. PSDR<15> should be programmed normally.
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The following table shows the location of the bits within HSSP control register 2. Both bits are set
to one to ensure serial port 2’s pins default to normal “true” data operation following a reset of the
SA-1100. Note that the HSSP and UART must be disabled (RXE=TXE=0) when changing the state
of these bits. Also note that reads of reserved bits return zero and writes have no effect.
Address: 0h 9006 0028
HSCR2
Read/Write
Bit
23
22
21
0
20
0
19
18
TXP
1
17
16
0
Reserved
RXP
1
Reserved
Reset
0
0
0
Bit
Name
Description
17..16
—
Reserved.
18
TXP
RXP
—
Transmit pin polarity select.
0 – Data output from the HSSP, UART, or PPC is first inverted before being output to TXD2.
1 – Data output from the HSSP, UART, or PPC to TXD2 is true or non-inverted data.
19
Receive pin polarity select.
0 – Data input from RXD2 is first inverted before being used by the HSSP, UART, or PPC.
1 – Data input from RXD2 to the HSSP, UART, or PPC is true or non-inverted data.
23..20
Reserved.
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11.10.9 HSSP Data Register
The HSSP data register (HSDR) is an 8-bit register corresponding to both the top and bottom entry
of the transmit and receive FIFOs, respectively.
When HSDR is read, the lower 8 bits of the bottom entry of the 11-bit receive FIFO is accessed. As
data enters the top of the receive FIFO, bits 8 – 10 are used as tags to indicate various conditions
that occur during reception of each piece of data. The tag bits are transferred down the FIFO along
with the data byte that encountered the condition. When data reaches the bottom, bit 8 of the
bottom FIFO entry is automatically transferred to the end-of-frame (EOF) flag, bit 9 to the CRC
error (CRE) flag, and bit 10 to the receiver overrun (ROR) flag, all within HSSP status register 1.
The user can read these flags to determine if the value at the bottom of the FIFO represents the last
byte within the frame or if an error was encountered during reception. After checking the flags, the
FIFO value can then be read, which causes the data in the next location of the receive FIFO to
automatically transfer down to the bottom entry and its EOF/CRE/ROR bits to be transferred to the
status register.
The end/error in FIFO (EIF) flag is set within status register 0 whenever one or more of the tag bits
(8 – 10) are set within any of the bottom eight entries of the receive FIFO and is cleared when no
error bits are set in the bottom eight entries of the FIFO. When EIF is set, an interrupt is generated
and receive FIFO DMA requests are disabled so that the user can manually empty the FIFO,
always checking the end-of-frame, CRC error, and overrun error flags in status register 1 first
before removing each data value from the FIFO. After each entry is removed, the user should
check the EIF bit to see if any set end or error tag remains, and repeat the procedure until all set
tags are flushed from the bottom eight entries of the FIFO. Once EIF is cleared, servicing of the
receive FIFO by the DMA controller is automatically reenabled.
When HSDR is written, the topmost entry of the 8-bit transmit FIFO is accessed. After a write, data
is automatically transferred down to the lowest location within the transmit FIFO, which does not
already contain valid data. Data is removed from the bottom of the FIFO one piece at a time by the
transmit logic, encoded using the 4PPM modulation technique, loaded into the transmit serial
shifter, then serially shifted out onto the TXD2 pin.
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The following table shows the bit locations corresponding to the data field, end-of-frame bit as well
as the cyclic redundancy check and receiver overrun error bits within the HSSP data register. Note
that both FIFOs are cleared when the SA-1100 is reset, the transmit FIFO is cleared when TXE=0,
and the receive FIFO is cleared when RXE=0.
Address: 0h 8004 006C
HSDR
Read/Write
Bit
10
ROR
0
9
CRE
0
8
EOF
0
7
0
6
0
5
4
3
2
1
0
0
Bottom of receive FIFO data
Reset
0
0
0
0
0
Read Access
(Note: ROR, CRE, EOF are not read, but rather transferred to corresponding status bits in the HSSP
status register 1(HSSR1) each time a new data value is transferred to HSDR).
Bit
7
0
6
0
5
4
3
2
1
0
0
0
Top of transmit FIFO data
Reset
0
0
0
0
Write Access
Bit
7..0
Name
DATA
Description
Top/bottom of transmit/receive FIFO data.
Read – Bottom of receive FIFO.
Write –Top of transmit FIFO.
8
EOF
End of frame.
0 – The last byte of the frame has not been encountered.
1 – The data value at the bottom of the receive FIFO represents the last byte of the
frame.
Note: Each time an 11-bit value reaches the bottom of the receive FIFO, bit 8 from the
last FIFO entry is transferred to the EOF bit in HSSR1.
9
CRE
CRC error.
0 – CRC not encountered yet, or the CRC value calculated on the incoming data
matched the received CRC value.
1 – The CRC value calculated on the incoming data did not match the received CRC
value.
Note: Each time an 11-bit value reaches the bottom of the receive FIFO, bit 9 from the
last FIFO entry is transferred to the CRE bit in HSSR1.
10
ROR
Receiver overrun.
0 – No receiver overrun has been detected.
1 – Receive logic attempted to place data into receive FIFO while it was full; one or more
data values after the data value at the bottom of the receive FIFO were lost.
Note: Each time an 11-bit value reaches the bottom of the receive FIFO, bit 10 from the
last FIFO entry is transferred to the ROR bit in HSSR1.
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11.10.10 HSSP Status Register 0
HSSP status register 0 (HSSR0) contains bits that signal the transmit FIFO service request, receive
FIFO service request, receiver abort, transmit FIFO underrun, framing error, and the end/error in
receive FIFO conditions. Each of these hardware-detected events signal an interrupt request to the
interrupt controller.
A bit that can cause an interrupt signals the interrupt request as long as the bit is set. Once the bit is
cleared, the interrupt is cleared. Read/write bits are called status bits; read-only bits are called flags.
Status bits are referred to as “sticky” (once set by hardware, must be cleared by software). Writing
a one to a sticky status bit clears it; writing a zero has no effect. Read-only flags are set and cleared
by hardware; writes have no effect. Additionally, some bits that cause interrupts have
corresponding mask bits in the control registers and are indicated in the following sections. Note
that the user has the ability to mask all HSSP interrupts by clearing bit 16 within the interrupt
controller mask register (ICMR).
11.10.10.1 End/Error in FIFO Status (EIF) (read-only, nonmaskable interrupt)
The end/error in FIFO flag (EIF) is a read-only bit that is set when any tag bits (8 through 10) are
set within the bottom eight entries of the receive FIFO and is cleared when no tag bits are set within
the bottom eight entries of the FIFO. When EIF is set, an interrupt is signalled and DMA requests
to empty the receive FIFO are disabled until EIF is cleared. To discover which FIFO entry contains
the end-of-frame or an error condition, the user should check the state of the EOF, CRE, and ROR
bits (described in the following sections), then read the corresponding value from the HSDR. This
procedure should be repeated until EIF is cleared because set flag bits that are present within any of
the eight lowest entries in the receive FIFO can set EIF. Once all tags are cleared from the bottom
eight entries of the receive FIFO, EIF is automatically cleared, which in turn, clears the interrupt
and reenables receive FIFO DMA requests.
11.10.10.2 Transmit Underrun Status (TUR) (read/write, maskable interrupt)
The transmit underrun status bit (TUR) is set when the transmit logic attempts to fetch data from
the transmit FIFO after it has been completely emptied. When an underrun occurs, the transmitter
takes one of two actions. When the transmit underrun select bit is clear (TUS=0), the transmitter
ends the frame by shifting out the CRC that is calculated continuously on outgoing data, followed
by a stop flag and SIP pulse. When TUS=1, the transmitter is forced to transmit an abort and
continues to transmit chips containing all zeros (0000) until valid data is again available within the
FIFO. Once data resides within the bottom entry of the transmit FIFO, a new data frame is initiated
by transmitting 16 preambles and a start flag followed by the transmission of data from the FIFO.
When the TUR bit is set, an interrupt request is made unless it is masked. When TUS=0, the
interrupt is masked; when TUS=1, it is enabled. Note that underruns are not generated when the
HSSP transmitter is first enabled and is in the idle state (continuously transmits flags).
11.10.10.3 Receiver Abort Status (RAB) (read/write, nonmaskable interrupt)
The receiver abort status bit (RAB) is set when an abort is detected during receipt of an incoming
frame. An abort is signalled when two or more chips that do not contain any pulses (0000) or chips
containing 0011, 1001, 1010, or 0101(invalid chips not contained within the stop flag) are detected
after a valid start flag has been detected but before a complete stop flag has been received (an
incorrect chip in the stop flag generates an abort as well). When an abort is received, the EOF tag is
set in the FIFO entry that corresponds to the last piece of data received before the frame was
aborted. The receiver then enters hunt mode, searching for the preamble.
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11.10.10.4 Transmit FIFO Service Request Flag (TFS) (read-only, maskable
interrupt)
The transmit FIFO service request flag (TFS) is a read-only bit that is set when the transmit FIFO is
nearly empty and requires service to prevent an underrun. TFS is set any time the transmit FIFO
has eight or fewer entries of valid data (half-full or less), and is cleared when it has nine or more
entries of valid data. When the TFS bit is set, an interrupt request is made unless the transmit FIFO
interrupt request mask (TIE) bit is cleared. The state of TFS is also sent to the DMA controller, and
can be used to signal a DMA service request. Note that TIE has no effect on the generation of the
DMA service request. After the DMA or CPU fills the FIFO, such that eight or more locations are
filled within the transmit FIFO, the TFS flag (and the service request and/or interrupt) is
automatically cleared.
11.10.10.5 Receive FIFO Service Request Flag (RFS) (read-only, maskable
interrupt)
The receive FIFO service request flag (RFS) is a read-only bit that is set when the receive FIFO is
nearly filled and requires service to prevent an overrun. The amount of data that causes RFS to be
set is nondeterministic. However, the range in which RFS will be set is guaranteed. RFS is set at
some point when the receive FIFO is two- to three-fifths full (or more). The HSSP’s FIFOs are
self-timed to reduce cost and save power. As a result, the depth at which the receive FIFO service
request is generated is variable. This is the reason the receive FIFO is 20 entries deep instead of 16
like the transmit FIFO. At which entry in the FIFO the request is actually triggered is dependent on
IC process, operating temperature, and so on. The receive FIFO is designed to signal the RFS bit to
be set when it contains 12 entries of valid data. However, because of the variability of the
self-timed logic, RFS may also be set when 11, 10, or 9 entries of valid data are present within the
FIFO. Likewise, under normal circumstances, RFS is cleared when the receive FIFO has 11
remaining entries of valid data. However, again due to variations, RFS may be cleared when 10 or
9 entries of data remain.
When the RFS bit is set, a DMA service request is made. An interrupt request is also made unless
the receive FIFO interrupt request mask (RIE) bit is cleared. Even though more than eight entries
of data may exist within the receive FIFO, the user must configure the DMA burst size to eight
words. If programmed I/O is used to service the receive FIFO, a maximum of eight words may be
removed without checking if data is valid. After this point, the receive FIFO not empty (RNE) flag
must be polled before each read to see if more data remains. After the DMA or CPU empties the
FIFO such that nine or more empty locations are available within the receive FIFO, the RFS flag
(as well as the DMA and interrupt request) is automatically cleared.
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11.10.10.6 Framing Error Status (FRE) (read/write, nonmaskable interrupt)
The framing error status (FRE) bit is set when a frame alignment error is detected by the receive
logic. A frame alignment error is detected on received data when a preamble is followed by
something other than another preamble or a start flag.
The following table shows the bit locations corresponding to the status and flag bits within HSSP
status register 0. Note that the reset state of all writable status bits is unknown (indicated by
question marks) and must be cleared (by writing a one to them) before enabling the HSSP. Also
note that writes to reserved bits are ignored and reads return zeros.
.
Address: 0h 8004 0074
HSSR0
Read/Write & Read-Only
Bit
7
6
5
FRE
?
4
3
TFS
0
2
RAB
?
1
TUR
?
0
EIF
?
Reserved
RFS
0
Reset
0
0
Bit
Name
EIF
Description
0
End/error in FIFO (read-only).
0 – Bits 8–10 are not set within any of the eight bottom entries of the receive FIFO.
Receive FIFO DMA service requests are enabled.
1 – One or more tag bits (8 – 10) are set within one or more of the bottom eight entries of
the receive FIFO. Request interrupt, disable receive FIFO DMA service requests.
1
2
TUR
RAB
Transmit FIFO underrun.
0 – Transmit FIFO has not experienced an underrun.
1 – Transmit logic attempted to fetch data from transmit FIFO while it was empty;
interrupt request signalled if not masked (if TUS=1).
Receiver abort.
0 – No abort has been detected for the incoming frame.
1– Abort detected during receipt of incoming frame. Two or more chips containing no
pulses (0000) detected on receive pin. EOF bit set in receive FIFO next to last piece of
“good” data received before the abort, interrupt requested.
3
TFS
RFS
Transmit FIFO service request (read-only).
0 – Transmit FIFO is more than half-full (nine or more entries filled) or transmitter
disabled.
1 – Transmit FIFO is half-full or less (eight or fewer entries filled) and transmitter
operation is enabled. DMA service request signalled; interrupt request signalled if not
masked (if TIE=1).
4
5
Receive FIFO service request (read-only).
0 – Receive FIFO contains 11 or fewer entries of data or receiver disabled.
1 – Receive FIFO is two- to three-fifths full (contains 9, 10, 11, or 12 entries of data) or
more, and receiver operation is enabled. DMA service request signalled; interrupt
request signalled if not masked (if RIE=1).
FRE
—
Framing error.
0 – No framing errors encountered in the receipt of this data.
1 – Framing error occurred; preamble followed by something other than another
preamble or start flag, request interrupt.
7..6
Reserved.
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11.10.11 HSSP Status Register 1
HSSP status register 1 (HSSR1) contains flags that indicate when the receiver is synchronized, the
transmitter is active, the transmit FIFO is not full, the receive FIFO is not empty, and when an
end-of-frame, CRC error, or underrun error has occurred. All bits within HSSR1 are read-only and
noninterruptible.
11.10.11.1 Receiver Synchronized Flag (RSY) (read-only, noninterruptible)
The receiver synchronized (RSY) flag is a read-only bit that is set when the receiver is
synchronized with the incoming data stream, and is cleared when the receive logic is in hunt mode
(looking for the preamble to achieve byte and frame synchronization), or the receiver is disabled
(RXE=0). This bit does not request an interrupt.
11.10.11.2 Transmitter Busy Flag (TBY) (read-only, noninterruptible)
The transmitter busy (TBY) flag is a read-only bit that is set when the transmitter is actively
transmitting a frame (address, control, data, CRC, start or stop flag), and is cleared when the
transmitter is idle (transmitting preambles) or the transmitter is disabled (TXE=0). This bit does not
request an interrupt.
11.10.11.3 Receive FIFO Not Empty Flag (RNE) (read-only, noninterruptible)
The receive FIFO not empty flag (RNE) is a read-only bit that is set whenever the receive FIFO
contains one or more bytes of valid data and is cleared when it no longer contains any valid data.
This bit can be polled when using programmed I/O to remove remaining bytes of data from the
receive FIFO because DMA service and CPU interrupt requests are made only when 12, 11, 10, or
9 bytes reside within the FIFO. Data will remain after each service request as well as at the end of a
frame. This bit does not request an interrupt.
11.10.11.4 Transmit FIFO Not Full Flag (TNF) (read-only, noninterruptible)
The transmit FIFO not full flag (TNF) is a read-only bit that is set whenever the transmit FIFO
contains one or more entries that do not contain valid data and is cleared when the FIFO is
completely full. This bit can be polled when using programmed I/O to fill the transmit FIFO over
its halfway mark. This bit does not request an interrupt.
11.10.11.5 End-of-Frame Flag (EOF) (read-only, noninterruptible)
The end-of-frame flag (EOF) is set when the last byte of data within a frame (including aborted
frames) resides within the bottom entry of the receive FIFO.
The receive FIFO contains three tag bits (8, 9, and 10) that are not directly readable. The 8th bit is
set at the top of the FIFO whenever the last byte within a frame is moved from the receive serial
shifter to the top of the receive FIFO. This tag travels along with the last data value as it moves
down the FIFO. Each time a data value is transferred to the bottom of the FIFO (caused by a read
of the previous value), the state of the tag bit is moved from the FIFO to the EOF bit in the status
register. Whenever EOF is set within the bottom eight entries of the receive FIFO, EIF is set within
HSSR0, an interrupt is signalled, and the receive FIFO DMA request is disabled. After the
end/error in FIFO (EIF) status bit is set, the user should always read HSSR1 first to check EOF
before reading the data value from HSDR because EOF corresponds to the current data byte at the
bottom of the receive FIFO and is updated each time data is removed from the FIFO.
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11.10.11.6 CRC Error Status (CRE) (read-only, noninterruptible)
The CRC error flag (CRE) is set when the CRC value calculated by the receive logic does not
match the CRC value contained within the incoming serial data stream.
The receive FIFO contains three tag bits (8, 9, and 10) that are not directly readable. Whenever a
CRC error is detected, the 9th bit is set within the top entry of the receive FIFO corresponding to
the last byte of data within the frame. This tag travels along with the last piece of data from the
frame as it moves down the FIFO. Each time a data value is transferred to the bottom of the FIFO
(caused by a read of the previous value), the state of the tag bit is moved from the FIFO to the CRE
bit in the status register, indicating whether or not the frame has encountered a CRC error.
Whenever CRE is set within the bottom half of the receive FIFO, EIF is set within HSSR0, an
interrupt is signalled, and the receive FIFO DMA request is disabled. After the end/error in FIFO
(EIF) status bit is set, the user should always read HSSR1 first to check CRE before reading the
data value from HSDR because CRE corresponds to the current data byte at the bottom of the
receive FIFO and is updated each time data is removed from the FIFO.
11.10.11.7 Receiver Overrun Status (ROR) (read-only, noninterruptible)
The receiver overrun flag (ROR) is set when the receive logic attempts to place data into the
receive FIFO after it has been completely filled.
The receive FIFO contains three tag bits (8, 9, and 10) that are not directly readable. The 10th bit is
set within the top entry of the receive FIFO whenever an overrun occurs. This tag travels along
with the last “good” data value before the overflow occurred as it moves down the FIFO. Each time
a data value is transferred to the bottom of the FIFO (caused by a read of the previous value), the
state of the tag bit is moved from the FIFO to the ROR bit in the status register, indicating that the
next value in the FIFO is the last “good” piece of data before the overflow occurred. Whenever
ROR is set within the bottom eight entries of the receive FIFO, EIF is set within HSSR0, an
interrupt is signalled, and the receive FIFO DMA request is disabled. After the end/error in FIFO
(EIF) status bit is set, the user should always read HSSR1 first to check ROR before reading the
data value from HSDR because ROR corresponds to the current data byte at the bottom of the
receive FIFO and is updated each time data is removed from the FIFO.
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The following table shows the location of the flags within HSSP status register 1. The bits within
this register are read-only and do not produce interrupt requests. Note that writes to bit 7 are
ignored and reads return zero.
Address: 0h 8004 0078
HSSR1
Read-Only
Bit
7
Res.
0
6
ROR
0
5
CRE
0
4
3
TNF
1
2
RNE
0
1
TBY
0
0
RSY
0
EOF
0
Reset
Bit
Name
RSY
Description
0
Receiver synchronized flag (read-only).
0 – Receiver is in hunt more or is disabled.
1 – Receiver logic is synchronized with the incoming data (no interrupt generated).
1
TBY
Transmitter busy flag (read-only).
0 – Transmitter is idle (continuous preambles) or disabled.
1 – Transmit logic is currently transmitting a frame (address, control, data, CRC, or
start/stop flag); no interrupt generated.
2
3
4
5
RNE
TNF
EOF
CRE
Receive FIFO not empty (read-only).
0 – Receive FIFO is empty.
1 – Receive FIFO is not empty (no interrupt generated).
Transmit FIFO not full (read-only).
0 – Transmit FIFO is full.
1 – Transmit FIFO is not full (no interrupt generated).
End of frame (read-only).
0 – Current frame has not completed.
1 – The value at the bottom of the receive FIFO is the last byte of data within the frame.
CRC error (read-only).
0 – No CRC check errors encountered in the receipt of data.
1 – CRC calculated on the incoming data. Does not match CRC value contained within
the received frame.
6
7
ROR
—
Receive FIFO overrun (read-only).
0 – Receive FIFO has not experienced an overrun.
1 – Receive logic attempted to place data into receive FIFO while it was full; the next data
value in the FIFO is the last piece of “good” data before the FIFO was overrun.
Reserved.
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11.10.12 UART Register Locations
Table 11-16 shows the registers associated with the UART block and the physical addresses used to
access them.
Table 11-16. UART Control, Data, and Status Register Locations
Address
Name
UTCR0
Description
UART control register 0
0h 8003 0000
0h 8003 0004
0h 8003 0008
0h 8003 000C
0h 8003 0010
0h 8003 0014
0h 8003 0018
0h 8003 001C
0h 8003 0020
UTCR1
UTCR2
UTCR3
UTCR4
UTDR
—
UART control register 1
UART control register 2
UART control register 3
UART control register 4
UART data register
Reserved
UTSR0
UTSR1
UART status register 0
UART status register 1
0h 8003 0024 –
0h 8003 005C
—
Reserved
11.10.13 HSSP Register Locations
Table 11-17 shows the registers associated with the HSSP block and the physical addresses used to
access them.
Table 11-17. HSSP Control, Data, and Status Register Locations
Address
0h 8004 0060
Name
HSCR0
Description
HSSP control register 0
0h 8004 0064
HSCR1
—
HSSP control register 1
Reserved
0h 8004 0068
0h 8004 006C
HSDR
—
HSSP data register
Reserved
0h 8004 0070
0h 8004 0074
HSSR0
HSSR1
—
HSSP status register 0
HSSP status register 1
Reserved
0h 8004 0078
0h 8004 007C - 0h 8004 FFFF
Note: HSCR2 resides within the same address space as the PPC.
0h 9006 0028
HSCR2
HSSP Control register 2
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11.11
Serial Port 3 - UART
Serial port 3 is a general-purpose, full-duplex, universal asynchronous receiver/transmitter (UART)
that supports much of the functionality of the 16550 protocol. It can operate at baud rates from
56.24 bps to 230.4 Kbps. It supports 7 or 8 bits of data (odd, even, or no parity), one start bit, either
one or two stop bits, and can transmit a continuous break signal. An external clock can also be
input using GPIO pin 20 to synchronously sample and drive data on either edge of the clock as
programmed by the user. The external pins dedicated to this interface are TXD3 and RXD3. If use
of the UART is not required, these pins can be used by the peripheral pin controller (PPC) to
perform general- purpose input/output (noninterruptible).
An 8-entry x 8-bit FIFO is used to buffer outgoing data, and a 12-entry x 11-bit FIFO is used to
buffer incoming data (3 bits per entry are used to store framing, parity, and receive FIFO overrun
error flags for each character received). The FIFOs are filled or emptied using the DMA or the
CPU. An interrupt is generated when a framing, parity, or receiver overrun error is present within
the bottom four entries of the receive FIFO, when the transmit FIFO is half-empty or the receive
FIFO is one- to two-thirds full, when a begin and end of break is detected on the receiver, and when
the receive FIFO is partially full and the receiver is idle for three or more frame periods.
Modem control signals (RTS, CTS, DTR, and DSR) are not implemented in this block, but can be
11.11.1 UART Operation
Following hardware reset, the UART is disabled, which causes the peripheral pin controller (PPC)
to assume control of the UART’s pins. Reset causes the PPC to configure all of the peripheral pins
as inputs, including the UART’s transmit (TXD3) and receive (RXD3) pins. Reset also causes the
UART’s transmit and receive FIFOs to be flushed (all entries invalidated). Before enabling the
UART, the user must first clear any writable or “sticky” status bits that are set by writing a one to
each bit. Next, the desired mode of operation is programmed in the control registers. At this point,
the user may “prime” the transmit FIFO by writing up to eight values, or the FIFO can remain
empty and the transmit FIFO DMA or interrupt request may be used to trigger its service when the
transmitter is enabled. When the UART is enabled, transmission and reception of data can begin on
the transmit (TXD3) and receive (RXD3) pins.
Figure 11-29 shows the format of a single UART data frame.
Figure 11-29. Example UART Data Frame
Start
Bit
Stop
Bit 1
Stop
Bit 2
Data
<0>
Data
<1>
Data
<2>
Data
<3>
Data
<4>
Data
<5>
Data
<6>
Data Parity
<7> Bit
Optional
TXD3 or RXD3 pin
Optional
MSB
LSB
Receive data sample counter frequency = 16x bit frequency, each bit sampled on eighth clock.
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11.11.1.1 Frame Format
NRZ encoding is used by the UART to represent individual bit values. A one is represented by a
encoding of the data byte 8b 0100 1011. Note that the byte’s LSB is transmitted first.
Figure 11-30. NRZ Bit Encoding Example – (0100 1011)
LSB
1
MSB
0
Bit
Value
1
0
1
0
0
1
Digital
Data
NRZ
Data
Each data frame is between 9 bits and 12 bits long depending on the size of data programmed, if
parity is enabled and if a second stop bit is enabled. The frame begins with a start bit that is
represented by a high to low transition. Next, either 7 bits or 8 bits of data are transmitted,
beginning with the least significant bit. An optional parity bit follows, which is set if even parity is
enabled and an odd number of ones exist within the data byte, or if odd parity is enabled and the
data byte contains an even number of ones. The data frame ends with either one or two stop bits as
programmed by the user, which is represented by one or two successive bit periods of a logic one.
Note that the receiver only tests for one stop bit per frame.
11.11.1.2 Baud Rate Generation
The baud or bit rate is derived by dividing down the 3.6864-MHz clock generated by the on-chip
PLL. The clock is first divided by a programmable number between 1 and 4097, and then by a
fixed value of 16. The receive baud clock is synchronized with the data stream using a digital PLL
each time the start bit is detected on the receive data line. Receive data is then sampled halfway
through each bit period by counting 8 of the 16 clocks, which are produced before the fixed divide
11.11.1.3 Receive Operation
The UART receives incoming data by using a serial shifter. It latches the frame, strips it of its start,
parity, and stop bits, and then places the data within receive FIFO. If parity is enabled, the number
of data bits, which is one, is counted as data and is extracted from each frame. Parity is then
checked by comparing this value to the stripped parity bit. Either odd or even parity is checked as
specified by the programmer. If a parity error is detected, the parity error bit is set in the FIFO entry
corresponding to the data value that caused the error. Additionally, if a logic zero is detected by the
receive logic where a stop bit was expected, the framing error bit is set in the FIFO entry
corresponding to the errant data. When the FIFO fills between one- to two-thirds full, an interrupt
or DMA request is signalled. If the FIFO is completely filled and the receive logic attempts to place
additional data within the FIFO, the overrun bit is set next to the last byte of data received within
the FIFO. Any data received while the FIFO is completely full is discarded.
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The parity, framing, and overrun error bits are transferred down the receive FIFO along with the data
that caused the error. Whenever any of the four bottom FIFO entries contain one or more error bits that
are set, an interrupt is generated and receive FIFO DMA requests are disabled until the error is flushed
from the FIFO and the status bit that signalled the interrupt is cleared. At this point, the user should use
programmed I/O to check the error bits and remove data one piece at a time until the four FIFO entries
are flushed. Each time a data value is transferred to the bottom of the FIFO, the state of the parity,
framing, and overrun bits within the last FIFO entry are automatically transferred to their respective
flag bits in the status register. When any of these three flags are set in the UART status register, it
indicates that the next data value available within the FIFO contains an error. The user must first check
the state of these three flags to see if the next value within the FIFO contains an error, then read the
FIFO value. After four values have been removed from the FIFO and the errors are identified, the
DMA is automatically reenabled once the error in FIFO bits are removed from the FIFO.
If the receive FIFO contains valid data and three frame periods elapse without the reception of data
on RXD3, the receiver idle interrupt is generated. Also, if the receive logic detects a null character
(all zeros, including the parity bit) followed by a framing error (stop bit is zero as well), the receive
logic generates a beginning of break detect, which interrupts the CPU. Because breaks can be
signalled for long periods of time, after the break is negated and the receive pin transitions high, the
receive logic generates an end of break detect, which again interrupts the CPU.
11.11.1.4 Transmit Operation
The UART transmit logic operates at the same time as the receive logic (full-duplex). Data is taken
from the transmit FIFO; start, parity, and stop bits are added to generate a frame; and the value is
loaded into a serial shift register. The contents are shifted out onto the TXD3 pin, clocked by the
programmed baud clock. When the transmit FIFO is emptied more than halfway, an interrupt or
DMA request is signalled. If the transmit FIFO is completely emptied, the transmit line remains
high (one) after the last data value is transmitted to indicate the transmitter is idle. The TXD3 pin
remains high until additional data is written to the transmit FIFO.
11.11.1.5 Transmit and Receive FIFOs
To reduce chip size and power consumption, the UART’s FIFOs use self-timed logic (they are not
clocked). Because of process and environmental variations, the depth at which a service request is
triggered to empty the receive FIFO is variable. This variation spans a maximum of four FIFO
entries; the receive FIFO service request can be made at four different FIFO depths.To compensate
for this variability and guarantee that at least four valid entries of data exist within the FIFO before
generating a service request, an extra four entries have been added to the receive FIFO (four entries
more than the transmit FIFO). The transmit FIFO is 8 entries deep and the receive FIFO is 12
entries deep. The point at which the receive FIFO service request is triggered spans the middle
third of the 12-entry FIFO. The service request is signalled at a depth from one-third full to
two-thirds full (when the FIFO contains five, six, seven, or eight entries of data).
This service request variation applies only to an empty FIFO that is filled (receive FIFO). It does
not apply to a full FIFO that is emptied (transmit FIFO). The transmit FIFO is guaranteed to signal
a service request when it has four or more empty entries and negate the request when the FIFO
contains five or more entries that are filled.
If the DMA is used to service either one or both of the UART’s FIFOs, the burst size must be set to
4 words even though more than four entries of data may exist within the receive FIFO. If
programmed I/O is used to service the FIFOs, a maximum of 4 words may be added to the transmit
FIFO without checking if more space is available. Likewise, a maximum of 4 words may be
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removed from the receive FIFO without checking if more data is available. After this point, the
user must poll a set of status bits that indicates if any data remains in the receive FIFO or if space is
available in the transmit FIFO before emptying or filling the FIFOs any further.
11.11.1.6 CPU and DMA Register Access Sizes
Bit positioning, byte ordering, and addressing of the UART is described in terms of little endian
ordering. All UART registers are 8 bits wide and are located in the least significant byte of
individual words. The ARM peripheral bus does not support byte or half-word operations. All
reads and writes of the UART by the CPU should be wordwide. Two separate dedicated DMA
requests exist for both the transmit and the receive FIFO. If the DMA controller is used to service
the transmit and/or receive FIFOs, the user must ensure the DMA is properly configured to perform
bytewide accesses, using 4 bytes per burst.
11.11.2 UART Register Definitions
There are seven bytewide registers within the UART: four control registers, one data register, and
two status registers. The control registers are used to program the baud rate, data length, number of
stop bits, and odd or even parity. They are used to receive and transmit sample clock edge type, and
to transmit a break. Also, they are used to enable or disable transmit and receive operation, parity,
use of the sample clock input, and loopback mode. The data register is 8 bits and addresses the top
location of the transmit FIFO and bottom location of the receive FIFO. When it is read, the receive
FIFO is accessed, and when it is written, the transmit FIFO is accessed. The status registers contain
bits that signal the transmit FIFO service request, receive FIFO service request, receiver idle, the
begin and end of break detect, and error in FIFO conditions. Each of these status conditions signal
an interrupt request to the interrupt controller. The status registers also flag when the UART is
actively transmitting characters, when the transmit FIFO is not full, when the receive FIFO is not
empty, and when a parity, framing, or overrun error was detected for the data value currently
located in the bottom entry of the receive FIFO (no interrupt generated).
11.11.3 UART Control Register 0
UART control register 0 (UTCR0) contains seven different bit fields that control various functions
within the UART.
11.11.3.1 Parity Enable (PE)
The parity enable (PE) bit is used to enable or disable parity checking by the receive data logic as
well as parity generation by the transmit logic. When parity is enabled (PE=1), the odd/even parity
select (OES) control bit is decoded to determine which type of parity should be checked and
generated. The parity of each data frame received is checked. If the parity type programmed in the
OES bit does not match the parity of the data received, the parity error (PRE) bit is set in the same
entry in the receive FIFO where the errant data resides. When parity is disabled (PE=0), the parity
check and generation logic is disabled, parity bits are not inserted into transmitted frames, and the
receive logic expects a stop bit to occur after the MSB of each data value is received.
11.11.3.2 Odd/Even Parity Select (OES)
The odd/even parity select (OES) bit is used to select whether odd or even parity should be used by
the transmit and receive logic. When OES=0, odd parity is selected; when OES=1, even parity is
selected. When parity is enabled (PE=1), the parity bit is placed after the data’s MSB in each frame.
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The transmit logic sets or clears the parity bit to make the total number of ones transmitted
(including the parity bit) match the parity type programmed using OES
(if even parity is selected (OES=1) and there is an odd number of ones in the data to be
transmitted, the parity bit is set). The receive data logic counts the number of ones encountered in
the incoming data stream (including the parity bit), then strips the parity bit from the data. If the
parity type of the frame does not match the parity selected by OES, the parity error bit is set (bit 8)
within the FIFO entry corresponding to the data that produced the parity error.
11.11.3.3 Stop Bit Select (SBS)
The stop bit select (SBS) bit selects whether one or two stop bits should be used in transmission.
When SBS=0, one stop bit is inserted in the transmit frame for each character. When SBS=1, two
stop bits are inserted. SBS does not affect the UART’s receive logic. The receiver always checks to
make sure there is at least one stop bit per character.
11.11.3.4 Data Size Select (DSS)
The data size select (DSS) bit is programmed to select the size of the data transmitted and received
within each frame. Data can be 7 or 8 bits in length. When 7-bit data is programmed, the data is
right justified within the FIFOs. The unused bit is zero filled within the receive FIFO, and is
ignored within the transmit FIFO. Note that the user must right justify data supplied to the transmit
FIFO when 7-bit data is selected.
11.11.3.5 Sample Clock Enable (SCE)
The sample clock enable (SCE) bit is used to enable or disable the use of a clock input from a
GPIO pin to synchronously sample and drive data to and from the UART. When SCE=0, the
on-chip 3.6864-MHz PLL, the UART’s programmable baud rate generator, and the receive logic’s
digital PLL are used. When SCE=1, a clock is input from a GPIO pin and is used to synchronously
drive both the transmit and receive logic. Note that the user must configure the GPIO pin as an
input by clearing the corresponding bit in the GPIO pin direction register (GPDR) and switch
control of the GPIO pin to the UART by setting the corresponding bit in the GPIO alternate
For the receive logic, the RCE bit is decoded to select which edge of the input clock is used to latch
each bit of the incoming frame. Note that the clock is not embedded within the data stream and the
digital PLL is shut down to conserve power. For the transmit logic, the TCE bit is decoded to select
which edge of the input clock is used to drive each bit of the outgoing frame. Note that the clock
driving the programmable baud rate generator is shut down when SCE=1 to conserve power. Also
note that SCE does not affect the frame format of data being transmitted and received by the
UART.
The SA-1100 has a total of three UARTs (serial ports 1, 2 and 3). When the external sample clock
function is enabled, serial port 1 uses the GPIO<18> pin and serial port 3 uses GPIO<19>. Serial
port 2 does not support the sample clock function.
11.11.3.6 Receive Clock Edge Select (RCE)
When SCE=1, the receive clock edge select (RCE) bit is used to select which edge of the clock
input from the GPIO pin to use (rising or falling) to synchronously sample data from the receive
pin. When RCE=0, each bit received is sampled on the rising edge of the sample input clock; when
RCE=1, bits are sampled on the clock’s falling edge. Note that the internal baud rate generator and
receive logic’s digital PLL are not used in this mode. RCE is ignored when SCE=0.
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11.11.3.7 Transmit Clock Edge Select (TCE)
When SCE=1, the transmit clock edge select (TCE) bit is used to select which edge of the clock
input from the GPIO pin to use (rising or falling) to synchronously drive data onto the transmit pin.
When TCE=0, each bit transmitted is driven on the rising edge of the sample input clock; when
TCE=1, bits are driven on the clock’s falling edge. Note that the internal baud rate generator is not
used in this mode. TCE is ignored when SCE=0.
The following table shows the bit locations corresponding to the seven different control bit fields
within UART control register 0. The UART must be disabled (RXE=TXE=0) when changing the
state of any bit within this register. The reset state of these control bits is unknown (indicated by
question marks) and must be initialized before enabling the UART. Note that writes to bit 7 are
ignored and reads return zero.
Address: 0h 8005 0000
UTCR0
Read/Write
Bit
7
Res
0
6
TCE
?
5
RCE
?
4
3
DSS
?
2
SBS
?
1
OES
?
0
PE
?
SCE
?
Reset
Bit
Name
PE
Description
0
Parity enable.
0 – Parity checking on received data and parity generation on transmitted data is disabled.
1 – Parity checking on received data and parity generation on transmitted data is enabled.
1
OES
Odd/even parity select.
0 – Odd parity checking/generation selected. Parity error bit set if even number of ones
counted in data field (including the parity bit).
1 – Even parity checking/generation selected. Parity error bit set if odd number of ones
counted in data field (including the parity bit).
2
3
SBS
DSS
Stop bit select.
0 – One stop bit transmitted per frame.
1 – Two stop bits transmitted per frame.
Note: Receiver not affected by SBS; always checks for one stop bit.
Data size select.
0 – 7-bit data.
1 – 8-bit data.
Note: For 7-bit mode, the data is right justified within the FIFO entries, the MSBs in the
receive FIFO are zero filled, and the MSBs in the transmit FIFO are ignored.
4
SCE
Sample clock enable.
0 – on-chip baud rate generator and digital PLL used to transmit and receive
asynchronous data.
1 – A clock is input via GPIO pin 20 and is used synchronously to sample receive data
and drive transmit data.
Note: Serial port 1’s UART uses GPIO pin 18 for the sample clock input; serial port 2
does not support the sample clock function. The user must also program the appropriate
bits in the GPDR and GAFR registers within the system control module.
5
6
RCE
TCE
Receive clock edge select.
0 – Rising edge of clock input on GPIO pin 20 used to latch data from the receive pin if SCE=1.
1 – Falling edge of clock input on GPIO pin 20 used to latch data from the receive pin if SCE=1.
Transmit clock edge select.
0 – Rising edge of clock input on GPIO pin 20 used to drive data onto the transmit pin if SCE=1.
1 – Falling edge of clock input on GPIO pin 20 used to drive data onto the transmit pin if
SCE=1.
7
—
Reserved.
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11.11.4 UART Control Registers 1 and 2
UART control register 1 (UTCR1) contains the upper 4 bits and UTCR2 the lower 8 bits of the
baud rate divisor field.
11.11.4.1 Baud Rate Divisor (BRD)
The 12-bit baud rate divisor (BRD) field is used to select the baud or bit rate of the UART. A total
of 4096 different baud rates can be selected, ranging from a minimum of 56.24 bps to a maximum
of 230.4 Kb/ps. The baud rate generator uses the 3.6864-MHz clock generated by the on-chip PLL
divided by 16 to generate the bit clock. A digital PLL is used to synchronize the baud rate of the
receiver each time the start bit is detected on the receive pin and each bit of the receive data stream
is sampled on the eighth clock of the divide by 16 counter (halfway through the bit period). The
resultant baud rate, given a specific BRD value or required BRD value and given a desired baud
rate, can be calculated using the following two respective equations, where BRD is the decimal
equivalent of the binary value programmed within the bit field:
6
3.6864×10
BaudRate = --------------------------------------
16x(BRD + 1)
6
3.6864×10
BRD = --------------------------------------- – 1
16xBaudRate
The following tables show the bit locations corresponding to the baud rate divisor field that is split
between two 8-bit registers. The upper four bits of BRD reside within UTCR1 and the lower eight bits
reside within UTCR2. The UART must be disabled (RXE=TXE=0) whenever these registers are written.
The reset state of the BRD field is unknown (indicated by question marks) and must be initialized before
enabling the UART. Note that writes to reserved bits are ignored and reads return zeros.
Address: 0h 8005 0004
UTCR1
Read/Write
Bit
7
6
5
0
4
0
3
?
2
1
0
?
Reserved
BRD<11:8>
Reset
0
0
?
?
Bit
3..0
Name
BRD<11:8> Baud rate divisor.
Description
Encoded value (from 0 to 4096) used to generate the baud rate of the UART.
6
Baud Rate = 3.6864x10 /(16x(BRD+1)), where BRD is a decimal value.
7..4
—
Reserved.
Address: 0h 8005 0008
UTCR2
Read/Write
Bit
Reset
7
6
5
?
4
3
2
?
1
0
?
BRD<7:0>
?
?
?
?
?
Bit
7..0
Name
BRD<7:0> Baud rate divisor.
Description
Encoded value (from 0 to 4096) used to generate the baud rate of the UART.
6
Baud Rate = 3.6864x10 /(16x(BRD+1)), where BRD is a decimal value.
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11.11.5 UART Control Register 3
UART control register 3 (UTCR3) contains six different bit fields that control various functions
within the UART.
11.11.5.1 Receiver Enable (RXE)
The receiver enable (RXE) bit is used to enable and disable all UART receive operations. When RXE=1,
the UART receive logic is enabled; when RXE=0, it is disabled. When the receiver is disabled, control of
the RXD3 pin is given to the peripheral pin controller (PPC) so that it may be used for general-purpose
page 11-184 for a description of the PPC.
It is required that the user first program all other control bits before setting RXE (even the transmit
bits). If the RXE bit is cleared to zero while the UART is actively receiving data, reception is
stopped immediately and the remaining bits within the receive serial shifter are reset. In addition,
all entries within the receive FIFO are reset (all other control/status/flag bits remain intact).
11.11.5.2 Transmitter Enable (TXE)
The transmitter enable (TXE) bit is used to enable and disable all UART transmit operations. When
TXE=1, UART transmit logic is enabled; when TXE=0, it is disabled. When the transmitter is disabled,
control of the TXD3 pin is given to the peripheral pin controller (PPC) for general-purpose input and
It is required that the user first program all other control bits before setting TXE (even the receive
bits). If the TXE bit is cleared to zero while the UART is actively transmitting data, transmission is
stopped immediately and the remaining bits within the transmit serial shifter are reset. In addition,
all entries within the transmit FIFO are reset (all other control/status/flag bits remain intact).
11.11.5.3 Break (BRK)
The break (BRK) control bit is used to continuously transmit a break by forcing the transmit pin
(TXD3) low. When the BRK bit is set, the transmit pin is forced low immediately. If the transmitter is
actively transmitting data, the remaining bits in the serial shifter continue to be shifted out, but the bits
are ignored (not placed on the transmit pin). Asserting BRK also prevents the transmit logic from
fetching any additional data from the transmit FIFO once the shifter is empty. The transmit pin
remains low until the BRK bit is cleared, or alternatively, if the transmitter is disabled (TXE=0, or a
reset occurs). Once BRK is negated, transmission starts again. The user must ensure that the BRK bit
is asserted long enough to cause the off-chip receiver to detect the break condition. The user should
also check the transmitter busy (TBY) flag in the status register to ensure that no bits remain in the
transmitter’s serial shifter before negating BRK. TBY is asserted as long as the transmitter is actively
clocking data through the serial shifter. Once the TBY bit becomes zero, the BRK bit can be negated,
and data is once again fetched from the transmit FIFO. Break does not affect the receive portion of the
FIFO; normal operation on the receive line continues during the signalling of a break.
11.11.5.4 Receive FIFO Interrupt Enable (RIE)
The receive FIFO interrupt enable (RIE) bit is used to mask or enable both the receive FIFO service request
interrupt and receiver idle interrupt. When RIE=0, the interrupts are masked and the receive FIFO service
request (RFS) and receiver idle status (RID) bits are ignored by the interrupt controller. When RIE=1, the
interrupts are enabled and whenever RFS or RID is set (one), an interrupt request is made to the interrupt
controller. Note that programming RIE=0 does not affect the current state of RFS or RID nor the receive
logic’s ability to set and clear these bits; it only blocks the generation of the interrupt request. Also note that
RIE does not affect generation of the receive FIFO DMA request that is asserted whenever RFS=1.
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11.11.5.5 Transmit FIFO Interrupt Enable (TIE)
The transmit FIFO interrupt enable (TIE) bit is used to mask or enable the transmit FIFO service
request interrupt. When TIE=0, the interrupt is masked and the state of the transmit FIFO service
request (TFS) bit is ignored by the interrupt controller. When TIE=1, the interrupt is enabled, and
whenever TFS is set (one), an interrupt request is made to the interrupt controller. Note that
programming TIE=0 does not affect the current state of TFS nor the transmit FIFO logic’s ability to
set and clear TFS; it only blocks the generation of the interrupt request. Also note that TIE does
not affect generation of the transmit FIFO DMA request that is asserted whenever TFS=1.
11.11.5.6 Loopback Mode (LBM)
The loopback mode (LBM) bit is used to enable and disable the ability of the UART transmit and
receive logic to communicate. When LBM=0, the UART operates normally. The transmit and receive
data paths are independent and communicate via their respective pins. When LBM=1, the output of
the transmit serial shifter is directly connected to the input of the receive serial shifter internally, and
control of the TXD3 and RXD3 pins is given to the peripheral pin control (PPC) unit.
The following table shows the bit location of the bits within UART control register 3. RXE and
TXE are the only control bits that are reset to a known state to ensure the UART is disabled
following a reset of the SA-1100. The reset state of all other control bits is unknown (indicated by
question marks) and must be initialized before enabling the UART. Note that UTCR3 is the only
control register that may be written while the UART is enabled. Also note that writes to reserved
bits are ignored and reads return zeros.
Address: 0h 8005 000C
UTCR3
Read/Write
Bit
7
6
5
LBM
?
4
3
RIE
?
2
BRK
?
1
TXE
0
0
RXE
0
Reserved
TIE
?
Reset
0
0
Bit
Name
RXE
Description
0
1
2
3
Receiver enable.
0 – UART receive operation disabled; PPC is given control of RXD3.
1 – UART receive operation enabled.
TXE
BRK
RIE
Transmitter enable.
0 – UART transmit operation disabled; PPC is given control of TXD3.
1 – UART transmit operation enabled.
Break.
0 – UART in normal operation.
1 – Force TXD3 low (all bits in the frame are a zero) to generate a break.
Receive FIFO interrupt enable.
0 – Receive FIFO one- to two-thirds full (or more) and receiver idle conditions do not
generate an interrupt (RFS and RID bit ignored).
1 – Receive FIFO one- to two-thirds full (or more) and receiver idle conditions generate
an interrupt (state of RFS and RID sent to interrupt controller).
4
5
TIE
Transmit FIFO interrupt enable.
0 –Transmit FIFO half-full or less condition does not generate an interrupt (TFS bit
ignored).
1 – Transmit FIFO half-full or less condition generates an interrupt (state of TFS sent to
interrupt controller).
LBM
—
Loopback mode.
0 – Normal serial port operation enabled.
1 – Output of transmit serial shifter is connected to input of receive serial shifter internally
and control of TXD3 and RXD3 pins is given to the PPC unit.
7.. 6
Reserved.
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Peripheral Control Module
11.11.6 UART Data Register
The UART data register (UTDR) is an 8-bit register corresponding to both the top and bottom
entries of the transmit and receive FIFOs, respectively.
When UTDR is read, the lower 8 bits of the bottom entry of the 10-bit receive FIFO are accessed. As
data enters the top of the receive FIFO, bits 8..10 are used to indicate various error conditions that
occur during reception of each piece of data. The error bits are transferred down the FIFO along with
the value that caused the error. When data reaches the bottom, bit 8 of the bottom FIFO entry is
automatically transferred to the parity error (PRE) flag, bit 9 to the framing error (FRE) flag, and bit
10 to the receiver overrun (ROR) flag, all within the UART status register. The user can read these
flags to determine if the value at the bottom of the FIFO encountered an error during reception. After
checking the flags, the FIFO value can then be read, which causes the data in the next location of the
receive FIFO to automatically be transferred down to the bottom entry and its error bits to be
transferred to the status register. The error in FIFO (EIF) flag bit is set whenever one or more of the
error bits (8..10) is set within any of the bottom four entries of the receive FIFO and is cleared when
no error bits are set in the bottom four entries of the FIFO. When EIF is set, an interrupt is generated
and receive FIFO DMA requests are disabled so that the user can manually empty the FIFO, always
checking the parity, framing, and overrun flags in the status register first before removing the data
values from the FIFO. After each entry is removed, the user should check the EIF bit to see if any
errors remain, and repeat the procedure until all errors are flushed from the FIFO. Once EIF is
cleared, servicing of the receive FIFO by the DMA controller is automatically reenabled.
When UTDR is written, the topmost entry of the 8-bit transmit FIFO is accessed. After a write, data is
automatically transferred down to the lowest location within the transmit FIFO that does not already
contain valid data. Data is removed from the bottom of the FIFO one piece at a time by the transmit
logic and is loaded into the transmit serial shifter along with start and stop bits (and the optional parity
and second stop bits), then is serially shifted out onto the TXD3 pin at the programmed baud rate.
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Peripheral Control Module
The following table shows the bit locations corresponding to the data field, parity, framing, and
receiver overrun error bits within the UART data register. Note that both FIFOs are cleared when
the SA-1100 is reset, the transmit FIFO is cleared when writing TXE=0, and the receive FIFO is
cleared when writing RXE=0.
Address: 0h 8005 0014
UTDR
Read/Write
Bit
10
ROR
0
9
FRE
0
8
PRE
0
7
0
6
0
5
4
3
2
1
0
0
Bottom of receive FIFO data
Reset
0
0
0
0
0
Read Access
(Note: ROR, FRE, PRE are not read, but rather are transferred to
corresponding status bits in UTSR1 each time a data value is transferred to UTDR.)
Bit
7
0
6
0
5
4
3
2
1
0
0
0
Top of transmit FIFO data
Reset
0
0
0
0
Write Access
Bit
7..0
Name
DATA
Description
Top/bottom of transmit/receive FIFO data.
Read – Bottom of receive FIFO data.
Write – Top of transmit FIFO data.
8
PRE
FRE
ROR
Parity error.
0 – No parity errors encountered in the receipt of this data (or parity disabled).
1 – Parity error encountered in the receipt of this data.
Note: Each time an 11-bit value reaches the bottom of the receive FIFO, bit 8 from the
last FIFO entry is transferred to the PRE bit in UTSR1.
9
Framing error.
0 – Stop bit for this frame was a one.
1 – Stop bit for this frame was a zero.
Note: Each time an 11-bit value reaches the bottom of the receive FIFO, bit 9 from the
last FIFO entry is transferred to the FRE bit in UTSR1.
10
Receiver overrun.
0 – No receiver overrun has been detected.
1 – Receive logic attempted to place data into receive FIFO while it was full; one or more
data values following this entry were lost.
Note: Each time an 11-bit value reaches the bottom of the receive FIFO, bit 10 from the
last FIFO entry is transferred to the ROR bit in UTSR1.
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Peripheral Control Module
11.11.7 UART Status Register 0
UART status register 0 (UTSR0) contains bits that signal the transmit FIFO interrupt request,
receive FIFO interrupt request, receiver idle detect, the begin and end of receiver break detect
conditions, and the error in receive FIFO condition. Each of these hardware-detected events signals
an interrupt request to the interrupt controller.
Interruptible status bits signal an interrupt requested as long as the bit is set. Once the bit is cleared,
the interrupt is cleared. Read/write bits are called status bits, read-only bits are called flags. Status
bits are referred to as “sticky” (once set by hardware, must be cleared by software). Writing a one
to a sticky status bit clears it; writing a zero has no effect. Read-only flags are set and cleared by
hardware; writes have no effect. Additionally, some bits that cause interrupts have corresponding
enable/mask bits in the control registers and are indicated in the following section headings. Note
that the user has the ability to mask all UART interrupts by clearing bit 17 within the interrupt
11.11.7.1 Transmit FIFO Service Request Flag (TFS) (read-only, maskable
interrupt)
The transmit FIFO service request flag (TFS) is a read-only bit that is set when the transmit FIFO is
nearly empty and requires service to prevent an underrun. TFS is set any time the transmit FIFO
has four or fewer entries of valid data (half-full or less), and is cleared when it has five or more
(more than half-full) entries of valid data. When the TFS bit is set, a DMA service request is made.
An interrupt request is also made unless the transmit FIFO interrupt request mask (TIE) bit is
cleared. After the DMA or CPU fills the FIFO such that five or more locations are filled within the
transmit FIFO, the TFS flag (as well as the DMA and interrupt request) is automatically cleared.
11.11.7.2 Receive FIFO Service Request Flag (RFS) (read-only, maskable
interrupt)
The receive FIFO service request flag (RFS) is a read-only bit that is set when the receive FIFO is
nearly filled and requires service to prevent an overrun. The amount of data that causes RFS to be
set is nondeterministic. However, the range in which RFS will be set is guaranteed. RFS is set at
some point when the receive FIFO is one- to two-thirds full (or more). The UART’s FIFOs are
self-timed to reduce cost and save power. As a result, the depth at which the receive FIFO service
request is generated is variable. This is the reason the receive FIFO is 12 entries deep instead of
eight like the transmit FIFO. At which entry in the FIFO the request is actually triggered is
dependent on IC process, operating temperature, and so on. The receive FIFO is designed to signal
the RFS bit to be set when it contains eight entries of valid data. However, because of the
variability of the self-timed logic, RFS may also be set when seven, six, or five entries of valid data
are present within the FIFO. Likewise, under normal circumstances, RFS is cleared when the
receive FIFO has seven remaining entries of valid data. However, again due to variations, RFS may
be cleared when six, five, or four entries of data remain.
When the RFS bit is set, a DMA service request is made. An interrupt request is also made unless
the receive FIFO interrupt request enable (RIE) bit is cleared. Even though more than four entries
of data may exist within the receive FIFO, the user must configure the DMA burst size to 4 words.
If programmed I/O is used to service the receive FIFO, a maximum of 4 words may be removed
without checking if data is valid. After this point, the receive FIFO not empty (RNE) flag must be
polled before each read to see if more data remains. After the DMA or CPU empties the FIFO such
that five or more empty locations are available within the receive FIFO, the RFS flag (as well as the
DMA and interrupt request) is automatically cleared.
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Peripheral Control Module
11.11.7.3 Receiver Idle Status (RID) (read/write, maskable interrupt)
The receiver idle status bit (RID) is set when the receiver is enabled (RXE=1), the receive FIFO is
not empty (contains at least one entry of data), and three frame periods elapse without any data
having being received. When RID is set, an interrupt request is made unless the receive FIFO
interrupt request mask (RIE) bit is cleared.
11.11.7.4 Receiver Begin of Break Status (RBB) (read/write, nonmaskable
interrupt)
The receiver begin of break status bit (RBB) is set when the receive logic detects a null character
(contains all zeros, including the parity bit), followed by a framing error, which indicates the start
bit is zero. In other words, a begin of break is detected when the receive line is held low for one
frame duration (whatever size the frame is programmed to). When RBB is set, an interrupt is
signalled, a single null frame is placed in the receive FIFO, the framing error bit is set, and all
subsequent null frames with framing errors are ignored (not placed within the FIFO). After RBB is
cleared by the user, it cannot be set again until the receiver end of break status (REB) bit is set. This
interlock is used to prevent added null characters from entering the receive FIFO, and also allows
the user to clear the RBB bit (clearing the interrupt) and wait for the receiver end of break interrupt
(described in the next section). This interlock is cleared when REB is set, when RXE is cleared, or
when the SA-1100 is reset.
11.11.7.5 Receiver End of Break Status (REB) (read/write, nonmaskable
interrupt)
The receiver end of break status bit (REB) is set when the receive pin transitions high (rising edge)
and the RBB interlock is currently set (described in the preceding section). In other words, an end
of break is detected after a begin of break is detected and the receive line transitions from low to
high (indicating a new frame is about to occur or the receiver is entering the idle state). When REB
is set, an interrupt is signalled, and the RBB interlock is cleared, allowing any future data frame to
be stored to the receive FIFO. After the bit is cleared, it cannot be set again until the receiver begin
of break status (RBB) bit is once again set.
11.11.7.6 Error in FIFO Flag (EIF) (read-only, nonmaskable interrupt)
The error in FIFO flag (EIF) is a read-only bit that is set when any error bits (8 through 10) are set
within the bottom four entries of the receive FIFO and is cleared when no error bits are set within
the bottom four entries of the FIFO. When EIF is set, an interrupt is signalled and DMA requests to
empty the receive FIFO are disabled until EIF is cleared. To discover the source of the errors, the
user should check the state of the FRE, PRE, and ROR bits in UTSR1, then read the corresponding
value from UTDR. This procedure should be repeated until EIF is cleared because errors that are
present within any of the four lowest entries in the receive FIFO will set EIF. Once all error tags are
cleared from the bottom half of the receive FIFO, EIF is automatically cleared, which in turn,
clears the interrupt and reenables the receive FIFO DMA request.
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Peripheral Control Module
The following table shows the bit locations corresponding to the status bits within UART status
register 0. Note that the reset state of all writable status bits is unknown (indicated by question
marks) and must be cleared (by writing a one to them) before enabling the UART. Also note that
writes to reserved bits are ignored and reads return zeros.
.
Address: 0h 8005 001C
UTSR0
Read/Write & Read-Only
Bit
7
6
5
EIF
0
4
REB
?
3
2
RID
?
1
RFS
0
0
TFS
0
Reserved
RBB
?
Reset
0
0
Bit
Name
TFS
Description
0
Transmit FIFO service request (read-only).
0 – Transmit FIFO is more than half-full (five or more entries filled) or transmitter
disabled.
1 – Transmit FIFO is half-full (four or fewer entries filled) and transmitter operation is
enabled, DMA service request signalled, and interrupt request signalled if not masked (if
TIE=1).
1
RFS
Receive FIFO service request (read-only).
0 – Receive FIFO contains seven or fewer entries of data or receiver disabled.
1 – Receive FIFO is one- to two-thirds full (contains 5, 6, 7, or 8 entries of data) or more,
and receiver operation is enabled, DMA service request signalled, and interrupt request
signalled if not masked (if RIE=1).
2
3
RID
Receiver idle.
0 – Receiver is busy, receive FIFO is empty, or receiver is disabled.
1 – Receiver is enabled, receive FIFO not empty, 3 frame times elapsed without
receiving data, request interrupt.
RBB
Receiver begin of break.
0 – No break detected.
1 – Null character followed by parity and stop bits containing zeroes received, request
interrupt.
Note: Setting this bit allows the setting of REB, and also prevents further null characters
with framing errors from being stored in the receive FIFO (only one stored).
4
5
REB
Receiver end of break.
0 – No end of break detected.
1 – Beginning of break was detected (interlock set) and a rising edge detected on the
receive pin, request interrupt.
Note: Setting of this bit allows the setting of RBB, and also allows characters to once
again be stored in the receive FIFO.
EIF
—
Error in FIFO (read-only).
0 – Bits 8..10 are not set within any of the four bottom entries of the receive FIFO,
receive FIFO DMA service requests are enabled.
1 – One or more error bits (8..10) are set within one or more of the bottom four entries of
the receive FIFO, request interrupt, disable receive FIFO DMA service requests.
7.. 6
Reserved.
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Peripheral Control Module
11.11.8 UART Status Register 1
UART status register 1 (UTSR1) contains flags that indicate when the UART is actively
transmitting characters, that the transmit FIFO is not full, that the receive FIFO is not empty, and
when parity, framing, overrun, and underrun errors have occurred. All bits within UTSR1 are
read-only and are noninterruptible.
11.11.8.1 Transmitter Busy Flag (TBY) (read-only, noninterruptible)
The transmitter busy (TBY) flag is a read-only bit that is set when the transmitter is actively
processing data for transmission (the serial shifter contains data), and is cleared when the
transmitter is idle or is disabled (TXE=0). This bit does not request an interrupt.
11.11.8.2 Receive FIFO Not Empty Flag (RNE) (read-only, noninterruptible)
The receive FIFO not empty flag (RNE) is a read-only bit that is set when the receive FIFO
contains one or more bytes of valid data and is cleared when it no longer contains any valid data.
This bit can be polled when using programmed I/O to remove remaining bytes of data from the
receive FIFO because DMA service and CPU interrupt requests are made only when 8, 7, 6, or 5
bytes reside within the FIFO. This bit does not request an interrupt.
11.11.8.3 Transmit FIFO Not Full Flag (TNF) (read-only, noninterruptible)
The transmit FIFO not full flag (TNF) is a read-only bit that is set when the transmit FIFO contains
one or more entries that do not contain valid data and is cleared when the FIFO is completely full.
This bit can be polled when using programmed I/O to fill the transmit FIFO over its halfway mark.
This bit does not request an interrupt.
11.11.8.4 Parity Error Flag (PRE) (read-only, noninterruptible)
The parity error flag (PRE) is set when parity is enabled (PE = 1), and the parity type programmed
using OES does not correspond to the parity check of the incoming serial data stream, which is
calculated by the receive logic. The parity error bit is set when PE=1, OES=0, and UTDR<7:0>,
and the incoming parity bit contain an even number of ones, or PE=1, OES=1, and UTDR<7:0>,
and the incoming parity bit contain an odd number of ones.
The receive FIFO contains three bits (8, 9, and 10) that are not directly readable. The 8th bit in the
FIFO is set at the top of the FIFO whenever a byte of data that incurs a parity error is moved from
the receive serial shifter to the top of the receive FIFO. This tag travels along with the errant data
value as it moves down the FIFO. Each time a data value is transferred to the bottom of the FIFO
(caused by a read of the previous value), the state of this bit is moved from the FIFO to the PRE bit
in the status register. After the error in FIFO (EIF) status bit is set, the user should always read
UTSR1 first to check PRE before reading the data value from UDR because PRE corresponds to
the current data byte at the bottom of the receive FIFO and is updated each time data is removed
from the FIFO.
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11.11.8.5 Framing Error Flag (FRE) (read-only, noninterruptible)
The framing error status bit (FRE) is set when the stop bit within a frame of incoming serial data is
a zero instead of a one.
The receive FIFO contains three bits (8, 9, and 10) that are not directly readable. The 9th bit in the
FIFO is set at the top of the FIFO whenever a byte of data that incurs a framing error is moved from
the receive serial shifter to the top of the receive FIFO. This tag travels along with the errant data
value as it moves down the FIFO. Each time a data value is transferred to the bottom of the FIFO
(caused by a read of the previous value), the state of this bit is moved from the FIFO to the FRE bit in
the status register. After the error in FIFO (EIF) status bit is set, the user should always read UTSR1
first to check FRE before reading the data value from UDR because FRE corresponds to the current
data byte at the bottom of the receive FIFO and is updated each time data is removed from the FIFO.
11.11.8.6 Receiver Overrun Flag (ROR) (read-only, noninterruptible)
The receiver overrun status bit (ROR) is set when the receive logic attempts to place data into the
receive FIFO after it has been completely filled.
The receive FIFO contains three bits (8, 9, and 10) that are not directly readable. The 10th bit in the
FIFO is set within the top entry of the receive FIFO whenever an overrun occurs. This tag travels
along with the last “good” data value before the overflow occurred as it moves down the FIFO.
Each time a data value is transferred to the bottom of the FIFO (caused by a read of the previous
value), the state of this bit is moved from the FIFO to the ROR bit in the status register, indicating
that the next value in the FIFO is the last “good” piece of data before the overflow occurred. After
the error in FIFO (EIF) status bit is set, the user should always read UTSR1 first to check ROR
before reading the data value from UDR because ROR corresponds to the current data byte at the
bottom of the receive FIFO and is updated each time data is removed from the FIFO.
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The following table shows the bit locations corresponding to the flag bits within UART status
register 1. Note that these flags do not generate interrupts, all bits are read-only, writes are ignored,
and reads of reserved bits return zeros.
Address: 0h 8005 0020
UTSR1
Read-Only
Bit
7
6
5
4
3
2
1
0
Reserved
0
ROR
0
FRE
0
PRE
TNF
1
RNE
0
TBY
0
Reset
0
0
Bit
Name
TBY
Description
0
Transmitter busy flag (read-only).
0 – Transmitter is idle or UART is disabled.
1 – Transmit logic is currently transmitting a frame (data within the serial shifter); no
interrupt generated.
1
2
3
RNE
TNF
PRE
Receive FIFO not empty (read-only).
0 – Receive FIFO is empty.
1 – Receive FIFO is not empty (no interrupt generated).
Transmit FIFO not full (read-only).
0 – Transmit FIFO is full.
1 – Transmit FIFO is not full (no interrupt generated).
Parity error (read-only).
0 – No parity errors encountered in the receipt of the next data value in the FIFO (or
parity disabled).
1 – Parity error encountered in the receipt of the next data value in the FIFO (no interrupt
generated).
4
5
FRE
Framing error (read-only).
0 – Stop bit for the next frame in the FIFO was a one.
1– Stop bit for the next frame in the FIFO was a zero (no interrupt generated).
ROR
Receive FIFO overrun (read-only).
0 – Receive FIFO has not experienced an overrun.
1 – Receive logic attempted to place data into receive FIFO while it was full, the next
data value in the FIFO is the last piece of “good” data before the FIFO was overrun (no
interrupt generated).
7..6
—
Reserved.
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11.11.9 UART Register Locations
Table 11-18 shows the registers associated with serial port 3 and the physical addresses used to
access them.
Table 11-18. Serial Port 3 Control, Data, and Status Register Locations
Address
Name
UTCR0
Description
UART control register 0
0h 8005 0000
0h 8005 0004
0h 8005 0008
0h 8005 000C
0h 8005 0010
0h 8005 0014
0h 8005 0018
0h 8005 001C
0h 8005 0020
UTCR1
UTCR2
UTCR3
—
UART control register 1
UART control register 2
UART control register 3
Reserved
UTDR
—
UART data register
Reserved
UTSR0
UTSR1
UART status register 0
UART status register 1
0h 8005 0024 –
0h 8005 FFFF
—
Reserved
11.12
Serial Port 4 – MCP / SSP
Serial port 4 contains two separate full-duplex synchronous serial interfaces. The multimedia
communications port (MCP) provides an interface to the Philips UCB1100 and UCB1200 codecs.
Both devices have an audio codec, a telecom codec, a touch-screen interface, four general-purpose
analog-to-digital converter inputs, and ten programmable digital I/O lines. The MCP interface is
used by the SA-1100 both to input and output digital data to and from the codec, and to configure
and acquire status information from the codecs’ 16 registers. The synchronous serial port (SSP) is
used to interface to a variety of analog-to-digital converters, audio and telecom codecs, memory
chips, and keypad controllers as well as other miscellaneous serial devices. The SSP supports the
National Microwire and Texas Instruments* synchronous serial protocols as well as a subset of the
Motorola* serial peripheral interface (SPI) protocol.
In MCP mode, serial port 4 controls communication between the SA-1100 and either the UCB1100
or UCB1200. The MCP produces two 64-bit subframes per frame (totalling 128 bits per frame)
using a bit clock and frame synchronization signal. Data is communicated full-duplex via a
separate transmit and receive data line. Selecting the on-chip clock, a bit clock frequency of either
9.585 Mbps or 11.981 Mbps can be programmed. Alternatively, GPIO pin 21 can be used to input a
bit clock from an off-chip source. This feature allows users to select a frame rate that is an exact
multiple of the desired audio/telecom sample rate. The MCP communicates to the codec in the first
of the two subframes. The second subframe is used in high-end applications to communicate with a
second stereo codec; however, this feature is not supported by the MCP. Each 64-bit subframe
contains seven different fields of information. These fields include: audio conversion data, telecom
conversion data, data valid flags, control register address, control register data, and read/write
control. Both transmit and receive data contains these seven fields. The transmit frame contains
data for D-to-A conversion as well as address, data, and control signals to write to or read from the
codec’s registers, and the receive frame contains A-to-D samples and the data returned from a read
of a codec register.
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Both the MCP and the off-chip codec contain programmable 7-bit divisors, one each for the
telecom and audio data. These values are used to divide the bit clock to generate a desired sampling
frequency. When the codec is enabled, the divisor pairs are synchronously transferred to their
respective modulus registers within the MCP and off-chip codec, and decrement using the bit
clock. This technique allows telecom and audio data to be transferred between the MCP and codec,
lock-step in sync with the sampling/conversion frequency of the codec.
The MCP contains two pairs of transmit FIFOs and two pairs of receive FIFOs, one each for audio
and telecom data, totalling four separate 8-entry x 16-bit FIFOs. The MCP also contains a 21-bit
data register used to transmit codec register reads and writes, as well as another 21-bit register to
receive the results of codec register reads. Touch-screen and ADC conversions are triggered, the
digital I/O lines are controlled using codec register writes, and the converted data and the state of
digital I/O lines are accessed using a codec register read.
In SSP mode, serial port 4 controls full-duplex synchronous serial transfers between the SA-1100
and off-chip devices that support National Microwire*, Texas Instruments* synchronous serial, or
the Motorola* SPI protocol. The SSP functions as a master only and communicates to the off-chip
slave device by driving a serial bit rate clock ranging from 7.2 kHz to 1.8432 MHz along with a
frame synchronization pulse to denote the start of each frame transfer, and supports any data format
between 4 and 16 bits. Transmit and receive data is stored/collected using two separate
8-entry x 16-bit FIFOs. MCP operation takes precedence over SSP operation. If use of both the
MCP and SSP is required at the same time, the user can configure the SSP to take over control of
GPIO pins 10 through 13, and the MCP uses the serial port 4 pins for transmission.
The external pins dedicated to this interface are TXD4, RXD4, SCLK, and SFRM. If use of both
the MCP and SSP is not required and serial port 4 is disabled, control of these pins is given to the
peripheral pin controller (PPC) to be used to perform general-purpose input/output
operation of the PPC. The MCP operation takes precedence over the SSP if both units are enabled.
Both the MCP and SSP support word reads/writes of their registers, and half-word DMA transfers
to or from their FIFOs that are 16-bits wide.
11.12.1 MCP Operation
Following reset, both the MCP and SSP logic within serial port 4 is disabled and control of its pins
is given to the PPC, which configures all four pins as inputs. To enable MCP operation, the
programmer should first clear any interruptible status bits, which are set following the reset, by
writing a one to them. Next, the user should program the MCP control register with the desired
mode of operation using word writes, ensuring that the enable bit is programmed last. The user can
choose to either “prime” the audio and telecom transmit FIFOs, before enabling the MCP, by
writing up to eight 16-bit values each, or allow the FIFO service requests to interrupt the CPU or
trigger a DMA transfer to fill the FIFOs. Once the off-chip codec is programmed and data resides
within the bottom entries of the audio and/or telecom FIFOs, transmission/reception of data begins
on the transmit (TXD4) and receive (RXD4) pins, and is synchronously controlled by the serial
clock (SCLK) pin and a serial frame (SFRM) pin at a rate of 9.585 MHz or 11.981 MHz. The serial
clock rate is selected by programming a control bit. Note that the two SCLK rates are derived by
first multiplying the 3.6864-MHz on-chip oscillator by 13, then by dividing either by 5
(9.58464 MHz) or by 4 (11.9808 MHz). Also note that an off-chip clock can be used to drive the
MCP when a sample rate that is not a multiple of 3.6864 MHz is required.
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11.12.1.1 Frame Format
Each MCP data frame is 128 bits long and is divided into two subframes: 0 and 1. Subframe 0 is
used by the MCP to communicate data to and from the UCB1100 or UCB1200. Subframe 1 is not
used by the MCP because it is typically used to interface to high-performance stereo codecs such as
Crystal’s CS4216/18.
After the MCP is enabled, SCLK begins to transition at the programmed clock rate and the start of the
first frame is signalled by pulsing the SFRM pin high for one SCLK period. The rising edge of SFRM
coincides with the rising edge of SCLK. The SFRM pulse causes the MCP to transfer any available
audio and/or telecom data from their respective transmit FIFOs to a 64-bit serial shifter, setting the
appropriate audio/telecom valid flags as well. If the codec control register contains valid data, the
register value and address are placed within the appropriate fields in the shifter, and the read/write bit
is configured to indicate which type of register access is to be made. For any field that does not have
valid data available, the previous value transmitted is used. As long as the MCP is enabled, data
frames are continuously transferred, even if no valid data is available for transmission. The format of
USB1200 data sheets use big-endian notation; little-endian notation is used in the following figure to
remain consistent with the rest of the SA-1100 specification.
Figure 11-31. MCP Frame Data Format
3
1
1
6
1
5
63
48
47
46
43
42
41
34
33
32
0
Bit
TX
Audio Transmit Data
Audio Receive Data
0
Address
R/W
00000000
AV TV Telecom Transmit Data
Control Register Write
RX
0
Address
R/W
00000000
AV TV Telecom Receive Data
Control Register Read
AV – Audio Data Valid TV – Telecom Data Valid R/W – Write=1, Read=0 Address – Codec Register Address
Both the MCP and the off-chip codec drive data on the rising edge of SCLK and latch data on its
falling edge. After SFRM is negated, subframe 0 begins and the data within the 64-bit shifter is
driven onto the TXD4 pin a bit at a time, starting with the MSB (bit<63>). As each bit of data is
shifted onto the TXD4 pin from one side of the shifter, a bit is also shifted into the opposite end of
the shifter from the RXD4 pin. After 64 SCLK cycles elapse, all data within the shifter has been
transmitted, and the shifter contains the 64-bit receive data frame. The MCP takes the data from
each field and places it in its respective receive FIFO or data register. The next 64 SCLK cycles
make up subframe 1. When subframe 1 is active, the clocks to all MCP resources that are not
Figure 11-32. MCP Frame Pin Timing
Frame Clock
Count
1
2
...
63
64
65
66
...
127
128
1
Subframe 0
Subframe 1
Subframe
SCLK
SFRM
TXD4
...
...
...
Bit<63>
Bit<63>
Bit<62>
Bit<62>
...
...
Bit<1>
Bit<1>
Bit<0>
Bit<0>
...
...
Bit<63>
Bit<63>
RXD4
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Note that the transmit line is pulled low any time data is not being driven onto the pin. The
UCB1100 and UCB1200 have a programming option that allows them to either tristate or drive the
occur back-to-back. The SFRM pin is pulsed high during the last clock (128th) of the frame to
indicate the start of a new frame the following SCLK period. Values contained within the transmit
FIFOs are loaded to the shift register on the rising edge of SFRM.
11.12.1.2 Audio and Telecom Sample Rates and Data Transfer
The UCB1100 and UCB1200 contain both an audio and telecom codec with sample rates that can
be individually programmed, and are derived from the programmed serial clock (SCLK) that is
supplied by the MCP. For the audio codec, the sample rate is derived by dividing the serial clock
first by a fixed value of 32, then by a value from 6 to 127. The same is true for the telecom codec,
except that the programmable divisor ranges from 16 to 127. The codec and the MCP both contain
an audio and a telecom sample rate counter. These counters are used to achieve conversion rate
synchronization between the codec and MCP so that data may be coherently transferred between
the MCP and the codec. For the remainder of this description, references made to the audio codec
also apply to the telecom portion of the codec and MCP.
Before enabling the audio codec, the audio sample rate counters within the codec and MCP must
programmed with the same divisor value so that they have the same clock rate. The codec’s audio
sample rate divisor is programmed by issuing a control register write transfer, and the MCP’s
divisor is programmed using the CPU by writing to the MCP’s control register. Both the MCP and
the codec’s audio counters are reloaded with the programmed modulus value any time the audio
portion of the codec is enabled (which is also accomplished by performing a control register write
transfer), or whenever the sample rate counters reach zero.
The MCP and the audio codec decrement their counters in lock-step with one another, both starting
on the occurrence of the first SFRM pulse after the audio codec is enabled. Samples/conversions
audio codec enable and decrements of the MCP and audio codec’s sample counter.
Figure 11-33. MPC/Codec Sampling Counter Synchronization
Subframe
SFRM
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Ena
Dis
TXD4
Audio Ena
Counters
Samp/Conv
12....12
12.11.10.9.8.7.6.5.4.3.2.1
12.11.10.9.8.7.6.5.4.3.2.1
12.11.10.9.8.7.6
12...................12
In the preceding figure, “Ena,” within the data frame on TXD4, represents a control register write to the
codec to enable the input portion of the audio codec. The register is updated with the write at the end of
subframe and the audio enable signal within the codec goes high. Both the MCP and codec’s audio
sample rate counters then start to decrement on the next SFRM pulse. In the example, a divisor value of
12 is used, causing the counter to decrement to zero after 384 (32*12=384) SCLK cycles occur.
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If the input portion of the audio codec is enabled, when the counter reaches zero, a sample and
A-to-D conversion is made and the converted value is placed within the correct field of the codec’s
serial shift register for transmission back to the MCP in the next data frame. If the output portion of
the audio codec is enabled, an audio data value is taken from the received data supplied by the
MCP and is used for a D-to-A conversion. Data used in the D-to-A conversion is always taken
from the previous MCP input frame. If no new data is available within the MCP’s audio transmit
FIFO since the last D-to-A conversion, then the same data is used again (causing audio distortion).
Samples and conversions occur twice in the preceding figure. However, while the counter is decrementing
for the third time, the CPU disables the audio codec by issuing another control register write, represented
by the “Dis” data frame on TXD4. The SFRM pulse following the write causes the disable to take effect,
and the MCP and codec’s audio sample rate counters are stopped and reset to their modulus values.
The MCP and the codec’s audio sample rate counters must be enabled coherently so that
synchronization is achieved between the two. This is accomplished by first programming both the
MCP and codec’s sample rate modulus values, then performing a codec control register write to
enable the audio sampling rate counter within the codec. The MCP automatically decodes a write
to the audio codec input and output enable bits, and enables the MCP’s audio sample rate counter at
the same time as the codec’s counter to ensure synchronization.
The UCB1100 and UCB1200 each have an individual data valid bit for audio and telecom A/D
samples. Whenever these bits are set in the data frame returned from the codec to the MCP, the
audio and telecom data is taken from the frame and placed in their respective receive FIFOs. The
UCB1100 and UCB1200 have two different modes of operation to control the setting of the audio
and telecom data valid bits. In the first mode, a data valid bit is set any time a frame contains
“reliable” data ( the codec is enabled and at least one A-to-D sample has been taken). In this mode,
once the data valid bit is set, it remains set until the codec A-to-D input is disabled. In the second
mode, the codec only sets the data valid bit corresponding to a new A-to-D sample. Once the data
is transmitted to the MCP within a receive data frame, the data valid bit is reset to zero for
subsequent data frames until a new A-to-D sample is triggered.
11.12.1.3 MCP Transmit and Receive FIFO Operation
The MCP contains four 8-entry x 16-bit FIFOs: one for audio and one for telecom A-to-D samples
received by the MCP, as well as one for audio and one for telecom D-to-A conversions transmitted
to the codec. For the remainder of this description, references made to the audio codec also apply to
the telecom portion of the codec and MCP.
For each incoming data frame, if the audio data valid bit is set, the 16-bit audio A-to-D sample is
extracted and placed in the audio receive FIFO. Note that the MCP also supports a mode in which
the audio data valid bit is ignored after the first conversion has been saved to the FIFO, and the
MCP’s audio sample rate counter is used to signal when a new A-to-D sample has been taken and
is available within the incoming frame. Audio data is transferred from the incoming data frames to
the receive FIFO only if the audio enable bit is set within the MCP’s status register.
The MCP’s audio and telecom sample rate counters are used to trigger when new D/A conversions
are to be transmitted to the codec. The user should take care in ensuring sample rate counters in the
MCP are synchronized with the respective sample rate counters in the codec as described in
preceding sections. When the audio enable status bit transitions from a 0 to a 1 within the MCP status
register, the next available entry of data is taken from the audio transmit FIFO and is placed within the
correct field in the MCP’s serial shifter. This value is then continuously transferred by the MCP in
each data frame to the codec. The codec uses the value only when its audio sample rate counter
decrements to zero. After the audio D-to-A conversion is made, both the codec and the MCP’s audio
sample rate counters reload with their modulus values. This reload triggers the audio transmit FIFO to
transfer the next available entry of data to the MCP’s serial shifter. Again, this value is continuously
transmitted to the codec in each data frame until it is used in the next audio D-to-A conversion.
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The width of each entry within the audio and telecom FIFOs is 16 bits. However, the audio codec’s
sample/conversion data size is 12 bits and the telecom is 14 bits. Conversions and samples are left
justified within the 16-bit audio and telecom data fields in the MCP frame as well as within the
receive audio and telecom FIFOs. The user must left justify data to be transmitted, and shift
received data to the right before using the results.
Figure 11-34. Audio/Telecom Transmit/Receive FIFO Data Format
Bit
Bit
15
15
14
14
13
13
12
12
11
11
10
9
8
8
7
7
6
6
5
5
4
4
3
0
2
0
1
0
0
0
Audio Data
10
9
3
2
1
0
0
0
Telecom Data
To reduce chip size as well as power consumption, the MCP’s FIFOs use self-timed logic (not
clocked). Because of process and environmental variations, the depth at which a service request is
triggered to empty the receive FIFOs is variable. This variation spans a maximum of four FIFO
entries, thus the audio and telecom receive FIFO service requests can be made at four different
FIFO depths.To compensate for this variability and guarantee that at least four valid entries of data
exist within either FIFO before generating a service request, an extra four entries have been added
to both receive FIFOs (four entries more than the transmit FIFOs). Thus the audio and telecom
transmit FIFOs are 8-entries deep and the audio and telecom receive FIFOs are 12-entries deep.
The point at which the receive FIFO service requests are triggered spans one-third (four entries) of
the 12-entry FIFOs. The service request is signalled at a depth from one-third full to two-thirds full
(when the FIFOs contains five, six, seven, or eight entries of data).
11.12.1.4 Codec Control Register Data Transfer
The UCB1100 and UCB1200 contain sixteen 16-bit registers used to configure the chip, and store
touch-screen and ADC samples as well as digital I/O pin state and edge interrupt status. These
registers are read and written via the MCP’s serial interface using three fields that exist within the
codec, bits 46:43 contain the register address of the current read or write, and bit 42 is used by the
MCP to signal a read or write cycle to the codec. These fields are configured by the CPU by writing
to MCP control register 2, and are then transmitted to the off-chip codec. These fields are also
received every data frame by the MCP from the codec and are placed in MCP control register 2,
which can be read by the CPU. Note that the contents of the addressed register are returned in the
receive data frame regardless of the state of the read/write bit. Thus for write cycles, both a write
and a read occurs, and for read cycles, only a read occurs.
A register write is performed by writing a value to the MCP control register 2 that contains the
value to store to the register, the address of the register, and the read/write bit set to one. Once this
register is written, its contents are transferred to the correct fields within the serial shifter on the
next rising edge of the SFRM signal. The register information is transmitted to the UCB1100 or
UCB1200 during subframe 0, and the value is written to the selected codec register at the end of
subframe 0 (during the 65th bit of the frame). The control register value and address are also
returned to the MCP and stored in MCP control register 2. The read/write bit is zero in the return
frame. Because the addressed register is updated at the end of subframe 0, the data returned during
the frame in which the write occurred represents the previous contents of the register. The updated
value is returned during the next data frame.
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A register read is performed by writing a value to MCP data register 2 that contains the address of
the register and the read/write bit set to a zero. Again, the data is transferred to the serial shifter on
the next rising edge of the SFRM signal and is transmitted to the UCB1100 or UCB1200 during
subframe 0. Because the address and read/write control bit fields occur near the beginning of the
serial stream output, the codec performs the read immediately after the read/write bit is received
(during the 41st bit of the frame) and the value contained within the addressed register is sent back
to the MCP in the same data frame.
Once the codec control register is written with a value to execute a read or write, the operation is
performed every MCP data frame until a new value is written to the register. Thus, continual reads
or writes are made to the addressed codec register until a new read or write operation is configured.
11.12.1.5 External Clock Operation
Under normal operation, the MCP is programmed to use one of two on-chip clocks to produce a
9.585-Mbps or 11.981-Mbps bit rate. This clock is also used to increment the audio and telecom
sample rate counters. The MCP also supports a special mode that allows the user to control the
MCP’s frame rate and audio/telecom sample rates. This mode is useful when sample rates that are
not an integer multiple of 12 MHz are required. In this mode, the MCP uses GPIO<21> to input a
clock supplied from off-chip. The frequency of the off-chip clock can be any value within the
allowable frequency range of the UCB100, up to 12 MHz. When using GPIO pin 21 for the input
clock, the user must also set bit 21 of the GPIO alternate function register (GAFR) and clear bit 21
of the GPIO pin direction register (GPDR). See the Section 9.1, “General-Purpose I/O” on
11.12.1.6 Alternate SSP Pin Assignment
MCP operation takes precedence over SSP operation. Thus if both are enabled, serial port 4
defaults to MCP mode. However, if the MCP and SSP both need to be used at the same time,
general-purpose I/O pins 10..13 (GPIO<10..13>) can be reassigned by programming the PPC pin
assignment register (PPAR). This allows the MCP dedicated use of the four pins assigned to serial
port 4, and the SSP dedicated use of the GPIO pins. When the SSP pin reassignment (SPR) bit is
set in PPAR, the following pin assignments are made: GPIO<10> is used for transmit, GPIO<11>
for receive, GPIO<12> for serial clock, and GPIO<13> for serial frame. Note that the user must
also set bits 10 through 13 in the GPIO alternate function register (GAFR) as well as set bits 10, 12,
and 13, and clear bit 11 in the GPIO pin direction register (GPDR). Once the reassignment is made,
these pins are no longer usable by the GPIO unit. See the Section 9.1, “General-Purpose I/O” on
unit.
11.12.1.7 CPU and DMA Register Access Sizes
Bit positioning and addressing of the MCP is described in terms of little endian ordering. All MCP
registers are 32 bits wide. The ARM peripheral bus does not support byte or half-word operations.
All reads and writes of the MCP by the CPU should be wordwide. Four separate dedicated DMA
requests exist for the audio and telecom transmit and receive FIFOs. If the DMA controller is used
to service the transmit and/or receive FIFOs, the user must ensure the DMA is properly configured
to perform half-word accesses, using 4 half-words per burst (half the size of the FIFOs). Note that a
separate set of registers also exist to configure SSP operation. See the following sections for a full
description of programming and operation of serial port 4 as an SSP, a summary of serial port 4’s
MCP registers, and a summary of its SSP registers.
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11.12.2 MCP Register Definitions
There are six registers within the MCP: two control registers, three data registers, and one status
register. The control register is used to program the audio and telecom sample rates, to mask or
unmask interrupt requests to service the MCP’s FIFOs, to select whether an on-chip or off-chip clock
is used to drive the bit rate, and to enable/disable operation. The first data register addresses the top of
the audio transmit FIFO and the bottom of the audio receive FIFO. Likewise, the second data register
addresses the top/bottom of the telecom transmit/receive FIFOs, respectively. A read accesses the
receive FIFOs; a write accesses the transmit FIFOs. Note that these are four physically separate
FIFOs to allow full-duplex transmission. The third data register is 21 bits and is used to transmit read
and write operations to the codec’s control, data, and status registers. Values written to the register are
used in the transmit data frame and values read are taken from the received data frame. The status
register contains bits that signal FIFO overrun and underrun errors, and transmit and receive FIFO
service requests. Each of these status conditions signals an interrupt request to the interrupt controller.
The status register also flags when audio and telecom transmit FIFOs are not full, when the audio and
telecom receive FIFOs are not empty, when a codec control register read or write is complete, and
when the audio or telecom portion of the codec is enabled (no interrupt generated).
11.12.3 MCP Control Register
The MCP control register (MCCR) contains 11 different bit fields that control various functions
within the MCP.
11.12.3.1 Audio Sample Rate Divisor (ASD)
The 7-bit audio sample rate divisor (ASD) bit field is used to synchronize the MCP with the sample
rate of the audio codec. Sample rate synchronization is required such that the MCP’s audio transmit
FIFO logic knows when to load a new value for D-to-A conversion to the MCP’s serial shifter for
transmission. This field is programmed with the same value that is written to the codec’s sample
rate divisor via a codec control register write. When the audio codec is enabled, the first audio
transmit value is placed in the serial output stream by the transmit FIFO, and both the MCP’s and
codec’s sample rate counters begin to decrement in lock-step with one another. When the audio
codec’s counter decrements to zero, it uses the value transmitted to it by the MCP to perform the
D-to-A conversion. After the conversion is made, the MCP and codec’s counters reset to their
modulus values, and the MCP’s audio transmit FIFO loads the next value to the serial shifter for
transmission. This new value is then transmitted to the audio codec and is used for the next D-to-A
conversion, which is signalled when the sample rate counter decrements to zero again.
A total of 122 different audio sample rates can be selected, ranging from a minimum of 2.358 K
samples per second using the 9.585-MHz internal clock to a maximum of 62.401 K samples per
second using the 11.981-MHz internal clock. Note that slower sample rates can be achieved using
an externally supplied clock. The sample rate clock generator uses either a 9.585-MHz or
11.981-MHz clock produced by the on-chip PLL or the clock supplied to the MCP via GPIO
pin 21, and is divided by a fixed value of 32 and then by the programmable ASD value to generate
the audio sample clock. This clock is automatically enabled when:
• A codec control register write to the audio control register B is made (address=0b100), which
sets either the audio codec input or output enable bits (bit 14 = aud_in_ena, bit 15 =
aud_out_ena), followed by
• The rising edge of the next SFRM pulse after the write has been made.
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Once enabled, the MCP’s audio sample rate clock decrements at the programmed frequency with a 50%
duty cycle. The action outlined in the above first bullet item causes the MCP’s audio transmit FIFO logic
to transfer the next available value to the audio data field within the serial shifter. Each time the audio
sample rate clock decrements to zero, it is reloaded with its programmed ASD modulus value, triggers
the audio transmit FIFO logic to transfer the next available value to the audio data field within the serial
shifter, and continues to decrement. The MCP’s audio sample rate clock is automatically disabled when:
• A codec control register write to the audio control register B is made (address=0b100), which
clears both the audio codec input and output enable bits (bit 14 = aud_in_ena, bit 15 =
aud_out_ena), followed by
• The rising edge of the next SFRM pulse after the write has been made.
The resultant audio sample clock rate, given a specific ASD value, can be calculated using the following
equation, where ASD is the decimal equivalent of the binary value programmed within the bit field. Note
that ASD must be programmed with a value of 6 or larger. Unpredictable results occur for ASD values
smaller than 6. Note that one of three clock frequencies can be selected. The first two frequencies are
internal clocks selected by the CFS bit in MCCR1 and the third frequency is a user-defined clock that is
input via GPIO pin 21 and is divided as defined by the ECP bit field described in following sections.
6
12×10
SampleRate = -----------------------
32xASD
Valid ASD values are from 6 (00000110) to 127 (11111111)
6
Note: The 12x10 value within the formula’s numerator should be replaced with the frequency
of the clock driven to GPIO pin 21 when an off-chip clock source is used to drive the MCP.
11.12.3.2 Telecom Sample Rate Divisor (TSD)
The 7-bit telecom sample rate divisor (TSD) bit field is used to synchronize the MCP with the
sample rate of the telecom codec. The telecom sample rate clock is required for the same reason
and works exactly like the audio sample rate clock, except for one minor difference. The valid TSD
values range from 16 to 127 (instead of 6), allowing a total of 112 different audio sample rates to be
selected, ranging from a minimum of 2.358 K samples per second using the 9.585-MHz internal
clock to a maximum of 23.400 K samples per second using the 11.98-MHz internal clock. Note
that slower sample rates can be achieved using an externally supplied clock.
The resultant telecom sample clock rate, given a specific TSD value, can be calculated using the
following equation, where TSD is the decimal equivalent of the binary value programmed within
the bit field. Note that TSD must be programmed with a value of 16 or larger. Unpredictable results
occur for TSD values smaller than 16. Note that one of three clock frequencies can be selected. Thr
first two frequencies are internal clocks selected by the CFS bit in MCCR1 and the third frequency
is a user-defined clock that is input via GPIO pin 21 and is divided by the ECP bit field described in
the following sections.
6
12×10
SampleRate = -----------------------
32xTSD
Valid TSD values are from 16 (00010000) to 127 (11111111)
6
Note: The 12x10 value within the formula’s numerator should be replaced with the frequency of
the clock driven to GPIO pin 21 when an off-chip clock source is used to drive the MCP.
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Peripheral Control Module
11.12.3.3
Multimedia Communications Port Enable (MCE)
The MCP enable (MCE) bit is used to enable and disable all MCP operation. Since the MCP and
SSP both share the same pins, only one can be enabled at a time. If the user enables both at the
same time, the MCP has precedence and the SSP remains disabled. However, both can be enabled
when the SSP pin reassignment (SPR) bit within the PPC unit is set, which assigns the SSP to
GPIO pins. See the following sections for a description of the SSP enable (SSE) bit.
When the MCP is disabled, all of its clocks are powered down to minimize power consumption. If
the SSP is also disabled, the TXD4, RXD4, SCLK, and SFRM pins can be used for
general-purpose input/output. See the Section 11.13, “Peripheral Pin Controller (PPC)” on
page 11-184 for a description of how to program the PPC unit to reassign the SSP’s pins and to use
serial port 4’s pins as I/Os. Note that MCE and CFS are the only control bits within the MCP that
are reset to a known state. MCE is cleared to zero to ensure the MCP is disabled following a reset
of the SA-1100.
When the MCP is enabled, SCLK begins to transition and the start of the first frame is signalled by
pulsing the SFRM pin high for one SCLK period. The rising edge of SFRM coincides with the
rising edge of SCLK. As long as the MCE bit is set, the MCP operates continuously, transmitting
and receiving 128 bit data frames. When the MCE bit is cleared, the MCP is disabled immediately,
causing the current frame, which is being transmitted, to be terminated and control of serial port 4’s
pins to be given to the PPC unit. Clearing MCE resets the MCP’s FIFOs. However, MCP data
register 3, the control, and the status registers are not reset. The user must ensure these registers are
properly reconfigured before reenabling the MCP.
11.12.3.4 External Clock Select (ECS)
The external clock select (ECS) bit selects whether one of the two on-chip clocks derived by the
3.6864-MHz oscillator is used by the MCP or if an off-chip clock is supplied via GPIO pin 21.
When ECS=0, the MCP can be programmed to select one of two frequencies: either 9.585 MHz or
11.981 MHz. This clock is also used to increment the audio and telecom sample rate counters. (See
preceding sections.) When ECS=1, the MCP uses GPIO<21> to input a clock supplied from
off-chip. The frequency of the off-chip clock after being scaled by the ECP bit field can be any
value within the allowable frequency range of the UCB100 up to 12 MHz. This off-chip clock is
useful when a sample rate frequency, which is not a multiple of 9.585 MHz or 11.981 MHz is
required for synchronization with either the audio and/or telecom portion of the UCB1100 or
UCB1200 codecs. When using GPIO pin 21 for the input clock, the user must also set bit 21 of the
GPIO alternate function register (GAFR) and clear bit 21 of the GPIO pin direction register
11.12.3.5 A/D Sampling Mode (ADM)
The A/D sampling mode (ADM) bit selects whether the MCP takes audio and telecom data from
the incoming frame only when their respective data valid bits are set or whenever the MCP’s audio
and telecom sample rate counters time-out, indicating that the data in the next incoming frame is
valid. When ADM=0, data is taken from the incoming frame and is placed into the audio or
telecom FIFO whenever the incoming audio or telecom data valid bit is set. When ADM=1, after
the MCP is enabled, data is taken from the incoming frame when the data valid bit is set for the
first time. After this point, the data valid bit is ignored, and samples are stored each time the audio
or telecom sample rate counters decrement to zero, indicating that a new A-to-D sample was taken
and will be available in the next frame.
The UCB1100 and UCB1200 have two different modes of operation to control the setting of the
audio and telecom data valid bits. In one mode, the codec only sets the data valid bit when a new
A-to-D sample is contained within the incoming data frame. Once the data is transmitted to the
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Peripheral Control Module
MCP within a receive data frame, the data valid bit is reset to zero for subsequent data frames until
a new A-to-D sample is triggered and transmitted to the MCP. In this mode, the user should
program ADM=0. In the other mode, the data valid bit is set once when the first A-to-D conversion
is made and is placed in the receive data frame. However, the data valid bit remains set and the
MCP cannot determine when new A-to-D conversions are available within the incoming frame.
Programming ADM=1 prevents multiple copies of the same A-to-D conversion to be placed in the
FIFO, storing samples only when the sample rate counter times out.
11.12.3.6 Telecom Transmit FIFO Interrupt Enable (TTE)
The telecom transmit FIFO interrupt enable (TTE) bit is used to mask or enable the telecom
transmit FIFO service request interrupt. When TTE=0, the interrupt is masked and the state of the
telecom transmit FIFO service request (TTS) bit within the MCP status register is ignored by the
interrupt controller. When TTE=1, the interrupt is enabled, and whenever TTS is set (one), an
interrupt request is made to the interrupt controller. Note that programming TTE=0 does not affect
the current state of TTS or the telecom transmit FIFO logic’s ability to set and clear TTS; it only
blocks the generation of the interrupt request. Also note that TTE does not affect generation of the
telecom transmit FIFO DMA request, which is asserted any time TTS=1.
11.12.3.7 Telecom Receive FIFO Interrupt Enable (TRE)
The telecom receive FIFO interrupt enable (TRE) bit is used to mask or enable the telecom receive
FIFO service request interrupt. When TRE=0, the interrupt is masked, and the state of the telecom
receive FIFO service request (TRS) bit within the MCP status register is ignored by the interrupt
controller. When TRE=1, the interrupt is enabled, and whenever TRS is set (one), an interrupt
request is made to the interrupt controller. Note that programming TRE=0 does not affect the
current state of TRS or the telecom receive FIFO logic’s ability to set and clear TRS; it only blocks
the generation of the interrupt request. Also note that TRE does not affect generation of the telecom
receive FIFO DMA request, which is asserted any time TRS=1.
11.12.3.8 Audio Transmit FIFO Interrupt Enable (ATE)
The audio transmit FIFO interrupt enable (ATE) bit is used to mask or enable the audio transmit
FIFO service request interrupt. When ATE=0, the interrupt is masked and the state of the audio
transmit FIFO service request (ATS) bit within the MCP status register is ignored by the interrupt
controller. When AT=1, the interrupt is enabled, and whenever ATS is set (one), an interrupt
request is made to the interrupt controller. Note that programming ATE=0 does not affect the
current state of ATS or the audio transmit FIFO logic’s ability to set and clear ATS; it only blocks
the generation of the interrupt request. Also note that ATE does not affect generation of the audio
transmit FIFO DMA request, which is asserted any time ATS=1.
11.12.3.9 Audio Receive FIFO Interrupt Enable (ARE)
The audio receive FIFO interrupt enable (ARE) bit is used to mask or enable the audio receive
FIFO service request interrupt. When ARE=0, the interrupt is masked, and the state of the audio
receive FIFO service request (ARS) bit within the MCP status register is ignored by the interrupt
controller. When ARE=1, the interrupt is enabled, and whenever ARS is set (one), an interrupt
request is made to the interrupt controller. Note that programming ARE=0 does not affect the
current state of ARS or the audio receive FIFO logic’s ability to set and clear ARS; it only blocks
the generation of the interrupt request. Also note that ARE does not affect generation of the audio
receive FIFO DMA request, which is asserted any time ARS=1.
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Peripheral Control Module
11.12.3.10 Loopback Mode (LBM)
The loopback mode (LBM) bit is used to enable and disable the ability of the MCP’s transmit and
receive logic to communicate. When LBM=0, the MCP operates normally. The transmit and
receive data paths are independent and communicate via their respective pins. When LBM=1, the
output of the serial shifter (MSB) is directly connected to the input of the serial shifter (LSB)
internally and control of the TXD4, RXD4, SCLK, and SFRM pins are given to the peripheral pin
control (PPC) unit.
11.12.3.11 External Clock Prescaler (ECP)
The 2-bit external clock select (ECP) field is used to divide the clock input via GPIO pin 21 when
the external clock function is enabled. When ECS=1, ECP is decoded to divide the clock input on
the GPIO<21> pin by 1, 2, 3, or 4 before being used to drive the MCP’s frame rate. When
ECP=00, the input clock is divided by 1; when ECP=01, it is divided by 2; when ECP=10, it is
divided by 3; and when ECP=11, it is divided by 4. Note that the ECP bit field is ignored when the
internal clock (ECS=0) is used to drive the MCP’s frame rate. Also note that the resultant clock
frequency after the divide has taken place can be any value within the allowable frequency range of
the UCB1100 or UCB1200 (up to 12 MHz).
The following table shows the bit locations corresponding to the 10 different control bit fields
within the MCP control register. Note that the MCE bit is the only control bit that is reset to a
known state to ensure the MCP is disabled following a reset of the SA-1100. The reset state of all
other control bits is unknown (indicated by question marks) and must be initialized before enabling
the MCP. The user can program all 11 bit fields and enable the MCP using a single word write to
MCCR0. Writes to reserved bits are ignored and reads return zeros.
Address: 0h 8006 0000
31 30
Reserved
MCP Control Register 0: MCCR
Read/Write
Bit
29
0
28
0
27
0
26
0
25
24
23
22
21
ATE
?
20
19
TTE
?
18
17
16
ECP
0
LBM
?
ARE
?
TRE
?
ADM
?
ECS
?
MCE
0
Reset
0
0
0
Bit
15
14
TSD
?
13
?
12
?
11
?
10
?
9
?
8
7
6
5
?
4
?
3
?
2
?
1
?
0
?
Res.
0
Res.
0
ASD
?
Reset
?
Bit
Name
Description
6..0
ASD
Audio sample rate divisor.
Value (from 6 to 127) used to match the sample rate of the audio codec within the UCB1100
or UCB1200 to time when audio D/A data should be supplied by the audio transmit FIFO.
Sample Rate = Programmed clock rate/(32xASD), where ASD is a decimal value.
7
—
Reserved.
14..8
TSD
Telecom sample rate divisor.
Value (from 16 to 127) used to match the sample rate of the telecom codec within the
UCB1100 or UCB1200 to time when telecom D/A data should be supplied by the telecom
transmit FIFO.
Sample Rate = Programmed clock rate/(32xTSD), where TSD is a decimal value.
Reserved.
15
—
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Peripheral Control Module
Bit
16
Name
Description
Multimedia communications port enable.
MCE
0 – MCP operation disabled, control of the TXD4, RXD4, SCLK, and SFRM pins given to the
PPC to be used as general-purpose I/O pins.
1 – MCP operation enabled.
Note that the MCP has precedence over the SSP, if MCE=1; SSE is ignored unless the SPR
bit is set within the PPC, which allows the SSP to use GPIO pins while the MCP uses serial
port 4’s pin for transmission.
17
ECS
External clock select.
0 – on-chip clock used to produce the frame rate as further programmed by the CFS control
bit in MCCR1. It is also used to clock the audio and telecom sample rate counters.
1 – Clock input using GPIO pin 21 to select a frame rate that is an exact multiple of the
desired audio/telecom sample rate.
Frame Rate = Input Clock Freq /(ECP x 32).
Sample Rate = Input Clock Freq /(ECP x 32 x ASD or TSD).
18
19
20
21
22
23
ADM
TTE
TRE
ATE
ARE
LBM
A/D data sampling mode.
0 – Audio and telecom receive data is stored to their respective FIFOs whenever their receive
data valid bits are valid.
1– Audio and telecom receive data is stored when the receive data valid bit is set the first time,
and from that point on whenever the MCP’s audio and telecom sample rate counters time out.
Telecom transmit FIFO interrupt enable.
0 – Telecom transmit FIFO half-full or less condition does not generate an interrupt (TTS bit
ignored).
1 – Telecom transmit FIFO half-full or less condition generates an interrupt (state of TTS
sent to interrupt controller).
Telecom receive FIFO interrupt enable.
0 – Telecom receive FIFO one- to two-thirds full or more condition does not generate an
interrupt (TRS bit ignored).
1 – Telecom receive FIFO one- to two-thirds full or more condition generates an interrupt
(state of TRS sent to interrupt controller).
Audio transmit FIFO interrupt enable.
0 – Audio transmit FIFO half-full or less condition does not generate an interrupt (ATS bit
ignored).
1 – Audio transmit FIFO half-full or less condition generates an interrupt (state of ATS sent to
interrupt controller).
Audio receive FIFO interrupt enable.
0 – Audio receive FIFO one- to two-thirds full or more condition does not generate an
interrupt (ARS bit ignored).
1 – Audio receive FIFO one- to two-thirds full or more condition generates an interrupt (state
of ARS sent to interrupt controller).
Loopback mode.
0 – Normal serial port operation enabled.
1 – Output of serial shifter is connected to input of serial shifter internally and control of
TXD4, RXD4, SCLK, and SFRM pins is given to the PPC unit.
25..24 ECP
External clock prescaler.
00 – Clock input using GPIO pin 21 is divided by one before being used to drive the frame rate.
00 – Clock input using GPIO pin 21 is divided by two before being used to drive the frame rate.
00 – Clock input using GPIO pin 21 is divided by three before being used to drive the frame rate.
00 – Clock input using GPIO pin 21 is divided by four before being used to drive the frame rate.
Note: ECP is used only when ECS=1. Also, the maximum clock frequency allowed to drive
the frame rate after ECS has divided down the input clock is 12 MHz.
31.. 26
—
Reserved.
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Peripheral Control Module
11.12.4 MCP Control Register 1
The MCP control register 1 (MCCR1) contains one bit that selects one of two fixed frequencies to
drive the MCP. Note that this register resides within the PPC’s address space.
11.12.4.1 Clock Frequency Select (CFS)
When the on-chip clock is enabled (ECS=0), the clock frequency select (CFS) bit is used to select
either a 9.585-MHz or an 11.981-MHz clock to drive the MCP’s serial clock rate. When ECS=0
and CFS=0, the on-chip 3.6864-MHz oscillator is first multiplied by 13 then divided by 4, resulting
in an 11.9808-MHz bit clock frequency. When ECS=0 and CFS=1, the on-chip 3.6864 MHz
oscillator is first multiplied by 13 then divided by 5, resulting in a 9.58464-MHz bit clock
frequency. Note that when ECS=1, CFS is ignored and an external clock is input to the MCP via
GPIO pin 21. Also note that CFS is cleared following a reset of the SA-1100 so that the MCP
defaults to 11.981-MHz operation, which is standard for the UCB1100/1200.
The following table shows the location of the CFS control bit within the MCP control register 1.
The CFS is cleared to zero selecting 11.981-MHz operation following a reset of the SA-1100.
Writes to reserved bits are ignored and reads return zeros. MCCR1 resides within the PPC’s
address space.
Address: 0h 9006 0030
MCP Control Register 1: MCCR1
Read/Write
Bit
Reset
Bit
31
30
29
0
28
0
27
0
26
Reserved
0
25
24
23
22
21
0
20
CFS
0
19
0
18
0
17
16
0
Reserved
0
0
0
0
0
0
0
1
0
15
0
14
0
13
0
12
0
11
0
10
0
9
8
7
6
5
4
0
3
2
0
Reserved
0
Reset
Bit
0
0
0
0
0
0
0
Name
Description
19..0
—
Reserved.
Clock frequency select.
20
CFS
0 – If ECS=0, bit rate clock frequency of 11.981 MHz is selected.
1 – If ECS=0, bit rate clock frequency of 9.585 MHz is selected.
If ECS=1, CFS is ignored and an external clock supplied by GPIO pin 21 is used.
31..21
—
Reserved.
11.12.5 MCP Data Registers
The MCP contains three data registers. MCDR0 addresses the top entry of the audio transmit FIFO
and bottom entry of the audio receive FIFO, MCDR1 addresses the top and bottom entries of the
telecom transmit and receive FIFOs respectively, and MCDR2 is used to perform reads and writes
to any of the codec’s 16 registers via the MCP’s serial interface.
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Peripheral Control Module
11.12.5.1 MCP Data Register 0
When MCP data register 0 (MCDR0) is read, the bottom entry of audio receive FIFO is accessed.
As data is removed by the MCP’s receive logic from the incoming data frame, it is placed into the
top entry of the audio receive FIFO and is transferred down an entry at a time until it reaches the
last empty location within the FIFO. Data is removed by reading MCDR, which accesses the
bottom entry of the audio FIFO. After MCDR0 is read, the bottom entry is invalidated and all
remaining values within the FIFO automatically transfer down one location.
When MCDR0 is written, the topmost entry of the audio transmit FIFO is accessed. After a write,
data is automatically transferred down to the lowest location within the transmit FIFO, which does
not already contain valid data. Data is removed from the bottom of the FIFO one value at a time by
the transmit logic, is loaded into the correct position within the 64-bit transmit serial shifter, and
then is serially shifted out onto the TXD4 pin during subframe 0.
Audio data is 12 bits wide and must be left justified by the user before writing it to the transmit FIFO
(MSB of audio data corresponds to bit 16 of transmit FIFO). The lower four bits of the FIFO are
automatically zero filled by the transmit logic when a 16-bit value is written to MCDR0 for
transmission. The UCB1100 or UCB1200 automatically forces bits 0 through 3 to zero before
transmitting the value to the MCP. The user must right justify received audio data before using it.
The following table shows MCDR0. Note that the transmit and receive audio FIFOs are cleared
when the SA-1100 is reset or by writing a zero to MCE (MCP disabled). Also note that writes to
reserved bits are ignored and reads return zeros.
Address: 0h 8006 0008
MCP Data Register 0: MCDR0
Read/Write
Bit
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Reserved
Reset
Bit
0
0
0
0
0
0
0
9
0
8
0
7
0
6
0
5
0
4
0
3
0
0
0
2
0
0
0
1
0
0
0
0
0
0
15
14
13
12
11
10
Bottom of Audio Receive FIFO
Reset
Bit
0
0
0
0
0
0
0
0
0
0
0
0
Read Access
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Reserved
Reset
Bit
0
0
0
0
0
0
0
9
0
8
0
7
0
6
0
5
0
4
0
3
0
0
0
2
0
0
0
1
0
0
0
0
0
0
15
14
13
12
11
10
Top of Audio Transmit FIFO
Reset
0
0
0
0
0
0
0
0
0
0
0
0
Write Access
Bit
Name
Description
3..0
—
Reserved for future enhancements.
Read – Data returned, but UCB1100 and UCB1200 currently zero fill these four bits.
Write – MCP’s transmit logic automatically zero fills these bits.
15..4
Audio
Data
Transmit/receive audio FIFO data.
Read – Bottom of audio receive FIFO data.
Write – Top of audio transmit FIFO data.
31..16
—
Reserved.
SA-1100 Developer’s Manual
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Peripheral Control Module
11.12.5.2 MCP Data Register 1
When MCP data register 1 (MCDR1) is read, the bottom entry of the telecom receive FIFO is
accessed. As data is removed by the MCP’s receive logic from the incoming data frame, it is placed
into the top entry of the telecom receive FIFO and is transferred down an entry at a time until it
reaches the last empty location within the FIFO. Data is removed by reading MCDR1, which
accesses the bottom entry of the telecom FIFO. After MCDR1 is read, the bottom entry is
invalidated, and all remaining values within the FIFO automatically transfer down one location.
When MCDR1 is written, the topmost entry of the telecom transmit FIFO is accessed. After a
write, data is automatically transferred down to the lowest location within the transmit FIFO,
which does not already contain valid data. Data is removed from the bottom of the FIFO one value
at a time by the transmit logic, is loaded into the correct position within the 64-bit transmit serial
shifter, and then is serially shifted out onto the TXD4 pin during subframe 0.
Telecom data is 14 bits wide and must be left justified by the user before writing it to the transmit
FIFO (MSB of telecom data corresponds to bit 16 of transmit FIFO). The lower two bits of the FIFO
are automatically zero filled by the transmit logic when a 16-bit value is written to MCDR1 for
transmission. The UCB1100 or UCB1200 automatically forces bits 0 and 1 to zero before
transmitting the value to the MCP. The user must right justify received telecom data before using it.
The following table shows MCDR1. Note that the transmit and receive telecom FIFOs are cleared
when the SA-1100 is reset, or by writing a zero to MCE (MCP disabled). Also note that writes to
reserved bits are ignored and reads return zeros.
Address: 0h 8006 000C
MCP Data Register 1: MCDR1
Read/Write
Bit
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Reserved
Reset
Bit
0
0
0
0
0
0
0
9
0
8
0
7
0
6
0
5
0
4
0
3
0
2
0
1
0
0
0
0
0
0
15
14
13
12
11
10
Bottom of Telecom Receive FIFO
Reset
Bit
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Read Access
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Reserved
Reset
Bit
0
0
0
0
0
0
0
9
0
8
0
7
0
6
0
5
0
4
0
3
0
2
0
1
0
0
0
0
0
0
15
14
13
12
11
10
Top of Telecom Transmit FIFO
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Write Access
Bit
Name
Description
1..0
—
Reserved for future enhancements.
Read – Data returned, but UCB1100 or UCB1200 currently zero fills these two bits.
Write – MCP’s transmit logic automatically zero fills these bits.
15..2
Telecom
Data
Transmit/receive telecom FIFO data.
Read – Bottom of telecom receive FIFO data.
Write – Top of telecom transmit FIFO data.
31..16
—
Reserved.
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Peripheral Control Module
11.12.5.3 MCP Data Register 2
MCDR2 contains 21 bits and is used to perform reads and writes to any of the UCB1100’s or
UCB1200’s registers. MCDR2 contains three separate fields: MCDR2<15:0> is the 16-bit register
data field, MCDR2<16> is a 1-bit read/write control bit, and MCDR2<20:17> is the 4-bit register
address field. A value written to MCDR2 is placed in the correct position within the 64-bit
subframe 0, is transmitted to the off-chip codec, and is used to perform a read or write operation to
the addressed codec register. Note that the contents of the addressed register are always returned in
the receive data frame and placed in the MCDR2 regardless of the state of the read/write bit. Thus
for write cycles, both a write and a read occurs, and for read cycles, only a read occurs. When
MCDR2 is read, the value returned from the last read or write operation, which was completed to
the codec, is returned.
A register write is performed by writing the correct value to each of the three fields within MCDR2
using one 16- or 32-bit write, ensuring that the read/write bit is set. Its contents are then transferred
to the correct fields within the serial shifter on the next rising edge of the SFRM signal, and then to
the codec via the TXD4 pin during subframe 0. The value within MCDR2<15:0> is written to the
selected codec register at the end of subframe 0 (during the 65th bit of the frame). The data written
to the control register and its address is returned to the MCP during the next data frame, and is
placed back within MCDR2 with the read/write bit reset to zero. For a write operation, since the
addressed register is written at the end of subframe 0, the data returned during the frame in which
the write occurred represents the previous contents of the register. The updated value is returned
during the next data frame.
A register read is performed by writing the address of the register to read while clearing the
read/write bit to zero within MCDR2. Again, the data is transferred to the serial shifter on the next
rising edge of the SFRM signal and is transmitted to the UCB1100 or UCB1200 during subframe 0.
Because the address and read/write control bit fields are placed near the beginning of the serial
stream output, the codec performs the read immediately after the read/write bit is received (during
the 41st bit of the frame), and the value contained within the addressed register is sent back to the
MCP in the same data frame, and is placed within MCDR2.
Once MCDR2 is written with a value to execute a read or write, the operation is performed every
MCP data frame until a new value is written to the register. Thus continual reads or writes are made
to the addressed codec register until a new read or write operation is configured.
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Peripheral Control Module
The following table shows the location of MCP data register 2. Note that the reset state of all
MCDR2 bits is unknown (indicated by question marks), writes to reserved bits are ignored, and
reads return zeros.
.
Address: 0h 8006 0010
MCP Data Register 2: MCDR2
Read/Write
Bit
Reset
Bit
31
30
29
28
0
27
0
26
Reserved
0
25
24
23
22
21
0
20
19
18
17
16
Reg Address R/W
0
?
0
0
0
0
0
0
0
?
4
?
?
2
?
?
1
?
15
?
14
?
13
?
12
11
10
9
8
7
6
5
3
0
?
Data Value Returned by a Codec Register Read or Write
Reset
?
?
?
?
?
?
?
?
?
?
Read Access
Bit
31
30
29
28
27
26
Reserved
0
25
24
23
22
21
20
19
18
17
16
R/
W
Reg Address R/W
Reset
Bit
0
15
?
0
14
?
0
13
?
0
0
0
9
0
8
0
7
0
6
0
5
?
?
?
2
?
?
1
?
?
0
?
12
11
10
4
3
Data Value to be Written to the Addressed Codec Register
Reset
?
?
?
?
?
?
?
?
?
?
Write Access
Bit
Name
Codec
Description
15..0
Codec register read/write data.
Register
Read/
Write
Read – If a codec write was last performed, contains data of previous register access;
next frame contains the data that was written. If a codec read was last performed,
contains data from the read register.
Data
Write – Used to specify what data to write to the addressed register, ignored for a codec
register read.
16
R/W
Read/write.
Read – Returns a zero.
Write – Used to control whether the addressed register is read or written (write = 1,
read = 0).
20..17
Codec
Register
Read/
Write
Address
Codec register read/write address.
Read – If a codec write was last performed, contains address of previous register
access; next frame contains the address of the write. If a codec read was last
performed, contains address of the register read.
Write – Used to address a register to perform a read or write.
Reserved.
31.. 21
—
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11.12.6 MCP Status Register
The MCP status register (MCSR) contains bits that signal FIFO overrun and underrun errors, and
FIFO service requests. Each of these conditions signal an interrupt request to the interrupt
controller. The status register also flags when transmit FIFOs are not full, when the receive FIFOs
are not empty, when a codec control register read or write is complete, and when the audio or
telecom portion of the codec is enabled (no interrupt generated).
A bit that can cause an interrupt signals the interrupt request as long as the bit is set. Once the bit is
cleared, the interrupt is cleared. Read/write bits are called status bits; read-only bits are called flags.
Status bits are referred to as “sticky” (once set by hardware, must be cleared by software). Writing
a one to a sticky status bit clears it; writing a zero has no effect. Read-only flags are set and cleared
by hardware; writes have no effect. Additionally, some bits that cause interrupts have
corresponding mask/enable bits in the control register and are indicated in the following section
headings. Note that the user has the ability to mask all MCP interrupts by clearing bit 18 within the
11.12.6.1 Audio Transmit FIFO Service Request Flag (ATS) (read-only,
maskable interrupt)
The audio transmit FIFO service request flag (ATS) is a read-only bit that is set when the audio
transmit FIFO is nearly empty and requires service to prevent an underrun. ATS is set any time the
audio transmit FIFO has four or fewer entries of valid data (half-full or less), and is cleared when it
has five or more entries of valid data. When the ATS bit is set, an interrupt request is made unless
the audio transmit FIFO interrupt request mask (ATE) bit is cleared. The state of ATS is also sent to
the DMA controller, and can be used to signal a DMA service request. Note that ATE has no effect
on the generation of the DMA service request. After the DMA or CPU fills the FIFO such that four
or more locations are filled within the audio transmit FIFO, the ATS flag (and the service request
and/or interrupt) is automatically cleared.
11.12.6.2 Audio Receive FIFO Service Request Flag (ARS) (read-only, maskable
interrupt)
The audio receive FIFO service request flag (ARS) is a read-only bit that is set when the audio
receive FIFO is nearly filled and requires service to prevent an overrun. ARS is set whenever the
audio receive FIFO has four or more entries of valid data (half-full or more), and is cleared when it
has three or fewer (less than half-full) entries of data. When the ARS bit is set, an interrupt request
is made unless the audio receive FIFO interrupt request mask (ARE) bit is cleared. The state of
ARS is also sent to the DMA controller, and can be used to signal a DMA service request. Note that
ARE has no effect on the generation of the DMA service request. After the DMA or CPU fills the
FIFO such that four or more locations are filled within the receive FIFO, the ARS flag (and the
service request and/or interrupt) is automatically cleared.
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Peripheral Control Module
11.12.6.3 Telecom Transmit FIFO Service Request Flag (TTS) (read-only,
maskable interrupt)
The telecom transmit FIFO service request flag (TTS) is a read-only bit that is set when the
telecom transmit FIFO is nearly empty and requires service to prevent an underrun. TTS is set
whenever the telecom transmit FIFO has four or fewer entries of valid data (half-full or less), and is
cleared when it has five or more entries of valid data. When the TTS bit is set, an interrupt request
is made unless the telecom transmit FIFO interrupt request mask (TTE) bit is cleared. The state of
TTS is also sent to the DMA controller, and can be used to signal a DMA service request. Note that
TTE has no effect on the generation of the DMA service request. After the DMA or CPU fills the
FIFO such that four or more locations are filled within the telecom transmit FIFO, the TTS flag
(and the service request and/or interrupt) is automatically cleared.
11.12.6.4 Telecom Receive FIFO Service Request Flag (TRS) (read-only,
maskable interrupt)
The telecom receive FIFO service request flag (TRS) is a read-only bit that is set when the telecom
receive FIFO is nearly filled and requires service to prevent an overrun. TRS is set whenever the
telecom receive FIFO has four or more entries of valid data (half-full or more), and is cleared when
it has three or fewer (less than half-full) entries of data. When the TRS bit is set, an interrupt
request is made unless the telecom receive FIFO interrupt request mask (TRE) bit is cleared. The
state of TRS is also sent to the DMA controller, and can be used to signal a DMA service request.
Note that TRE has no effect on the generation of the DMA service request. After the DMA or CPU
fills the FIFO such that four or more locations are filled within the receive FIFO, the TRS flag (and
the service request and/or interrupt) is automatically cleared.
11.12.6.5 Audio Transmit FIFO Underrun Status (ATU) (read/write,
nonmaskable interrupt)
The audio transmit FIFO underrun status bit (ATU) is set when the audio transmit logic attempts to
fetch data from the FIFO after it has been completely emptied. When an underrun occurs, the audio
transmit logic continuously transmits the last valid audio value, which was transmitted before the
underrun occurred. Once data is placed in the FIFO and it is transferred down to the bottom, the
audio transmit logic uses the new value within the FIFO for transmission. When the ATU bit is set,
an interrupt request is made.
11.12.6.6 Audio Receive FIFO Overrun Status (ARO) (read/write, nonmaskable
interrupt)
The audio receive FIFO overrun status bit (ARO) is set when the audio receive logic attempts to
place data into the audio receive FIFO after it has been completely filled. Each time a new piece of
data is received, the set signal to the ARO status bit is asserted, and the newly received data is
discarded. This process is repeated for each new piece of data received until at least one empty
FIFO entry exists. When the ARO bit is set, an interrupt request is made.
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11.12.6.7 Telecom Transmit FIFO Underrun Status (TTU) (read/write,
nonmaskable interrupt)
The telecom transmit FIFO underrun status bit (TTU) is set when the telecom transmit logic
attempts to fetch data from the FIFO after it has been completely emptied. When an underrun
occurs, the telecom transmit logic continuously transmits the last valid telecom value, which was
transmitted before the underrun occurred. Once data is placed in the FIFO and it is transferred
down to the bottom, the telecom transmit logic uses the new value within the FIFO for
transmission. When the TTU bit is set, an interrupt request is made.
11.12.6.8 Telecom Receive FIFO Overrun Status (TRO) (read/write,
nonmaskable interrupt)
The telecom receive FIFO overrun status bit (TRO) is set when the telecom receive logic places
data into the telecom receive FIFO after it has been completely filled. Each time a new piece of
data is received, the set signal to the TRO status bit is asserted, and the newly received data is
discarded. This process is repeated for each new piece of data received until at least one empty
FIFO entry exists. When the TRO bit is set, an interrupt request is made.
11.12.6.9 Audio Transmit FIFO Not Full Flag (ANF) (read-only, noninterruptible)
The audio transmit FIFO not full flag (ANF) is a read-only bit that is set whenever the audio
transmit FIFO contains one or more entries that do not contain valid data and is cleared when the
FIFO is completely full. This bit can be polled when using programmed I/O to fill the audio
transmit FIFO over its halfway mark. This bit does not request an interrupt.
11.12.6.10 Audio Receive FIFO Not Empty Flag (ANE) (read-only,
noninterruptible)
The audio receive FIFO not empty flag (ANE) is a read-only bit that is set whenever the audio
receive FIFO contains one or more entries of valid data and is cleared when it no longer contains
any valid data. This bit can be polled when using programmed I/O to remove remaining bytes of
data from the receive FIFO because DMA service and CPU interrupt requests are made only when
four or more bytes reside within the FIFO (3, 2, or 1 bytes may remain at the end of a frame). This
bit does not request an interrupt.
11.12.6.11 Telecom Transmit FIFO Not Full Flag (TNF) (read-only,
noninterruptible)
The telecom transmit FIFO not full flag (TNF) is a read-only bit that is set whenever the telecom
transmit FIFO contains one or more entries that do not contain valid data and is cleared when the
FIFO is completely full. This bit can be polled when using programmed I/O to fill the telecom
transmit FIFO over its halfway mark. This bit does not request an interrupt.
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Peripheral Control Module
11.12.6.12 Telecom Receive FIFO Not Empty Flag (TNE) (read-only,
noninterruptible)
The telecom receive FIFO not empty flag (TNE) is a read-only bit that is set whenever the telecom
receive FIFO contains one or more entries of valid data and is cleared when it no longer contains
any valid data. This bit can be polled when using programmed I/O to remove remaining bytes of
data from the receive FIFO because DMA service and CPU interrupt requests are made only when
four or more bytes reside within the FIFO (3, 2, or 1 bytes may remain at the end of a frame). This
bit does not request an interrupt.
11.12.6.13 Codec Write Completed Flag (CWC) (read-only, noninterruptible)
The codec write completed (CWC) flag is set after the following sequence occurs: a register write
command is issued to the codec by writing to MCDR2; the write command is sent to the codec via
subframe 0; the data value is latched within the addressed codec register at the beginning of
subframe 1 (the 65th bit of the frame); the address and value that was written is returned to the
MCP via the next subframe 0; and the returned values are latched in MCDR2. CWC is
automatically cleared when MCDR2 is read or written. This bit does not request an interrupt.
11.12.6.14 Codec Read Completed Flag (CRC) (read-only, noninterruptible)
The codec read completed (CRC) flag is set after the following sequence occurs: a register read
command is issued to the codec by writing to MCDR2; the read command is sent to the codec via
subframe 0; the data value contained within the addressed codec register is loaded into the codec’s
serial shift register during subframe 0 (the 41st bit of the frame); the address and value that was
read is returned to the MCP via the same subframe 0; and the returned values are latched in
MCDR2. CRC is automatically cleared when MCDR2 is read or written. This bit does not request
an interrupt.
11.12.6.15 Audio Codec Enabled Flag (ACE) (read-only, noninterruptible)
The audio codec enabled (ACE) flag indicates when the audio codec input and/or output is enabled,
which in turn, indicates that the audio sample rate counter is enabled. This flag is set after the
following sequence occurs: a register write command is issued to Audio Control Register B
(register 8), and either bit 14 or 15 is set (aud_in_ena or aud_out_ena) by writing to MCDR2; the
write command is sent to the codec via subframe 0; the data value is latched within codec register
8; and SFRM is asserted to indicate the start of the next frame. ACE is automatically cleared using
the same sequence with the exception that bits 14 and 15 are cleared, disabling both the input and
output paths of the audio codec. This bit does not request an interrupt.
11.12.6.16 Telecom Codec Enabled Flag (TCE) (read-only, noninterruptible)
The telecom codec enabled (TCE) flag indicates when the telecom codec input and/or output is
enabled, which in turn, indicates that the telecom sample rate counter is enabled. This flag is set
after the following sequence occurs: a register write command is issued to Telecom Control
Register B (register 6), and either bit 14 or 15 is set (tel_in_ena or tel_out_ena) by writing to
MCDR2; the write command is sent to the codec via subframe 0; the data value is latched within
codec register 6; and SFRM is asserted to indicate the start of the next frame. TCE is automatically
cleared using the same sequence with the exception that bits 14 and 15 are cleared, disabling both
the input and output paths of the telecom codec. This bit does not request an interrupt.
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The following table shows the bit locations corresponding to the status and flag bits within the
MCP status register. MCSR contains a collection of read/write, read-only, interruptible, and
noninterruptible bits (refer to the bit descriptions above). Writes to read-only bits have no effect.
The user must clear set status bits before enabling the MCP. Note that writes to reserved bits are
ignored and reads return zeros; question marks indicate that the values are unknown at reset.
Read/Write &
Address: 0h 8006 0018
MCP Status Register: MCSR
Read-Only
Bit
Reset
Bit
31
30
29
0
28
0
27
0
26
0
25
24
23
22
0
21
0
20
0
19
0
18
0
17
16
0
Reserved
0
0
0
0
0
0
15
TCE
0
14
ACE
0
13
CRC
0
12
CWC
0
11
TNE
0
10
TNF
1
9
ANE
0
8
ANF
1
7
TRO
?
6
TTU
?
5
ARO
?
4
ATU
?
3
TRS
0
2
TTS
0
1
ARS
0
0
ATS
0
Reset
Bit
Name
Description
Audio transmit FIFO service request flag (read-only).
0
ATS
ARS
TTS
TRS
0 – Audio transmit FIFO is more than half-full (five or more entries filled) or MCP
disabled.
1 – Audio transmit FIFO is half-full or less (four or fewer entries filled) and MCP
operation is enabled, DMA service request signalled, interrupt request signalled if not
masked (if ATE=1).
1
2
3
Audio receive FIFO service request (read-only).
0 – Audio receive FIFO is less than half-full (three or fewer entries filled) or MCP
disabled.
1 – Audio receive FIFO is half-full or more (four or more entries filled) and MCP
operation is enabled, DMA service request signalled, interrupt request signalled if not
masked (if ARE=1).
Telecom transmit FIFO service request flag (read-only).
0 – Telecom transmit FIFO is more than half-full (five or more entries filled) or MCP
disabled.
1 – Telecom transmit FIFO is half-full or less (four or fewer entries filled) and MCP
operation is enabled, DMA service request signalled, interrupt request signalled if not
masked (if TTE=1).
Telecom receive FIFO service request (read-only).
0 – Telecom receive FIFO is less than half full (three or fewer entries filled) or MCP
disabled.
1 – Telecom receive FIFO is half full or more (four or more entries filled) and MCP
operation is enabled, DMA service request signalled, interrupt request signalled if not
masked (if TRE=1).
4
5
ATU
Audio transmit FIFO underrun.
0 – Audio transmit FIFO has not experienced an underrun.
1 – Audio transmit logic attempted to fetch data from transmit FIFO while it was empty
request interrupt.
ARO
Audio receive FIFO overrun.
0 – Audio receive FIFO has not experienced an overrun.
1 – Audio receive logic attempted to place data into receive FIFO while it was full,
request
interrupt.
SA-1100 Developer’s Manual
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Peripheral Control Module
Bit
Name
Description
6
TTU
Telecom transmit FIFO underrun.
0 – Telecom transmit FIFO has not experienced an underrun.
1 – Telecom transmit logic attempted to fetch data from transmit FIFO while it was
empty, request interrupt.
7
TRO
Telecom receive FIFO overrun.
0 – Telecom receive FIFO has not experienced an overrun.
1 – Telecom receive logic attempted to place data into receive FIFO while it was full,
request interrupt.
8
ANF
ANE
TNF
TNE
CWC
CRC
Audio transmit FIFO not full (read-only).
0 – Audio transmit FIFO is full.
1– Audio transmit FIFO is not full.
9
Audio receive FIFO not empty (read-only).
0 – Audio receive FIFO is empty.
1 – Audio receive FIFO is not empty.
10
11
12
13
Telecom transmit FIFO not full (read-only).
0 – Telecom transmit FIFO is full.
1 – Telecom transmit FIFO is not full.
Telecom receive FIFO not empty (read-only).
0 – Telecom receive FIFO is empty.
1 – Telecom receive FIFO is not empty.
Codec write completed (read-only).
0 – A write to a codec register has not completed since the last time this bit was cleared.
1 – A write to a codec register has been transmitted and has updated the register.
Codec read completed (read-only).
0 – The value read from the addressed codec register has not been returned to
MCDR2.
1 – The value read from the addressed codec register is now in MCDR2.
Audio codec enabled (read-only).
14
15
ACE
TCE
—
0 – The audio codec input and output is disabled (bits 14 and 15 are 0 in Audio Control
Reg B).
1 – Audio codec input and/or output is enabled (bits 14 and/or 15 is 1 in Audio Control
Reg B).
Telecom codec enabled.
0 – The telecom codec input and output is disabled (bits 14 and 15 are 0 in Telecom
Cntl Reg B).
1 – Telecom codec input and/or output is enabled (bits 14 and/or 15 is 1 in Telecom Cntl
Reg B).
31..16
Reserved.
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Peripheral Control Module
11.12.7 SSP Operation
Following reset, both the MCP and SSP logic within serial port 4 is disabled and control of its pins is
given to the PPC that configures all four pins as inputs. To enable SSP operation, the programmer
should first clear any interruptible status bits, which are set following the reset by writing a one to
them. Next, the user should program the SSP’s control registers with the desired mode of operation,
ensuring that the register containing the SSP enable bit is programmed last. Note that the MCP has
precedence over the SSP and must be disabled first before enabling the SSP. The user can choose to
either “prime” the transmit FIFO by writing up to eight 16-bit values, or allow the transmit FIFO
service request to interrupt the CPU or trigger a DMA transfer to fill the FIFO. Once enabled,
transmission/reception of data begins on the transmit (TXD4) and receive (RXD4) pins, and is
synchronously controlled by the serial clock (SCLK) and serial frame (SFRM) pins.
11.12.7.1 Frame Format
Each data frame is between 4 and 16 bits long depending on the size of data programmed, and is
transmitted starting with the MSB. There are three basic frame types that can be selected: Motorola*
SPI, Texas Instruments* synchronous serial, and National Microwire*. For all three formats, the
serial clock (SCLK) is held low or inactive, while the SSP is idle and transitions at the programmed
frequency only during active transmission of data. For Motorola* SPI and National Microwire*
frame formats, the serial frame (SFRM) pin is active low, and is asserted (pulled down) during the
entire frame’s transmission. In these modes, the SFRM pin is used to select the off-chip slave serial
device, enabling it for transmission. For Texas Instruments* format, the SFRM pin is pulsed for one
serial clock period starting at its rising edge, prior to each frame’s transmission. The type of serial
clock edges used to drive and sample data are different for all three modes. For National Microwire*
format, both the SSP and the off-chip slave device drive their output data on the falling edge of
SCLK, and latch data from the other device on the rising edge. For Texas Instruments* format, both
the SSP and the off-chip slave device drive their output data on the rising edge of SCLK, and latch
data from the other device on the falling edge. For Motorola* SPI format, the user has the option of
which edge of SCLK to drive and sample data, as well as the phase of the SCLK signal (whether it is
shifted one-half period to the left or right during the frame transmission).
Unlike the full-duplex transmission of the other two frame formats, the National Microwire*
format uses a special master-slave messaging technique that operates at half-duplex. In this mode,
when a frame begins, an 8-bit control message is transmitted to the off-chip slave. During this
transmit, no incoming data is received by the SSP. After the message has been sent, the off-chip
slave decodes it and responds with the requested data after waiting one serial clock after the last bit
of the 8-bit control message has been sent. The returned data can be 4 to 16 bits in length, making
the total frame length anywhere from 13 to 25 bits.
SA-1100 Developer’s Manual
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Peripheral Control Module
Figure 11-35 shows the Texas Instruments* synchronous serial frame format for a single
transmitted frame and when back-to-back frames are transmitted. In this mode, SCLK and SFRM
are forced low, and the transmit data line SA-1100. Once the bottom entry of the transmit FIFO
contains data, SFRM is pulsed high for one SCLK period and the value to be transmitted is
transferred from the transmit FIFO to the transmit logic’s serial shift register. On the next rising
edge of SCLK, the MSB of the 4- to 16-bit data frame is shifted to the TXD4 pin. Likewise, the
MSB of the received data is shifted onto the RXD4 pin by the off-chip serial slave device. Both the
SSP and the off-chip serial slave device then latch each data bit into their serial shifter on the
falling edge of each SCLK. The received data is transferred from the serial shifter to the receive
FIFO on the first rising edge of SCLK after the LSB has been latched. Note that the transmit pin
retains the last value it transmits (the value of bit <0>, when the frame completes and the SSP
enters idle mode). If the SSP is disabled or a reset occurs, the transmit pin is reset to zero.
Figure 11-35. Texas Instruments* Synchronous Serial Frame Format
.
SCLK
...
SFRM
...
TXD4
RXD4
Bit<N>
Bit<N..1>
Bit<N..1>
...
Bit<1>
Bit<1>
Bit<0>
Bit<N>
MSB
...
Bit<0>
LSB
4 to 16 Bits
Single Transfer
SCLK
SFRM
TX/RX
...
...
...
...
...
Bit<0>
Bit<N>
Bit<N..1>
...
Bit<1>
Bit<0>
Bit<N>
Bit<N..1>
Bit<1>
Bit<0>
Continuous Transfers
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Peripheral Control Module
Figure 11-36 shows one of the four possible configurations for the Motorola* SPI frame format for
a single transmitted frame and when back-to-back frames are transmitted. In this mode, SCLK and
the transmit data line (TXD4) are forced low and SFRM is forced high, whenever the SSP is
disabled or the SA-1100 is reset. Once the bottom entry of the transmit FIFO contains data, SFRM
is pulled low and remains low for the duration of the frame’s transmission. The falling edge of
SFRM causes the value for transmission to be transferred from the bottom transmit FIFO entry to
the transmit logic’s serial shift register, and the MSB of the 4- to 16-bit data frame is shifted onto
the TXD4 pin a half an SCLK period later (note that the SCLK pin does not transition at this point).
The MSB of the received data is shifted onto the RXD4 pin by the off-chip serial slave device as
soon as the serial framing signal goes low. Both the SSP and the off-chip serial slave device then
latch each data bit into their serial shifter on the rising edge of each SCLK. At the end of the frame,
the SFRM pin is pulled high one SCLK period after the last bit has been latched in the receive
serial shifter, which causes the data to be transferred to the receive FIFO. Note that the off-chip
slave device can tristate the receive line either on the falling edge of SCLK after the LSB has been
latched by the receive shifter or when the SFRM pin goes high. Also note that the transmit pin
retains the last value it transmits (the value of bit <0>, when the frame completes and the SSP
enters idle mode). If the SSP is disabled or a reset occurs, the transmit pin is reset to zero. All four
frame programming options are described in the SSP Control Register 1 section.
For continuous transfers, data transmission begins and ends in the same manner as a single transfer;
however, the SFRM line is continuously asserted (held low) and transmission of data occurs
back-to-back (the MSB of the next frame follows directly after the LSB of the previous frame). In
this example, each of the received data values is transferred from the receive shifter to the receive
FIFO on the falling edge SCLK after the LSB of the frame has been latched into the SSP.
Figure 11-36. Motorola* SPI Frame Format
SCLK
...
SFRM
...
TXD4
RXD4
Bit<N>
Bit<N..1>
Bit<N..1>
...
Bit<1>
Bit<1>
Bit<0>
Bit<N>
...
Bit<0>
LSB
MSB
4 to 16 Bits
Single Transfer
SCLK
SFRM
TX/RX
...
...
...
...
...
Bit<0>
Bit<N>
Bit<N..1>
...
Bit<1>
Bit<0>
Bit<N>
Bit<N..1>
Bit<1>
Bit<0>
Continuous Transfers
Note: The phase and polarity of SCLK can be configured for four different modes. This example shows just one of those modes.
See the Section 11.12.10, “SSP Control Register 1” on page 11-177 for a complete description of each mode.
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Peripheral Control Module
back-to-back frames are transmitted. Microwire format is very similar to SPI format, except that
transmission is half- instead of full-duplex, using a master-slave message passing technique. Each
serial transmission begins with an 8-bit control word that is transmitted from the SSP to the
off-chip slave device. During this transmit, no incoming data is received by the SSP. After the
message has been sent, the off-chip slave decodes it and responds with the requested data after
waiting one serial clock after the last bit of the 8-bit control message has been sent. The returned
data is 4 to 16 bits in length, making the total frame length anywhere from 13 to 25 bits.
SCLK and the transmit data line (TXD4) is forced low, and SFRM is forced high whenever the SSP
is disabled or following a reset of the SA-1100. Once enabled, transmission is triggered by writing
a control byte to the transmit FIFO. The falling edge of SFRM causes the value contained within
the bottom entry of the transmit FIFO to be transferred to the transmit logic’s serial shift register
and the MSB of the 8-bit control frame to be shifted onto the TXD4 pin. SFRM remains low for the
duration of the frame’s transmission. The RXD4 pin remains tristated during this transmission. The
off-chip serial slave device latches each control bit into its serial shifter on the rising edge of each
SCLK. After the last bit is latched by the slave device, the control byte is decoded during a
one-clock waitstate, and the slave responds by transmitting data back to the SSP, driving each bit
onto the RXD4 line on the falling edge of SCLK. The SSP, in turn, latches each bit on the rising
edge of SCLK. At the end of the frame, for single transfers, the SFRM signal is pulled high one
SCLK period after the last bit has been latched in the receive serial shifter, which causes the data to
be transferred to the receive FIFO. Note that the off-chip slave device can tristate the receive line
either on the falling edge of SCLK after the LSB has been latched by the receive shifter or when
the SFRM pin goes high. Also note that the transmit pin retains the last value it transmits (the value
of bit <0>, when the frame completes and the SSP enters idle mode). If the SSP is disabled or a rest
occurs, the transmit pin is reset to zero.
For continuous transfers, data transmission begins and ends in the same manner as a single transfer;
however, the SFRM line is continuously asserted (held low) and transmission of data occurs
back-to-back (the control byte of the next frame follows directly after the LSB of the received data
from the previous frame). Each of the received data values is transferred from the receive shifter on
the falling edge SCLK after the LSB of the frame has been latched into the SSP.
Figure 11-37. National Microwire* Frame Format
SCLK
SFRM
...
...
...
...
...
TXD4
RXD4
Bit<7>
...
8-Bit Control
...
Bit<0>
1 Clk
Bit<N>
...
Bit<0>
4 to 16 Bits
Single Transfer
SCLK
SFRM
...
...
...
...
...
...
...
...
...
TXD4
RXD4
Bit<0>
Bit<7>
Bit<0>
1 Clk
1 Clk
Bit<N>
...
Bit<0>
Continuous Transfers
...
Bit<N>
...
Bi
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Peripheral Control Module
11.12.7.2 Baud Rate Generation
The baud or bit rate is derived by dividing down the 3.6864-MHz clock generated by the on-chip
PLL. The clock is first divided by a fixed value of 2 and then by a programmable number between
1 and 256. This programmability provides a range of transmission rates ranging from 7.2 Kbps to
1.8432 Mbps. The resultant clock is used to drive the SCLK pin and by the transmit and receive
logic’s serial shifters to drive and latch data, respectively.
11.12.7.3
SSP Transmit and Receive FIFOs
To reduce chip size as well as power consumption, the SSP’s FIFOs use self-timed logic (they are
not clocked). Because of process and environmental variations, the depth at which a service request
is triggered to empty the receive FIFO is variable. This variation spans a maximum of four FIFO
entries, thus the receive FIFO service request can be made at four different FIFO depths. To
compensate for this variability and guarantee that at least four valid entries of data exist within the
FIFO before generating a service request, an extra four entries have been added to the receive FIFO
(four entries more than the transmit FIFO). Thus the transmit FIFO is 8 entries deep and the receive
FIFO is 12 entries deep. The point at which the receive FIFO service request is triggered spans
one-third (four entries) of the 12-entry FIFO. The service request is signalled at a depth from
one-third full to two-thirds full (when the FIFO contains five, six, seven, or eight entries of data).
This service request variation only applies to an empty FIFO that is filled (receive FIFO). It does
not apply to a full FIFO that is emptied (transmit FIFO). Thus the transmit FIFO is guaranteed to
signal a service request when it has four or more empty entries and negate the request when the
FIFO contains five or more entries that are filled.
If the DMA is used to service either one or both of the SSP’s FIFOs, the burst size must be set to
four half-words, even though more than four entries of data may exist within the receive FIFO. If
programmed I/O is used to service the FIFOs, a maximum of four words may be added to the
transmit FIFO without checking if more space is available. Likewise, a maximum of four words
may be removed from the receive FIFO without checking if more data is available. After this point,
the user must poll a set of status bits, which indicates if any data remains in the receive FIFO or if
space is available in the transmit FIFO, before emptying or filling the FIFOs any further.
The width of each entry within the FIFOs is 16 bits. However, the SSP supports data sizes of 4
through 16 bits. Any data that is less than 16-bits wide must be left-justified when writing or
DMAing data to the transmit FIFO. Likewise, data received by the SSP is left-justified when it is
and receive FIFOs. The user must left-justify data to be transmitted, and shift received data to the
right before using the results.
Figure 11-38. Transmit/Receive FIFO Data Format
Bit
15
14
13
12
11
0
10
0
9
0
8
0
7
0
6
0
5
0
4
0
3
0
2
0
1
0
0
0
4-Bit Data
5-Bit Data
0
0
0
0
0
0
0
0
0
0
0
0
..
15-Bit Data
16-bit Data
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11.12.7.4 CPU and DMA Register Access Sizes
Bit positioning, byte ordering, and addressing of the SSP are described in terms of little endian
ordering. All SSP registers are 16-bits wide and are located in the least significant half-word of
individual words. The ARM peripheral bus does not support byte or half-word operations. All
reads and writes of the SSP by the CPU should be word wide. Two separate dedicated DMA
requests exist for both the transmit and the receive FIFO. If the DMA controller is used to service
the transmit and/or receive FIFOs, the user must ensure the DMA is properly configured to perform
half-word wide accesses, using four half-words per burst (half the size of the FIFOs). Byte-wide
DMA accesses for data widths of 4..8 bits are not permitted. For all data sizes 4..16 bits, the user
must left-justify the data within each individual half-word in external memory for the DMA,
starting with the most significant bit. Likewise, when using programmed I/O to service the SSP’s
transmit FIFO, the user must also left-justify the data written or read to/from the data register. Note
that a separate set of registers also exist to configure MCP operation. See the following sections for
a full description of programming and operation of serial port 4 as an MCP, a summary of serial
port 4’s MCP registers, and for a summary of its SSP registers.
11.12.7.5 Alternate SSP Pin Assignment
If the SSP and MCP both need to be used at the same time, general-purpose I/O pins 10 through 13
(GPIO<10-13>) can be reassigned by programming the PPC pin assignment register (PPAR). This
allows the MCP dedicated use of the four pins assigned to serial port 4, and the SSP dedicated use of
the GPIO pins. When the SSP pin reassignment (SPR) bit is set in PPAR, the following pin
assignments are made: GPIO<10> is used for transmit, GPIO<11> for receive, GPIO<12> for serial
clock, and GPIO<13> for serial frame. Note that the user must also set bits 10 through 13 in the GPIO
alternate function register (GAFR) as well as set bits 10, 12, and 13 and clear bit 11 in the GPIO pin
direction register (GPDR). Once the reassignment is made, these pins are no longer usable by the
system control module and the Section 11.13, “Peripheral Pin Controller (PPC)” on page 11-184
for a description of how to program the PPC unit.
11.12.8 SSP Register Definitions
There are four registers within the SSP: two control registers, one data register, and one status
register. The control registers are used to program the baud rate, data length, and frame format, and
to select whether the CPU or DMA is used to service the SSP, and to enable/disable operation. The
data register is 16 bits and addresses both the transmit and receive buffers. A read accesses the
receive buffer; a write accesses the transmit buffer. Note that these are two physically separate
buffers to allow full-duplex transmission. The status register contains bits that signal an overrun
error, a transmit buffer service request, and a receive buffer service request. Each of these status
conditions signal an interrupt request to the interrupt controller. The status register also flags when
the SSP is actively transmitting data, when the transmit FIFO is not full, and when the receive
FIFO is not empty (no interrupt generated).
11.12.9 SSP Control Register 0
The SSP control register 0 (SSCR0) contains four different bit fields that control various functions
within the SSP.
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11.12.9.1 Data Size Select (DSS)
The 4-bit data size select (DSS) field is used to select the size of the data transmitted and received by
the SSP. Data can be 4 to 16 bits in length. When data is programmed to be less than 16 bits, received
data is automatically right justified and the upper bits in the receive FIFO are zero filled by the
receive logic. Transmit data must be right justified by the user before being placed into the transmit
FIFO; however, the upper unused bits are ignored by the SSP’s transmit logic. Although it is possible
to program data sizes of 1, 2, and 3 bits, these sizes are reserved and produce unpredictable results in
the SSP. When National Microwire* frame format is selected, this bit field selects the size of the
received data. Note that the size of the transmitted data is always 8 bits in this mode.
11.12.9.2 Frame Format (FRF)
The 2-bit frame format (FRF) bit field is used to select which frame format to use: Motorola* SPI
(FRF=00), Texas Instruments* synchronous serial (FRF=01), or National Microwire* (FRF=10).
See the preceding sections for a complete description of each frame format. Note that FRF=11 is
reserved and produces unpredictable results.
11.12.9.3 Synchronous Serial Port Enable (SSE)
The SSP enable (SSE) bit is used to enable and disable all SSP operation. When SSE=0, the SSP is
disabled; when SSE=1, it is enabled. Since the MCP and SSP both share the same pins, only one
can be enabled at a time. If the user enables both at the same time, the MCP has precedence and the
SSP remains disabled. However, both can be enabled when the SSP pin reassignment (SPR) bit
within the PPC unit is set, which assigns the SSP to GPIO pins.
When the SSP is disabled, all of its clocks are powered down to minimize power consumption. If
the MCP is also disabled, the TXD4, RXD4, SCLK, and SFRM pins can be used for
general-purpose input/output. See the Section 11.13, “Peripheral Pin Controller (PPC)” on
serial port 4’s pins as I/Os. Note that SSE is the only control bit within the SSP that is reset to a
known state. It is cleared to zero to ensure the SSP is disabled following a reset of the SA-1100.
When the SSE bit is cleared during active operation, the SSP is disabled immediately, causing the
current frame, which is being transmitted, to be terminated and control of serial port 4’s pins to be
given to the PPC unit. Clearing SSE resets the SSP’s FIFOs. However the SSP’s control and status
registers are not reset. The user must ensure these registers are properly reconfigured before
reenabling the SSP.
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Peripheral Control Module
11.12.9.4 Serial Clock Rate (SCR)
The 8-bit serial clock rate (SCR) bit field is used to select the baud or bit rate of the SSP. A total of
256 different bit rates can be selected, ranging from a minimum of 7.2 Kbps to a maximum of
1.8432 Mbps. The serial clock generator uses the 3.6864-MHz clock produced by the on-chip PLL,
divided by a fixed value of 2, and then the programmable SCR value to generate the serial clock
(SCLK). The resultant clock rate is driven out on the SCLK pin and is also used by the SSP’s transmit
logic to drive data out on the TXD4 pin, and latch data on the RXD4 pin. Depending on the frame
format selected, each transmitted bit is either driven on the rising or falling edge of SCLK, and is
sampled on the opposite clock edge. The resultant serial clock rate, given a specific SCR value or
required SCR value given a desired bit rate, can be calculated using the following two respective
equations, where SCR is the decimal equivalent of the binary value programmed within the bit field:
6
6
3.6864×10
3.6864×10
SCR = ------------------------------ – 1
BitRate = -----------------------------------
2BitRate
The following table shows the bit locations corresponding to the five different control bit fields
within SSP control register 0. Note that the SSE bit is the only control bit that is reset to a known
state to ensure the SSP is disabled following a reset of the SA-1100. The reset state of all other
control bits is unknown (indicated by question marks) and must be initialized before enabling the
SSP. Reads of bit 6, which is reserved, return zero; writes have no effect.
Address: 0h 8007 0060
SSP Control Register 0: SSCR0
Read/Write
Bit
15
14
13
12
?
11
?
10
9
8
7
6
5
?
4
?
3
?
2
?
1
DSS
?
0
?
SCR
SSE Res.
FRF
Reset
?
?
?
?
?
?
0
0
Bit
Name
DSS
Description
3..0
Data size select.
0000 – Reserved, undefined operation.
0001 – Reserved, undefined operation.
0010 – Reserved, undefined operation.
0011 – 4-bit data.
0100 – 5-bit data.
0101 – 6-bit data.
0110 – 7-bit data.
0111 – 8-bit data.
1000 – 9-bit data.
1001 – 10-bit data.
1010 – 11-bit data.
1011 – 12-bit data.
1100 – 13-bit data.
1101 – 14-bit data.
1110 – 15-bit data.
1111 – 16-bit data.
5..4
FRF
Frame Format.
00 – Motorola SPI frame format.
01 – Texas Instruments Synchronous serial frame format.
10 – National Microwire frame format.
11 – Reserved, undefined operation.
Reserved.
6
7
—
SSE
Synchronous serial port enable.
0 – SSP operation disabled, control of pins given to PPC if MCP is also disabled.
1 – SSP operation enabled if MCP disabled or if the PPC SSP pin reassignment bit is set
(reassigns GPIO<13..10> to the SSP).
15..8
SCR
Serial clock rate.
Value (from 0 to 255) used to generate the transmission rate of the SSP.
6
Bit Rate = 3.6864x10 /(2x(SCR+1)), where SCR is a decimal value.
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Peripheral Control Module
11.12.10 SSP Control Register 1
The SSP control register 1 (SSCR1) contains six different bit fields that control various functions
within the SSP.
11.12.10.1 Receive FIFO Interrupt Enable (RIE)
The receive FIFO interrupt enable (RIE) bit is used to mask or enable the receive FIFO service
request interrupt. When RIE=0, the interrupt is masked and the state of the receive FIFO service
request (RFS) bit within the SSP status register is ignored by the interrupt controller. When RIE=1,
the interrupt is enabled, and whenever RFS is set (one), an interrupt request is made to the interrupt
controller. Note that programming RIE=0 does not affect the current state of RFS or the receive
FIFO logic’s ability to set and clear RFS, it only blocks the generation of the interrupt request. Also
note that RIE does not affect generation of the receive FIFO DMA request, which is asserted
whenever RFS=1.
11.12.10.2 Transmit FIFO Interrupt Enable (TIE)
The transmit FIFO interrupt enable (TIE) bit is used to mask or enable the transmit FIFO service
request interrupt. When TIE=0, the interrupt is masked and the state of the transmit FIFO service
request (TFS) bit within the SSP status register is ignored by the interrupt controller. When TIE=1,
the interrupt is enabled, and whenever TFS is set (one), an interrupt request is made to the interrupt
controller. Note that programming TIE=0 does not affect the current state of TFS or the transmit
FIFO logic’s ability to set and clear TFS; it only blocks the generation of the interrupt request. Also
note that TIE does not affect generation of the transmit FIFO DMA request, which is asserted
whenever TFS=1.
11.12.10.3 Loopback Mode (LBM)
The loopback mode (LBM) bit is used to enable and disable the ability of the SSP transmit and
receive logic to communicate. When LBM=0, the SSP operates normally. The transmit and receive
data paths are independent and communicate via their respective pins. When LBM=1, the output of
the transmit serial shifter is directly connected to the input of the receive serial shifter internally
and control of the TXD4, RXD4, SCLK, and SFRM pins are given to the peripheral pin control
(PPC) unit.
11.12.10.4 Serial Clock Polarity (SPO)
The serial clock polarity (SPO) bit selects the polarity or active/inactive state of the serial clock
(SCLK) pin when Motorola* SPI format is selected (FRF=00). When SPO=0, the inactive or idle
state of SCLK is low. Thus when the SSP is not actively transmitting/receiving data, the SCLK pin
is held low. When SPO=1, the inactive or idle state of SCLK is high. Thus when the SSP is not
actively transmitting/receiving data, the SCLK pin is held high. The programming of SPO alone
does not determine which SCLK edges are used to drive and latch data to or from the transmit and
receive pins. The programming of SPO and the serial clock phase (SPH) bit determines this. Note
that SPO is ignored in all other modes except Motorola* SPI format (FRF=00).
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Peripheral Control Module
11.12.10.5 Serial Clock Phase (SPH)
The serial clock phase (SPH) bit selects the phase relationship of the serial clock (SCLK) signal
with the serial frame (SFRM) signal when Motorola* SPI format is selected (FRF=00). When
SPH=0, SCLK remains in its inactive state (as programmed by SPO) for one full SCLK period
duration after SFRM is asserted (driven low). SCLK continues to transition during the entire frame
and is driven to its inactive state one-half SCLK period duration before SFRM is negated (driven
high). When SPH=1, SCLK remains in its inactive state (as programmed by SPO) for one-half
SCLK period duration after SFRM is asserted (driven low). SCLK continues to transition during
the entire frame and is driven to its inactive state one full SCLK period duration before SFRM is
negated (driven high). Using SPH and SPO together determine when SCLK is active during the
assertion of SFRM and which edge of SCLK is used to drive data to the transmit pin as well as
latch data from the receive pin. When SPO and SPH are the same value (both 0 or both 1), transmit
data is driven on the falling edge of SCLK and receive data is latched on the rising edge of SCLK.
Alternatively, when SPO and SPH are of opposite value (one 0 and the other 1), transmit data is
driven on the rising edge of SCLK and receive data is latched on the falling edge of SCLK. Note
that SPH is ignored in all other modes, except Motorola* SPI format (FRF=00).
Figure 11-39 shows the pin timing for all four programming combinations of SPO and SPH. Note
that SPO inverts the polarity of the SCLK signal, and SPH determines the phase relationship
between SCLK and SFRM, shifting the SCLK signal one-half phase to the left or right during the
assertion of SFRM.
Figure 11-39. Motorola* SPI Frame Formats for SPO and SPH Programming
SCLK SPO=0
SCLK SPO=1
SFRM
...
...
...
Bit<N..> ...
TXD4
RXD4
Bit<N>
Bit<1>
Bit<1>
Bit<0>
Bit<N>
Bit<N..>
...
Bit<0>
LSB
MSB
4 to 16 Bits
SPH = 0
SCLK SPO=0
SCLK SPO=1
SFRM
...
...
...
Bit<N>
Bit<N..>
Bit<1>
Bit<0>
TXD4
RXD4
...
...
Bit<N>
MSB
Bit<N..>
Bit<1>
Bit<0>
LSB
4 to 16 Bits
SPH = 1
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Peripheral Control Module
11.12.10.6 External Clock Select (ECS)
The external clock select (ECS) bit selects whether the on-chip 3.6864-MHz clock is used by the
SSP or if an off-chip clock is supplied via GPIO pin 19. When ECS=0, the SSP uses the on-chip
3.6864-MHz clock to produce a range of serial transmission rates ranging from 7.2 Kbps to a
maximum of 1.8432 Mbps. When ECS=1, the SSP uses GPIO<19> to input a clock supplied from
off-chip. The frequency of the off-chip clock can be any value up to 3.6864 MHz. This off-chip
clock is useful when a serial transmission rate, which is not an even multiple of 3.6864 MHz, is
required for synchronization with the target off-chip slave device. When using GPIO pin 19 for the
input clock, the user must also set bit 19 of the GPIO alternate function register (GAFR), and clear
bit 19 of the GPIO pin direction register (GPDR). See the System Control Module chapter.
The following table shows the bit locations corresponding to the three different control bit fields
within SSP control register 1. The reset state of all bits is unknown (indicated by question marks)
and must be initialized before enabling the SSP. Note that writes to reserved bits are ignored and
reads return zero.
Address: 0h 8007 0064
SSP Control Register 1: SSCR1
Read/Write
Bit
15
0
14
0
13
0
12
0
11
10
9
0
8
0
7
0
6
0
5
4
3
2
1
0
RIE
?
SP
O
Reserved
ECS SPH
LBM TIE
Reset
0
0
?
?
?
?
?
Bit
Name
Description
0
RIE
Receive FIFO interrupt enable.
0 – Receive FIFO one- to two-thirds full or more condition does not generate an interrupt
(RFS bit ignored).
1 – Receive FIFO one- to two-thirds full or more condition generates an interrupt (state
of RFS sent to interrupt controller).
1
2
TIE
Transmit FIFO interrupt enable.
0 – Transmit FIFO half-full or less condition does not generate an interrupt (TFS bit
ignored).
1 – Transmit FIFO half-full or less condition generates an interrupt (state of TFS sent to
interrupt controller).
LBM
Loopback mode.
0 – Normal serial port operation enabled.
1 – Output of transmit serial shifter is connected to input of receive serial shifter
internally and control of TXD4, RXD4, SCLK, and SFRM pins is given to the PPC unit.
3
4
SPO
SP
Serial clock polarity.
0 – The inactive or idle state of SCLK is low.
1 – The inactive or idle state of SCLK is high.
Serial clock phase.
0 – SCLK is in its inactive state one full cycle at the start of the frame and one-half cycle
at the end of the frame.
1 – SCLK is in its inactive state one-half cycle at the start of the frame and one full cycle
at the end of the frame.
5
ECS
External clock select.
0 – on-chip clock used to product the SSP’s serial clock and control all timing.
1 – Clock input using GPIO pin 19 to drive the serial clock and all timing when serial
rates that are not a multiple of 3.6864 MHz are needed.
Note that bit 19 within GFAR and GPDR must be correctly configured within the system
control module.
15..6
—
Reserved.
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Peripheral Control Module
11.12.11 SSP Data Register
The SSP data register (SSDR) is 16 bits wide and corresponds to the top and bottom entries of the
transmit and receive FIFOs, respectively. When SSDR is read, the bottom entry of receive FIFO is
accessed. As data is removed by the SSP’s receive logic from the incoming data frame, it is placed
into the top entry of the receive FIFO and is transferred down an entry at a time until it reaches the
last empty location within the FIFO. Data is removed by reading SSDR, which accesses the bottom
entry of the FIFO. After SSDR is read, the bottom entry is invalidated, and all remaining values
within the FIFO automatically transfer down one location.
When SSDR is written, the topmost entry of the transmit FIFO is accessed. After a write, data is
automatically transferred down to the lowest location within the transmit FIFO, which does not
already contain valid data. Data is removed from the bottom of the FIFO one value at a time by the
transmit logic, is loaded into the transmit serial shifter, and then is serially shifted onto the TXD4
pin at the programmed bit rate.
When a data size of less than 16 bits is selected, the user should left justify data written to the
transmit FIFO. The transmit logic ignores the upper unused bits. Received data less than 16 bits is
automatically right justified in the receive buffer and unused bits are zero filled. When the SSP is
programmed for National Microwire* frame format, the default size for transmit data is 8 bits (the
most significant byte is ignored) and the receive data size is controlled by the programmer.
The following table shows the location of the SSP data register. Note that both FIFOs are cleared
when the SA-1100 is reset or by writing a zero to SSE (SSP disabled).
Address: 0h 8007 006C
SSP Data Register: SSDR
Read/Write
Bit
15
14
13
12
0
11
0
10
9
8
7
6
5
0
4
0
3
0
2
1
0
Bottom of Receive FIFO
Reset
0
0
0
0
0
0
0
0
0
0
0
Read Access
Bit
15
0
14
0
13
0
12
0
11
0
10
0
9
8
7
6
5
0
4
0
3
0
2
0
1
0
0
0
Top of Transmit FIFO
Reset
0
0
0
0
Write Access
Bit
Name
Data
Description
15..0
Top/bottom of transmit/receive FIFO.
Read – Bottom of receive FIFO.
Write – Top of transmit FIFO.
Note: User should left justify data when SSP programmed for a data size less than 16
bits. Top unused bits are ignored by transmit logic. Receive logic automatically right
justifies data and zero fills unused bits.
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11.12.12 SSP Status Register
The SSP status register (SSSR) contains bits that signal overrun errors as well as the transmit and
receive FIFO service requests. Each of these hardware-detected events signals an interrupt request
to the interrupt controller. The status register also contains flags that indicate when the SSP is
actively transmitting characters, when the transmit FIFO is not full, and when the receive FIFO is
not empty (no interrupt generated).
A bit that can cause an interrupt signals the interrupt request as long as the bit is set. Once the bit is
cleared, the interrupt is cleared. Read/write bits are called status bits; read-only bits are called flags.
Status bits are referred to as “sticky” (once set by hardware, must be cleared by software). Writing
a one to a sticky status bit clears it; writing a zero has no effect. Read-only flags are set and cleared
by hardware; writes have no effect. Additionally, some bits that cause interrupts have
corresponding mask/enable bits in the control registers and are indicated in the following section
headings. Note that the user has the ability to mask all SSP interrupts by clearing bit 19 within the
interrupt controller mask register (ICMR). See the Section 9.2, “Interrupt Controller” on page 9-11.
11.12.12.1 Transmit FIFO Not Full Flag (TNF) (read-only, noninterruptible)
The transmit FIFO not full flag (TNF) is a read-only bit that is set whenever the transmit FIFO
contains one or more entries that do not contain valid data and is cleared when the FIFO is
completely full. This bit can be polled when using programmed I/O to fill the transmit FIFO over
its halfway mark. This bit does not request an interrupt.
11.12.12.2 Receive FIFO Not Empty Flag (RNE) (read-only, noninterruptible)
The receive FIFO not empty flag (RNE) is a read-only bit that is set whenever the receive FIFO
contains one or more entries of valid data and is cleared when it no longer contains any valid data.
This bit can be polled when using programmed I/O to remove remaining bytes of data from the
receive FIFO because DMA service and CPU interrupt requests are only made when four or more
bytes reside within the FIFO (3, 2, or 1 bytes may remain at the end of a frame). This bit does not
request an interrupt.
11.12.12.3 SSP Busy Flag (BSY) (read-only, noninterruptible)
The SSP busy (BSY) flag is a read-only bit that is set when the SSP is actively transmitting and/or
receiving data, and is cleared when the SSP is idle or disabled (SSE=0). This bit does not request
an interrupt.
11.12.12.4 Transmit FIFO Service Request Flag (TFS) (read-only, maskable
interrupt)
The transmit FIFO service request flag (TFS) is a read-only bit that is set when the transmit FIFO is
nearly empty and requires service to prevent an underrun. TFS is set whenever the transmit FIFO
has four or fewer entries of valid data (half-full or less), and is cleared when it has five or more
entries of valid data. When the TFS bit is set, an interrupt request is made unless the transmit FIFO
interrupt request enable (TIE) bit is cleared. The state of TFS is also sent to the DMA controller,
and can be used to signal a DMA service request. Note that TIE has no effect on the generation of
the DMA service request. After the DMA or CPU fills the FIFO such that four or more locations
are filled within the transmit FIFO, the TFS flag (and the service request and/or interrupt) is
automatically cleared.
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11.12.12.5 Receive FIFO Service Request Flag (RFS) (read-only, maskable
interrupt)
The receive FIFO service request flag (RFS) is a read-only bit that is set when the receive FIFO is nearly
filled and requires service to prevent an overrun. RFS is set whenever the receive FIFO has four or more
entries of valid data (half-full or more), and is cleared when it has three or fewer (less than half-full)
entries of data. When the RFS bit is set, an interrupt request is made unless the receive FIFO interrupt
request enable (RIE) bit is cleared. The state of RFS is also sent to the DMA controller, and can be used
to signal a DMA service request. Note that RIE has no effect on the generation of the DMA service
request. After the DMA or CPU fills the FIFO such that four or more locations are filled within the
receive FIFO, the RFS flag (and the service request and/or interrupt) is automatically cleared.
11.12.12.6 Receiver Overrun Status (ROR) (read/write, nonmaskable interrupt)
The receiver overrun status bit (ROR) is a read/write bit that is set when the receive logic attempts
to place data into the receive FIFO after it has been completely filled. Each time a new piece of
data is received, the set signal to the ROR bit is asserted, and the newly received data is discarded.
This process is repeated for each new piece of data received until at least one empty FIFO entry
exists. When the ROR bit is set, an interrupt request is made.
The following table shows the bit locations corresponding to the status and flag bits within the SSP
status register. All bits are read-only except ROR, which is read/write. Writes to TNF, RNE, BSY, TFS,
and RFS have no effect. The reset state of ROR is unknown (indicated by a question mark) and must be
initialized before enabling the SSP. Note that writes to reserved bits are ignored and reads return zeros.
Read/Write &
Address: 0h 8007 0074
SSP Status Register: SSSR
Read-Only
Bit
15
14
13
0
12
0
11
Reserved
0
10
0
9
8
7
6
ROR
?
5
RFS
0
4
TFS
0
3
BSY
0
2
RNE
0
1
TNF
1
0
Res
0
Reset
0
0
0
0
0
Bit
Name
Description
0
—
Reserved.
1
TNF
RNE
BSY
TFS
Transmit FIFO not full (read-only).
0 – Transmit FIFO is full.
1 – Transmit FIFO is not full.
2
3
4
Receive FIFO not empty (read-only).
0 – Receive FIFO is empty.
1 – Receive FIFO is not empty.
SSP busy flag (read-only).
0 – SSP is idle or disabled.
1 – SSP is currently transmitting and/or receiving a frame (no interrupt generated).
Transmit FIFO service request (read-only).
0 – Transmit FIFO is more than half-full (five or more entries filled) or SSP disabled.
1 – Transmit FIFO is half-full or less (four or fewer entries filled) and SSP operation is
enabled, DMA service request signalled, interrupt request signalled if not masked (if TIE=1).
5
6
RFS
Receive FIFO service request (read-only).
0 – Receive FIFO is less than half-full (three or fewer entries filled) or SSP disabled.
1 – Receive FIFO is half-full or more (four or more entries filled) and SSP operation is
enabled, DMA service request signalled, interrupt request signalled if not masked (if RIE=1).
ROR
—
Receive FIFO overrun.
0 – Receive FIFO has not experienced an overrun.
1 – Receive logic attempted to place data into receive FIFO while it was full, request interrupt.
15..7
Reserved.
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11.12.13 MCP Register Locations
Table 11-19 shows the registers associated with the MCP and the physical addresses used to access them.
Table 11-19. MCP Control, Data, and Status Register Locations
Address
0h 8006 0000
Name
MCCR0
Description
MCP control register 0
0h 8006 0004
—
Reserved
0h 8006 0008
MCDR0
MCDR1
MCDR2
—
MCP data register 0
MCP data register 1
MCP data register 2
Reserved
0h 8006 000C
0h 8006 0010
0h 8006 0014
0h 8006 0018
MCSR
—
MCP status register
Reserved
0h 8006 001C – 0h 8006 005C
Note: MCCR1 resides within the same address space as the PPC.
0h 9006 0030 MCCR1 MCP control register 1
11.12.14 SSP Register Locations
Table 11-20 shows the registers associated with the SSP and the physical addresses used to access them.
Table 11-20. SSP Control, Data, and Status Register Locations
Address
0h 8007 0060
Name
SSCR0
Description
SSP control register 0
0h 8007 0064
SSCR1
—
SSP control register 1
Reserved
0h 8007 0068
0h 8007 006C
SSDR
—
SSP data register
Reserved
0h 8007 0070
0h 8007 0074
SSSR
—
SSP status register
Reserved
0h 8007 0078 – 0h 8007 FFFF
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11.13
Peripheral Pin Controller (PPC)
The peripheral pin controller (PPC) takes individual control of the LCD’s and serial port 1..4’s pins
when one or more of the units are disabled, allowing the user to utilize them as general-purpose
digital I/O pins to communicate to off-chip resources. When controlled by the PPC, peripheral
control module (PCM) pins operate similarly to GPIO pins except that they cannot perform edge
detection and interrupt generation. The PPC is also used to specify the direction of the peripherals’
pins when sleep mode is entered.
Note that serial ports 1..3 contain individual enables for their transmit and receive serial engines.
Thus, if only half-duplex transmission is needed, one pin can be used for serial communication and
the other for digital I/O communication. Also note that serial port 0’s pins are dedicated to the USB
device controller (UDC), which uses the pins to drive a differential transceiver, preventing them
from being used as digital I/O pins when the UDC is disabled.
11.13.1 PPC Operation
Following a hardware reset of the SA-1100 (nRESET asserted then negated), all peripheral control
module units are disabled, giving control of their pins to the PPC (except serial port 0). The PPC, in
turn, configures all peripheral pins it controls as inputs. Once reset is negated, the user should
program the peripherals as soon as possible, and configure the pins of any peripheral that is not
usable to function as general-purpose I/O signals. This should be done quickly to limit the amount
of power consumed at startup because pins that are intended to function as outputs within the
system are initially configured as inputs, and the receiving device to which they are connected will
float and consume power.
The PPC contains special resources to limit off-chip power consumption during and immediately
following the assertion of sleep mode. The PPC contains a sleep mode direction register, which is
programmed by the user, and individually configures 22 of the peripherals’ pins either as inputs or
outputs during sleep mode. When configured as an output, the pin is forced low in sleep mode. This
special register is required because the first action taken when sleep mode is entered is the assertion
of reset to all the peripherals, which would, in turn, errantly configure all peripheral pins as inputs.
The sleep mode direction register is not reset; the user can maintain the correct direction
programmed for each of the peripherals’ pins while in sleep mode. When sleep mode is exited, the
user can then reprogram the peripherals and the PPC registers to resume control of the peripherals’
pins. To keep the same pin direction and state after sleep mode has been negated but before the user
reprograms the peripherals, the system control module’s power manager maintains the peripherals’
pin direction and state following sleep negation until the peripheral control hold bit (PSSR:PH),
located in the power manager, is cleared (by writing a one to it). Therefore, the pin direction and
state established during sleep using the sleep mode direction register remains intact following the
negation of sleep until the PH bit is cleared. Once PH is cleared, control of the peripherals’ pins is
given back to the individual peripherals and to the PPC unit.
Most of the SA-1100’s peripherals can take control of one or more GPIO pins (which are normally
controlled within the system control module) to act as input or output triggers, or to drive or supply
clocks to the peripherals. The GPIO unit contains a GPIO alternate function register (GAFR) that
the user must program to give control of the GPIO pins to the individual peripheral units for each
of the alternate functions. The user must also program the GPIO pin direction register (GPDR) for
the corresponding pins that are used by the peripheral units. The GPIO pin alternate functions are
then enabled within the individual peripherals using a control bit. However, two control bits exist
within the PPC that configure six of the GPIO unit’s pins for peripheral alternate functions.
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Serial port 1 and serial port 4 both contain two serial-to-parallel engines that operate independently.
However, because each port contains only one set of serial pins, the user can assign these pins to
only one of the two protocols at a time. To allow the user to utilize both protocols, the PPC can
assign one of its two serial-to-parallel engines to the pins that are dedicated to the port, and the
other to a set of GPIO pins. Serial port 1 contains an SDLC and a UART. By setting a bit in the
PPC and the appropriate GAFR and GPDR bits in the GPIO unit, SDLC operation defaults to the
TXD1 and RXD1 pins, and the UART transmits via the GPIO<14> pin and receives via the
GPIO<15> pin. Likewise, serial port 4 contains the MCP and the SSP synchronous serial engines.
The user can configure the PPC and GPIO units to cause the MCP to default to the TXD4, RXD4,
SCLK, and SFRM pins, and the SSP is assigned to GPIO<10> for transmit, GPIO<11> for receive,
GPIO<12> for serial clock, and GPIO<13> for serial frame.
When the SA-1100 is reset or enters sleep mode, the GPIO unit’s registers are reset, which gives
control of the GPIO pins back to the system control module.
11.13.2 PPC Register Definitions
There are five registers within the PPC: one pin direction register, one pin state register, one pin
assignment register, one sleep mode pin direction register, and one pin flag register.
11.13.3 PPC Pin Direction Register
Pin direction is controlled by programming the PPC pin direction register (PPDR). The PPDR
contains individual direction control bits for 22 of the 24 peripheral pins. Serial port 0 has
dedicated pins (UDC+ and UDC-) that are not controlled by the PPC when the UDC is disabled.
Each bit is used only if the corresponding peripheral that it controls is disabled. Provided the
corresponding peripheral is disabled, if the direction bit is programmed to a one, the pin is an
output. If it is programmed to a zero, it is an input. Following reset, all peripherals are disabled,
which causes the PPC to take control of all of their pins. Serial ports 1..3 contain individual enables
for their transmit and receive serial engines. Thus, if only half-duplex transmission is needed, one
pin can be used for serial communication and the other for digital I/O communication. Note that
PPDR is reset such that all the pins are configured as inputs. For reserved bits, writes are ignored
and reads return zero. The following table shows the location of each pin direction bit and to which
peripheral pin it corresponds.
Address: 0h 9006 0000
PPDR: PPC Pin Direction Register
Read/Write
Bit
Reset
Bit
31
30
29
0
28
0
27
26
25
24
23
22
21
SFRM
0
20
SCLK
0
19
RXD4
0
18
TXD4
0
17
RXD3
0
16
TXD3
0
Reserved
0
0
0
0
0
0
0
0
15
RXD2
0
14
TXD2
0
13
RXD1
0
12
TXD1
0
11
10
9
8
7
6
5
4
3
2
1
0
LDD
<7>
LDD
<6>
LDD
<5>
LDD
<4>
LDD
<3>
LDD
<2>
L_
BIAS
L_
FCLK
L_
LCLK
L_
PCLK
LDD
<1>
LDD
<0>
Reset
0
0
0
0
0
0
0
0
0
0
0
0
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Bit
7..0
Name
Description
LDD<7:0 LCD data pin direction.
>
0 – If LCD controller disabled, LCD data pin configured as general-purpose input.
1 – If LCD controller disabled, LCD data pin configured as general-purpose output.
8
L_PCLK
L_LCLK
L_FCLK
L_BIAS
TXD1
RXD1
TXD2
RXD2
TXD3
RXD3
TXD4
RXD4
SCLK
SFRM
—
LCD pixel clock pin direction.
0 – If LCD controller disabled, LCD pixel clock pin configured as general-purpose input.
1 – If LCD controller disabled, LCD pixel clock pin configured as general-purpose output.
9
LCD line clock pin direction.
0 – If LCD controller disabled, LCD line clock pin configured as general-purpose input.
1 – If LCD controller disabled, LCD line clock pin configured as general-purpose output.
10
11
LCD frame clock pin direction.
0 – If LCD controller disabled, LCD frame clock pin configured as general-purpose input.
1 – If LCD controller disabled, LCD frame clock pin configured as general-purpose output.
LCD AC bias pin direction.
0 – If LCD controller disabled, LCD ac bias pin configured as general-purpose input.
1 – If LCD controller disabled, LCD ac bias pin configured as general-purpose output.
12
13
14
15
16
17
18
19
20
21
31..22
Serial port 1: SDLC/UART transmit pin direction.
0 – If serial port 1 transmitter disabled, transmit pin configured as general-purpose input.
1 – If serial port 1 transmitter disabled, transmit pin configured as general-purpose output.
Serial port 1: SDLC/UART receive pin direction.
0 – If serial port 1 receiver disabled, receive pin configured as general-purpose input.
1 – If serial port 1 receiver disabled, receive pin configured as general-purpose output.
Serial port 2: IPC transmit pin direction.
0 – If serial port 2 transmitter disabled, transmit pin configured as general-purpose input.
1 – If serial port 2 transmitter disabled, transmit pin configured as general-purpose output.
Serial port 2: IPC receive pin direction.
0 – If serial port 2 receiver disabled, receive pin configured as general-purpose input
1 – If serial port 2 receiver disabled, receive pin configured as general-purpose output
Serial port 3: UART transmit pin direction.
0 – If serial port 3 transmitter disabled, transmit pin configured as general-purpose input
1 – If serial port 3 transmitter disabled, transmit pin configured as general-purpose output
Serial port 3: UART receive pin direction.
0 - If serial port 3 receiver disabled, receive pin configured as general-purpose input.
1 - If serial port 3 receiver disabled, receive pin configured as general-purpose output.
Serial port 4: MCP/SSP transmit pin direction.
0 - If serial port 4 disabled, transmit pin configured as general-purpose input.
1 - If serial port 4 disabled, transmit pin configured as general-purpose output.
Serial port 4: MPC/SSP receive pin direction.
0 – If serial port 4 disabled, receive pin configured as general-purpose input.
1 – If serial port 4 disabled, receive pin configured as general-purpose output.
Serial port 4: MPC/SSP serial clock pin direction.
0 – If serial port 4 disabled, serial clock pin configured as general-purpose input.
1 – If serial port 4 disabled, serial clock pin configured as general-purpose output.
Serial port 4: MPC/SSP serial frame pin direction.
0 – If serial port 4 disabled, serial frame pin configured as general-purpose input.
1 – If serial port 4 disabled, serial frame pin configured as general-purpose output.
Reserved.
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11.13.4 PPC Pin State Register
Pin state is both monitored and controlled by reading/writing the PPC pin state register (PPSR). The
PPSR contains 1 state bit for each of the 22 peripheral pins. This register may be read at any time to
determine the current state of all peripheral pins, even when pins are controlled by the peripheral
rather than the PPC. If a peripheral is disabled and its corresponding pin direction is programmed as
an output in the PPDR, its PPSR bit is used to control the state of the peripheral pin. Writing a zero to
the pin’s state bit causes the pin to be forced low, and writing a one causes the pin to be forced high.
Writing a value to a pin state bit that is an input or is not under the control of the PPC has no effect. To
alter the state of an output pin, the user should first read the PPSR, then logically AND the value read
with a mask, which contains ones in every bit position except the one the user wishes to clear. To set a
pin, the user should logically OR the value read with a mask, which contains zeros in every bit
position except the one the user wishes to set. This mechanism allows the user to set or clear
individual pins without changing the state of other pins that are configured as outputs.
Serial port 2 contains two bits that control the polarity of data input via the receive pin (RXD2) and
data output via the transmit pin (TXD2). The user must ensure that these polarity bits are set
(RXP = TXP = 1), which selects true or noninverted data before using TXD2 or RXD2 as GPIO
pins.
Note that PPSR is implemented as two separate registers. A write to PPSR addresses one of the
registers and is used to set and clear pins configured as GPIO outputs, while a read addresses the
other register that is used to store and monitor pin state. The register used to store pin state contains
logic to synchronize the signal input from the pin to allow the user to read it. The pins are sampled
at a rate of 7.3728 MHz; each synchronization cycle takes 135.6 ns. Depending on the CPU
frequency programmed by the user, after changing the state of an output pin via a write, one or
more dummy read cycle waitstates may need to be inserted to allow the value to be output to the
pin and to allow the synchronizer to resample the pin.
The following table shows the location of each pin state bit and to which peripheral pin it
corresponds. Note that this register is not reset and that for reserved bits, writes are ignored and
reads return zero.
Address: 0h 9006 0004
PPSR: PPC Pin StateRegister
Read/Write
Bit
Reset
Bit
31
30
29
0
28
0
27
26
0
25
24
23
22
0
21
SFRM
0
20
SCLK
0
19
RXD4
0
18
TXD4
0
17
RXD3
0
16
TXD3
0
Reserved
0
0
0
0
0
0
15
RXD2
0
14
TXD2
0
13
RXD1
0
12
TXD1
0
11
10
9
8
7
6
5
4
3
2
1
0
L_
L_
L_
LDD
<7>
LDD
<6>
LDD
<5>
LDD
<4>
LDD
<3>
LDD
<2>
L_
FCK
LDD
<1>
LDD
<0>
BIAS
LCK
PCK
Reset
0
0
0
0
0
0
0
0
0
0
0
0
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Bit
7..0
Name
Description
LDD<7:0 LCD data pin state.
>
Read – Current state of LCD data pin returned.
Write – If LCD disabled and pin configured as an output, drive value to LCD data pin.
8
L_PCLK
L_LCLK
L_FCLK
L_BIAS
TXD1
LCD pixel clock pin state.
Read – Current state of LCD pixel clock pin returned.
Write – If LCD disabled and pin configured as an output, drive value to LCD pixel clock pin.
9
LCD line clock pin state.
Read – Current state of LCD line clock pin returned.
Write – If LCD disabled and pin configured as an output, drive value to LCD line clock pin.
10
11
12
LCD frame clock pin state.
Read – Current state of LCD frame clock pin returned.
Write – If LCD disabled and pin configured as an output, drive value to LCD frame clock pin.
LCD AC bias pin state.
Read – Current state of LCD AC bias pin returned.
Write – If LCD disabled and pin configured as an output, drive value to LCD AC bias pin.
Serial port 1: SDLC/UART transmit pin state.
Read – Current state of serial port 1 transmit pin returned.
Write – If serial port 1 transmitter disabled and pin configured as an output, drive value
to transmit pin.
13
RXD1
TXD2
RXD2
TXD3
RXD3
TXD4
RXD4
SCLK
SFRM
—
Serial port 1: SDLC/UART receive pin state.
Read – Current state of serial port 1 receive pin returned.
Write – If serial port 1 receiver disabled and pin configured as an output, drive value to
receive pin.
14
Serial port 2: IPC transmit pin state.
Read – Current state of serial port 1 transmit pin returned.
Write – If serial port 2 transmitter disabled and pin configured as an output, drive value
to transmit pin.
15
Serial port 2: IPC receive pin state.
Read – Current state of serial port 2 receive pin returned.
Write – If serial port 2 receiver disabled and pin configured as an output, drive value to
receive pin.
16
Serial port 3: UART transmit pin state.
Read – Current state of serial port 3 transmit pin returned.
Write – If serial port 3 transmitter disabled and pin configured as an output, drive value
to transmit pin.
17
Serial port 3: UART receive pin state.
Read – Current state of serial port 3 receive pin returned.
Write – If serial port 3 receive disabled and pin configured as an output, drive value to
receive pin.
18
Serial port 4: MCP/SSP transmit pin state.
Read – Current state of serial port 4 transmit pin returned.
Write – If serial port 4 transmitter disabled and pin configured as an output, drive value
to transmit pin.
19
Serial port 4: MCP/SSP receive pin state.
Read – Current state of serial port 4 receive pin returned.
Write – If serial port 4 receive disabled and pin configured as an output, drive value to
receive pin.
20
Serial port 4: MCP/SSP serial clock pin state.
Read – Current state of serial port 4 serial clock pin returned.
Write – If serial port 4 disabled and pin configured as an output, drive value to serial
clock pin.
21
Serial port 4: MCP/SSP serial frame pin state.
Read – Current state of serial port 4 serial frame pin returned.
Write – If serial port 4 disabled and pin configured as an output, drive value to serial
frame pin.
31..22
Reserved.
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11.13.5 PPC Pin Assignment Register
The UART in serial port 1 and the SSP in serial port 4 can be reassigned to GPIO pins using the
PPC pin assignment register (PPAR). The PPAR contains two bits that control the reassignment of
each serial engine to an individual set of GPIO pins.
11.13.5.1 UART Pin Reassignment (UPR)
The UART pin reassignment (UPR) bit is used to select whether serial port 1’s UART is assigned
to GPIO pins 14 and 15. When UPR=0, serial port 1 uses its TXD1 and RXD1 pins, and the
SDLC/UART select (SUS) bit is used to select which protocol is enabled. When UPR=1, SUS is
ignored, serial port 1 defaults to SDLC operation using the TXD1 and RXD1 pins, and the UART
is configured to use GPIO<14> for transmit and GPIO<15> for receive. Note that the user must set
bits 14 and 15 in the GPIO alternate function register (GAFR) as well as set bit 14 and clear bit 15
in the GPIO pin direction register (GPDR). See the Section 9.1, “General-Purpose I/O” on
11.13.5.2 SSP Pin Reassignment (SPR)
The SSP pin reassignment (SPR) bit is used to select whether serial port 4’s SSP is assigned to GPIO pins
10 through 13. When SPR=0, serial port 4 uses its TXD4, RXD4, SCLK, and SFRM pins; the MCP
enable (MCE) and SSP enable (SSE) bits are used to select which protocol is enabled (MCE has
precedence over SSE). When SPR=1, MCE and SSE must both be set; serial port 4 defaults to MCP
operation using the TXD4, RXD4, SCLK, and SFRM pins, and the SSP is configured to use GPIO<10>
for transmit, GPIO<11> for receive, GPIO<12> for serial clock, and GPIO<13> for serial frame. Note
that the user must set bits 10 through 13 in the GPIO alternate function register (GAFR) as well as set bits
10, 12, and 13 and clear bit 11 in the GPIO pin direction register (GPDR). See the Section 9.1,
The following table shows the location of the two pin reassignment bits. Note that for reserved bits,
writes are ignored and reads return zero. Both control bits are cleared to zero following a reset of
the SA-1100, giving control of all GPIO pins to the system control module.
Address: 0h 9006 0008
PPAR: PPC Pin Assignment Register
Read/Write
Bit
Reset
Bit
31
30
29
28
0
27
0
26
25
Reserved
0
24
23
22
21
0
20
0
19
0
18
SPR
0
17
16
Reserved
0
0
0
0
0
0
0
0
1
0
0
0
0
15
0
14
Reserved
0
13
0
12
UPR
0
11
0
10
0
9
0
8
7
6
5
4
3
2
0
Reserved
Reset
0
0
0
0
0
0
Bit
Name
Description
11..0
—
Reserved.
UART pin reassignment.
12
UPR
0 – No pin reassignment made, GPIO<14-15> controlled by GPIO unit, serial port 1
UART assigned to TXD1 and RXD1 if SUS=1.
1 – Pin reassignment made, serial port 1 defaults to SDLC operation (SUS ignored),
UART transmit assigned to GPIO<14> and receive to GPIO<15>, GAFR and GPDR
must be configured in GPIO unit.
17..13
18
—
Reserved.
SPR
SSP pin reassignment.
0 – No pin reassignment made, GPIO<10-13> controlled by GPIO unit, serial port 4
SSP assigned to TXD4, RXD4, SCLK, and SFRM if MCE=0 and SSE=1.
1– Pin reassignment made, serial port 4 defaults to MCP operation, SSP transmit
assigned to GPIO<10>, receive to GPIO<11>, serial clock to GPIO<12>, and serial
frame to GPIO<13>, GAFR and GPDR must be configured in GPIO unit.
31..19
—
Reserved.
SA-1100 Developer’s Manual
11-189
Peripheral Control Module
11.13.6 PPC Sleep Mode Pin Direction Register
When sleep mode is entered, reset is asserted to all of the SA-1100’s peripherals and to the PPC unit.
The PPC pin direction register is cleared during a hard, soft, or sleep reset, causing the peripheral pins
under the PPC’s control to be configured as inputs. If this register were also used to determine pin
direction during sleep, the pins would all be configured as inputs. This action would cause any off-chip
device that expects data to be output from the SA-1100 to burn power during sleep because its input
would float. The sleep mode pin direction register (PSDR) prevents this undesired power consumption
by allowing the user to establish peripheral pin direction during and immediately following sleep mode.
When sleep mode is entered, both the peripherals and the PPC are reset; however, PSDR is not reset
like PPDR. Once the user programs PSDR, it retains its data after sleep mode is entered and reset is
asserted. The power manager uses the values in PSDR to determine the direction and state of the 22
peripheral pins. When a sleep mode direction bit is programmed to a zero, the corresponding pin is
configured as an output and is driven low (zero). If it is programmed to a one, it is an input. The
power manager latches the contents of PSDR before VDD is removed from the SA-1100 to maintain
the peripheral pin direction and state after the main power supply is removed. Once VDD is removed,
the data in PSDR is lost and must be reprogrammed after exiting sleep mode. The power manager
contains a control bit called the peripheral control hold (PSSR:PH). This bit is set upon exit from
sleep mode and indicates that the peripheral pins are being held in their sleep state. Following sleep,
the user should first reprogram the peripherals and the PPC, then clear PH (by writing a one to it) in
order to give control of the pins back to the peripheral units. Note that sleep mode invocation causes
RPP to be cleared so that the pins are once again held in their sleep state until the user can set RPP.
Because the peripherals are reset when sleep mode is entered, serial port 2’s transmit and receive
pin (TXD2 and RXD2) polarity bits (TXP and RXP) are both reset to one, which configures
transmit and receive data as true or noninverted data. Thus the user need not reprogram these bits
prior to the invocation of sleep mode.
Note that PPSR is initialized only by a hardware or power-on reset (negation of the nRESET pin). It is
not affected by a software reset or a reset that occurs as a result of the SA-1100 entering sleep mode.
Also note that for reserved bits, writes are ignored and reads return zero. The following table shows
the location of each sleep mode pin direction bit and to which peripheral pin it corresponds.
Address: 0h 9006 000C
PSDR: PPC Sleep Mode Pin Direction Register
Read/Write
Bit
Hard Reset
Bit
31
30
29
0
28
0
27
26
25
24
23
22
21
SFRM
1
20
SCLK
1
19
RXD4
1
18
TXD4
1
17
RXD3
1
16
TXD3
1
Reserved
0
0
0
0
0
0
0
0
15
14
TXD2
1
13
RXD1
1
12
TXD1
1
11
10
9
8
7
6
5
4
3
2
1
0
L_
L_
L_
L_
LDD
<7>
LDD
<6>
LDD
<5>
LDD
<4>
LDD
<3>
LDD
<2>
RXD
2
LDD
<1>
LDD
<0>
BIAS
FCLK
LCLK
PCLK
Hard Reset
1
1
1
1
1
1
1
1
1
1
1
1
1
11-190
SA-1100 Developer’s Manual
Peripheral Control Module
Bit
7..0
Name
Description
LDD<7:0 LCD data sleep mode pin direction.
>
0 – LCD data pin configured as output and is driven low during sleep.
1 – LCD data pin configured as input during sleep.
8
L_PCLK
L_LCLK
L_FCLK
L_BIAS
TXD1
LCD pixel clock sleep mode pin direction.
0 – LCD pixel clock pin configured as output and is driven low during sleep.
1 – LCD pixel clock pin configured as input during sleep.
9
LCD line clock sleep mode pin direction.
0 – LCD line clock pin configured as output and is driven low during sleep.
1 – LCD line clock pin configured as input during sleep.
10
11
12
13
14
15
16
17
18
LCD frame clock sleep mode pin direction.
0 – LCD frame clock pin configured as output and is driven low during sleep.
1 – LCD frame clock pin configured as input during sleep.
LCD ac bias sleep mode pin direction.
0 – LCD ac bias pin configured as output and is driven low during sleep.
1 – LCD ac bias pin configured as input during sleep.
Serial port 1: SDLC/UART transmit sleep mode pin direction.
0 – Transmit pin configured as output and is driven low during sleep.
1 – Transmit pin configured as input during sleep.
RXD1
Serial port 1: SDLC/UART receive sleep mode pin direction.
0 – Receive pin configured as output and is driven low during sleep.
1 – Receive pin configured as input during sleep.
TXD2
Serial port 2: IPC transmit sleep mode pin direction.
0 – Transmit pin configured as output and is driven low during sleep.
1 – Transmit pin configured as input during sleep.
RXD2
Serial port 2: IPC receive sleep mode pin direction.
0 – Receive pin configured as output and is driven low during sleep.
1 – Receive pin configured as input during sleep.
TXD3
Serial port 3: UART transmit sleep mode pin direction.
0 – Transmit pin configured as output and is driven low during sleep.
1 – Transmit pin configured as input during sleep.
RXD3
Serial port 3: UART receive sleep mode pin direction.
0 – Receive pin configured as output and is driven low during sleep.
1 – Receive pin configured as input during sleep.
TXD4
Serial port 4: MCP/SSP transmit sleep mode pin direction.
0 – Transmit pin configured as output and is driven low during sleep.
1 – Transmit pin configured as input during sleep.
19
RXD4
SCLK
SFRM
—
Serial port 4: MCP/SSP receive sleep mode pin direction.
0 – Receive pin configured as output and is driven low during sleep.
1 – Receive pin configured as input during sleep.
20
Serial port 4: MCP/SSP serial clock sleep mode pin direction.
0 – Serial clock pin configured as output and is driven low during sleep.
1 – Serial clock pin configured as input during sleep.
21
Serial port 4: MCP/SSP serial frame sleep mode pin direction.
0 – Serial frame pin configured as output and is driven low during sleep.
1 – Serial frame pin configured as input during sleep.
31..22
Reserved.
SA-1100 Developer’s Manual
11-191
Peripheral Control Module
11.13.7 PPC Pin Flag Register
The PPC pin flag register (PPFR) is used to determine which peripherals are currently under the
control of the PPC unit. The eight read-only flags denote whether or not each of the peripherals
(except serial port 0) is enabled or is disabled and being controlled by the PPC. Note that serial
ports 1..3 contain individual enables for their transmit and receive serial engines. Thus, separate
flag bits exist for their transmit and receive pins. When a flag is set, it indicates that the
corresponding peripheral is disabled and is controlled by the PPC; when it is cleared, it indicates
that the peripheral is enabled and its pins are being used for serial transmission (serial ports 1..4) or
for LCD operation. Note that for reserved bits, writes are ignored and reads return zero. The
following table shows the location of each pin flag bit and to which peripheral pin it corresponds.
Address: 0h 9006 0010
PPFR: PPC Pin Flag Register
Read-Only
Bit
31
30
29
28
27
26
25
Reserved
0
24
23
22
0
21
20
19
18
SP4
1
17
16
SP3
RX
SP3
TX
Reset
Bit
0
0
0
0
0
0
0
8
0
7
0
5
0
4
0
3
1
1
15
14
13
12
11
10
9
0
6
2
0
1
0
LCD
1
SP2
RX
SP2
TX
SP1
RX
SP1
TX
Reserved
0
Reset
1
1
1
1
0
0
0
0
0
0
0
0
Bit
Name
LCD
Description
0
LCD controller flag (read-only).
0 – LCD controller enabled.
1 – LCD disabled, PPC currently controlling all 12 of its pins: LDD<7:0>, L_PCLK,
L_LCLK, L_FCLK, L_BIAS.
11..1
12
—
Reserved.
SP1 TX
Serial port 1: SDLC/UART transmit flag (read-only).
0 – SDLC or UART transmit enabled.
1 – SDLC and UART transmitters disabled, PPC currently controlling the transmit pin:
TXD1.
13
14
15
SP1 RX
SP2 TX
SP2 RX
Serial port 1: SDLC/UART receive flag (read-only).
0 – SDLC or UART receive enabled.
1 – SDLC and UART receivers disabled, PPC currently controlling the receive pin:
RXD1.
Serial port 2: ICP transmit flag (read-only).
0 – HSSP or UART transmit enabled.
1– HSSP and UART transmitters disabled, PPC currently controlling the transmit pin:
TXD2.
Serial port 2: ICP receive flag (read-only).
0 – HSSP or UART receive enabled.
1 – HSSP and UART receivers disabled, PPC currently controlling the receive pin:
RXD2.
16
17
18
SP3 TX
SP3 RX
SP4
Serial port 3: UART transmit flag (read-only).
0 – UART transmit enabled.
1 – UART transmit disabled, PPC currently controlling the transmit pin: TXD3.
Serial port 3: UART receive flag (read-only).
0 – UART receive enabled.
1 – UART receive disabled, PPC currently controlling the receive pin: RXD3.
Serial port 4: MCP/SSP flag (read-only).
0 – MCP or SSP enabled.
1– MCP and SSP disabled, PPC currently controlling all 4 of its pins:
TXD4, RXD4, SCLK, SFRM.
31..19
—
Reserved.
11-192
SA-1100 Developer’s Manual
Peripheral Control Module
11.13.8 PPC Register Locations
Table 11-21 shows the registers associated with the PPC and the physical addresses used to access
them. Note that serial port 2 (ICP) has implemented HSSP control register 2 and serial port 4
(MCP) has also implemented MCP control register 1 within the PPC’s address space at 0h 9006
0028 and 0h 9006 0030 respectively. The user should ensure that these registers are not
accidentally written by any PPC routines that may attempt to write to all of the PPC’s address
space, including its reserved registers during initialization.
Table 11-21. PPC Control and Flag Register Locations
Address
Name
PPDR
Description
PPC pin direction register
0h 9006 0000
0h 9006 0004
0h 9006 0008
0h 9006 000C
0h 9006 0010
PPSR
PPAR
PSDR
PPFR
PPC pin state register
PPC pin assignment register
PPC sleep mode direction register
PPC pin flag register
0h 9006 0014 –
0h 9006 FFFF
—
Reserved
SA-1100 Developer’s Manual
11-193
DC Parameters
12
This chapter defines the dc parameters for the Intel® StrongARM® SA-1100 Microprocessor
(SA-1100).
12.1
Absolute Maximum Ratings
Table 12-1 lists the absolute maximum ratings for the SA-1100.
Table 12-1. SA-1100 DC Maximum Ratings
Symbol
VDD
Parameter
Min
VSS – 0.5
Max
Units
Note
Core supply voltage
VSS + 2.1
V
1
MIN(VSS – 0.05,
VDD – 0.3)
VDDX
I/O voltage
VSS + 3.6
V
1
Vip
Voltage applied to any pin
Voltage applied to *XTAL pins
Storage temperature
VSS – 0.5
VSS + 3.6
V
V
1
1
1
Vip (*XTAL)
Ts
0
1
– 40
125
°C
NOTE:
1. These are stress SA-1100 ratings only. Exceeding the absolute maximum ratings may permanently
damage the device. Operating the device at absolute maximum ratings for extended periods may affect
device reliability.
SA-1100 Developer’s Manual
12-1
DC Parameters
12.2
DC Operating Conditions
Table 12-2. SA-1100 DC Operating Conditions
Symbol
Parameter
Min
Nom
Max
VDDX
Units
Notes
†
Vihc
IC input high voltage
0.8 × VDDX
—
V
V
V
V
1, 2
1, 2
1, 3
1, 3
—
†
Vilc
IC input low voltage
0.0
—
—
—
—
—
—
10
0.2 × VDDX
Vohc
Volc
Iohc
Iolc
Ta
OCZ output high voltage
OCZ output low voltage
High-level output current
Low-level output current
Ambient operating temperature
IC input leakage current
0.8 × VDDX
VDDX
0.0
—
—
0
0.2 × VDDX
– 2
2
mA
mA
°C
—
70
—
—
Iin
—
µA
—
Output high current
(Vout = VDD – 0.4 V)
Ioh
Iol
—
—
2
2
—
—
mA
mA
—
—
Output high current
(Vout = VSS + 0.4 V)
Cin
Input capacitance
HBM model ESD
—
—
5
1
—
—
pF
4
ESD
KV
—
NOTES:
1. Voltages measured with respect to VSS.
2. IC – CMOS-level inputs (includes IC and ICOCZ pin types).
3. OCZ – Output, CMOS levels, tristateable.
4. Parameter guaranteed by design
†
Not tested at this time
12-2
SA-1100 Developer’s Manual
DC Parameters
12.3
Power Supply Voltages and Currents
Table 12-3 specifies the power supply voltages and currents for the SA-1100. For power supply
voltages and currents for 2.0-V devices, contact the Intel Massachusetts Customer Technology
Center..
Table 12-3. SA-1100 Power Supply Voltages and Currents with TQFP Package
SA-1100
Parameter
Units
AA/AB†
CA/CB†
DA/DB†
EA/EB†
190
Maximum operating frequency
133
160
220
MHz
Maximum run mode power
(total VDD + VDDX)
400
230
55
1100
430
n/a
1100
550
n/a
500
330
85
mW
mW
mW
mW
uA
Typical run mode power
(total VDD + VDDX)
††
Maximum idle mode power
(total VDD + VDDX)
††
Typical idle mode power
50
n/a
n/a
65
(total VDD + VDDX)
††
Maximum sleep mode current
(total VDD + VDDX)
50
n/a
n/a
50
††
Typical sleep mode current
25
n/a
n/a
30
uA
(total VDD + VDDX)
VDD
Minimum internal power supply voltage
Nominal internal power supply voltage
Maximum internal power supply voltage
1.42
1.50
1.58
1.90
2.00
2.10
1.90
2.00
2.10
1.42
1.50
1.58
V
V
V
VDDX
Minimum external power supply voltage
Nominal external power supply voltage
Maximum external power supply voltage
3.00
3.30
3.60
3.00
3.30
3.60
3.00
3.30
3.60
3.00
3.30
3.60
V
V
V
†
AA, CA, DA and EA refer to TQFP package. AB, CB, DB and EB refer to mBGA package.
††
Room temperature specification.
SA-1100 Developer’s Manual
12-3
AC Parameters
13
This chapter defines the ac parameters for the Intel® StrongARM® SA-1100 Microprocessor
(SA-1100).
13.1
Test Conditions
The AC timing diagrams presented in this chapter assume that the outputs of SA-1100 have been
loaded with a 50-pF capacitive load on output signals. The output pads of SA-1100 are CMOS
drivers that exhibit a propagation delay that increases with the increase in load capacitance.
Table 13-1 lists the output derating figure for each output pad, showing the approximate rate of
increase of delay with increasing or decreasing load capacitance for a typical process at room
temperature. For derating figures for 2.0-V devices, contact the Intel Massachusetts Customer
Technology Center.
Table 13-1. SA-1100 Output Derating
Output
Derating
Output
Derating
Output
Derating
Output
Derating
Load for
Output Signal
Nominal
Value
(ns/pF)
VDD = 1.5 V
rising edge
(ns/pF)
VDD = 1.5 V
falling edge
(ns/pF)
VDD = 2.0 V
rising edge
(ns/pF)
VDD = 2.0 V
falling edge
Note
All outputs
50 pF
0.086
0.077
0.08
0.072
1
NOTE:
1. Parameter guaranteed by design
SA-1100 Developer’s Manual
13-1
AC Parameters
13.2
Module Considerations
The edge rates for the SA-1100 processor are such that the lumped load model presented above can
only be used for etch lengths up to one inch. Over one inch of etch, the signal is a transmission line
and needs to be modeled as such.
13.3
Memory Bus and PCMCIA Signal Timings
During production test, the SA-1100 is placed in testclock bypass mode by the assertion of the
TCKBYP pin. This mode (not intended for use by customers) bypasses the 3.686-MHz oscillator
and the main PLL and sources the processor clock from the TESTCLK pin. During this test mode,
all clocks on the SA-1100 are synchronous to TESTCLK. In this mode, the basic functionality of
the chip is tested and the pin timings relative to TESTCLK are measured. The ac parameters are
measured in this way for each available processor clock speed and supply voltage at which the
device is offered.
The ac specifications for the SA-1100 memory and PCMCIA interfaces are provided relative to the
memory clock. In the testclock bypass mode, memory clock is one-half the frequency of
TESTCLK. Under normal operation, memory clock is one-half the frequency of the processor
clock generated by the main PLL.
Even though this clock is not visible to the user, the required pin timing may be inferred through
these numbers. Input pins are specified by a required setup and hold to the memory clock. Outputs
are specified by a propagation delay from the edge of the memory clock where the drive starts to
the time the pin actually transitions. A 50-pF lumped load is assumed to be on each pin.
parameters.
Figure 13-1. Memory Bus AC Timing Definitions
Memory Clock
Input hold from memory clock rise
Input setup to memory clock rise
Memory Bus In
(A)
Input hold from memory clock fall
Input setup to memory clock fall
Memory Bus In
(B)
Memory clock rise to output driven valid
Memory clock fall to output driven valid
Memory Bus Out
(A)
Memory Bus Out
(B)
A4776-01
13-2
SA-1100 Developer’s Manual
AC Parameters
13.4
LCD Controller Signals
Figure 13-2 describes the LCD timing parameters. The LCD pin timing specifications are
referenced to the pixel clock (L_PCLK).
Figure 13-2. LCD AC Timing Definitions
L_PCLK
T
pclkdv
L_LDD[7:0]
(rise)
T
pclkdv
L_LDD[7:0]
(fall)
T
pclklv
L_LCLK
L_BIAS
L_FCLK
T
pclkbv
T
pclkfv
A4775-01
13.5
MCP Signals
Figure 13-3 describes the MCP timing parameters. The MCP pin timing specifications are
referenced to SCLK_C.
Figure 13-3. MCP AC Timing Definitions
SCLK_C
SFRM_C
TXD_C
T
sfmv
T
sfmv
T
T
rxdh
rxds
RXD_C
A4774-01
SA-1100 Developer’s Manual
13-3
AC Parameters
13.6
Timing Parameters
Table 13-2 lists the ac timing parameters for the SA-1100 for AA and BA parts. For timing
parameters for 2.0-V devices, contact the Intel Massachusetts Customer Technology Center.
Table 13-2. SA-1100 AC Timing Table for AA and BA Parts
Pin Name
Memory Bus
Symbol
Parameter
Min Max Unit Note
Memory clock fall to D<31:0> driven valid
D<31:0> valid to memory clock rise/fall
Memory clock rise/fall to data invalid (input
Tdfov
Tds
—
0
10
—
—
ns
ns
ns
—
1
D>31:0>
Tdh
4
1
5
nPOE, nPWE, nPIOR,
nPIOW, PSKTSEL,
nPREG, nPCE<1,2>,
A<25:0>
—
—
—
—
Tmfov
Memory clock fall to output driven valid
—
10
ns
nIOIS16 valid to memory clock rise (input
Memory clock rise to nIOIS16 negated
Tio16s
Tio16h
1
3
—
—
ns
ns
6
6
nIOIS16
—
—
nWE, nOE
Tmrov
Memory clock rise to output driven valid
—
10
ns
Memory clock rise to output driven valid
Memory clock rise/fall to nCAS<3:0> driven
Memory clock rise to nCS<3:0> driven valid
nRAS<3:0>
nCAS<3:0>
nCS<3:0>
Tmrdv
Tcasd
Tcsd
—
—
—
12
12
10
ns
ns
ns
—
2
—
MCP (CODEC) Interface
SFRM_C
Tsfrmv
Trxds
Trxdh
Ttxdv
SCLK_C rise to SFRM_C driven valid
RXD_C valid to SCLK_C fall (input setup)
SCLK_C fall to RXD_C invalid (input hold)
SCLK_C rise to TXD_C valid
—
0
21
—
—
22
ns
ns
ns
ns
—
—
—
—
RXD_C
4
TXD_C
—
LCD Controller
L_LDD<7:0>
L_LCLK
Tpclkdv L_PCLK rise/fall to L_LDD<7:0> driven valid
—
—
—
14
14
14
ns
ns
ns
3
4
4
Tpclklv
Tpclkfv
L_PCLK fall to L_LCLK driven valid
L_PCLK fall to L_LFCLK driven valid
L_PCLK rise to L_BIAS driven valid
L_FCLK
L_BIAS
Tpclkbv
—
14
ns
ns
4
All output signals
Output pin transition between 0.4V and 2.4V 1.6
4.5
NOTES:
1. These input pins may be sampled on either the rising or falling edge of the memory clock.
2. These output pins may be driven on either the rising or falling edge of the memory clock.
3. The LCD data pins can be programmed to be driven on either the rising or falling edge of the pixel clock
(L_PCLK).
4. These LCD signals can, at times, transition when L_PCLK is not clocking (between frames). At this time,
they are clocked with the internal version of the pixel clock before it is driven out onto the L_PCLK pin.
5. These signals are PCMCIA outputs and are driven by a state machine clocked by BCLK. The user defines
BCLK by programming the number of processor clocks per BCLK. Two processor clocks make one
memory clock cycle. To ensure proper operation, the user must adhere to the protocol description.
6. These signals are PCMCIA inputs and are sampled by a state machine clocked by BCLK. The user defines
BCLK by programming the number of processor clocks per BCLK. Two processor clocks make one
memory clock cycle. To ensure proper operation, the user must adhere to the protocol description.
13-4
SA-1100 Developer’s Manual
AC Parameters
13.6.1
Asynchronous Signal Timing Descriptions
nPWAIT is an input and is received through a synchronizer. As such, it has no setup and hold
specification. The user must adhere to the protocol definition.
When the peripheral pins are in GPIO mode, they are read or written under software control. As
outputs, they are driven valid on the pin approximately 20 ns after they are written by software.
When inputs, they are received by a synchronizer and must be valid for approximately 20 ns before
they are able to be recognized by a CPU read.
nRESET must remain asserted for 150 ms after VDD and VDDX are stable to properly reset the
SA-1100.
nRESET_OUT is asserted for all types of reset (hard, watchdog, sleep, and software) and appears
on the pin asynchronously to all clocks.
BATT_FAULT and VDD_FAULT are asynchronous inputs and are synchronized to the
32.768-kHz clock after entering the SA-1100. They must be valid for approximately 60 ms before
they are recognized by the SA-1100.
PWR_EN asserts when the SA-1100 enters sleep mode and is driven onto the pin following the
rising edge of the 32.768-kHz clock. It negates on the same edge as sleep mode is exited.
GP<27:0> are read and written under software control. In addition, an asynchronous edge detect
may be performed. When writing a value to these pins, the pin transitions approximately 20 ns after
the write is performed. When reading these pins, the signal is first synchronized to the internal
memory clock and must be valid for at least 20 ns before it is visible to a processor read. For edge
detects, the value on the pin following an edge must be stable for at least 10 ns for the edge to be
caught by the edge detect circuit.
UDC+, UDC-, TXD_1, RXD_1, TXD_2, RXD_2, TXD_3, and RXD_3 are asynchronous relative
to any device outside the SA-1100. The output pins, like all outputs on the SA-1100, have been
characterized while driving a 50-pF lumped load capacitance.
SA-1100 Developer’s Manual
13-5
Package and Pinout
14
14.1
Mechanical Data and Packaging Information
Figure 14-1 shows the SA-1100 208-pin LQFP mechanical drawing. All measurements are in
millimeters. Table 14-1 lists the SA-1100 pins in numeric order, showing the signal type for each pin.
Figure 14-1. Quad Flat Pack – 1.4mm (LQFP)
30.00
28.00
View from above
Pin 208
Pin 157
Pin 1
Pin 156
SA-1100
Pin 105
Pin 52
Pin 53
Pin 104
0.50 typ
0.60 typ
0.22
.
SA-1100 Developer’s Manual
14-1
Package and Pinout
Table 14-1. SA-1100 Pinout – 208-Pin Quad Flat Pack
Pin
Signal
RXD_C
Type
Pin
Signal
GP[25]
Type
Pin
Signal
Type
Pin
Signal
Type
1
I/O
I/O
–
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
I/O
I/O
I/O
I/O
–
105 nPIOR
106 nPIOW
107 VSSX
108 VDDX2
109 VSS
O
O
–
157 A[11]
O
O
O
O
–
2
TXD_C
VDDX2
VSSX
VDD
GP[24]
GP[23]
GP[22]
VDDX1
VSSX
GP[21]
GP[20]
GP[19]
GP[18]
GP[17]
GP[16]
GP[15]
GP[14]
VDDX1
VSSX
GP[13]
GP[12]
GP[11]
GP[10]
GP[9]
158 A[10]
3
159 A[9]
4
–
–
160 A[8]
5
–
–
161 VSSX
162 VDDX1
163 A[7]
6
VSS
–
–
110 VDD
–
–
7
D[0]
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
–
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
–
111 PSKTSEL
112 nIOIS16
113 nPWAIT
114 nPREG
115 nPCE2
116 nPCE1
117 nWE
O
I
O
O
O
O
O
O
O
O
–
8
D[8]
164 A[6]
9
D[16]
D[ 24]
D[ 1]
I
165 A[5]
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
O
O
O
O
O
–
166 A[4]
167 A[3]
D[ 9]
168 A[2]
D[ 17]
D[25]
VDDX2
VSSX
D[2]
169 A[1]
118 nOE
170 A[0]
119 VSSX
120 VDDX2
121 nRAS[3]
122 nRAS[2]
123 nRAS[1]
124 nRAS[0]
125 nCAS[3]
126 nCAS[2]
127 nCAS[1]
128 nCAS[0]
129 VSSX
130 VDDX2
131 VSS
171 VSSX
172 VDDX1
173 UDC-
174 UDC+
175 RXD_1
176 TXD_1
177 RXD_2
178 TXD_2
179 RXD_3
180 TXD_3
181 VSSX
182 VDDX1
183 VSS
–
–
–
–
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
–
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
–
O
O
O
O
O
O
O
O
–
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
–
D[10]
D[18]
D[26]
D[3]
D[11]
D[19]
D[27]
VDD
GP[8]
GP[7]
GP[6]
VDDX1
VSSX
VDD
VSS
–
–
–
–
VDDX2
VSSX
D[4]
–
–
–
–
–
VSS
–
132 VDD
–
184 TXTAL
185 TEXTAL
186 PEXTAL
187 PXTAL
188 VDDP
189 VSS
I
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
–
GP[5]
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
–
133 nCS[3]
134 nCS[2]
135 nCS[1]
136 nCS[0]
137 A[25]
O
O
O
O
O
O
O
O
–
O
O
I
D[12]
D[20]
D[28]
D[5]
GP[4]
GP[3]
GP[2]
–
GP[1]
–
D[13]
D[21]
D[29]
VDDX2
VSSX
D[6]
GP[0]
138 A[24]
190 VDD
–
L_BIAS
L_PCLK
VDDX1
VSSX
LDD0
139 A[23]
191 nRESET
192 nRESET_OUT
193 VDDX3
194 ROMSEL
195 TCK_BYP
196 TESTCLK
197 TMS
I
140 A[22]
O
I
141 VSSX
142 VDDX2
143 A[21]
–
–
–
I
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
–
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
–
O
O
O
O
O
O
O
O
–
I
D[14]
D[22]
D[30]
D[7]
LDD1
144 A[20]
I
LDD2
145 A[19]
I
LDD3
146 A[18]
198 TCK
I
LDD4
147 A[17]
199 TDI
I
D[15]
D[23]
D[31]
VDD
LDD5
148 A[16]
200 TDO
O
I
LDD6
149 A[15]
201 nTRST
202 BATT_FAULT
203 VSSX
204 VDDX1
205 VDD_FAULT
206 PWR_EN
207 SFRM_C
208 SCLK_C
LDD7
150 A[14]
I
VDDX1
151 VSS
–
VSS
–
100 VSSX
101 L_LCLK
102 L_FCLK
103 nPOE
104 nPWE
–
152 VDD
–
–
VDDX2
VSSX
GP[27]
GP[26]
–
I/O
I/O
O
153 VSSX
154 VDDX2
155 A[13]
–
I
–
–
O
O
O
I/O
I/O
O
O
O
156 A[12]
Note: All VDDX1, VDDX2, and VDDX3 pins should be connected directly to the VDDX power plane
of the system board. VDDP should be connected directly to the VDD plane of the system board.
14-2
SA-1100 Developer’s Manual
Package and Pinout
14.2
Mini-Ball Grid Array – (mBGA)
Figure 14-2 shows the SA-1100 256 mini-ball grid array (mBGA) mechanical drawing.
Figure 14-2. SA-1100 256 Mini-Ball Grid Array Mechanical Drawing
A6843-01
SA-1100 Developer’s Manual
14-3
Package and Pinout
Table 14-2. SA-1100 Pinout – 256-Pin Mini-Ball Grid Array
BGA
Pad
B1
C2
J13
A1
C1
D3
D2
D1
F4
BGA
Pad
N6
P6
D9
F7
R6
R7
T6
P7
T7
N8
P8
R8
BGA
Pad
G7
BGA
Pad
D7
D6
A6
B6
C6
C5
A5
B5
B4
A4
H7
E8
C4
A3
B3
A2
H8
H9
H10
H11
J6
J7
J8
Pin Signal Type
Pin
Signal Type
Pin
35
Type
Pin
Signal
Type
1
2
3
4
5
6
7
8
9
RXD_C I/O
TXD_C I/O
65 GP[15]
66 GP[14]
67 VDDX1
68 VSSX
69 GP[13]
70 GP[12]
71 GP[11]
72 GP[10]
73 GP[9]
74 GP[8]
75 GP[7]
76 GP[6]
77 VDDX1
78 VSSX
79 VDD
I/O
I/O
–
129 VSSX
130 VDDX2
131 VSS
–
–
–
–
O
O
O
O
O
O
O
O
–
193 VDDX3
I
I
I
I
I
I
I
O
I
L12 194 ROMSEL
J16
J14
H14 197 TMS
H13 198 TCK
H16 199 TDI
H15 200 TDO
G14 201 nTRST
G16 202 BATT_FAULT
G15 203 VSSX
F15 204 VDDX1
VDDX2
VSSX
VDD
VSS
–
–
–
–
195 TCK_BYP
196 TESTCLK
–
132 VDD
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
–
–
–
–
I/O
I/O
I/O
I/O
I/O
I/O
I/O
133 nCS[3]
134 nCS[2]
135 nCS[1]
136 nCS[0]
137 A[25]
138 A[24]
139 A[23]
140 A[22]
D[0]
D[8]
D[16]
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
–
10 D[ 24]
11 D[ 1]
12 D[ 9]
13 D[ 17]
14 D[25]
15 VDDX2
16 VSSX
17 D[2]
18 D[10]
19 D[18]
20 D[26]
21 D[3]
22 D[11]
23 D[19]
24 D[27]
25 VDD
26 VSS
27 VDDX2
28 VSSX
29 D[4]
30 D[12]
31 D[20]
32 D[28]
33 D[5]
34 D[13]
35 D[21]
36 D[29]
37 VDDX2
38 VSSX
39 D[6]
40 D[14]
41 D[22]
42 D[30]
43 D[7]
44 D[15]
45 D[23]
46 D[31]
47 VDD
48 VSS
49 VDDX2
50 VSSX
E3
E2
E1
F3
I
–
–
I
K10 141 VSSX
G8
205 VDD_FAULT
F2
F8
T8
R9
P9
T9
142 VDDX2
143 A[21]
144 A[20]
145 A[19]
146 A[18]
–
L13 206 PWR_EN
F14 207 SFRM_C
F13 208 SCLK_C
O
O
O
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
K5
B2
F1
G2
G3
H4
G1
H3
H2
J3
O
O
O
O
O
O
O
O
–
–
–
–
O
O
O
O
O
O
–
–
80 VSS
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
–
81 GP[5]
82 GP[4]
83 GP[3]
84 GP[2]
85 GP[1]
86 GP[0]
87 L_BIAS
88 L_PCLK I/O
89 VDDX1
90 VSSX
F16
E15
E14
E16
D14
D15
D16
C15
G9
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
VSSX
VSSX
VSSX
VSSX
VSSX
VSSX
VSSX
VSSX
VSSX
VSSX
VSSX
VSSX
VSSX
VSSX
VSSX
VSSX
N10 147 A[17]
R10 148 A[16]
P10 149 A[15]
T10 150 A[14]
R11 151 VSS
P11 152 VDD
D11 153 VSSX
J9
H1
J2
–
–
J10
J11
K6
K7
K8
K9
L6
L7
L8
–
–
–
F9
154 VDDX2
M5
D13 91 LDD0
C3
J1
K4
K3
K2
K1
L3
L2
L1
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
–
N12 155 A[13]
T11 156 A[12]
R12 157 A[11]
P12 158 A[10]
P13 159 A[9]
T12 160 A[8]
R13 161 VSSX
T13 162 VDDX1
K11 163 A[7]
F10 164 A[6]
R14 165 A[5]
T14 166 A[4]
R15 167 A[3]
T15 168 A[2]
P14 169 A[1]
P15 170 A[0]
F11 171 VSSX
C16
B16
C14
B14
B15
A16
G10
E6
A15
A14
B13
C13
A13
B12
C12
D12
G11
E7
A12
C11
B11
A11
B10
D10
C10
A10
H6
92 LDD1
93 LDD2
94 LDD3
95 LDD4
96 LDD5
97 LDD6
98 LDD7
99 VDDX1
100 VSSX
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
–
VSSX
VSSX
–
L9
L11
E9
O
O
O
O
O
O
O
O
–
VDDX1
VDDX1
VDDX1
VDDX1
VDDX1
VDDX1
VDDX1
VDDX1
VDDX1
VDDX1
VDDX1
VDDX1
VDDX1
VDDX2
VDDX2
VDDX2
VDDX2
VDDX2
VDDX2
VDDX2
VDDX2
VDDX2
VDDX2
VDDX2
VDDX2
VDDX2
VDDX2
VDDX2
VDDX2
VDDX2
–
I/O
K12 101 L_LCLK
E10
E11
M6
M7
M8
M9
M10
M11
N7
–
D4
M4
M3
M2
M1
N3
N2
P3
P2
N1
P1
E4
E5
R1
T1
R2
P4
T2
R3
D5
F6
T3
R4
T4
P5
R5
T5
102 L_FCLK I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
–
103 nPOE
104 nPWE
105 nPIOR
106 nPIOW
107 VSSX
108 VDDX2
109 VSS
O
O
O
O
–
–
–
–
L4
172 VDDX1
–
T16 173 UDC-
R16 174 UDC+
P16 175 RXD_1
N15 176 TXD_1
N16 177 RXD_2
N14 178 TXD_2
M13 179 RXD_3
M15 180 TXD_3
M14 181 VSSX
M16 182 VDDX1
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
–
–
–
I
O
O
I
–
–
110 VDD
111 PSKTSEL O
N9
N11
E12
E13
F5
F12
G4
G5
G12
G13
H5
H12
J4
J5
J12
M12
N4
–
–
–
112 nIOIS16
113 nPWAIT
114 nPREG
115 nPCE2
116 nPCE1
117 nWE
I
I
O
O
O
O
O
–
51 GP[27] I/O
52 GP[26] I/O
53 GP[25] I/O
54 GP[24] I/O
55 GP[23] I/O
56 GP[22] I/O
118 nOE
119 VSSX
L10
A9
B9
C9
A8
B8
C8
D8
A7
G6
L5
183 VSS
184 TXTAL
120 VDDX2
121 nRAS[3]
122 nRAS[2]
123 nRAS[1]
124 nRAS[0]
125 nCAS[3]
126 nCAS[2]
127 nCAS[1]
128 nCAS[0]
–
57 VDDX1
58 VSSX
–
–
O
O
O
O
O
O
O
O
L15 185 TEXTAL
L14 186 PEXTAL
L16 187 PXTAL
K13 188 VDDP
K15 189 VSS
K14 190 VDD
K16 191 nRESET
J15
59 GP[21] I/O
60 GP[20] I/O
61 GP[19] I/O
62 GP[18] I/O
63 GP[17] I/O
64 GP[16] I/O
–
I
B7
C7
N5
N13
192 nRESET_OUT O
Note: All VDDX1, VDDX2, and VDDX3 pins should be connected directly to the VDDX power plane
of the system board. VDDP should be connected directly to the VDD plane of the system board.
14-4
SA-1100 Developer’s Manual
Debug Support
15
Due to the integration level of the Intel® StrongARM® SA-1100 Microprocessor (SA-1100), many
functions are not directly visible on the external pins. Therefore, some basic debug facilities are
provided that are not present on the Intel® StrongARM® SA-110 Microprocessor (SA-110). These
facilities are in the form of breakpoints that provide the user with the ability to stop execution after
seeing a specific reference in either the instruction or data streams. Execution then proceeds to an
exception routine during which the user may examine the internal state of the machine. The
instruction and data breakpoint facilities are described in this chapter. The breakpoints are enabled
through additions to coprocessor 15.
15.1
Instruction Breakpoint
The instruction breakpoint allows the user to stop the processor execution after the execution of an
instruction at a selected address. This address is programmed into the instruction breakpoint
address and control register (IBCR). This register is 32 bits wide and contains the address value for
the breakpoint, and a bit to enable the breakpoint. Bit 0 is the enable bit. When set, this bit enables
the breakpoint and when cleared, it disables the breakpoint. Bit 1 is reserved and has no effect
when written. Bits 31..2 are compared against the fetch address to qualify the breakpoint. When the
breakpoint is enabled, the SA-1100 executes until the instruction at this address is fetched and the
fetch address equals the program counter (ignoring bits 0 and 1 of the address). At this point, the
processor takes a prefetch abort exception. The interrupt routine must examine R14 (the saved
program counter) to determine if the exception was caused by the breakpoint.
The IBCR is loaded by way of coprocessor 15, register 14. Access to this register is privileged. See
instruction used to access the IBCR.
15.2
Data Breakpoint
The data breakpoint allows the user to stop the processor execution after a load or store operation
to a particular address. The data breakpoint address is programmed into the data breakpoint address
register (DBAR) and is a full 32-bit value (to permit breakpoints on byte accesses).
For stores, the breakpoint condition may also be programmed to include a particular data pattern as
well as the reference address. The data value is programmed by way of the data breakpoint value
register (DBVR) and the data breakpoint mask register (DBMR). The DBVR is a 32-bit register
containing the value against which the store data is compared. The data value can be further
qualified through the data breakpoint mask register (DBMR). The DBMR is a 32-bit register
containing mask information indicating which bits in the store data should be compared against the
DBMR. A 1 in a particular bit position in the DBMR indicates that bit in the DBVR should be
compared against the store data to qualify the breakpoint. To cause a breakpoint on a store data
value, the address breakpoint must also be enabled, otherwise, no breakpoint will occur.
Breakpoints on loads are permitted only through an address match. Breakpoints on load address,
store address, and store data are enabled and disabled through the data breakpoint control register
(DBCR). A single bit is defined for each action. When a breakpoint is taken, the processor takes a
data abort exception and sets bit 9 in the fault status register (FSR).
The DBAR, DBVR, and DBMR are loaded by way of coprocessor 15, register 14. Access to this
register is privileged.
SA-1100 Developer’s Manual
15-1
Boundary-Scan Test Interface
16
The boundary-scan interface conforms to the IEEE Std. 1149.1 – 1990, Standard Test Access Port
and Boundary-Scan Architecture. (Refer to this standard for an explanation of the terms used in
this section and for a description of the TAP controller states.) The Intel® StrongARM® SA-1100
Microprocessor (SA-1100) supports only JTAG continuity testing.
16.1
Overview
The boundary-scan interface provides a means of driving and sampling all the external pins of the
device irrespective of the core state. This function permits testing of both the device’s electrical
connections to the circuit board and (in conjunction with other devices on the circuit board having
a similar interface) testing the integrity of the circuit board connections between devices. The
interface intercepts all external connections within the device, and each such “cell” is then
connected together to form a serial shift register (the boundary-scan register). The whole interface
state transitions that occur in the TAP controller. Note that all SA-1100 signals participate in the
boundary scan. However, in the case of the PWR_EN pin, the contents of the scan latches are not
placed on the pin. This is to prevent a scan operation from turning off power to the SA-1100.
Figure 16-1. Test Access Port (TAP) Controller State Transitions
Test-Logic Reset
tms=1
tms=0
tms=1
tms=1
tms=1
Run-Test/Idle
Select-DR-Scan
tms=0
Select-IR-Scan
tms=0
tms=0
Capture-DR
tms=0
Capture-IR
tms=0
tms=1
tms=1
Shift-DR
tms=1
Shift-IR
tms=1
tms=0
tms=0
tms=1
Exit1-DR
tms=0
Exit1-IR
tms=0
tms=1
tms=0
Pause-DR
tms=1
Pause-IR
tms=1
tms=0
tms=0
tms=0
Exit2-DR
tms=1
Exit2-IR
tms=1
Update-DR
Update-IR
tms=1
tms=0
tms=1
tms=0
SA-1100 Developer’s Manual
16-1
Boundary-Scan Test Interface
16.2
Reset
The boundary-scan interface includes a state-machine controller (the TAP controller). In order to
force the TAP controller into the correct state after power-up of the device, a reset pulse must be
applied to the nTRST pin. If the boundary-scan interface is to be used, then nTRST must be driven
low, and then high again. If the boundary-scan interface is not to be used, then the nTRST pin may
be tied permanently low. Note that a clock on TCK is not necessary to reset the device.
The action of reset (either a pulse or a dc level) is as follows:
• System mode is selected (the boundary-scan chain does NOT intercept any of the signals
passing between the pads and the core).
• IDcode mode is selected. If TCK is pulsed, the contents of the ID register will be clocked out
of TDO.
16.3
Pull-Up Resistors
The IEEE 1149.1 standard effectively requires that TDI, nTRST, and TMS should have internal
pull-up resistors. To minimize static current draw, nTRST has an internal pull-down resistor. These
pins can be left unconnected for normal operation and overdriven to use the JTAG features.
16.4
16.5
Instruction Register
The instruction register is 5 bits in length. There is no parity bit. The fixed value loaded into the
instruction register during the CAPTURE-IR controller state is: 00001.
Public Instructions
The following public instructions are supported:
Instruction
Binary Code
EXTEST
SAMPLE/PRELOAD
CLAMP
HIGHZ
IDCODE
BYPASS
00000
00001
00100
00101
00110
11111
Private
00010, 00011, 00111, 01000-01111, 10000-11110
In the descriptions that follow, TDI and TMS are sampled on the rising edge of TCK, and all output
transitions on TDO occur as a result of the falling edge of TCK.
16-2
SA-1100 Developer’s Manual
Boundary-Scan Test Interface
16.5.1
EXTEST (00000)
The boundary-scan (BS) register is placed in test mode by the EXTEST instruction. The EXTEST
instruction connects the BS register between TDI and TDO. When the instruction register is loaded
with the EXTEST instruction, all the boundary-scan cells are placed in their test mode of operation.
In the CAPTURE-DR state, inputs from the system pins and outputs from the boundary-scan
output cells to the system pins are captured by the boundary-scan cells. In the SHIFT-DR state, the
previously captured test data is shifted out of the BS register via the TDO pin, while new test data
is shifted in via the TDI pin to the BS register parallel input latch. In the UPDATE-DR state, the
new test data is transferred into the BS register parallel output latch. Note that this data is applied
immediately to the system logic and system pins.
16.5.2
SAMPLE/PRELOAD (00001)
The BS register is placed in normal (system) mode by the SAMPLE/PRELOAD instruction. The
SAMPLE/PRELOAD instruction connects the BS register between TDI and TDO. When the
instruction register is loaded with the SAMPLE/PRELOAD instruction, all the boundary-scan cells
are placed in their normal system mode of operation.
In the CAPTURE-DR state, a snapshot of the signals at the boundary-scan cells is taken on the
rising edge of TCK. Normal system operation is unaffected. In the SHIFT-DR state, the sampled
test data is shifted out of the BS register via the TDO pin, while new data is shifted in via the TDI
pin to preload the BS register parallel input latch. In the UPDATE-DR state, the preloaded data is
transferred into the BS register parallel output latch. Note that this data is not applied to the system
logic or system pins while the SAMPLE/PRELOAD instruction is active. This instruction should
be used to preload the boundary-scan register with known data prior to selecting EXTEST
instructions.
16.5.3
CLAMP (00100)
The CLAMP instruction connects a 1-bit shift register (the BYPASS register) between TDI and TDO.
When the CLAMP instruction is loaded into the instruction register, the state of all output signals is
defined by the values previously loaded into the boundary-scan register. A guarding pattern
(specified for this device at the end of this section) should be preloaded into the boundary-scan
register using the SAMPLE/PRELOAD instruction prior to selecting the CLAMP instruction.
In the CAPTURE-DR state, a logic 0 is captured by the bypass register. In the SHIFT-DR state, test
data is shifted into the bypass register via TDI and out via TDO after a delay of one TCK cycle.
Note that the first bit shifted out will be a zero. The bypass register is not affected in the
UPDATE-DR state.
SA-1100 Developer’s Manual
16-3
Boundary-Scan Test Interface
16.5.4
HIGHZ (00101)
The HIGHZ instruction connects a 1-bit shift register (the BYPASS register) between TDI and
TDO. When the HIGHZ instruction is loaded into the instruction register, all outputs are placed in
an inactive drive state.
In the CAPTURE-DR state, a logic 0 is captured by the bypass register. In the SHIFT-DR state, test
data is shifted into the bypass register via TDI and out via TDO after a delay of one TCK cycle.
Note that the first bit shifted out will be a zero. The bypass register is not affected in the
UPDATE-DR state.
16.5.5
IDCODE (00110)
The IDCODE instruction connects the device identification register (or ID register) between TDI
and TDO. The ID register is a 32-bit register that allows the manufacturer, part number and version
of a component to be determined through the TAP. When the instruction register is loaded with the
IDCODE instruction, all the boundary-scan cells are placed in their normal (system) mode of
operation.
In the CAPTURE-DR state, the device identification code (specified at the end of this section) is
captured by the ID register. In the SHIFT-DR state, the previously captured device identification
code is shifted out of the ID register via the TDO pin, while data is shifted in via the TDI pin into
the ID register. In the UPDATE-DR state, the ID register is unaffected.
16.5.6
BYPASS (11111)
The BYPASS instruction connects a 1-bit shift register (the BYPASS register) between TDI and
TDO. When the BYPASS instruction is loaded into the instruction register, all the boundary-scan
cells are placed in their normal (system) mode of operation. This instruction has no effect on the
system pins.
In the CAPTURE-DR state, a logic 0 is captured by the bypass register. In the SHIFT-DR state, test
data is shifted into the bypass register via TDI and out via TDO after a delay of one TCK cycle.
Note that the first bit shifted out will be a zero. The bypass register is not affected in the
UPDATE-DR state.
16-4
SA-1100 Developer’s Manual
Boundary-Scan Test Interface
16.6
Test Data Registers
Figure 16-2 illustrates the structure of the boundary-scan logic.
Figure 16-2. Boundary-Scan Block Diagram
BSINENCELL
®
BSINCELL
I/O
Intel
®
StrongARM
SA-1100
Cell
BSINCELL
BSOUTCELL
Core Logic
BSOUTNENCELL
BSOUTCELL
Device ID Register
Bypass Register
TDO
Instruction Decoder
Instruction Register
TDI
TMS
TCK
TAP
Controller
nTDOEN
nTRST
* StrongARM is a registered trademark of ARM Limited.
A6839-01
16.6.1
Bypass Register
Purpose: This is a single-bit register that can be selected as the path between TDI and TDO to
allow the device to be bypassed during boundary-scan testing.
Length: 1 bit
Operating Mode: When the BYPASS instruction is the current instruction in the instruction
register, serial data is transferred from TDI to TDO in the SHIFT-DR state with a delay of one TCK
cycle.
There is no parallel output from the bypass register.
A logic 0 is loaded from the parallel input of the bypass register in the CAPTURE-DR state.
SA-1100 Developer’s Manual
16-5
Boundary-Scan Test Interface
16.6.2
SA-1100 Device Identification (ID) Code Register
Purpose: This register is used to read the 32-bit device identification code. No programmable
supplementary identification code is provided.
Length: 32 bits
Operating Mode: When the IDCODE instruction is current, the ID register is selected as the serial
path between TDI and TDO.
The format of the ID register is as follows:
31
28 27
12 11
0
Version
Part Number
JEDEC Code
The high-order 4 bits of the ID register contains the version number of the silicon and changes with
each new revision.
There is no parallel output from the ID register.
The 32-bit device identification code is loaded into the ID register from its parallel inputs during
the CAPTURE-DR state.
16.6.3
SA-1100 Boundary-Scan (BS) Register
Purpose: The BS register consists of a serially connected set of cells around the periphery of the
device, at the interface between the core logic and the system input/output pads. This register can
be used to isolate the pins from the core logic and then drive or monitor the system pins.
Operating Modes: The BS register is selected as the register to be connected between TDI and
TDO only during the SAMPLE/PRELOAD and EXTEST instructions. Values in the BS register
are used, but are not changed, during the CLAMP instruction.
In the normal (system) mode of operation, straight-through connections between the core logic and
pins are maintained, and normal system operation is unaffected.
In TEST mode (when EXTEST is the currently selected instruction), values can be applied to the
output pins independently of the actual values on the input pins and core logic outputs. On the
SA-1100, all of the boundary-scan cells include update registers; thus, all of the pins can be
controlled in the above manner. An additional boundary-scan cell is interposed in the scan chain to
control the enabling of the data bus.
The EXTEST guard values should be clocked into the boundary-scan register (using the
SAMPLE/PRELOAD instruction) before the EXTEST instruction is selected, to ensure that known
data is applied to the core logic during the test. These guard values should also be used when new
EXTEST vectors are clocked into the boundary-scan register.
The values stored in the BS register after power-up are not defined. Similarly, the values previously
clocked into the BS register are not guaranteed to be maintained across a boundary-scan reset
(from forcing nTRST low or entering the Test Logic Reset state).
16-6
SA-1100 Developer’s Manual
Boundary-Scan Test Interface
Table 16-1 shows the SA-1100 boundary-scan interface timing specifications.
Table 16-1. SA-1100 Boundary-Scan Interface Timing
Symbol
Tbscl
Parameter
Minimum
Typical
Maximum
Units
Notes
TCK low period
50
50
10
10
5
–
–
–
–
–
–
–
–
–
ns
ns
ns
ns
ns
ns
ns
8
8
–
–
1
1
4
Tbsch
Tbsis
TCK high period
TDI,TMS setup to [TCr]
TDI,TMS hold from [TCr]
TDO hold time
–
Tbsih
Tbsoh
Tbsod
Tbsss
–
–
TCf to TDO valid
–
40
–
I/O signal setup to [TCr]
5
I/O signal hold from
[TCr]
Tbssh
20
–
–
ns
4
Tbsdh
Tbsdd
Tbsoe
Tbsoz
Tbsde
Tbsdz
Tbsr
Data output hold time
TCf to data output valid
TDO enable time
5
–
–
–
–
40
–
ns
ns
ns
ns
ns
ns
ns
ns
ns
5
–
5
–
1,2
1,3
5,6
5,7
—
8
TDO disable time
–
–
40
–
Data output enable time
Data output disable time
Reset period
5
–
–
–
40
—
—
—
30
10
10
—
—
—
Tbsrs
Tbsrh
NOTES:
TMS setup to [TRr]
TMS hold from [TRr]
8
1. Assumes a 25-pF load on TDO. Output timing derates at 0.072 ns/pF of extra load applied.
2. TDO enable time applies when the TAP controller enters the Shift-DR or Shift-IR states.
3. TDO disable time applies when the TAP controller leaves the Shift-DR or Shift-IR states.
4. For correct data latching, the I/O signals (from the core and the pads) must be set up and held with respect
to the rising edge of TCK in the CAPTURE-DR state of the SAMPLE/PRELOAD and EXTEST instructions.
5. Assumes that the data outputs are loaded with the ac test loads.
6. Data output enable time applies when the boundary-scan logic is used to enable the output drivers.
7. Data output disable time applies when the boundary scan is used to disable the output drivers.
8. TCK may be stopped indefinitely in either the low or high phase.
SA-1100 Developer’s Manual
16-9
Register Summary
A
This appendix describes all of the Intel® StrongARM® SA-1100 Microprocessor (SA-1100)
internal registers.
Physical Address
Symbol
Register Name
GPIO Registers
0h 9004 0000
0h 9004 0004
0h 9004 0008
0h 9004 000C
0h 9004 0010
0h 9004 0014
0h 9004 0018
0h 9004 001C
Interrupt Controller Registers
0h 9005 0000
0h 9005 0004
0h 9005 0008
0h 9005 0010
0h 9005 0020
0h 9005 000c
GPLR
GPDR
GPSR
GPCR
GRER
GFER
GEDR
GAFR
GPIO pin level register.
GPIO pin direction register.
GPIO pin output set register.
GPIO pin output clear register.
GPIO rising-edge register.
GPIO falling-edge register.
GPIO edge detect status register.
GPIO alternate function register.
ICIP
Interrupt controller irq pending register.
Interrupt controller mask register.
ICMR
ICLR
ICFP
ICPR
ICPR
Interrupt controller FIQ level register.
Interrupt controller FIQ pending register.
Interrupt controller pending register.
Interrupt controller control register.
Real-Time Clock Registers
0h 9001 0004
0h 9001 0000
0h 9001 0010
0h 9001 0008
OS Timer Registers
0h 9000 0000
0h 9000 0004
0h 9000 0008
0h 9000 000C
0h 9000 0010
0h 9000 0014
0h 9000 0018
0h 9000 001C
RCNR
RTAR
RTSR
RTTR
Real-time clock count register.
Real-time clock alarm register.
Real-time clock status register.
Real-time clock trim register.
OSMR[0]
OSMR[1]
OSMR[2]
OSMR[3]
OSCR
OS timer match registers[3:0].
OS timer counter register.
OSSR
OS timer status register.
OWER
OS timer watchdog enable register.
OS timer interrupt enable register.
OIER
SA-1100 Developer’s Manual
A-1
Register Summary
Physical Address
Symbol
Register Name
Power Manager Registers
0h 9002 0000
PMCR
PSSR
PSPR
PWER
PCFR
PPCR
PGSR
POSR
Power manager control register.
0h 9002 0004
Power manager sleep status register.
Power manager scratchpad register.
Power manager wakeup enable register.
Power manager configuration register.
Power manager PLL configuration register.
Power manager GPIO sleep state register.
Power manager oscillator status register.
0h 9002 0008
0h 9002 000C
0h 9002 0010
0h 9002 0014
0h 9002 0018
0h 9002 001C
Reset Controller Registers
0h 9003 0000
RSRR
RCSR
TUCR
Reset controller software reset register.
Reset controller status register.
Reserved for test.
0h 9003 0004
0h 9003 0008
Memory Controller Registers
0xA000 0000
MDCNFG
MDCAS0
MDCAS1
MDCAS2
MSC0
DRAM configuration register.
0xA000 0004
DRAM CAS waveform shift register 0.
DRAM CAS waveform shift register 1.
DRAM CAS waveform shift register 2.
Static memory control register 0.
Static memory control register 1.
Expansion bus configuration register.
0xA000 0008
0xA000 000C
0xA000 0010
0xA000 0014
MSC1
0xA000 0018
MECR
DMA Controller Registers
0h B000 0000
0h B000 0004
0h B000 0008
0h B000 000C
0h B000 0010
0h B000 0014
0h B000 0018
0h B000 001C
0h B000 0020
0h B000 0024
0h B000 0028
0h B000 002C
0h B000 0030
0h B000 0034
0h B000 0038
0h B000 003C
0h B000 0040
DDAR0
DCSR0
DMA device address register.
DMA control/status register 0 – write ones to set.
Write ones to clear.
Read only.
DBSA0
DBTA0
DBSB0
DBTB0
DDAR1
DMA buffer A start address 0.
DMA buffer A transfer count 0.
DMA buffer B start address 0.
DMA buffer B transfer count 0.
DMA device address register 1.
DMA control/status register 1 – write ones to set.
Write ones to clear.
DCSR1
Read only.
DBSA1
DBTA1
DBSB1
DBTB1
DDAR2
DMA buffer A start address 1.
DMA buffer A transfer count 1.
DMA buffer B start address 1.
DMA buffer B transfer count 1.
DMA device address register 2.
A-2
SA-1100 Developer’s Manual
Register Summary
Physical Address
Symbol
Register Name
0h B000 0044
0h B000 0048
0h B000 004C
0h B000 0050
0h B000 0054
0h B000 0058
0h B000 005C
0h B000 0060
0h B000 0064
0h B000 0068
0h B000 006C
0h B000 0070
0h B000 0074
0h B000 0078
0h B000 007C
0h B000 0080
0h B000 0084
0h B000 0088
0h B000 008C
0h B000 0090
0h B000 0094
0h B000 0098
0h B000 009C
0h B000 00A0
0h B000 00A4
0h B000 00A8
0h B000 00AC
0h B000 00B0
0h B000 00B4
0h B000 00B8
0h B000 00BC
DMA control/status register 2 – write ones to set.
Write ones to clear.
DCSR2
Read only.
DBSA2
DBTA2
DBSB2
DBTB2
DDAR3
DMA buffer A start address 2.
DMA buffer A transfer count 2.
DMA buffer B start address 2.
DMA buffer B transfer count 2.
DMA device address register 3.
DMA control/status register 3 – write ones to set.
Write ones to clear.
DCSR3
Read only.
DBSA3
DBTA3
DBSB3
DBTB3
DDAR4
DMA buffer A start address 3.
DMA buffer A transfer count 3.
DMA buffer B start address 3.
DMA buffer B transfer count 3.
DMA device address register 4.
DMA control/status register 4 – write ones to set.
Write ones to clear.
DCSR4
Read only.
DBSA4
DBTA4
DBSB4
DBTB4
DDAR5
DMA buffer A start address 4.
DMA buffer A transfer count 4.
DMA buffer B start address 4.
DMA buffer B transfer count 4.
DMA device address register 5.
DMA control/status register 5 – write ones to set.
Write ones to clear.
DCSR5
Read only.
DBSA5
DBTA5
DBSB5
DBTB5
DMA buffer A start address 5.
DMA buffer A transfer count 5.
DMA buffer B start address 5.
DMA buffer B transfer count 5.
SA-1100 Developer’s Manual
A-3
Register Summary
Physical Address
Symbol
Register Name
LCD Controller Registers
0hB010 0000
LCCR0
LCSR
—
LCD controller control register 0.
LCD controller status register.
Reserved.
0hB010 0004
0hB010 0008 – 0hB010 000C
0hB010 0010
DBAR1
DCAR1
DBAR2
DCAR2
LCCR1
LCCR2
LCCR3
—
DMA channel 1 base address register.
DMA channel 1 current address register.
DMA channel 2 base address register.
DMA channel 2 current address register.
LCD controller control register 1.
LCD controller control register 2.
LCD controller control register 3.
Reserved.
0hB010 0014
0hB010 0018
0hB010 001C
0hB010 0020
0hB010 0024
0hB010 0028
0hB010 002C – 0hB010 FFFF
UDC Registers (Serial Port 0)
0h8000 0000
UDCCR
UDCAR
UCDOMP
UDCIMP
UDCCS0
UDCCS1
UDCCS2
UDCD0
UDCWC
—
UDC control register.
0h8000 0004
UDC address register.
0h8000 0008
UDC OUT max packet register.
UDC IN max packet register.
UDC endpoint 0 control/status register.
UDC endpoint 1 (out) control/status register.
UDC endpoint 2 (in) control/status register.
UDC endpoint 0 data register.
UDC endpoint 0 write count register.
Reserved.
0h8000 000C
0h8000 0010
0h8000 0014
0h8000 0018
0h8000 001C
0h8000 0020
0h8000 0024
0h8000 0028
UDCDR
—
UDC transmit/receive data register (FIFOs).
Reserved.
0h8000 002C
0h8000 0030
UDCSR
UDC status/interrupt register.
UART Registers (Serial Port 1)
0h 8001 0000
UTCR0
UTCR1
UTCR2
UTCR3
—
UART control register 0.
UART control register 1.
UART control register 2.
UART control register 3.
Reserved.
0h 8001 0004
0h 8001 0008
0h 8001 000C
0h 8001 0010
0h 8001 0014
UTDR
—
UART data register.
Reserved.
0h 8001 0018
0h 8001 001C
UTSR0
UTSR1
—
UART status register 0.
UART status register 1.
Reserved.
0h 8001 0020
0h 8001 0024 – 0h 8001 FFFF
A-4
SA-1100 Developer’s Manual
Register Summary
Physical Address
Symbol
Register Name
SDLC Registers (Serial Port 1)
0h 8002 0060
SDCR0
SDCR1
SDCR2
SDCR3
SDCR4
—
SDLC control register 0.
SDLC control register 1.
SDLC control register 2.
SDLC control register 3.
SDLC control register 4.
Reserved.
0h 8002 0064
0h 8002 0068
0h 8002 006C
0h 8002 0070
0h 8002 0074
0h 8002 0078
SDDR
—
SDLC data register.
Reserved.
0h 8002 007C
0h 8002 0080
SDSR0
SDSR1
—
SDLC status register 0.
SDLC status register 1.
Reserved.
0h 8002 0084
0h 8002 0088 – 0h 8002 FFFF
ICP – UART Registers (Serial Port 2)
0h 8003 0000
UTCR0
UART control register 0.
UART control register 1.
UART control register 2.
UART control register 3.
UART control register 4.
UART data register.
Reserved.
0h 8003 0004
UTCR1
UTCR2
UTCR3
UTCR4
UTDR
—
0h 8031 0008
0h 8003 000C
0h 8003 0010
0h 8003 0014
0h 8003 0018
0h 8003 001C
0h 8003 0020
UTSR0
UTSR1
—
UART status register 0.
UART status register 1.
Reserved.
0h 8003 0024 – 0h 8003 FFFF
ICP – HSSP Registers (Serial Port 2)
0h 8004 0060
HSCR0
HSSP control register 0.
HSSP control register 1.
Reserved.
0h 8004 0064
HSCR1
—
0h 8004 0068
0h 8004 006C
HSDR
—
HSSP data register.
Reserved.
0h 8004 0070
0h 8004 0074
HSSR0
HSSR1
—
HSSP status register 0.
HSSP status register 1.
Reserved.
0h 8004 0078
0h 8004 007C – 0h 8004 FFFF
SA-1100 Developer’s Manual
A-5
Register Summary
Physical Address
Symbol
Register Name
UART Registers (Serial Port 3)
0h 8005 0000
UTCR0
UTCR1
UTCR2
UTCR3
—
UART control register 0.
UART control register 1.
UART control register 2.
UART control register 3.
Reserved.
0h 8005 0004
0h 8005 0008
0h 8005 000C
0h 8005 0010
0h 8005 0014
UTDR
—
UART data register.
Reserved.
0h 8005 0018
0h 8005 001C
UTSR0
UTSR1
—
UART status register 0.
UART status register 1.
Reserved.
0h 8005 0020
0h 8005 0024 – 0h 8005 FFFF
MCP Registers (Serial Port 4)
0h 8006 0000
MCCR0
—
MCP control register 0.
Reserved.
0h 8006 0004
0h 8006 0008
MCDR0
MCDR1
MCDR2
—
MCP data register 0.
MCP data register 1.
MCP data register 2.
Reserved.
0h 8006 000C
0h 8006 0010
0h 8006 0014
0h 8006 0018
MCSR
—
MCP status register.
Reserved.
0h 8006 001C – 0h 8006 005C
SSP Registers (Serial Port 4)
0h 8007 0060
SSCR0
SSCR1
—
SSP control register 0.
SSP control register 1.
Reserved.
0h 8007 0064
0h 8007 0068
0h 8007 006C
SSDR
—
SSP data register.
Reserved.
0h 8007 0070
0h 8007 0074
SSSR
—
SSP status register.
Reserved.
0h 8007 0078 – 0h 8007 FFFF
PPC Registers
0h 9006 0000
PPDR
PPSR
PPAR
PSDR
PPFR
MCCR1
—
PPC pin direction register.
PPC pin state register.
PPC pin assignment register.
PPC sleep mode direction register.
PPC pin flag register.
0h 9006 0004
0h 9006 0008
0h 9006 000C
0h 9006 0010
0h 9006 0030
MCP control register 1.
Reserved.
0h 9006 0034 – 0h 9006 FFFF
A-6
SA-1100 Developer’s Manual
3.6864–MHz Oscillator Specifications B
A 3.6864-MHz crystal oscillator is integrated on the Intel® StrongARM® SA-1100 Microprocessor
(SA-1100) for use as a reference frequency for the PLLs that generate the internal clocks to the
processor. The phase noise of this reference frequency should be minimized because it could be
amplified by the PLLs, resulting in PLL output frequency jitter. For this application, the long-term
stability and the temperature effect on the frequency are not important because they affect the
frequency by less than 1%. The oscillator circuit is designed to work across a range of crystal
parameters so that the system designer can choose from several 3.6864-MHz crystals available on
the market. In normal operation, the pins of the crystal, Q1 and Q2, are connected to the SA-1100
pins, PXTAL and PEXTAL. Note that a 3.5795-MHz crystal can also be used, but in order to meet
the frequency specifications of several of the integrated I/O ports, a 3.6864-MHz crystal is
required.
In some applications, it may be desirable to provide the 3.6864-MHz reference from an external
B.1
Specifications
This section includes specifications for the oscillator circuit and the quartz crystal.
B.1.1
System Specifications
This section includes the specifications of the oscillator circuit. It assumes that the crystal used
meets the specifications given in the following sections.
Temperature Range
This is the junction temperature range for the oscillator circuit on the SA-1100. The crystal itself
may be at the ambient temperature; the oscillator circuit integrated on the SA-1100 is most likely
operating at a higher temperature that is dependent on the activity of the SA-1100.
Current Consumption
Because this oscillator might run during the sleep mode of the processor, the power consumption is
critical. The specified current consumption is for the oscillator only. The power associated with the
oscillator output buffer is not included because this buffer is powered down in sleep.
Startup Time
This specification depends on the crystal characteristics and the layout of the printed circuit board
(PCB). The value given assumes that the crystal and board layout conform to the values given in
the remainder of this document. The critical parameters in the crystal specification are the shunt
capacitance (Co) and the motional resistance (Rm), which must be no greater than the maximums
specified. The critical parameters in the PCB layout are the parasitic capacitances between PXTAL
and PEXTAL, and between either of these nodes and VSS. Note that in some applications, such as
a system that includes a socketed SA-1100, it may be difficult to meet the parasitic capacitances
specified. While the 3.6864-MHz oscillator will start with parasitic capacitances, which are
SA-1110 Developer’s Manual
B-1
3.6864–MHz Oscillator Specifications
approximately twice the values given, the startup time in this situation will be about double the
specified startup time and the current consumption will increase. Capacitances larger than twice the
specified values may prevent the oscillator from starting.
B.1.1.1.
B.1.1.2.
Parasitic Capacitance Off-chip Between PXTAL and PEXTAL
The parasitic capacitance off-chip between PXTAL and PEXTAL is the board capacitance
between the PXTAL and PEXTAL pins.
Parasitic Capacitance Off-chip Between PXTAL or PEXTAL and VSS
The parasitic capacitance off-chip between PXTAL or PEXTAL and VSS is the parasitic board
capacitance between the PXTAL or PEXTAL pins and the VSS wire surrounding the crystal
connections.
B.1.1.3.
B.1.1.4.
Parasitic Resistance Between PXTAL and PEXTAL
The parasitic resistance between PXTAL and PEXTAL is the parasitic resistance between the
PXTAL and PEXTAL pins due to moisture and other effects.
Parasitic Resistance Between PXTAL or PEXTAL and VSS
The parasitic resistance between PXTAL or PEXTAL and VSS is the parasitic resistance between
the PXTAL or PEXTAL pins to VSS due to moisture and other effects.
The following table describes the system specifications of the oscillator circuit.
Specification
Minimum
Typical
Maximum
Unit
o
Temperature range
Supply voltage
0
100
3.6
0.3
40
C
3
3.3
—
V
Ripple voltage on the supply
Current consumption
Startup time
—
—
—
V
15
15
µA
ms
150
Parasitic capacitance off-chip
between PXTAL and PEXTAL
pF
pF
—
—
—
—
1
2
Parasitic capacitance off-chip
between PXTAL or PEXTAL and
VSS
Parasitic resistance between
PXTAL or PEXTAL to VSS
1
1
—
—
—
—
MΩ
Parasitic resistance between
PXTAL and PEXTAL
MΩ
B-2
SA-1110 Developer’s Manual
3.6864–MHz Oscillator Specifications
B.1.2
Quartz Crystal Specification
The following specifications for the quartz crystal are shown in the figure and table below.
Resonance frequency (fs):
Resonance frequency of the crystal.
Equivalent serial capacitance in the crystal
model.
Motional capacitance (Cm):
Motional inductance (Lm):
Not generally given in supplier specification.
Motional resistance (Rm):
Equivalent serial resistance in the crystal
model. Some crystal providers refer to this
resistance as the Equivalent Series
Resistance (ESR) or simply Series
Resistance.
Shunt capacitance (Co):
Parasitic capacitance between Q1 and Q2.
Load capacitance (CL):
Needed load capacitance viewed by the
crystal to oscillate at fs.
Drive level:
Power dissipated in the equivalent serial
resistance (Rm).
Aging:
Resonance frequency shift due to aging.
Co
Q1
Q2
Cm
Lm
Rm
Specification
Minimum
Typical
Maximum
Unit
Resonance frequency (fs)
Motional resistance (Rm)
Shunt capacitance (Co)
Drive level
3.5795
40
3.6864
180
—
—
300
7
MHz
W
—
pF
—
—
10
µW
Crystal type
AT cut crystal
SA-1110 Developer’s Manual
B-3
32.768–kHz Oscillator Specifications C
A 32.768-kHz crystal oscillator is integrated on the Intel® StrongARM® SA-1100 Microprocessor
(SA-1100) for use as a time base for the real-time clock (RTC). The output frequency of the crystal
oscillator is divided by 32768 (215) to deliver a 1-Hz signal to the RTC. A digital tuning circuit is
included on the SA-1100 in order to calibrate the 1-Hz output for each crystal and circuit based on a
set of values stored in an external EEPROM. The oscillator circuit is designed to work across a range
of crystal parameters so that the system designer can choose from several 32.768-kHz crystals
available on the market. In normal operation, the pins of the crystal, Q1 and Q2, are connected to the
SA-1100 pins, TXTAL and TEXTAL.
In some applications, it may be desirable to provide the 32.768-kHz reference from an external
C.1
Specifications
This section includes specifications for the oscillator circuit and the quartz crystal.
C.1.1
System Specifications
This section includes the specifications of the oscillator circuit. It assumes that the crystal used
meets the specifications given in the following sections.
C.1.1.1.
C.1.1.2.
C.1.1.3.
Temperature Range
This is the junction temperature range for the oscillator circuit on the SA-1100. The crystal itself
may be at the ambient temperature; the oscillator circuit integrated on the SA-1100 is most likely
operating at a higher temperature that is dependent on the activity of the SA-1100.
Current Consumption
Because this oscillator runs during the sleep mode of the processor, the power consumption is
critical. The specified current consumption is for the oscillator and its output buffer only. The
power of the tuning circuit and RTC is not included in the value specified.
Startup Time
This specification depends on the crystal characteristics and the layout of the printed circuit board
(PCB). The value given assumes that the crystal and board layout conform to the values given in
the remainder of this document. The critical parameters in the crystal specification are the shunt
capacitance (Co) and the motional resistance (Rm), which must be no greater than the maximums
specified. The critical parameters in the PCB layout are the parasitic capacitances between TXTAL
and TEXTAL, and between either of these nodes and VSS. Note that in some applications, such as
a system that includes a socketed SA-1100, it may be difficult to meet the parasitic capacitances
specified. While the 32.768-kHz oscillator will start with parasitic capacitances which are
SA-1100 Developer’s Manual
C-1
32.768–kHz Oscillator Specifications
approximately twice the values given; the startup time in this situation will be about double the
specified startup time and the current consumption will increase. Capacitances larger than twice the
specified values may prevent the oscillator from starting.
C.1.1.4.
Frequency Shift Due to Temperature Effect on the Circuit
The frequency shift due to temperature effect on the circuit is the influence of the oscillator circuit
on the frequency of oscillation due to temperature effect. The appropriate temperature range is the
junction temperature on the SA-1100, not the ambient temperature. Note that this specification
does not include either the temperature effects on the quartz or the aging of the crystal. It includes
the temperature effect of the circuit only. The frequency shift of the crystal itself due to temperature
may be significantly larger than that of the oscillator circuit. However, for a long-term stability
calculation, it may be appropriate to consider the average temperature of the crystal rather than the
extreme values of temperature.
C.1.1.5.
C.1.1.6.
Parasitic Capacitance Off-chip Between TXTAL and TEXTAL
The parasitic capacitance off-chip between TXTAL and TEXTAL is the board capacitance between
the TXTAL and TEXTAL pins.
Parasitic Capacitance Off-chip Between TXTAL or TEXTAL and VSS
The parasitic capacitance off-chip between TXTAL or TEXTAL and VSS is the parasitic board
capacitance between the TXTAL or TEXTAL pins and the VSS wire surrounding the crystal
connections.
C.1.1.7.
C.1.1.8.
Parasitic Resistance Between TXTAL and TEXTAL
The parasitic resistance between TXTAL and TEXTAL is the parasitic resistance between the
TXTAL and TEXTAL pins due to moisture and other effects.
Parasitic Resistance Between TXTAL or TEXTAL and VSS
The parasitic resistance between TXTAL or TEXTAL and VSS is the parasitic resistance between
the TXTAL or TEXTAL pins to VSS due to moisture and other effects.
The following table describes the specifications of the oscillator circuit.
Specification
Minimum Typical
Maximum Unit
o
Temperature range
0
100
3.6
0.3
2
C
Supply voltage
3
3.3
—
1
V
Ripple voltage on the supply
Current consumption
—
—
—
—
V
µA
s
Startup time
—
—
2
Frequency shift due to temperature effect on the circuit
+/-3
ppm
Parasitic capacitance off-chip
between TXTAL and TEXTAL
—
—
1
pF
C-2
SA-1100 Developer’s Manual
32.768–kHz Oscillator Specifications
Parasitic capacitance off-chip
between TXTAL or TEXTAL and VSS
—
—
—
2
pF
Parasitic resistance between
TXTAL or TEXTAL to VSS
10
—
MΩ
Parasitic resistance between
TXTAL and TEXTAL
10
—
—
MΩ
C.1.2
Quartz Crystal Specification
The following specifications for the quartz crystal are shown in the figure and table below.
Resonance frequency (fs):
Motional capacitance (Cm):
Motional inductance (Lm):
Resonance frequency of the crystal.
Equivalent serial capacitance in the crystal model.
Not generally given in supplier specification.
Equivalent serial resistance in the crystal model. Some crystal
providers refer to this resistance as the Equivalent Series
Resistance (ESR) or simply Series Resistance.
Motional resistance (Rm):
Other providers supply a Quality Factor, Q, instead of Rm;
therefore, the values for Q
corresponding to specified range of Rm are supplied in the
following table.
Shunt capacitance (Co):
Load capacitance (CL):
Drive level:
Parasitic capacitance between Q1 and Q2.
Needed load capacitance viewed by the crystal to oscillate at fs.
Power dissipated in the equivalent serial resistance (Rm).
Resonance frequency shift due to aging.
Aging:
Co
Q1
Q2
Cm
Lm
Rm
Specification
Minimum
Typical
Maximum
Unit
Hz
—
Resonance frequency (fs)
Quality factor (Q)
—
32768
80K
3
—
40K
2
200K
4
Motional capacitance (Cm)
Motional resistance (Rm)
Shunt capacitance (Co)
fF
—
—
50K
2
W
0.9
—
pF
SA-1100 Developer’s Manual
C-3
32.768–kHz Oscillator Specifications
Load capacitance (CL)
Drive level
10
12.5
25
pF
—
—
1
µW
o
o
Crystal type
Tuning fork (X+5 or X+2 cut)
The following values are not required for the crystal oscillator to function, but they directly affect
the performance of the oscillator in the system because they determine the accuracy of the crystal
itself. The values given represent those seen on typical crystals used for timekeeping, and are
provided for information only.
Specification
Minimum
Typical
Maximum
Unit
Frequency tolerance
Parabolic curvature
Turnover temperature
Temperature range
Aging
+/-5
—
20
0
+/-20
-0.042
25
+/-30
-0.05
30
ppm
o
ppm/ C
o
C
o
—
60
C
—
+/-3
+/-5
ppm/year
C-4
SA-1100 Developer’s Manual
Internal Test
Internal Test
D
The Test Unit contains a register that enables certain test modes. Some of these test modes are
reserved for manufacturing test and should not be invoked by an end user.
D.1
Test Unit Control Register (TUCR)
The Test Unit Control Register (TUCR) contains control bits that put the Intel® StrongARM®
SA-1100 Microprocessor (SA-1100) in various test modes. It is recommended that the operating
system write protect these registers under normal conditions to prevent them from being
inadvertently written. The following figure shows the format of this register. At reset reserved bits
are zero. Writing reserved bits to one can lead to UNPREDICTABLE results.
Bit 31
30
29
28
27
26
25
24
23
22
21
20
19
18
17 16
Reserved
R/W
TSEL2 TSEL1 TSEL0
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit 15
R/W
Reset
14
13
12
11
10
9
PMD
8
7
6
5
4
3
2
1
Reserved
MR
Reserved
0
0
0
0
0
0
0
0
0
0
0
0
A6071-02
Bit
0..5
Name
Description
Reserved
Reserved
Reserved
Reserved
PMD
—
—
—
—
6
7
8
9
Power management disable.
When PMD is set, sleep mode is disabled and the SA-1100 ignores the
ForceSleep bit, as well as the BATT_FAULT and VDD_Fault pins. This bit is
cleared on hard reset.
10
MR
Memory request mode. Controls two GPIO pins used for external arbitration and
for the memory bus.
0 – GP<21> and GP<22> are not used for an alternate function.
1 – GP<21> and GP<22> are reserved for use as MBGNT and MBREQ,
respectively.
11..19
20
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
—
—
—
—
—
—
—
—
21
22
23
24
25
26
SA-1100 Developer’s Manual
D-1
Internal Test
Bit
Name
Description
27..28 Reserved
—
29..31 TSEL2-0
Test selects. Routes internal signals out onto GPIO<27> for observing internal
clock signals. To observe these clocks, set bit 27 to one in the GAFR and GPDR
registers and set the TSEL bits to the following settings to select which clock is
driven onto GP<27>:
TSEL2
TSEL1 TSEL0 GP<27>(alternate function)
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
32-kHz oscillator
3.6864-MHz oscillator
VDD ring oscillator/16
96-MHz PLL/4
32-kHz oscillator (also enable rclk on GP<26>
3.6864-MHz oscillator
Main PLL/16
VDDL ring oscillator/4
D-2
SA-1100 Developer’s Manual
Support, Products, and Documentation
If you need general information or support, call 1-800-628-8686 or visit Intel’s website at:
http://www.intel.com
Copies of documents that have an ordering number and are referenced in this document, a product
catalog, or other Intel literature may be obtained by calling 1-800-548-4725 or by visiting Intel’s
website for developers at:
http://developer.intel.com
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