TMS320C645x DSP
Ethernet Media Access Controller (EMAC)/
Management Data Input/Output (MDIO)
User's Guide
Literature Number: SPRU975B
August 2006
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Contents
Preface.............................................................................................................................. 10
1
Introduction.............................................................................................................. 11
1.1
1.2
1.3
1.4
Purpose of the Peripheral ..................................................................................... 11
Features ......................................................................................................... 11
Functional Block Diagram ..................................................................................... 12
Industry Standard(s) Compliance Statement ............................................................... 13
2
EMAC Functional Architecture .................................................................................... 14
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
Clock Control.................................................................................................... 14
Memory Map .................................................................................................... 15
System Level Connections .................................................................................... 16
Ethernet Protocol Overview ................................................................................... 24
Programming Interface......................................................................................... 26
EMAC Control Module ......................................................................................... 37
Management Data Input/Output (MDIO) Module........................................................... 38
EMAC Module................................................................................................... 43
Media Independent Interfaces ................................................................................ 46
2.10 Packet Receive Operation..................................................................................... 50
2.11 Packet Transmit Operation.................................................................................... 55
2.12 Receive and Transmit Latency ............................................................................... 55
2.13 Transfer Node Priority.......................................................................................... 56
2.14 Reset Considerations .......................................................................................... 56
2.15 Initialization ...................................................................................................... 57
2.16 Interrupt Support................................................................................................ 60
2.17 Power Management............................................................................................ 63
2.18 Emulation Considerations ..................................................................................... 63
EMAC Control Module Registers ................................................................................. 64
3
4
3.1
3.2
3.3
Introduction ...................................................................................................... 64
EMAC Control Module Interrupt Control Register (EWCTL).............................................. 64
MDIO Registers ......................................................................................................... 66
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
Introduction ...................................................................................................... 66
MDIO Version Register (VERSION) ......................................................................... 67
MDIO Control Register (CONTROL)......................................................................... 68
PHY Acknowledge Status Register (ALIVE) ................................................................ 69
PHY Link Status Register (LINK)............................................................................. 70
4.12 MDIO User Access Register 0 (USERACCESS0) ......................................................... 77
4.13 MDIO User PHY Select Register 0 (USERPHYSEL0) .................................................... 78
4.14 MDIO User Access Register 1 (USERACCESS1) ......................................................... 79
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4.15 MDIO User PHY Select Register 1 (USERPHYSEL1) .................................................... 80
5
EMAC Port Registers ................................................................................................. 81
5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8
5.9
Introduction ...................................................................................................... 81
Transmit Identification and Version Register (TXIDVER) ................................................. 85
Transmit Control Register (TXCONTROL) .................................................................. 86
Transmit Teardown Register (TXTEARDOWN) ............................................................ 87
Receive Identification and Version Register (RXIDVER).................................................. 88
Receive Control Register (RXCONTROL) .................................................................. 89
Receive Teardown Register (RXTEARDOWN)............................................................. 90
Transmit Interrupt Status (Unmasked) Register (TXINTSTATRAW) .................................... 91
5.10 Transmit Interrupt Mask Set Register (TXINTMASKSET) ................................................ 93
5.11 Transmit Interrupt Mask Clear Register (TXINTMASKCLEAR) .......................................... 94
5.12 MAC Input Vector Register (MACINVECTOR) ............................................................. 95
5.13 Receive Interrupt Status (Unmasked) Register (RXINTSTATRAW)..................................... 96
5.14 Receive Interrupt Status (Masked) Register (RXINTSTATMASKED) ................................... 97
5.15 Receive Interrupt Mask Set Register (RXINTMASKSET)................................................. 98
5.16 Receive Interrupt Mask Clear Register (RXINTMASKCLEAR)........................................... 99
5.17 MAC Interrupt Status (Unmasked) Register (MACINTSTATRAW)..................................... 100
5.18 MAC Interrupt Status (Masked) Register (MACINTSTATMASKED) ................................... 101
5.19 MAC Interrupt Mask Set Register (MACINTMASKSET)................................................. 102
5.20 MAC Interrupt Mask Clear Register (MACINTMASKCLEAR)........................................... 103
5.22 Receive Unicast Enable Set Register (RXUNICASTSET)............................................... 106
5.23 Receive Unicast Clear Register (RXUNICASTCLEAR).................................................. 107
5.24 Receive Maximum Length Register (RXMAXLEN) ....................................................... 108
5.25 Receive Buffer Offset Register (RXBUFFEROFFSET) .................................................. 109
5.26 Receive Filter Low Priority Frame Threshold Register (RXFILTERLOWTHRESH) .................. 110
5.28 Receive Channel 0-7 Free Buffer Count Register (RXnFREEBUFFER) .............................. 112
5.29 MAC Control Register (MACCONTROL) .................................................................. 113
5.30 MAC Status Register (MACSTATUS) ...................................................................... 115
5.31 Emulation Control Register (EMCONTROL) .............................................................. 117
5.32 FIFO Control Register (FIFOCONTROL) .................................................................. 118
5.33 MAC Configuration Register (MACCONFIG).............................................................. 119
5.34 Soft Reset Register (SOFTRESET) ........................................................................ 120
5.35 MAC Source Address Low Bytes Register (MACSRCADDRLO)....................................... 121
5.36 MAC Source Address High Bytes Register (MACSRCADDRHI) ....................................... 122
5.37 MAC Hash Address Register 1 (MACHASH1) ............................................................ 123
5.38 MAC Hash Address Register 2 (MACHASH2) ............................................................ 124
5.39 Back Off Test Register (BOFFTEST)....................................................................... 125
5.40 Transmit Pacing Algorithm Test Register (TPACETEST) ............................................... 126
5.41 Receive Pause Timer Register (RXPAUSE) .............................................................. 127
5.42 Transmit Pause Timer Register (TXPAUSE).............................................................. 128
5.43 MAC Address Low Bytes Register (MACADDRLO)...................................................... 129
5.44 MAC Address High Bytes Register (MACADDRHI) ...................................................... 130
5.45 MAC Index Register (MACINDEX) ......................................................................... 131
5.46 Transmit Channel 0-7 DMA Head Descriptor Pointer Register (TXnHDP)............................ 132
5.47 Receive Channel 0-7 DMA Head Descriptor Pointer Register (RXnHDP) ............................ 133
4
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5.48 Transmit Channel 0-7 Completion Pointer Register (TXnCP)........................................... 134
5.49 Receive Channel 0-7 Completion Pointer Register (RXnCP) ........................................... 135
5.50 Network Statistics Registers................................................................................. 136
Appendix A Glossary ...................................................................................................... 145
Appendix B Revision History ............................................................................................ 147
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List of Figures
1
EMAC and MDIO Block Diagram ........................................................................................ 12
Ethernet Configuration with MII Interface ............................................................................... 16
Ethernet Configuration with RMII Interface ............................................................................. 18
Ethernet Configuration with GMII Interface ............................................................................. 20
Ethernet Configuration with RGMII Interface ........................................................................... 22
Ethernet Frame ............................................................................................................. 24
Basic Descriptor Format................................................................................................... 26
Typical Descriptor Linked List ............................................................................................ 27
Transmit Descriptor Format............................................................................................... 30
Receive Descriptor Format................................................................................................ 33
EMAC Control Module Block Diagram .................................................................................. 37
MDIO Module Block Diagram............................................................................................. 39
EMAC Module Block Diagram............................................................................................ 43
EMAC Control Module Interrupt Control Register (EWCTL).......................................................... 64
EMAC Control Module Interrupt Timer Count Register (EWINTTCNT)............................................. 65
MDIO Version Register (VERSION) ..................................................................................... 67
MDIO Control Register (CONTROL)..................................................................................... 68
PHY Acknowledge Status Register (ALIVE)............................................................................ 69
PHY Link Status Register (LINK)......................................................................................... 70
MDIO Link Status Change Interrupt (Unmasked) Register (LINKINTRAW)........................................ 71
MDIO Link Status Change Interrupt (Masked) Register (LINKINTMASKED) ...................................... 72
MDIO User Command Complete Interrupt (Unmasked) Register (USERINTRAW)............................... 73
MDIO User Command Complete Interrupt (Masked) Register (USERINTMASKED) ............................. 74
MDIO User Command Complete Interrupt Mask Set Register (USERINTMASKSET) ........................... 75
MDIO User Command Complete Interrupt Mask Clear Register (USERINTMASKCLEAR) ..................... 76
MDIO User Access Register 0 (USERACCESS0)..................................................................... 77
MDIO User PHY Select Register 0 (USERPHYSEL0) ................................................................ 78
MDIO User Access Register 1 (USERACCESS1)..................................................................... 79
MDIO User PHY Select Register 1 (USERPHYSEL1) ................................................................ 80
Transmit Identification and Version Register (TXIDVER)............................................................. 85
Transmit Control Register (TXCONTROL).............................................................................. 86
Transmit Teardown Register (TXTEARDOWN)........................................................................ 87
Receive Identification and Version Register (RXIDVER) ............................................................. 88
Receive Control Register (RXCONTROL) .............................................................................. 89
Receive Teardown Register (RXTEARDOWN) ........................................................................ 90
Transmit Interrupt Status (Unmasked) Register (TXINTSTATRAW) ................................................ 91
Transmit Interrupt Status (Masked) Register (TXINTSTATMASKED) .............................................. 92
Transmit Interrupt Mask Set Register (TXINTMASKSET) ............................................................ 93
Transmit Interrupt Mask Clear Register (TXINTMASKCLEAR) ...................................................... 94
MAC Input Vector Register (MACINVECTOR) ......................................................................... 95
Receive Interrupt Status (Unmasked) Register (RXINTSTATRAW) ................................................ 96
Receive Interrupt Status (Masked) Register (RXINTSTATMASKED)............................................... 97
Receive Interrupt Mask Set Register (RXINTMASKSET)............................................................. 98
Receive Interrupt Mask Clear Register (RXINTMASKCLEAR) ...................................................... 99
MAC Interrupt Status (Unmasked) Register (MACINTSTATRAW) ................................................ 100
MAC Interrupt Status (Masked) Register (MACINTSTATMASKED)............................................... 101
MAC Interrupt Mask Set Register (MACINTMASKSET)............................................................. 102
MAC Interrupt Mask Clear Register (MACINTMASKCLEAR) ...................................................... 103
Receive Multicast/Broadcast/Promiscuous Channel Enable Register (RXMBPENABLE) ...................... 104
Receive Unicast Enable Set Register (RXUNICASTSET) .......................................................... 106
Receive Unicast Clear Register (RXUNICASTCLEAR) ............................................................. 107
Receive Maximum Length Register (RXMAXLEN)................................................................... 108
2
3
4
5
6
7
8
9
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
6
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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
Receive Buffer Offset Register (RXBUFFEROFFSET).............................................................. 109
Receive Filter Low Priority Frame Threshold Register (RXFILTERLOWTHRESH).............................. 110
Receive Channel n Flow Control Threshold Register (RXnFLOWTHRESH) ..................................... 111
Receive Channel n Free Buffer Count Register (RXnFREEBUFFER) ............................................ 112
MAC Control Register (MACCONTROL) .............................................................................. 113
MAC Status Register (MACSTATUS).................................................................................. 115
Emulation Control Register (EMCONTROL) .......................................................................... 117
FIFO Control Register (FIFOCONTROL).............................................................................. 118
MAC Configuration Register (MACCONFIG) ......................................................................... 119
Soft Reset Register (SOFTRESET) .................................................................................... 120
MAC Source Address Low Bytes Register (MACSRCADDRLO)................................................... 121
MAC Source Address High Bytes Register (MACSRCADDRHI)................................................... 122
MAC Hash Address Register 1 (MACHASH1)........................................................................ 123
MAC Hash Address Register 2 (MACHASH2)........................................................................ 124
Back Off Random Number Generator Test Register (BOFFTEST)................................................ 125
Transmit Pacing Algorithm Test Register (TPACETEST) ........................................................... 126
Receive Pause Timer Register (RXPAUSE) .......................................................................... 127
Transmit Pause Timer Register (TXPAUSE).......................................................................... 128
MAC Address Low Bytes Register (MACADDRLO).................................................................. 129
MAC Address High Bytes Register (MACADDRHI).................................................................. 130
MAC Index Register (MACINDEX) ..................................................................................... 131
Transmit Channel n DMA Head Descriptor Pointer Register (TXnHDP) .......................................... 132
Receive Channel n DMA Head Descriptor Pointer Register (RXnHDP) .......................................... 133
Transmit Channel n Completion Pointer Register (TXnCP)......................................................... 134
Receive Channel n Completion Pointer Register (RXnCP) ......................................................... 135
Statistics Register......................................................................................................... 136
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List of Tables
1
Interface Selection Pins ................................................................................................... 16
EMAC and MDIO Signals for MII Interface ............................................................................. 17
EMAC and MDIO Signals for RMII Interface ........................................................................... 19
EMAC and MDIO Signals for GMII Interface ........................................................................... 21
EMAC and MDIO Signals for RGMII Interface ......................................................................... 23
Ethernet Frame Description............................................................................................... 24
Basic Descriptors........................................................................................................... 26
Receive Frame Treatment Summary .................................................................................... 53
Middle of Frame Overrun Treatment .................................................................................... 54
Emulation Control .......................................................................................................... 63
EMAC Control Module Registers......................................................................................... 64
EMAC Control Module Interrupt Control Register (EWCTL) Field Descriptions ................................... 64
EMAC Control Module Interrupt Timer Count Register (EWINTTCNT) Field Descriptions....................... 65
Management Data Input/Output (MDIO) Registers .................................................................... 66
MDIO Version Register (VERSION) Field Descriptions............................................................... 67
MDIO Control Register (CONTROL) Field Descriptions .............................................................. 68
PHY Acknowledge Status Register (ALIVE) Field Descriptions ..................................................... 69
PHY Link Status Register (LINK) Field Descriptions .................................................................. 70
MDIO Link Status Change Interrupt (Unmasked) Register (LINKINTRAW) Field Descriptions ................. 71
MDIO Link Status Change Interrupt (Masked) Register (LINKINTMASKED) Field Descriptions................ 72
MDIO User Command Complete Interrupt (Unmasked) Register (USERINTRAW) Field Descriptions ........ 73
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
MDIO User Command Complete Interrupt Mask Clear Register (USERINTMASKCLEAR) Field
Descriptions ................................................................................................................. 76
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
MDIO User Access Register 0 (USERACCESS0) Field Descriptions............................................... 77
MDIO User PHY Select Register 0 (USERPHYSEL0) Field Descriptions.......................................... 78
MDIO User Access Register 1 (USERACCESS1) Field Descriptions............................................... 79
MDIO User PHY Select Register 1 (USERPHYSEL1) Field Descriptions.......................................... 80
Ethernet Media Access Controller (EMAC) Registers................................................................. 81
Transmit Identification and Version Register (TXIDVER) Field Descriptions....................................... 85
Transmit Control Register (TXCONTROL) Field Descriptions ....................................................... 86
Transmit Teardown Register (TXTEARDOWN) Field Descriptions.................................................. 87
Receive Identification and Version Register (RXIDVER) Field Descriptions ....................................... 88
Receive Control Register (RXCONTROL) Field Descriptions........................................................ 89
Receive Teardown Register (RXTEARDOWN) Field Descriptions .................................................. 90
Transmit Interrupt Status (Unmasked) Register (TXINTSTATRAW) Field Descriptions.......................... 91
Transmit Interrupt Status (Masked) Register (TXINTSTATMASKED) Field Descriptions ........................ 92
Transmit Interrupt Mask Set Register (TXINTMASKSET) Field Descriptions...................................... 93
Transmit Interrupt Mask Clear Register (TXINTMASKCLEAR) Field Descriptions................................ 94
MAC Input Vector Register (MACINVECTOR) Field Descriptions................................................... 95
Receive Interrupt Status (Unmasked) Register (RXINTSTATRAW) Field Descriptions .......................... 96
Receive Interrupt Status (Masked) Register (RXINTSTATMASKED) Field Descriptions......................... 97
Receive Interrupt Mask Set Register (RXINTMASKSET) Field Descriptions ...................................... 98
Receive Interrupt Mask Clear Register (RXINTMASKCLEAR) Field Descriptions ................................ 99
MAC Interrupt Status (Unmasked) Register (MACINTSTATRAW) Field Descriptions .......................... 100
MAC Interrupt Status (Masked) Register (MACINTSTATMASKED) Field Descriptions......................... 101
MAC Interrupt Mask Set Register (MACINTMASKSET) Field Descriptions ...................................... 102
MAC Interrupt Mask Clear Register (MACINTMASKCLEAR) Field Descriptions ................................ 103
Receive Multicast/Broadcast/Promiscuous Channel Enable Register (RXMBPENABLE) Field Descriptions 104
8
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50
51
52
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
A-1
B-1
Receive Unicast Enable Set Register (RXUNICASTSET) Field Descriptions .................................... 106
Receive Unicast Clear Register (RXUNICASTCLEAR) Field Descriptions ....................................... 107
Receive Maximum Length Register (RXMAXLEN) Field Descriptions ............................................ 108
Receive Buffer Offset Register (RXBUFFEROFFSET) Field Descriptions........................................ 109
Receive Filter Low Priority Frame Threshold Register (RXFILTERLOWTHRESH) Field Descriptions ....... 110
Receive Channel n Flow Control Threshold Register (RXnFLOWTHRESH) Field Descriptions............... 111
Receive Channel n Free Buffer Count Register (RXnFREEBUFFER) Field Descriptions ...................... 112
MAC Control Register (MACCONTROL) Field Descriptions........................................................ 113
MAC Status Register (MACSTATUS) Field Descriptions ........................................................... 115
Emulation Control Register (EMCONTROL) Field Descriptions.................................................... 117
FIFO Control Register (FIFOCONTROL) Field Descriptions........................................................ 118
MAC Configuration Register (MACCONFIG) Field Descriptions ................................................... 119
Soft Reset Register (SOFTRESET) Field Descriptions.............................................................. 120
MAC Source Address Low Bytes Register (MACSRCADDRLO) Field Descriptions ............................ 121
MAC Source Address High Bytes Register (MACSRCADDRHI) Field Descriptions............................. 122
MAC Hash Address Register 1 (MACHASH1) Field Descriptions ................................................. 123
MAC Hash Address Register 2 (MACHASH2) Field Descriptions ................................................. 124
Back Off Test Register (BOFFTEST) Field Descriptions ............................................................ 125
Transmit Pacing Algorithm Test Register (TPACETEST) Field Descriptions..................................... 126
Receive Pause Timer Register (RXPAUSE) Field Descriptions.................................................... 127
Transmit Pause Timer Register (TXPAUSE) Field Descriptions ................................................... 128
MAC Address Low Bytes Register (MACADDRLO) Field Descriptions ........................................... 129
MAC Address High Bytes Register (MACADDRHI) Field Descriptions............................................ 130
MAC Index Register (MACINDEX) Field Descriptions............................................................... 131
Transmit Channel n DMA Head Descriptor Pointer Register (TXnHDP) Field Descriptions.................... 132
Receive Channel n DMA Head Descriptor Pointer Register (RXnHDP) Field Descriptions .................... 133
Transmit Channel n Completion Pointer Register (TXnCP) Field Descriptions .................................. 134
Receive Channel n Completion Pointer Register (RXnCP) Field Descriptions................................... 135
Statistics Register Field Descriptions .................................................................................. 136
Physical Layer Definitions ............................................................................................... 146
Document Revision History.............................................................................................. 147
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Preface
SPRU975B–August 2006
Read This First
About This Manual
This document provides a functional description of the Ethernet Media Access Controller (EMAC) and
Physical layer (PHY) device Management Data Input/Output (MDIO) module integrated with
TMS320C645x devices.
Notational Conventions
This document uses the following conventions.
•
Hexadecimal numbers are shown with the suffix h. For example, the following number is 40
hexadecimal (decimal 64): 40h.
•
Registers in this document are shown in figures and described in tables.
–
Each register figure shows a rectangle divided into fields that represent the fields of the register.
Each field is labeled with its bit name, its beginning and ending bit numbers above, and its
read/write properties below. A legend explains the notation used for the properties.
–
Reserved bits in a register figure designate a bit that is used for future device expansion.
Related Documentation From Texas Instruments
The following documents describe the C6000™ devices and related support tools. Copies of these
documents are available on the Internet at www.ti.com. Tip: Enter the literature number in the search box
provided at www.ti.com.
TMS320C6000 CPU and Instruction Set Reference Guide (literature number SPRU732B) describes the
CPU architecture, pipeline, instruction set, and interrupts of the C64x and C64x+ DSPs.
TMS320C6455 Technical Reference (literature number SPRU965) gives an introduction to the
TMS320C6455™ DSP and discusses the application areas that are enhanced.
TMS320C6000 Programmer's Guide (literature number SPRU198) describes ways to optimize C and
assembly code for the TMS320C6000™ DSPs and includes application program examples.
TMS320C6000 Code Composer Studio Tutorial (literature number SPRU301) introduces the Code
Composer Studio™ integrated development environment and software tools.
Code Composer Studio Application Programming Interface Reference Guide (literature number
SPRU321) describes the Code Composer Studio™ application programming interface (API), which allows
you to program custom plug-ins for Code Composer.
TMS320C64x+ Megamodule Reference Guide (literature number SPRU871) describes the
TMS320C64x+ digital signal processor (DSP) megamodule. Included is a discussion on the internal direct
memory access (IDMA) controller, the interrupt controller, the power-down controller, memory protection,
bandwidth management, and the memory and cache.
TMS320C645x DSP Peripherals Overview Reference Guide (literature number SPRUE52) provides a
brief description of the peripherals available on the TMS320C645x digital signal processors (DSPs).
TMS320C6455 Chip Support Libraries (CSL) (literature number SPRC234) is a download with the latest
chip support libraries.
Trademarks
C6000, TMS320C6455, TMS320C6000, Code Composer Studio are trademarks of Texas Instruments.
10
Preface
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User's Guide
SPRU975B–August 2006
Ethernet Media Access Controller (EMAC)/Management
Data Input/Output (MDIO)
1
Introduction
This document provides a functional description of the Ethernet Media Access Controller (EMAC) and
Physical layer (PHY) device Management Data Input/Output (MDIO) module integrated with
TMS320C645x (C645x) devices. Included are the features of the EMAC and MDIO modules, a discussion
of their architecture and operation, how these modules connect to the outside world, and the registers
description for each module.
The EMAC controls the flow of packet data from the processor to the PHY. The MDIO module controls
PHY configuration and status monitoring.
Both the EMAC and the MDIO modules interface to the DSP through a custom interface that allows
efficient data transmission and reception. This custom interface is referred to as the EMAC control
module, and is considered integral to the EMAC/MDIO peripheral.
1.1 Purpose of the Peripheral
The EMAC module is used on TMS320C645x devices to move data between the device and another host
connected to the same network, in compliance with the Ethernet protocol.
1.2 Features
The basic feature set of the EMAC module integrated with C645x is:
•
•
•
•
Synchronous 10/100/1000 Mbps operation
Full duplex Gigabit operation (half duplex gigabit is not supported)
Little endian and big endian support
Supports four types of interfaces to the physical layer device (PHY): standard media independent
interface (MII), reduced pin count media independent interface (RMII), standard gigabit media
independent interface (GMII) and reduced pin count gigabit media independent interface (RGMII)
•
•
•
•
•
•
•
•
EMAC acts as DMA master to either internal or external device memory space
Eight receive channels with VLAN tag discrimination for receive quality of service (QOS) support
Eight transmit channels with round–robin or fixed priority for transmit quality of service (QOS) support
Ether-stats and 802.3-stats statistics gathering
Transmit CRC generation selectable on a per-channel basis
Broadcast frames selection for reception on a single channel
Multicast frames selection for reception on a single channel
Promiscuous receive mode frames selection for reception on a single channel (all frames, all good
frames, short frames, error frames)
•
•
Hardware flow control
8K byte local EMAC descriptor memory that allows the peripheral to operate on descriptors without
affecting the CPU. The descriptor memory holds enough information to transfer up to 512 ethernet
packets without CPU intervention.
•
Programmable interrupt logic permits the software driver to restrict the generation of back-to-back
interrupts, thus allowing more work to be performed in a single call to the interrupt service routine
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Introduction
1.3 Functional Block Diagram
•
•
•
EMAC control module
EMAC module
MDIO module
The EMAC control module is the main interface between the device core processor and the EMAC
module and MDIO module. The EMAC control module contains the necessary components to allow the
EMAC to make efficient use of device memory, plus it controls device interrupts. The EMAC control
module incorporates 8K byte internal RAM to hold EMAC buffer descriptors.
The management data input / output (MDIO) module implements the 802.3 serial management interface to
interrogate and control up to 32 ethernet PHY(s) connected to the device, using a shared two–wire bus.
Application software uses the MDIO module to configure the auto-negotiation parameters of each PHY
attached to the EMAC, retrieve the negotiation results, and configure required parameters in the EMAC
module for correct operation. The module is designed to allow almost transparent operation of the MDIO
interface, with very little maintenance from the core processor.
The ethernet media access controller (EMAC) module provides an efficient interface between the C645x
core processor and the networked community. The EMAC supports 10Base-T (10 Mbits / sec), and
100BaseTX (100 Mbits / sec), in either half or full duplex mode, and 1000BaseT (1000 Mbits / sec) in full
duplex mode, with hardware flow control and quality-of-service (QOS) support.
Figure 1. EMAC and MDIO Block Diagram
Interrupt
controller
DMA memory
transfer controller
Configuration bus
Peripheral bus
EMAC control module
EMAC module
EMAC/MDIO
interrupt
MDIO module
MII
RMII GMII RGMII
MDIO bus
The following connections are made to the device core:
•
The peripheral bus connection from the EMAC control module allows the EMAC module to read and
write both internal and external memory through the switch fabric interface.
•
The EMAC control, EMAC, and MDIO modules all have control registers. These registers are
memory-mapped into device memory space via the device configuration bus. The control module’s
internal RAM maps to this same range along with these registers.
•
The EMAC and MDIO interrupts are combined into a single interrupt within the control module. The
interrupt from the control module then goes to the device’s interrupt controller.
The EMAC and MDIO interrupts are combined within the control module, so only the control module
interrupt needs to be monitored by the application software or device driver. The interrupt is mapped to a
specific CPU interrupt via the enhanced interrupt selector within the C64x+ core. The combined EMAC /
MDIO interrupt maps to the interrupt controller input as system event 17.
12
Ethernet Media Access Controller (EMAC)/Management Data Input/Output (MDIO)
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Introduction
1.4 Industry Standard(s) Compliance Statement
The EMAC peripheral conforms to the IEEE 802.3 standard, describing the “Carrier Sense Multiple Access
with Collision Detection (CSMA/CD) Access Method and Physical Layer” specifications. ISO / IEC has
also adopted the IEEE 802.3 standard and re-designated it as ISO/IEC 8802-3:2000(E).
In difference from this standard, the EMAC peripheral integrated with the C645x devices does not use the
transmit coding error signal MTXER. Instead of driving the error pin when an underflow condition occurs
on a transmitted frame, the EMAC intentionally generates an incorrect check sum by inverting the frame
CRC so that the network will detect the transmitted frame as an error.
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EMAC Functional Architecture
2
EMAC Functional Architecture
This chapter discusses the architecture and basic function of the EMAC peripheral.
2.1 Clock Control
The frequencies for the transmit and receive clocks are fixed by the IEEE 802.3 specification as shown
below:
•
•
•
2.5 Mhz at 10 Mbps
25 Mhz at 100 Mbps
125 MHz at 1000 Mbps
The C645x device uses two PLL controllers to generate all of the clocks that the DSP needs. The primary
PLL controller generates a peripheral clock (SYSCLK2) that several peripherals use, including the EMAC.
SYSCLK2 runs at a rate equal to 1/6th of the CPU clock frequency (CPUclk/6), and is not programmable.
The secondary PLL controller conveniently generates a reference clock (SYSCLK1). The EMAC uses the
SYSCLK1 to generate the transmit and receive clocks for the GMII and RGMII interfaces. The frequency
of SYSCLK1 is equal to the secondary PLL controller’s input clock (25 MHz) multiplied by 10 and divided
by either 5 or 2. You must program SYSCLK1 to the correct frequency based on the interface that you are
Note: The RGMII interface does not require an interface clock. However, a reference clock that
is derived from SYSCLK1 is provided for your convenience. The reference clock is not a
free running clock. The reference clock stops while the DSP is in reset; therefore, you
must be careful if you use this clock elsewhere in the system.
The MDIO clock is based on a divide-down of the peripheral clock (SYSCLK2) and is specified to run up
to 2.5 MHz, although typical operation is 1.0 MHz. Since the peripheral clock frequency is variable, the
application software or driver controls the divide-down amount.
2.1.1
2.1.2
MII Clocking
When you select the MII clocking interface by setting MACSEL to the default value (00b), the transmit and
receive clock sources are provided from an external PHY via the MTCLK and MRCLK pins. These clocks
are inputs to the EMAC module and operate at 2.5 MHz in 10 Mbps mode, and at 25 MHz in 100 MHz
mode. The MII clocking interface is not used in 1000 Mbps mode. For timing purposes, data is transmitted
and received with reference to MTCLK and MRCLK, respectively.
RMII Clocking
When you select the RMII interface by setting MACSEL to 01b, you must provide a 50MHz reference
clock through the MREFCLK pin. The EMAC clocks the transmit and receive operations from the
reference clock. The MTCLK and MRCLK device pins are not used for this interface. The RMII protocol
turns one data phase of an MII transfer into two data phases at double the clock frequency. This is the
driving factor for the 50 MHz reference clock. Data at the IO pins are running at 5 MHZ in 10 Mbps mode,
and at 50 MHz in 100 Mbps mode.
2.1.3
GMII Clocking
When you set MACSEL to 02b to select GMII, the transmit and receive clock sources for 10/100 Mbps
modes are provided from an external PHY via the MTCLK and MRCLK pins. For 1000 Mbps mode, the
receive clock is provided by an external PHY via the MRCLK pin. For transmit in 1000 Mbps mode, the
clock is sourced synchronous with the data, and is provided by the EMAC to be output on the GMTCLK
pin.
The SYSCLK1 of the secondary PLL controller sources the GMTCLK. The divider generating SYSCLK1
needs to be programmed to /2 (the default value) for this interface to provide a 125 MHz clock to the
EMAC.
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For timing purposes, data in 10/100 mode is transmitted and received with reference to MTCLK and
MRCLK, respectively. For 1000 Mbps mode, receive timing is the same, but transmit is relative to
GMTCLK.
2.1.4
RGMII Clocking
When the RGMII interface is selected by setting MACSEL to 11b, you must configure the internal clock
(SYSCLK1) to a 125 MHz frequency by setting the divider for the secondary PLL controller to /5. This
provides a reference clock that you can use to source the clock on the RGMII PHY as necessary.
Note: This reference clock is not a free running clock. An external device should only use this
clock if it does not expect a valid clock during device reset.
The EMAC drives the transmit clock, while an external PHY generates the receive clock. The reference
clock drives the device pin that gives the 125 MHz clock to the PHY; this enables the PHY to generate the
receive clock that is sent to EMAC.
The RGMII protocol takes a GMII data stream and turns it into an interface with half of the data bus width
and sends the same amount of data with a reduced pinout. The RGMII protocol also allows for dynamic
switching of the mode between 10/100/1000 Mbps modes. This negotiation data is embedded in the
incoming data stream from the external PHY. For timing purposes, data is transmitted and received with
respect to MTCLK and MRCLK respectively.
The RGMII interface has separate I/O pins from the other EMAC pins because the interface voltage is
different from the other interfaces.
2.2 Memory Map
The EMAC includes an internal memory that holds information about the ethernet packets that are
received or transmitted. This internal RAM is 2K x 32 bits in size. You can write data to and read data
from the EMAC internal memory via either the EMAC or the CPU. It is used to store buffer descriptors that
are 4 words (16 bytes) deep. This 8K local memory can hold enough information to transfer up to 512
ethernet packets without CPU intervention.
You can put the packet buffer descriptors in internal processor memory (L2) on the C645x devices. There
are some trade-offs in terms of cache performance and throughput when you put descriptors in L2 versus
when you put them in EMAC’s internal memory. Cache performance improves when you put the buffer
descriptors in internal memory. However, the EMAC throughput is better when you put the descriptors in
the local EMAC RAM.
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EMAC Functional Architecture
2.3 System Level Connections
The C645x device supports four different interfaces to a physical layer device. You can only transfer data
on one interface at a given time. Each of these interfaces is selected in hardware via the configuration
pins (MACSEL[1:0]).
Table 1. Interface Selection Pins
MACSEL [1:0]
Interface
MII
00
01
10
11
RMII
GMII
RGMII
2.3.1
Media Independent Interface (MII) Connections
Figure 2 shows a device with integrated EMAC and MDIO interfaced via a MII connection. This interface is
only available in 10 Mbps and 100 Mbps modes.
Figure 2. Ethernet Configuration with MII Interface
MTCLK
MTXD[3−0]
2.5 MHz
or
25 MHz
MTXEN
MCOL
MCRS
Physical
System
core
layer
device
(PHY)
MRCLK
Transformer
RJ−45
MRXD[3−0]
MRXDV
MRXER
MDCLK
MDIO
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Table 2 summarizes the individual EMAC and MDIO signals for the MII interface. For more information,
refer to either the IEEE 802.3 standard or ISO/IEC 8802-3:2000(E).
The EMAC module does not include a transmit error (MTXER) pin. If a transmit error occurs, CRC
inversion is used to negate the validity of the transmitted frame.
Table 2. EMAC and MDIO Signals for MII Interface
Signal Name
I/O
Description
MTCLK
I
Transmit clock (MTCLK). The transmit clock is a continuous clock that provides the timing
reference for transmit operations. The MTXD and MTXEN signals are tied to this clock. The
clock is generated by the PHY and is 2.5 MHz at 10 Mbps operation and 25 MHz at 100
Mbps operation.
MTXD[3:0]
O
Transmit data (MTXD). The transmit data pins are a collection of 4 data signals comprising 4
bits of data. MTDX0 is the least-significant bit (LSB). The signals are synchronized by MTCLK
and valid only when MTXEN is asserted.
MTXEN
MCOL
O
I
Transmit enable (MTXEN). The transmit enable signal indicates that the MTXD pins are
generating nibble data for use by the PHY. It is driven synchronously to MTCLK.
Collision detected (MCOL). The MCOL pin is asserted by the PHY when it detects a collision
on the network. It remains asserted while the collision condition persists. This signal is not
necessarily synchronous to MTCLK nor MRCLK. This pin is used in half-duplex operation
only.
MCRS
I
I
I
Carrier sense (MCRS). The MCRS pin is asserted by the PHY when the network is not idle in
either transmit or receive. The pin is de-asserted when both transmit and receive are idle.
This signal is not necessarily synchronous to MTCLK or MRCLK. This pin is used in
half-duplex operation only.
MRCLK
MRXD[3:0]
Receive clock (MRCLK). The receive clock is a continuous clock that provides the timing
reference for receive operations. The MRXD, MRXDV, and MRXER signals are tied to this
clock. The clock is generated by the PHY and is 2.5 MHz at 10 Mbps operation and 25 MHz
at 100 Mbps operation.
Receive data (MRXD). The receive data pins are a collection of 4 data signals comprising 4
bits of data. MRDX0 is the least-significant bit (LSB). The signals are synchronized by
MRCLK and valid only when MRXDV is asserted.
MRXDV
MRXER
I
I
Receive data valid (MRXDV). The receive data valid signal indicates that the MRXD pins are
generating nibble data for use by the EMAC. It is driven synchronously to MRCLK.
Receive error (MRXER). The receive error signal is asserted for one or more MRCLK periods
to indicate that an error was detected in the received frame. This is meaningful only during
data reception when MRXDV is active.
MDCLK
MDIO
O
Management data clock (MDCLK). The MDIO data clock is sourced by the MDIO module on
the system. It is used to synchronize MDIO data access operations done on the MDIO pin.
The frequency of this clock is controlled by the CLKDIV bits in the MDIO control register
(CONTROL).
I/O
Management data input output (MDIO). The MDIO pin drives PHY management data into and
out of the PHY by way of an access frame consisting of start of frame, read/write indication,
PHY address, register address, and data bit cycles. The MDIO pin acts as an output for
everything except the data bit cycles, when the pin acts as an input for read operations.
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EMAC Functional Architecture
2.3.2
Reduced Media Independent Interface (RMII) Connections
Figure 3 shows a device with integrated EMAC and MDIO interfaced via a RMII connection. This interface
is only available in 10 Mbps and 100 Mbps modes. The RMII interface is only supported in full-duplex
mode for the C645x family of devices.
Figure 3. Ethernet Configuration with RMII Interface
MTXD[1−0]
MTXEN
MCRSDV
Transformer
Physical
System
core
layer
device
(PHY)
MREFCLK
MRXD[1−0]
RJ−45
MRXER
MDCLK
MDIO
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The RMII interface has the same functionality as the MII, but it does so with a reduced number of pins,
thus lowering the total cost for an application. In devices incorporating many PHY interfaces such as
switches, the number of pins can add significant cost as the port counts increase. Table 3 summarizes the
individual EMAC and MDIO signals for the RMII interface.
The RMII interface does not include an MCOL signal. A collision is detected from the receive and transmit
data delimiters. The data signals are 2 bits wide, and a single reference clock must be provided to the
MAC, operating at 50MHz to sustain the same data rate as MII.
Table 3. EMAC and MDIO Signals for RMII Interface
Signal Name
I/O
Description
MTXD[1-0]
O
Transmit data (MTXD). The transmit data pins are a collection of 2 data signals comprising 2
bits of data. MTDX0 is the least-significant bit (LSB). The signals are synchronized to the
RMII reference clock and valid only when MTXEN is asserted.
MTXEN
O
I
Transmit enable (MTXEN). The transmit enable signal indicates that the MTXD pins are
generating nibble data for use by the PHY. It is driven synchronously to the RMII reference
clock.
MCRSDV
Carrier sense/receive data valid (MCRSDV). The MCRSDV pin is asserted by the PHY when
the network is not idle in either transmit or receive. The data on MRXD is considered valid
once the MCRSDV signal is asserted. The pin is de-asserted when both transmit and receive
are idle. The assertion of this signal is asynchronous to the RMII reference clock. This pin is
used in half-duplex operation only.
MREFCLK
MRXD[1-0]
I
I
Reference clock (MREFCLK). A 50MHz clock must be provided through this pin for RMII
operation.
Receive data (MRXD). The receive data pins are a collection of 2 data signals comprising 2
bits of data. MRDX0 is the least-significant bit (LSB). The signals are synchronized to the
RMII reference clock and valid only when MCRSDV is asserted. In 10 Mbps operation, MRXD
is sampled every 10th cycle of the RMII reference clock.
MRXER
MDCLK
MDIO
I
Receive error (MRXER). The receive error signal is asserted for one or more reference clock
periods to indicate that an error was detected in the received frame. This is meaningful only
during data reception when MCRSDV is active. It is driven synchronously to the RMII
reference clock.
O
I/O
Management data clock (MDCLK). The MDIO data clock is sourced by the MDIO module on
the system. It is used to synchronize MDIO data access operations done on the MDIO pin.
The frequency of this clock is controlled by the CLKDIV bits in the MDIO control register
(CONTROL).
Management data input output (MDIO). The MDIO pin drives PHY management data into and
out of the PHY by way of an access frame consisting of start of frame, read/write indication,
PHY address, register address, and data bit cycles. The MDIO pin acts as an output for
everything except the data bit cycles, when the pin acts as an input for read operations.
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EMAC Functional Architecture
2.3.3
Gigabit Media Independent Interface (GMII) Connections
Figure 4 shows a device with integrated EMAC and MDIO interfaced via a GMII connection. This interface
is available in 10 Mbps, 100 Mbps, and 1000 Mbps modes.
Figure 4. Ethernet Configuration with GMII Interface
MTCLK
GMTCLK
2.5 MHz,
MTXD[7−0]
25 MHz,
MTXEN
MCOL
MCRS
or 125 MHz
Physical
layer
device
(PHY)
System
core
MRCLK
Transformer
RJ−45
MRXD[7−0]
MRXDV
MRXER
MDCLK
MDIO
The GMII interface supports 10/100/1000 Mbps modes. Only full-duplex mode is available in 1000 Mbps
mode. In 10/100 Mbps modes, the GMII interface acts like an MII interface, and only the lower 4 bits of
data are transferred for each of the data buses.
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Table 4. EMAC and MDIO Signals for GMII Interface
Signal Name
I/O
Description
MTCLK
I
Transmit clock (MTCLK). The transmit clock is a continuous clock that provides the timing
reference for transmit operations in 10/100 Mbps mode. The MTXD and MTXEN signals are
tied to this clock when in 10/100 Mbps mode. The clock is generated by the PHY and is 2.5
MHz at 10 Mbps operation, and 25 MHz at 100 Mbps operation.
GMTCLK
O
O
GMII source synchronous transmit clock (GMTCLK). This clock is used in 1000 Mbps mode
only, providing a continuous 125 MHz frequency for transmit operations. The MTXD and
MTXEN signals are tied to this clock when in Gigabit mode. The clock is generated by the
EMAC and is 125 MHz.
MTXD[7-0]
Transmit data (MTXD). The transmit data pins are a collection of 8 data signals comprising 8
bits of data. MTDX0 is the least-significant bit (LSB). The signals are synchronized by MTCLK
in 10/100 Mbps mode, and by GMTCLK in Gigabit mode, and valid only when MTXEN is
asserted.
MTXEN
MCOL
O
I
Transmit enable (MTXEN). The transmit enable signal indicates that the MTXD pins are
generating nibble data for use by the PHY. It is driven synchronously to MTCLK in 10/100
Mbps mode, and to GMTCLK in Gigabit mode.
Collision detected (MCOL). The MCOL pin is asserted by the PHY when it detects a collision
on the network. It remains asserted while the collision condition persists. This signal is not
necessarily synchronous to MTCLK nor MRCLK. This pin is used in half-duplex operation
only.
MCRS
I
I
I
Carrier sense (MCRS). The MCRS pin is asserted by the PHY when the network is not idle in
either transmit or receive. The pin is de-asserted when both transmit and receive are idle.
This signal is not necessarily synchronous to MTCLK nor MRCLK. This pin is used in
half-duplex operation only.
MRCLK
MRXD[7-0]
Receive clock (MRCLK). The receive clock is a continuous clock that provides the timing
reference for receive operations. The MRXD, MRXDV, and MRXER signals are tied to this
clock. The clock is generated by the PHY and is 2.5 MHz at 10 Mbps operation, 25 MHz at
100 Mbps operation and 125 MHz at 1000 Mbps operation.
Receive data (MRXD). The receive data pins are a collection of 8 data signals comprising 8
bits of data. MRDX0 is the least-significant bit (LSB). The signals are synchronized by
MRCLK and valid only when MRXDV is asserted.
MRXDV
MRXER
I
I
Receive data valid (MRXDV). The receive data valid signal indicates that the MRXD pins are
generating nibble data for use by the EMAC. It is driven synchronously to MRCLK.
Receive error (MRXER). The receive error signal is asserted for one or more MRCLK periods
to indicate that an error was detected in the received frame. This is meaningful only during
data reception when MRXDV is active.
MDCLK
MDIO
O
Management data clock (MDCLK). The MDIO data clock is sourced by the MDIO module on
the system. It is used to synchronize MDIO data access operations done on the MDIO pin.
The frequency of this clock is controlled by the CLKDIV bits in the MDIO control register
(CONTROL).
I/O
Management data input output (MDIO). The MDIO pin drives PHY management data into and
out of the PHY by way of an access frame consisting of start of frame, read/write indication,
PHY address, register address, and data bit cycles. The MDIO pin acts as an output for
everything except the data bit cycles, when the pin acts as an input for read operations.
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EMAC Functional Architecture
2.3.4
Reduced Gigabit Media Independent Interface (RGMII) Connections
interface is available in 10 Mbps, 100 Mbps, and 1000 Mbps modes.
Figure 5. Ethernet Configuration with RGMII Interface
TXC
TXD[3−0]
2.5 MHz
25 MHz,
TXCTL
or 125 MHz
REFCLK
Physical
layer
device
(PHY)
System
core
RXC
Transformer
RJ−45
RXD[3−0]
RXCTL
MDCLK
MDIO
The RGMII interface is a reduced pin alternative to the GMII interface. The data paths are reduced, control
signals are multiplexed together, and both edges of the clock are used.
The RGMII interface does not include a MCOL and a MCRS signal for half-duplex mode (only available in
10/100 Mbps mode).
Carrier sense (MCRS) is indicated by one of the following cases instead:
•
•
MRXDV signal (multiplexed in the RXCTL signal) is true
MRXDV is false, MRXERR (multiplexed in the RXCTL signal) is true, and a value of FFh exists on the
RXD[7:0] simultaneously
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Table 5. EMAC and MDIO Signals for RGMII Interface
Signal Name
I/O
Description
TXC
O
Transmit clock (TXC). The transmit clock is a continuous clock that provides the timing
reference for transmit operations. The TXD and TXCTL signals are tied to this clock. The
clock is driven by the EMAC and is 2.5 MHz at 10 Mbps operation, 25 MHz at 100 Mbps
operation, and 125 MHz at 1000 Mbps operation.
TXD[3-0]
O
Transmit data (TXD). The transmit data pins are a collection of 4 data signals comprising 4
bits of data. TDX0 is the least-significant bit (LSB). The signals are synchronized by TXC and
valid only when TXCTL is asserted. The lower 4 bits of data are transmitted on the rising
edge of the clock, and the higher 4 bits of data are transmitted on the falling edge of the TXC.
TXCTL
O
O
Transmit enable (TXCTL). The transmit enable signal indicates that the TXD pins are
generating nibble data for use by the PHY. It is driven synchronously to TXC.
REFCLK
Reference clock (REFCLK). This 125 MHz reference clock is provided as a convenience. It
can be used as a clock source to the PHY, so that the PHY may generate the RXC clock to
be sent to EMAC. This clock is stopped while the device is in reset.
RXC
I
I
I
Receive clock (RXC). The receive clock is a continuous clock that provides the timing
reference for receive operations. The RXD, and RXCTL signals are tied to this clock. The
clock is generated by the PHY and is 2.5 MHz at 10 Mbps operation, 25 MHz at 100 Mbps
operation, and 125 MHz at 1000 Mbps operation.
RXD[3-0]
RXCTL
Receive data (RXD). The receive data pins are a collection of 4 data signals comprising 4 bits
of data. RDX0 is the least-significant bit (LSB). The signals are synchronized by RXC and
valid only when RXCTL is asserted. The lower 4 bits of data are received on the rising edge
of the clock, and the higher 4 bits of data are received on the falling edge of the RXC.
Receive control (RXCTL). The receive control data has the receive data valid (MRXDV)
signal on the rising edge of the receive clock, and a derivative of receive data valid and
receive error (MRXER) on the falling edge of RXC.
When receiving a valid frame with no errors, MRXDV = TRUE is generated as a logic high on
the rising edge on RXC and MRXER = FALSE is generated as a logic high on the falling
edge of RXC.
When no frame is being received, MRXDV = FALSE is generated as a logic low on the rising
edge of RXC and MRXER = FALSE is generated as a logic low on the falling edge of RXC.
When receiving a valid frame with errors, MRXDV = TRUE is generated as a logic high on
the rising edge of RXC and MRXER = TRUE is generated as a logic low on the falling edge
of RXC.
MDCLK
MDIO
O
Management data clock (MDCLK). The MDIO data clock is sourced by the MDIO module. It
synchronizes MDIO data access operations done on the MDIO pin. The frequency of this
clock is controlled by the CLKDIV bits in the MDIO control register (CONTROL).
I/O
Management data input output (MDIO). The MDIO pin drives PHY management data into and
out of the PHY by way of an access frame consisting of start of frame, read/write indication,
PHY address, register address, and data bit cycles. The MDIO pin acts as an output for
everything except the data bit cycles, when the pin acts as an input for read operations.
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EMAC Functional Architecture
2.4 Ethernet Protocol Overview
Ethernet provides an unreliable, connectionless service to a networking application. A brief overview of the
ethernet protocol follows. For more information on the carrier sense multiple access with collision
detection (CSMA/CD) access method (ethernet’s multiple access protocol), see the IEEE 802.3 standard
document.
2.4.1
Ethernet Frame Format
All the ethernet technologies use the same frame structure. The format of an ethernet frame is shown in
Figure 6 and described in Table 6. The ethernet packet is the collection of bytes representing the data
The ethernet frames are of variable lengths, with no frame smaller than 64 bytes or larger than
RXMAXLEN bytes (header, data, and CRC).
Figure 6. Ethernet Frame
Number of bytes
7
1
6
6
2
46 − (RXMAXLEN - 18)
Data
4
Preamble
SFD
Destination
Source
Len
FCS
Legend: SFD=Start Frame Delimiter; FCS=Frame Check Sequence (CRC)
Table 6. Ethernet Frame Description
Field
Bytes
Description
Preamble
7
These 7 bytes have a fixed value of 55h. They wake up the receiving EMAC ports and
synchronize their clocks to that of the sender’s clock.
Start of Frame
Delimiter
1
6
This field with a value of 5Dh immediately follows the preamble pattern and indicates
the start of important data.
Destination
address
This field contains the Ethernet MAC address of the intended EMAC port for the frame.
It may be an individual or multicast (including broadcast) address. If the destination
EMAC port receives an Ethernet frame with a destination address that does not match
any of its MAC physical addresses, and no promiscuous, multicast or broadcast
channel is enabled, it discards the frame.
Source
address
6
2
This field contains the MAC address of the Ethernet port that transmits the frame to the
Local Area Network.
Length/Type
The length field indicates the number of EMAC client data bytes contained in the
subsequent data field of the frame. This field can also be used to identify the data type
carried by the frame.
Data
46 to (RXMAXLEN - 18) This field carries the datagram containing the upper layer protocol frame (the IP layer
datagram). The maximum transfer unit (MTU) of Ethernet is (RXMAXLEN - 18) bytes.
Therefore, if the upper layer protocol datagram exceeds (RXMAXLEN - 18) bytes, the
host must fragment the datagram and send it in multiple Ethernet packets. The
minimum size of the data field is 46 bytes. Thus, if the upper layer datagram is less
then 46 bytes, the data field must be extended to 46 bytes by appending extra bits after
the data field, but prior to calculating and appending the FCS.
Frame Check
Sequence
4
A cyclic redundancy check (CRC) is used by the transmit and receive algorithms to
generate a CRC value for the FCS field. The frame check sequence covers the 60 to
(RXMAXLEN - 4) bytes of the packet data. Note that the 4-byte FCS field may not be
included as part of the packet data, depending on the EMAC configuration.
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2.4.2
Multiple Access Protocol
Nodes in an ethernet local area network are interconnected by a broadcast channel. As a result, when an
EMAC port transmits a frame, all of the adapters on the local network receive the frame. Carrier sense
multiple access with collision detection (CSMA/CD) algorithms are used when the EMAC operates in
half-duplex mode. When operating in full-duplex mode, there is no contention for use of a shared medium,
because there are exactly two ports on the local network.
Each port runs the CSMA/CD protocol without explicit coordination with the other ports on the ethernet
network.
Within a specific port, the CSMA/CD protocol is as follows:
1. The port obtains data from upper layer protocols at its node, prepares an ethernet frame, and puts the
frame in a buffer.
2. If the port senses that the medium is idle, it starts to transmit the frame. If the port senses that the
transmission medium is busy, it waits until it senses no signal energy (plus an inter-packet gap time)
and then starts to transmit the frame.
3. While transmitting, the port monitors for the presence of signal energy coming from other ports. If the
port transmits the entire frame without detecting signal energy from other ethernet devices, the port is
finished with the frame.
4. If the port detects signal energy from other ports while transmitting, it stops transmitting its frame and
instead transmits a 48-bit jam signal.
5. After transmitting the jam signal, the port enters an exponential back off phase. Specifically, when
transmitting a given frame, after experiencing a number of collisions in a row for the frame, the port
chooses a random value that is dependent on the number of collisions. The port then waits an amount
of time which is multiple of this random value, and returns to Step 1.
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EMAC Functional Architecture
2.5 Programming Interface
2.5.1
Packet Buffer Descriptors
The buffer descriptor is a central part of the EMAC module. It determines how the application software
describes ethernet packets to be sent and empty buffers to be filled with incoming packet data.
Figure 7. Basic Descriptor Format
Word Offset
Bit Fields
31
16 15
0
0
1
2
3
Next Descriptor Pointer
Buffer Pointer
Buffer Offset
Flags
Buffer Length
Packet Length
Table 7. Basic Descriptors
Word
Field Description
Offset
Field
0
Next Descriptor
Pointer
The next descriptor pointer creates a single linked list of descriptors. Each descriptor describes a
packet or a packet fragment. When a descriptor points to a single buffer packet or the first fragment
of a packet, the start of packet (SOP) flag is set in the flags field. When a descriptor points to a
single buffer packet or the last fragment of a packet, the end of packet (EOP) flag is set. When a
packet is fragmented, each fragment must have its own descriptor and appear sequentially in the
descriptor linked list.
1
2
2
3
Buffer Pointer
Buffer Offset
Buffer Length
Flags
The buffer pointer refers to the memory buffer that either contains packet data during transmit
operations, or is an empty buffer ready to receive packet data during receive operations.
The buffer offset is the offset from the start of the packet buffer to the first byte of valid data. This
field only has meaning when the buffer descriptor points to a buffer that contains data.
The buffer length is the number of valid packet data bytes stored in the buffer. If the buffer is empty
and waiting to receive data, this field represents the size of the empty buffer.
The flags field contains more information about the buffer, such as whether it is the first fragment in
a packet (SOP), the last fragment in a packet (EOP), or contains an entire contiguous Ethernet
3
Packet Length
The packet length only has meaning for buffers that both contain data and are the start of a new
packet (SOP). For SOP descriptors, the packet length field contains the length of the entire Ethernet
packet, even if it is contained in a single buffer or fragmented over several buffers.
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EMAC Functional Architecture
For example, consider three packets to be transmitted, Packet A is a single fragment (60 bytes), Packet B
is fragmented over three buffers (1514 bytes total), and Packet C is a single fragment (1514 bytes).
Figure 8. Typical Descriptor Linked List
pNext
pBuffer
Packet A
0
60
60
60 bytes
SOP | EOP
pNext
Packet B
Fragment 1
512 bytes
pBuffer
0
512
SOP
1514
pNext
Packet B
Fragment 2
502 bytes
pBuffer
0
502
−−−
−−−
pNext
Packet B
Fragment 3
500 bytes
pBuffer
0
500
−−−
EOP
pNext (NULL)
pBuffer
Packet C
1514 bytes
0
1514
1514
SOP | EOP
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EMAC Functional Architecture
2.5.2
Transmit and Receive Descriptor Queues
The EMAC module processes descriptors in linked list chains (Section 2.5.1). The lists controlled by the
EMAC are maintained by the application software via the head descriptor pointer (HDP) registers. Since
the EMAC supports eight channels for both transmit and receive, there are eight head descriptor pointer
registers for both.
They are designated as follows:
•
•
TXnHDP: Transmit Channel n DMA Head Descriptor Pointer Register
RXnHDP: Receive Channel n DMA Head Descriptor Pointer Register
After an EMAC reset, and before enabling the EMAC for send or receive, you must initialize all 16 head
descriptor pointer registers to zero.
The EMAC uses a simple system to determine ownership of a descriptor (either the EMAC or the
application software). There is a flag in the descriptor flags field called OWNER. When this flag is set, the
EMAC owns the referenced packet.
Note: Ownership is assigned on a packet-based granularity, not on descriptor granularity. Thus,
only SOP descriptors make use of the OWNER flag. The EMAC patches the SOP
descriptor of the corresponding packet and clears the OWNER flag as packets are
processed. This means that the EMAC is finished processing all descriptors up to and
including the first with the EOP flag set. This indicates that you have reached the end of
the packet. This may only be one descriptor with both the SOP and EOP flags set.
To add a descriptor or a linked list of descriptors to an EMAC descriptor queue for the first time, the
software application writes the pointer to the descriptor or first descriptor of a list to the corresponding
HDP register. Note that the last descriptor in the list must have its next pointer cleared so that the EMAC
can detect the end of the list. If only a single descriptor is added, its next descriptor pointer must be
initialized to zero.
The HDP register must never be written to a second time while a previous list is active. To add additional
descriptors to a descriptor list already owned by the EMAC, the NULL next pointer of the last descriptor of
the previous list is patched with a pointer to the first descriptor in the new list. The list of new descriptors
to be appended to the existing list must itself be NULL terminated before the pointer patch is performed.
If the EMAC reads the next pointer of a descriptor as NULL in the instant before an application appends
additional descriptors to the list by patching the pointer, this may result in a race condition. Thus, the
software application must always examine the Flags field of all EOP packets, looking for a special flag
called end of queue (EOQ). The EOQ flag is set by the EMAC on the last descriptor of a packet when the
descriptor’s next pointer is NULL, allowing the EMAC to indicate to the software application that it has
reached the end of the list. When the software application sees the EOQ flag set, and there are more
descriptors to process, the application may then submit the new list or missed list portion by writing the
new list pointer to the same HDP register that started the process.
This process applies when adding packets to a transmit list, and empty buffers to a receive list.
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EMAC Functional Architecture
2.5.3
Transmit and Receive EMAC Interrupts
The EMAC synchronizes the descriptor list processing by using interrupts to the software application. The
interrupts are controlled by the application by using the interrupt masks, global interrupt enable, and the
completion pointer register (CP). This register is also called interrupt acknowledge register.
As the EMAC supports eight channels for both transmit and receive, there are eight CP registers for both.
They are designated as:
•
•
TXnCP: Transmit Channel n Completion Pointer (Interrupt Acknowledge) Register
RXnCP: Receive Channel n Completion Pointer (Interrupt Acknowledge) Register
These registers serve two purposes. When read, they return the pointer to the last descriptor that the
EMAC has processed. When written by the software application, the value represents the last descriptor
processed by the software application. If these two values do not match, the interrupt is active.
The system configuration determines whether an active interrupt can interrupt the CPU. In general, the
global interrupt for EMAC and MDIO must be enabled in the EMAC control module, and it also must be
mapped in the DSP interrupt controller and enabled as a CPU interrupt. If the system is configured
properly, the interrupt for a specific receive or transmit channel executes under these conditions when the
corresponding interrupt is enabled in the EMAC using the RXINTMASKSET or TXINTMASKSET registers.
The current state of the receive or transmit channel interrupt can be examined directly by the software
application by reading the RXINTSTATRAW and TXINTSTATRAW registers, whether or not the interrupt
is enabled.
Interrupts are acknowledged when the application software updates the value of TXnCP or RXnCP with a
value that matches the internal value kept by the EMAC.
This mechanism ensures that the application software never misses an EMAC interrupt, as the interrupt
and its acknowledgment are tied directly to the actual buffer descriptors processing.
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EMAC Functional Architecture
2.5.4
Transmit Buffer Descriptor Format
A transmit (TX) buffer descriptor (Figure 9) is a contiguous block of four 32-bit data words aligned on a
32-bit boundary that describes a packet or a packet fragment.
Figure 9. Transmit Descriptor Format
(a) Word 0
31
0
0
0
Next Descriptor Pointer
Buffer Pointer
(b) Word 1
31
(c) Word 2
31
16
15
Buffer Offset
Buffer Length
(d) Word 3
31
30
EOP OWNER EOQ TDOWN PASS
CMPLT CRC
29
28
27
26
25
16
0
SOP
Reserved
15
Packet Length
Example 1. Transmit Descriptor in C Structure Format
/*
// EMAC Descriptor
//
// The following is the format of a single buffer descriptor
// on the EMAC.
*/
typedef struct _EMAC_Desc {
struct _EMAC_Desc *pNext;
/* Pointer to next descriptor in chain */
Uint8
*pBuffer; /* Pointer to data buffer */
Uint32
Uint32
BufOffLen; /* Buffer Offset(MSW) and Length(LSW)
PktFlgLen; /* Packet Flags(MSW) and Length(LSW)
*/
*/
} EMAC_Desc;
/* Packet Flags */
#define EMAC_DSC_FLAG_SOP
#define EMAC_DSC_FLAG_EOP
#define EMAC_DSC_FLAG_OWNER
#define EMAC_DSC_FLAG_EOQ
#define EMAC_DSC_FLAG_TDOWNCMPLT
#define EMAC_DSC_FLAG_PASSCRC
0x80000000u
0x40000000u
0x20000000u
0x10000000u
0x08000000u
0x04000000u
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EMAC Functional Architecture
2.5.4.1
Next Descriptor Pointer
The next descriptor pointer indicates the 32-bit word aligned memory address of the next buffer descriptor
in the transmit queue. The pointer creates a linked list of buffer descriptors. If the value of this pointer is
zero, then the current buffer is the last buffer in the queue. The software application must set this value
prior to adding the descriptor to the active transmit list. The pointer is not altered by the EMAC.
The value of pNext should never be altered once the descriptor is in an active transmit queue, unless its
current value is NULL. If the pNext pointer is initially NULL, and more packets need to be queued for
transmit, the software application may alter this pointer to point to a newly appended descriptor. The
EMAC will use the new pointer value and proceed to the next descriptor unless the pNext value has
already been read. If the pNext value has already been read, the transmitter will halt on the specified
transmit channel, and the software application may restart it then. The software can detect this issue by
searching for an end of queue (EOQ) condition flag on the updated packet descriptor when it is returned
by the EMAC.
2.5.4.2
Buffer Pointer
The buffer pointer is the byte-aligned memory address of the memory buffer associated with the buffer
descriptor. The software application must set this value prior to adding the descriptor to the active transmit
list. This pointer is not altered by the EMAC.
2.5.4.3
Buffer Offset
This 16-bit field indicates how many unused bytes are at the start of the buffer. For example, a value of
0000h indicates that no unused bytes are at the start of the buffer and that valid data begins on the first
byte of the buffer. A value of 000Fh indicates that the first 15 bytes of the buffer are to be ignored by the
EMAC and that valid buffer data starts on byte 16 of the buffer. The software application must set this
value prior to adding the descriptor to the active transmit list. This field is not altered by the EMAC.
Note that this value is only checked on the first descriptor of a given packet (where the SOP flag is set). It
cannot specify the offset of subsequent packet fragments. Also, as the buffer pointer may point to any
byte-aligned address, this field may be unnecessary, depending on the device driver architecture.
The range of legal values for this field is 0 to (Buffer Length – 1).
2.5.4.4
2.5.4.5
2.5.4.6
Buffer Length
This 16-bit field indicates how many valid data bytes are in the buffer. On single fragment packets, this
value is also the total length of the packet data to be transmitted. If the buffer offset field is used, the offset
bytes are not counted as part of this length. This length counts only valid data bytes. The software
application must set this value prior to adding the descriptor to the active transmit list. This field is not
altered by the EMAC.
Packet Length
This 16-bit field specifies the number of data bytes in the entire packet. Any leading buffer offset bytes are
not included. The sum of the buffer length fields of each of the packet’s fragments (if more than one) must
be equal to the packet length. The software application must set this value prior to adding the descriptor to
the active transmit list. This field is not altered by the EMAC. This value is only checked on the first
descriptor of a given packet, where the SOP flag is set.
Start of Packet (SOP) Flag
When set, this flag indicates that the descriptor points to a packet buffer that is the start of a new packet.
For a single fragment packet, both the SOP and end of packet (EOP) flags are set. Otherwise, the
descriptor pointing to the last packet buffer for the packet sets the EOP flag. This bit is set by the software
application and is not altered by the EMAC.
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EMAC Functional Architecture
2.5.4.7
End of Packet (EOP) Flag
When set, this flag indicates that the descriptor points to the last packet buffer for a given packet. For a
single fragment packet, both the start of packet (SOP) and EOP flags are set. Otherwise, the descriptor
pointing to the last packet buffer for the packet sets the EOP flag. This bit is set by the software
application and is not altered by the EMAC.
2.5.4.8
Ownership (OWNER) Flag
When set, this flag indicates that all the descriptors for the given packet (from SOP to EOP) are currently
owned by the EMAC. This flag is set by the software application on the SOP packet descriptor before
adding the descriptor to the transmit descriptor queue. For a single fragment packet, the SOP, EOP, and
OWNER flags are all set. The OWNER flag is cleared by the EMAC once it is finished with all the
descriptors for the given packet. Note that this flag is valid on SOP descriptors only.
2.5.4.9
End of Queue (EOQ) Flag
When set, this flag indicates that the descriptor in question was the last descriptor in the transmit queue
for a given transmit channel, and that the transmitter has halted. This flag is initially cleared by the
software application prior to adding the descriptor to the transmit queue. This bit is set by the EMAC when
the EMAC identifies that a descriptor is the last for a given packet (the EOP flag is set), and there are no
more descriptors in the transmit list (next descriptor pointer is NULL).
The software application can use this bit to detect when the EMAC transmitter for the corresponding
channel has halted. This is useful when the application appends additional packet descriptors to a transmit
queue list that is already owned by the EMAC. Note that this flag is valid on EOP descriptors only.
2.5.4.10 Teardown Complete (TDOWNCMPLT) Flag
This flag is used when a transmit queue is being torn down, or aborted, instead of allowing transmission,
such as during device driver reset or shutdown conditions. The EMAC sets this bit in the SOP descriptor
of each packet as it is aborted from transmission.
Note that this flag is valid on SOP descriptors only. Also note that only the first packet in an unsent list has
the TDOWNCMPLT flag set. The EMAC does not process subsequent descriptors.
2.5.4.11 Pass CRC (PASSCRC) Flag
The software application sets this flag in the SOP packet descriptor before it adds the descriptor to the
transmit queue. Setting this bit indicates to the EMAC that the 4-byte Ethernet CRC is already present in
the packet data, and that the EMAC should not generate its own version of the CRC.
When the CRC flag is cleared, the EMAC generates and appends the 4-byte CRC. The buffer length and
packet length fields do not include the CRC bytes. When the CRC flag is set, the 4-byte CRC is supplied
by the software application and is appended to the end of the packet data. The buffer length and packet
length fields include the CRC bytes, as they are part of the valid packet data. Note that this flag is valid on
SOP descriptors only.
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EMAC Functional Architecture
2.5.5
Receive Buffer Descriptor Format
A receive (RX) buffer descriptor (Figure 10) is a contiguous block of four 32-bit data words aligned on a
32-bit boundary that describes a packet or a packet fragment.
Figure 10. Receive Descriptor Format
(a) Word 0
31
0
0
0
Next Descriptor Pointer
Buffer Pointer
(b) Word 1
31
(c) Word 2
31
16
15
Buffer Offset
Buffer Length
(d) Word 3
31
30
29
28
27
26
25
24
SOP
EOP
OWNER
EOQ
TDOWNCMPLT
PASSCRC
JABBER
OVERSIZE
23
22
21
20
19
18
17
16
FRAGMENT
UNDERSIZED
CONTROL
OVERRUN
CODEERROR
ALIGNERROR
CRCERROR
NOMATCH
15
0
Packet Length
Example 2. Receive Descriptor in C Structure Format
/*
// EMAC Descriptor
//
// The following is the format of a single buffer descriptor
// on the EMAC.
*/
typedef struct _EMAC_Desc {
struct _EMAC_Desc *pNext;
/* Pointer to next descriptor in chain */
Uint8
*pBuffer; /* Pointer to data buffer */
Uint32
Uint32
BufOffLen; /* Buffer Offset(MSW) and Length(LSW)
PktFlgLen; /* Packet Flags(MSW) and Length(LSW)
*/
*/
} EMAC_Desc;
/* Packet Flags */
#define EMAC_DSC_FLAG_SOP
#define EMAC_DSC_FLAG_EOP
#define EMAC_DSC_FLAG_OWNER
#define EMAC_DSC_FLAG_EOQ
0x80000000u
0x40000000u
0x20000000u
0x10000000u
0x08000000u
0x04000000u
0x02000000u
0x01000000u
0x00800000u
0x00400000u
0x00200000u
0x00100000u
0x00080000u
0x00040000u
0x00020000u
0x00010000u
#define EMAC_DSC_FLAG_TDOWNCMPLT
#define EMAC_DSC_FLAG_PASSCRC
#define EMAC_DSC_FLAG_JABBER
#define EMAC_DSC_FLAG_OVERSIZE
#define EMAC_DSC_FLAG_FRAGMENT
#define EMAC_DSC_FLAG_UNDERSIZED
#define EMAC_DSC_FLAG_CONTROL
#define EMAC_DSC_FLAG_OVERRUN
#define EMAC_DSC_FLAG_CODEERROR
#define EMAC_DSC_FLAG_ALIGNERROR
#define EMAC_DSC_FLAG_CRCERROR
#define EMAC_DSC_FLAG_NOMATCH
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EMAC Functional Architecture
2.5.5.1
Next Descriptor Pointer
The next descriptor pointer indicates the 32-bit word aligned memory address of the next buffer descriptor
in the receive queue. The pointer creates a linked list of buffer descriptors. If the value of the pointer is
zero, then the current buffer is the last buffer in the queue. The software application must set this value
prior to adding the descriptor to the active receive list. This pointer is not altered by the EMAC.
The value of pNext should never be altered once the descriptor is in an active receive queue, unless its
current value is NULL. If the pNext pointer is initially NULL, and more empty buffers can be added to the
pool, the software application may alter this pointer to indicate a newly appended descriptor. The EMAC
will use the new pointer value and proceed to the next descriptor unless the pNext value has already been
read. If the pNext value has already been read, the receiver will halt the receive channel in question, and
the software application may restart it at that time. The software can detect this case by searching for an
end of queue (EOQ) condition flag on the updated packet descriptor when it is returned by the EMAC.
2.5.5.2
Buffer Pointer
The buffer pointer is the byte-aligned memory address of the memory buffer associated with the buffer
descriptor. The software application must set this value prior to adding the descriptor to the active receive
list. This pointer is not altered by the EMAC.
2.5.5.3
Buffer Offset
This 16-bit field must be initialized to zero by the software application before adding the descriptor to a
receive queue.
This field will be updated depending on the RXBUFFEROFFSET register setting. When the offset register
is set to a non-zero value, the received packet is written to the packet buffer at an offset given by the
value of the register, and this value is also written to the buffer offset field of the descriptor.
When a packet is fragmented over multiple buffers because it does not fit in the first buffer supplied, the
buffer offset only applies to the first buffer in the list, which is where the start of packet (SOP) flag is set in
the corresponding buffer descriptor. In other words, the buffer offset field is only updated by the EMAC on
SOP descriptors.
The range of legal values for the BUFFEROFFSET register is 0 to (Buffer Length – 1) for the smallest
value of buffer length for all descriptors in the list.
2.5.5.4
Buffer Length
This 16-bit field has two functions:
•
Before the descriptor is first placed on the receive queue by the application software, the software
initializes the buffer length field with the physical size of the empty data buffer specified by the buffer
pointer field.
•
After the empty buffer has been processed by the EMAC and filled with received data bytes, the EMAC
updates the buffer length field to reflect the actual number of valid data bytes written to the buffer.
2.5.5.5
Packet Length
This 16-bit field specifies the number of data bytes in the entire packet. The software application initializes
this value to zero for empty packet buffers. The EMAC fills in the value on the first buffer used for a given
packet, as signified by the EMAC setting a start of packet (SOP) flag. The EMAC sets the packet length
on all SOP buffer descriptors.
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2.5.5.6
2.5.5.7
2.5.5.8
Start of Packet (SOP) Flag
When set, this flag indicates that the descriptor points to the starting packet buffer of a new packet. For a
single fragment packet, both the SOP and end of packet (EOP) flags are set. Otherwise, the descriptor
pointing to the last packet buffer for the packet has the EOP flag set. The software application initially
clears this flag before adding the descriptor to the receive queue. The EMAC sets this bit on SOP
descriptors.
End of Packet (EOP) Flag
When set, this flag indicates that the descriptor points to the last packet buffer for a given packet. For a
single fragment packet, both the start of packet (SOP) and EOP flags are set. Otherwise, the descriptor
pointing to the last packet buffer for the packet has the EOP flag set. The software application initially
clears this flag before adding the descriptor to the receive queue. The EMAC sets this bit on EOP
descriptors.
Ownership (OWNER) Flag
When set, this flag indicates that the descriptor is currently owned by the EMAC. The software application
sets this flag before adding the descriptor to the receive descriptor queue. The EMAC clears this flag once
it is finished with a given set of descriptors associated with a received packet. The EMAC updates the flag
on SOP descriptor only. If the application identifies that the OWNER flag is cleared on an SOP descriptor,
it may assume that the EMAC has released all descriptors up to and including the first with the EOP flag
set. Note that for single buffer packets, the same descriptor will have both the SOP and EOP flags set.
2.5.5.9
End of Queue (EOQ) Flag
When set, this flag indicates that the specified descriptor was the last descriptor in the receive queue for a
given receive channel, and that the corresponding receiver channel has halted. The software application
initially clears this flag prior to adding the descriptor to the receive queue. The EMAC sets this bit when
the EMAC identifies that a descriptor is the last for a given packet received (it also sets the EOP flag), and
there are no more descriptors in the receive list (the next descriptor pointer is NULL).
The software application uses this bit to detect when the EMAC receiver for the corresponding channel
has halted. This is useful when the application appends additional free buffer descriptors to an active
receive queue. Note that this flag is valid on EOP descriptors only.
2.5.5.10 Teardown Complete (TDOWNCMPLT) Flag
This flag is used when a receive queue is being torn down, or aborted, instead of being filled with received
data, such as during device driver reset or shutdown conditions. The EMAC sets this bit in the descriptor
of the first free buffer when the teardown occurs. No additional queue processing is performed.
2.5.5.11 Pass CRC (PASSCRC) Flag
The EMAC sets this flag in the SOP buffer descriptor, if the received packet includes the 4-byte CRC. The
software application must clear this flag before submitting the descriptor to the receive queue.
2.5.5.12 Jabber Flag
The EMAC sets this flag in the SOP buffer descriptor if the received packet is a jabber frame and was not
discarded because the RXCEFEN bit was set in the RXMBPENABLE register.
2.5.5.13 Oversize Flag
The EMAC sets this flag in the SOP buffer descriptor if the received packet is an oversized frame and was
not discarded because the RXCEFEN bit was set in the RXMBPENABLE register.
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EMAC Functional Architecture
2.5.5.14 Fragment Flag
The EMAC sets this flag in the SOP buffer descriptor if the received packet is only a packet fragment and
was not discarded because the RXCEFEN bit was set in the RXMBPENABLE register.
2.5.5.15 Undersized Flag
The EMAC sets this flag in the SOP buffer descriptor if the received packet is undersized and was not
discarded because the RXCSFEN bit was set in the RXMBPENABLE register.
2.5.5.16 Control Flag
The EMAC sets this flag in the SOP buffer descriptor if the received packet is an EMAC control frame and
was not discarded because the RXCMFEN bit was set in the RXMBPENABLE register.
2.5.5.17 Overrun Flag
The EMAC sets this flag in the SOP buffer descriptor if the received packet was aborted due to a receive
overrun.
2.5.5.18 Code Error (CODEERROR) Flag
The EMAC sets this flag in the SOP buffer descriptor if the received packet contained a code error and
was not discarded because the RXCEFEN bit was set in the RXMBPENABLE register.
2.5.5.19 Alignment Error (ALIGNERROR) Flag
The EMAC sets this flag in the SOP buffer descriptor if the received packet contained an alignment error
and was not discarded because the RXCEFEN bit was set in the RXMBPENABLE register.
2.5.5.20 CRC Error (CRCERROR) Flag
The EMAC sets this flag in the SOP buffer descriptor if the received packet contained a CRC error and
was not discarded because the RXCEFEN bit was set in the RXMBPENABLE register.
2.5.5.21 No Match (NOMATCH) Flag
The EMAC sets this flag in the SOP buffer descriptor if the received packet did not pass any of the
EMAC’s address match criteria and was not discarded because the RXCAFEN bit was set in the
RXMBPENABLE register. Although the packet is a valid Ethernet data packet, it is only received because
the EMAC is in promiscuous mode.
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EMAC Functional Architecture
2.6 EMAC Control Module
and provides a local memory space to hold EMAC packet buffer descriptors. Local memory is used to
avoid contention to device memory spaces. Other functions include the bus arbiter, and interrupt logic
control.
Figure 11. EMAC Control Module Block Diagram
Transmit and Receive
Arbiter and
bus switches
DMA Controllers
CPU
Configuration bus
8K byte
descriptor
memory
Configuration
registers
EMAC interrupts
MDIO interrupts
Single interrupt
to CPU
Interrupt
logic
2.6.1
Internal Memory
The control module includes 8K bytes of internal memory. The internal memory block allows the EMAC to
operate more independently of the CPU. It also prevents memory underflow conditions when the EMAC
issues read or write requests to descriptor memory. (The EMAC's internal FIFOs protect memory
accesses to read or write actual Ethernet packet data.)
A descriptor is a 16-byte memory structure that holds information about a single Ethernet packet buffer,
which may contain a full or partial Ethernet packet. Thus, with the 8K memory block provided for
descriptor storage, the EMAC module can send and receive up to a combined 512 packets before it must
be serviced by application or driver software.
2.6.2
Bus Arbiter
The control module’s bus arbiter operates transparently to the rest of the system. It arbitrates between the
device core and EMAC buses for access to internal descriptor memory, and arbitrates between internal
EMAC buses for access to system memory.
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EMAC Functional Architecture
2.6.3
Interrupt Control
The EMAC control module combines the multiple interrupt conditions generated by the EMAC and MDIO
modules into a single interrupt signal that is mapped to a CPU interrupt via the CPU interrupt controller.
The control module uses two registers to control the interrupt signal to the CPU. First, the INTEN bit in the
EWCTL register globally enables and disables the interrupt signal to the CPU. The INTEN bit drives the
interrupt line low during interrupt processing. Upon re-enabling the bit, the interrupt signal will rise if
another interrupt condition exists, creating a rising edge detectable by the CPU.
The EMAC control module interrupt timer count register (EWINTTCNT) is programmed with a value that
counts down once the EMAC/MDIO interrupts are enabled using EWCTL. The CPU interrupt signal is
prevented from rising again until this count reaches zero.
The EWINTTCNT has no effect on interrupts once the count reaches zero, so there is no induced interrupt
latency on random sporadic interrupts. However, the count delays the issuing of a second interrupt
immediately after a first. This protects the system from entering interrupt thrashing mode, in which the
software interrupt service routine (ISR) completes processing just in time to receive another interrupt. By
postponing subsequent interrupts in a back-to-back condition, the software application or driver can
perform more work in its ISR. The EWINTTCNT reset value can be adjusted from within the ISR according
to current system load, or set to a fixed value that assures a maximum number of interrupts per second.
The counter counts at the peripheral clock frequency of CPU clock/6. The default reset count is 0
(inactive), the maximum value is 1 FFFFh (131 071).
2.7 Management Data Input/Output (MDIO) Module
The Management Data Input/Output (MDIO) module manages up to 32 physical layer (PHY) devices
connected to the Ethernet Media Access Controller (EMAC). The MDIO module allows almost transparent
operation of the MDIO interface with little maintenance from the CPU.
The MDIO module enumerates all PHY devices in the system by continuously polling 32 MDIO addresses.
Once it detects a PHY device, the MDIO module reads the PHY status register to monitor the PHY link
state. The MDIO module stores link change events that can interrupt the CPU. The event storage allows
the CPU to poll the link status of the PHY device without continuously performing MDIO module accesses.
However, when the system must access the MDIO module for configuration and negotiation, the MDIO
module performs the MDIO read or write operation independent of the CPU. This independent operation
allows the DSP to poll for completion or interrupt the CPU once the operation has completed.
2.7.1
MDIO Module Components
MDIO), and to the DSP core through the EMAC control module and the configuration bus. The MDIO
module consists of the following logical components:
•
•
•
•
MDIO clock generator
Global PHY detection and link state monitoring
Active PHY monitoring
PHY register user access
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EMAC Functional Architecture
Figure 12. MDIO Module Block Diagram
Peripheral
MDIO
clock
clock
generator
MDCLK
MDIO
MDIO
interface
USERINT
EMAC
control
module
LINKINT
PHY
monitoring
PHY
polling
Control
registers
and logic
Configuration bus
2.7.1.1
2.7.1.2
MDIO Clock Generator
The MDIO clock generator controls the MDIO clock based on a divide-down of the peripheral clock
(CPUclk/6) in the EMAC control module. The MDIO clock is specified to run up to 2.5 MHz, although
typical operation would be 1.0 MHz. As the peripheral clock frequency is variable (CPUclk/6), the
application software or driver controls the divide-down amount.
Global PHY Detection and Link State Monitoring
The MDIO module enumerates all PHY devices in the system by continuously polling all 32 MDIO
addresses. The module tracks whether a PHY on a particular address has responded, and whether the
PHY currently has a link. This information allows the software application to quickly determine which
MDIO address the PHY is using, and if the system is using more than one PHY. The software application
can then quickly switch between PHYs based on their current link status.
2.7.1.3
Active PHY Monitoring
Once a PHY candidate has been selected for use, the MDIO module transparently monitors its link state
by reading the PHY status register. The MDIO device stores link change events that may optionally
interrupt the CPU. Thus, the system can poll the link status of the PHY device without continuously
performing MDIO accesses. Up to two PHY devices can be actively monitored at any given time.
2.7.1.4
PHY Register User Access
When the DSP must access the MDIO for configuration and negotiation, the PHY access module performs
the actual MDIO read or write operation independent of the CPU. Thus, the CPU can poll for completion
or receive an interrupt when the read or write operation has been performed. There are two user access
registers (USERACCESS0 and USERACCESS1), allowing the software to submit up to two access
requests simultaneously. The requests are processed sequentially.
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EMAC Functional Architecture
2.7.2
MDIO Module Operational Overview
The MDIO module implements the 802.3 serial management interface to simultaneously interrogate and
control up to two Ethernet PHYs, using a shared two-wired bus. It separately performs auto-detection and
records the current link status of up to 32 PHYs, polling all 32 MDIO addresses.
Application software uses the MDIO module to configure the auto-negotiation parameters of the primary
PHY attached to the EMAC, retrieve the negotiation results, and configure required parameters in the
EMAC. Up to two Ethernet PHYs can be directly controlled and queried. The Media Independent Interface
addresses of these two PHY devices are specified in the PHYADRMON fields of the USERPHYSELn
register. The module can be programmed to trigger a CPU interrupt on a PHY link change event by setting
the LINKINTENB bit in USERPHYSELn. Reads and writes to registers in these PHY devices are
performed using the USERACCESSn register.
The MDIO module powers up in an idle state until it is enabled by setting the ENABLE bit in the
CONTROL register. This also configures the MDIO clock divider and preamble mode selection. The MDIO
preamble is enabled by default, but it can be disabled if none of the connected PHYs require it.
Once the MDIO module is enabled, the MDIO interface state machine continuously polls the PHY link
status (by reading the generic PHY Status register) of all possible 32 PHY addresses and records the
results in the ALIVE and LINK registers. The corresponding bit for each PHY (0-31) is set in the ALIVE
register if the PHY responded to the read request. The corresponding bit is set in the LINK register if the
PHY responded and also is currently linked. In addition, any PHY register read transactions initiated by
the application software using the USERACCESSn register cause the ALIVE register to be updated.
The USERPHYSELn register is used to track the link status of any two of the 32 possible PHY addresses.
Changes in the link status of the two monitored PHYs sets the appropriate bit in the LINKINTRAW and
LINKINTMASKED registers, if they are enabled by the LINKINTENB bit in USERPHYSELn.
While the MDIO module is enabled, the host can issue a read or write transaction over the management
interface using the DATA, PHYADR, REGADR, and WRITE bits in the USERACCESSn register. When
the application sets the GO bit in USERACCESSn, the MDIO module begins the transaction without any
further intervention from the CPU. Upon completion, the MDIO module clears the GO bit and sets the
USERINTRAW[0-1] bit in the USERINTRAW register corresponding to the USERACCESSn used. The
corresponding USERINTMASKED bit in the USERINTMASKED register may also be set, depending on
the mask setting configured in the USERINTMASKSET and USERINTMASKCLEAR registers.
A round-robin arbitration scheme schedules transactions that may be queued using both USERACCESS0
and USERACCESS1. The application software must verify the status of the GO bit in USERACCESSn
before initiating a new transaction to ensure that the previous transaction has completed. The application
software can use the ACK bit in USERACCESSn to determine the status of a read transaction.
2.7.2.1
Initializing the MDIO Module
To have the application software or device driver initialize the MDIO device, perform the following:
1. Configure the PREAMBLE and CLKDIV bits in the CONTROL register.
2. Enable the MDIO module by setting the ENABLE bit in the CONTROL register.
3. The ALIVE register can be read after a delay to determine which PHYs responded, and the LINK
register can determine which of those (if any) already have a link.
4. Set up the appropriate PHY addresses in the USERPHYSELn register, and set the LINKINTENB bit to
enable a link change event interrupt if desirable.
5. If an interrupt on a general MDIO register access is desired, set the corresponding bit in the
USERINTMASKSET register to use the USERACCESSn register. If only one PHY is to be used, the
application software can set up one of the USERACCESSn registers to trigger a completion interrupt.
The other register is not set up.
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EMAC Functional Architecture
2.7.2.2
Writing Data to a PHY Register
The MDIO module includes a user access register (USERACCESSn) to directly access a specified PHY
device. To write a PHY register, perform the following:
1. Ensure that the GO bit in the USERACCESSn register is cleared.
2. Write to the GO, WRITE, REGADR, PHYADR, and DATA bits in USERACCESSn corresponding to the
desired PHY and PHY register.
3. The write operation to the PHY is scheduled and completed by the MDIO module. Completion of the
write operation can be determined by polling the GO bit in USERACCESSn for a 0.
4. Completion of the operation sets the corresponding bit in the USERINTRAW register for the
USERACCESSn used. If interrupts have been enabled on this bit using the USERINTMASKSET
register, then the bit is also set in the USERINTMASKED register and an interrupt is triggered on the
DSP.
2.7.2.3
Reading Data From a PHY Register
The MDIO module includes a user access register (USERACCESSn) to directly access a specified PHY
device. To read a PHY register, perform the following:
1. Ensure that the GO bit in the USERACCESSn register is cleared.
2. Write to the GO, REGADR, and PHYADR bits in USERACCESSn corresponding to the desired PHY
and PHY register.
3. The read data value is available in the DATA bits of USERACCESSn after the module completes the
read operation on the serial bus. Completion of the read operation can be determined by polling the
GO and ACK bits in USERACCESSn. Once the GO bit has cleared, the ACK bit is set on a successful
read.
4. Completion of the operation sets the corresponding bit in the USERINTRAW register for the
USERACCESSn used. If interrupts have been enabled on this bit using the USERINTMASKSET
register, then the bit is also set in the USERINTMASKED register and an interrupt is triggered on the
DSP.
2.7.2.4
Example of MDIO Register Access Code
The MDIO module uses the USERACCESSn register to access the PHY control registers. Software
functions that implement the access process include the following four macros:
PHYREG_read (regadr, phyadr )
PHYREG_write(regadr, phyadr, data )
PHYREG_wait ( )
Start the process of reading a PHY register
Start the process of writing a PHY register
Synchronize operation (make sure read/write is
idle)
PHYREG_wait Results (results )
Wait for read to complete and return data read
It is not necessary to wait after a write operation, as long as the status is checked before every operation
to make sure the MDIO hardware is idle. An alternative approach is to call PHYREG_wait () after every
write, and PHYREG_wait Results () after every read, then the hardware can be assumed to be idle when
starting a new operation.
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EMAC Functional Architecture
The implementation of these macros using the register layer Chip Support Library (CSL) is shown in
Note that this implementation does not check the ACK bit on PHY register reads; in other words, it does
not follow the procedure outlined in Section 2.7.2.3. As the ALIVE register initially selects a PHY, it is
assumed that the PHY is acknowledging read operations. It is possible that a PHY could become inactive
at a future point in time. For example, a PHY can have its MDIO addresses changed while the system is
running, although it is not a common occurrence. This condition can be tested by periodically checking the
PHY state in the ALIVE register.
Example 3. MDIO Register Access Macros
#define PHYREG_read(regadr, phyadr)
\
MDIO_REGS->USERACCESS0 =
\
CSL_FMK(MDIO_USERACCESS0_GO,1u)
CSL_FMK(MDIO_USERACCESS0_REGADR,regadr) |
CSL_FMK(MDIO_USERACCESS0_PHYADR,phyadr)
|
\
\
#define PHYREG_write(regadr, phyadr, data)
MDIO_REGS->USERACCESS0 =
CSL_FMK(MDIO_USERACCESS0_GO,1u)
CSL_FMK(MDIO_USERACCESS0_WRITE,1)
\
\
\
\
\
\
|
|
CSL_FMK(MDIO_USERACCESS0_REGADR,regadr) |
CSL_FMK(MDIO_USERACCESS0_PHYADR,phyadr) |
CSL_FMK(MDIO_USERACCESS0_DATA, data)
#define PHYREG_wait()
while (CSL_FEXT(MDIO_REGS->USERACCESS0,MDIO_USERACCESS0_GO) )
\
#define PHYREG_wait Results(results
)
{
\
while (CSL_FEXT(MDIO_REGS->USERACCESS0,MDIO_USERACCESS0_GO) ); \
results = CSL_FEXT(MDIO_REGS->USERACCESS0, MDIO_USERACCESS0_DATA); }
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EMAC Functional Architecture
2.8 EMAC Module
2.8.1
EMAC Module Components
Interfaces(MII, RMII, GMII, or RGMII), and interfaces to the system core through the EMAC control
module.
The EMAC module consists of the following logical components:
•
The receive path includes: receive DMA engine, receive FIFO, MAC receiver, and receive address
sub-module
•
•
•
•
•
•
The transmit path includes: transmit DMA engine, transmit FIFO, and MAC transmitter
Statistics logic
State RAM
Interrupt controller
Control registers and logic
Clock and reset logic
Figure 13. EMAC Module Block Diagram
Receive
Clock and
address
Configuration bus
reset logic
Receive
DMA engine
Receive
FIFO
MAC
receiver
MII
RMII
EMAC
control
module
Interrupt
controller
State
RAM
SYNC
Statistics
GMII
RGMII
Transmit
DMA engine
Transmit
FIFO
MAC
transmitter
Control
registers
Configuration bus
2.8.1.1
2.8.1.2
Receive DMA Engine
The receive DMA engine performs the data transfer between the receive FIFO and the device internal or
external memory. It interfaces to the processor through the bus arbiter in the EMAC control module. This
DMA engine is totally independent of the C645x DSP EDMA.
Receive FIFO
The receive FIFO consists of sixty-eight cells of 64 bytes each and associated control logic. The FIFO
buffers receive data in preparation for writing into packet buffers in device memory, and also enable
receive FIFO flow control.
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EMAC Functional Architecture
2.8.1.3
MAC Receiver
The MAC receiver detects and processes incoming network frames, de-frames them, and places them into
the receive FIFO. The MAC receiver also detects errors and passes statistics to the statistics RAM.
2.8.1.4
Receive Address
This sub-module performs address matching and address filtering based on the incoming packet’s
destination address. It contains a 32 by 53 bit two-port RAM in which up to 32 addresses can be stored to
be either matched or filtered by the EMAC.
The RAM may contain multicast packet addresses, but the associated channel must have the unicast
enable bit set, even though it is a multicast address. The unicast enable bits are used with multicast
addresses in the receive address RAM (not the multicast hash enable bits). Therefore, hash matches can
be disabled, but specific multicast addresses can be matched (or filtered) in the RAM. If a multicast packet
hash matches, the packet may still be filtered in the RAM. Each packet can be sent to only a single
channel.
2.8.1.5
2.8.1.6
2.8.1.7
Transmit DMA Engine
The transmit DMA engine performs the data transfer between the device internal or external memory and
the transmit FIFO. It interfaces to the processor through the bus arbiter in the EMAC control module. This
DMA engine is totally independent of the C645x DSP EDMA.
Transmit FIFO
The transmit FIFO consists of twenty-four cells of 64 bytes each and associated control logic. This
enables a packet of 1518 bytes (standard Ethernet packet size) to be sent without the possibility of
under-run. The FIFO buffers data in preparation for transmission.
MAC Transmitter
The MAC transmitter formats frame data from the transmit FIFO and transmits the data using the
CSMA/CD access protocol. The frame CRC can be automatically appended, if required. The MAC
transmitter also detects transmission errors and passes statistics to the statistics registers.
2.8.1.8
Statistics Logic
The statistics logic RAM counts and stores the Ethernet statistics, keeping track of 36 different Ethernet
packet statistics.
2.8.1.9
State RAM
The state RAM contains the head descriptor pointers and completion pointers registers for both transmit
and receive channels.
2.8.1.10 EMAC Interrupt Controller
The interrupt controller contains the interrupt related registers and logic. The 18 raw EMAC interrupts are
input to this sub-module and masked module interrupts are output.
2.8.1.11 Control Registers and Logic
The EMAC is controlled by a set of memory-mapped registers. The control logic also signals transmit,
receive, and status related interrupts to the CPU through the EMAC control module.
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EMAC Functional Architecture
2.8.1.12 Clock and Reset Logic
The clock and reset sub-module generates all the clocks and resets for the EMAC peripheral.
2.8.2
EMAC Module Operational Overview
After reset, initialization, and configuration of the EMAC, the application software running on the host may
initiate transmit operations. Transmit operations are initiated by host writes to the appropriate transmit
channel head descriptor pointer contained in the state RAM block. The transmit DMA controller then
fetches the first packet in the packet chain from memory. The DMA controller writes the packet into the
transmit FIFO in bursts of 64-byte cells. The MAC transmitter initiates the packet transmission when either
the threshold number of cells (configurable via TXCELLTHRESH in the FIFOCONTROL register) have
been written to the transmit FIFO, or a complete packet has been written, whichever is smaller. The SYNC
block transmits the packet over one of the MII interfaces in accordance with the 802.3 protocol. The
statistics block counts transmit statistics.
Receive operations are initiated by host writes to the appropriate receive channel head descriptor pointer
after host initialization and configuration. The SYNC sub-module receives packets and strips off the
Ethernet related protocol. The packet data is input to the MAC receiver, which checks for address match
(in conjunction with the receive address block) and processes errors. Accepted packets are written to the
receive FIFO in bursts of 64-byte cells. The receive DMA controller then writes the packet data to memory.
The statistics block counts receive statistics.
The EMAC module operates independently of the CPU. It is configured and controlled by its register set
mapped into device memory. Information about data packets is communicated using 16-byte descriptors
that are placed in an 8K-byte block of RAM in the EMAC control module.
For transmit operations, each 16-byte descriptor describes a packet or packet fragment in the system’s
internal or external memory. For receive operations, each 16-byte descriptor represents a free packet
buffer or buffer fragment. On both transmit and receive, an Ethernet packet is allowed to span one or
more memory fragments, represented by one 16-byte descriptor per fragment. In typical operation, there is
only one descriptor per receive buffer, but transmit packets may be fragmented, depending on the
software architecture.
An interrupt is issued to the CPU whenever a transmit or receive operation has completed. However, it is
not necessary for the CPU to service the interrupt while there are additional resources available. In other
words, the EMAC continues to receive Ethernet packets until its receive descriptor list has been
exhausted. On transmit operations, the transmit descriptors need only be serviced to recover their
associated memory buffer. Thus, it is possible to delay servicing of the EMAC interrupt if there are real
time tasks to perform.
Eight channels are supplied for both transmit and receive operations. On transmit, the eight channels
represent eight independent transmit queues. The EMAC can be configured to treat these channels as an
equal priority round-robin queue, or as a set of eight fixed-priority queues. On receive, the eight channels
represent eight independent receive queues with packet classification. Packets are classified based on the
destination MAC address. Each of the eight channels is assigned its own MAC address, enabling the
EMAC module to act like eight virtual MAC adapters. Also, specific types of frames can be sent to specific
channels. For example, multicast, broadcast, or other (promiscuous, error, etc.) frames can each be
received on a specific receive channel queue.
The EMAC tracks 36 different statistics, as well as recording the status of each individual packet in its
corresponding packet descriptor.
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EMAC Functional Architecture
2.9 Media Independent Interfaces
The EMAC supports four physical interfaces to external devices: Media Independent Interface (MII),
Reduced Media Independent Interface (RMII), Gigabit Media Independent Interface (GMII), and Reduced
Gigabit Media Independent Interface (RGMII). The physical interface used depends on the MACSEL pins.
The basic operation of all four interfaces is the same, with some minor differences.
The following sections discuss the operation of these interfaces in 10/100 Mbps mode (MII, RMII, GMII
and RGMII), and 1000 Mbps mode (GMII and RGMII). An IEEE 802.3 compliant Ethernet MAC controls
these interfaces.
2.9.1
Data Reception
2.9.1.1
Receive Control
Data received from the PHY is interpreted and output to the EMAC receive FIFO. Interpretation involves
detection and removal of the preamble and start of frame delimiter, extraction of the address and frame
length, data handling, error checking and reporting, cyclic redundancy checking (CRC), and statistics
control signal generation. Receive address detection and frame filtering of the frames that do not
address-match is performed outside the Media Independent interface.
2.9.1.2
Receive Inter-Frame Interval
The 802.3 required inter-packet gap (IPG) is 24 receive data clocks (96 bit times). However, the EMAC
can tolerate a reduced IPG (2 receive clocks in 10/100 Mbps mode and 5 receive clocks in 1000 Mbps
mode) with a correct preamble and start frame delimiter. This interval between frames must comprise (in
the following order):
1. An Inter-Packet Gap (IPG).
2. A seven bytes preamble (all bytes 55h).
3. A one byte start of frame delimiter (5Dh).
2.9.1.3
Receive Flow Control
When enabled and triggered, receive flow control is initiated to limit the EMAC from further frame
reception. Two forms of receive flow control are implemented on the C645x device:
•
Receive buffer flow control
•
Receive FIFO flow control
When enabled and triggered, receive buffer flow control prevents further frame reception based on the
number of free buffers available. Receive buffer flow control issues flow control collisions in half-duplex
mode and IEEE 802.3X pause frames for full-duplex mode.
Receive buffer flow control is triggered when the number of free buffers in any enabled receive channel
(RXnFREEBUFFER) is less than or equal to the channel flow control threshold register
(RXnFLOWTHRESH) value. Receive flow control is independent of receive QOS, except that both use the
free buffer values.
When enabled and triggered, receive FIFO flow control prevents further frame reception based on the
number of cells currently in the receive FIFO. Receive FIFO flow control may be enabled only in
full-duplex mode (FULLDUPLEX bit is set in the MACCONTROL register). Receive flow control prevents
reception of frames on the port until all of the triggering conditions clear, at which time frames may again
be received by the port.
Receive FIFO flow control is triggered when the occupancy of the FIFO is greater than or equal to the
RXFIFOFLOWTHRESH value in the FIFOCONTROL register. The RXFIFOFLOWTHRESH value must be
greater than or equal to 1h and less than or equal to 42h (decimal 66). The RXFIFOFLOWTHRESH reset
value is 2h.
Receive flow control is enabled by the RXBUFFERFLOWEN bit and the RXFIFOFLOWEN bit in the
MACCONTROL register. The FULLDUPLEX bit in the MACCONTROL register configures the EMAC for
collision or IEEE 802.3X flow control.
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2.9.1.4
Collision-Based Receive Buffer Flow Control
Collision-based receive buffer flow control provides a means of preventing frame reception when the
EMAC is operating in half-duplex mode (FULLDUPLEX bit is cleared in MACCONTROL register). When
receive flow control is enabled and triggered, the EMAC generates collisions for received frames. The jam
sequence transmitted is the twelve byte sequence C3.C3.C3.C3.C3.C3.C3.C3.C3.C3.C3.C3 in
hexadecimal. The jam sequence begins approximately when the source address starts to be received.
Note that these forced collisions are not limited to a maximum of 16 consecutive collisions, and are
independent of the normal back-off algorithm.
Receive flow control does not depend on the value of the incoming frame destination address. A collision
is generated for any incoming packet, regardless of the destination address, if any EMAC enabled
channel’s free buffer register value is less than or equal to the channel’s flow threshold value.
2.9.1.5
IEEE 802.3X Based Receive Buffer Flow Control
IEEE 802.3x based receive buffer flow control provides a means of preventing frame reception when the
EMAC is operating in full-duplex mode (the FULLDUPLEX bit is set in the MACCONTROL register). When
receive flow control is enabled and triggered, the EMAC transmits a pause frame to request that the
sending station stop transmitting for the period indicated within the transmitted pause frame.
The EMAC transmits a pause frame to the reserved multicast address at the first available opportunity
(immediately if currently idle, or following the completion of the frame currently being transmitted). The
pause frame contains the maximum possible value for the pause time (FFFFh). The EMAC counts the
receive pause frame time (decrements FF00h to 0) and retransmits an outgoing pause frame, if the count
reaches zero. When the flow control request is removed, the EMAC transmits a pause frame with a zero
pause time to cancel the pause request.
Note that transmitted pause frames are only a request to the other end station to stop transmitting.
Frames that are received during the pause interval are received normally (provided the receive FIFO is not
full).
Pause frames are transmitted if enabled and triggered, regardless of whether or not the EMAC is
observing the pause time period from an incoming pause frame.
The EMAC transmits pause frames as described below:
•
The 48-bit reserved multicast destination address 01.80.C2.00.00.01h.
The 48-bit source address (set via the MACSRCADDRLO and MACSRCADDRHI registers).
The 16-bit length/type field containing the value 88.08h.
The 16-bit pause opcode equal to 00.01h.
The 16-bit pause time value of FF.FFh. A pause-quantum is 512 bit-times. Pause frames sent to
cancel a pause request have a pause time value of 00.00h.
•
•
•
•
•
•
Zero padding to 64-byte data length (EMAC transmits only 64-byte pause frames).
The 32-bit frame-check sequence (CRC word).
All quantities are hexadecimal and are transmitted most-significant-byte first. The least-significant-bit
(LSB) is transferred first in each byte.
If the RXBUFFERFLOWEN bit in the MACCONTROL register is cleared while the pause time is nonzero,
then the pause time is cleared and a zero count pause frame is sent.
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EMAC Functional Architecture
2.9.2
Data Transmission
The EMAC passes data to the PHY from the transmit FIFO (when enabled). Data is synchronized to the
transmit clock rate. Transmission begins when there are TXCELLTHRESH cells of 64 bytes each, or a
complete packet, in the FIFO.
2.9.2.1
Transmit Control
A jam sequence is output if a collision is detected on a transmit packet. If the collision was late (after the
first 64 bytes have been transmitted), the collision is ignored. If the collision is not late, the controller will
back off before retrying the frame transmission. When operating in full-duplex mode, the carrier sense
(MCRS) and collision-sensing (MCOL) modes are disabled.
2.9.2.2
CRC Insertion
If the SOP buffer descriptor PASSCRC flag is cleared, the EMAC generates and appends a 32-bit
Ethernet CRC onto the transmitted data. For the EMAC-generated CRC case, a CRC (or placeholder) at
the end of the data is allowed but not required. The buffer byte count value should not include the CRC
bytes, if they are present.
If the SOP buffer descriptor PASSCRC flag is set, then the last four bytes of the transmit data are
transmitted as the frame CRC. The four CRC data bytes should be the last four bytes of the frame and
should be included in the buffer byte count value. The MAC performs no error checking on the outgoing
CRC.
2.9.2.3
Adaptive Performance Optimization (APO)
The EMAC incorporates adaptive performance optimization (APO) logic that may be enabled by setting
the TXPACE bit in the MACCONTROL register. Transmission pacing to enhance performance is enabled
when the TXPACE bit is set. Adaptive performance pacing introduces delays into the normal transmission
of frames, delaying transmission attempts between stations, and reducing the probability of collisions
occurring during heavy traffic (as indicated by frame deferrals and collisions). These actions increase the
chance of a successful transmission.
When a frame is deferred, suffers a single collision, multiple collisions, or excessive collisions, the pacing
counter is loaded with an initial value of 31. When a frame is transmitted successfully (without
experiencing a deferral, single collision, multiple collision, or excessive collision), the pacing counter is
decremented by 1 down to 0.
If the pacing counter is zero, this allows a new frame to immediately attempt transmission (after one IPG).
If the pacing counter is nonzero, the frame is delayed by a pacing delay of approximately four inter-packet
gap delays. APO only affects the IPG preceding the first attempt at transmitting a frame; APO does not
affect the back-off algorithm for re-transmitted frames.
2.9.2.4
Interpacket-Gap (IPG) Enforcement
The measurement reference for the IPG of 96 bit times is changed depending on frame traffic conditions.
If a frame is successfully transmitted without collision and MCRS is de-asserted within approximately 48
bit times of MTXEN being de-asserted, then 96 bit times is measured from MTXEN. If the frame suffered a
collision or MCRS is not de-asserted until more than approximately 48 bit times after MTXEN is
de-asserted, then 96 bit times (approximately, but not less) is measured from MCRS.
2.9.2.5
Back Off
The EMAC implements the 802.3 binary exponential back-off algorithm.
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2.9.2.6
Transmit Flow Control
When enabled, incoming pause frames are acted upon to prevent the EMAC from transmitting any further
frames. Incoming pause frames are only acted upon when the FULLDUPLEX and TXFLOWEN bits in the
MACCONTROL register are set. Pause frames are not acted upon in half-duplex mode. Pause frame
action is taken if enabled, but normally the frame is filtered and not transferred to memory. MAC control
frames are transferred to memory, if the RXCMFEN bit in the RXMBPENABLE register is set. The
TXFLOWEN and FULLDUPLEX bits affect whether MAC control frames are acted upon, but they have no
effect upon whether MAC control frames are transferred to memory or filtered.
Pause frames are a subset of MAC control frames with an opcode field of 0001h. Incoming pause frames
are only acted upon by the EMAC if the following conditions occur:
•
•
•
The TXFLOWEN bit is set in the MACCONTROL register.
The frame’s length is between 64 bytes and RXMAXLEN bytes inclusive.
The frame contains no CRC error or align/code errors.
The pause time value from valid frames is extracted from the two bytes following the opcode. The pause
time is loaded into the EMAC transmit pause timer and the transmit pause time period begins.
If a valid pause frame is received during the transmit pause time period of a previous transmit pause
frame, then either the destination address is not equal to the reserved multicast address or any enabled or
disabled unicast address, and the transmit pause timer immediately expires; or the new pause time value
is 0, and the transmit pause timer immediately expires. Otherwise, the EMAC transmit pause timer is set
immediately to the new pause frame pause time value. (Any remaining pause time from the previous
pause frame is discarded.)
If the TXFLOWEN bit in MACCONTROL is cleared, then the pause timer immediately expires.
The EMAC does not start the transmission of a new data frame any sooner than 512-bit times after a
pause frame with a non-zero pause time has finished being received (MRXDV going inactive). No
transmission begins until the pause timer has expired (the EMAC may transmit pause frames to initiate
outgoing flow control). Any frame already in transmission when a pause frame is received is completed
and unaffected.
Incoming pause frames consist of:
•
A 48-bit destination address equal to one of the following:
–
–
The reserved multicast destination address 01.80.C2.00.00.01h
Any EMAC 48-bit unicast address. Pause frames are accepted, regardless of whether the channel
is enabled.
•
•
•
•
•
•
The 48-bit source address of the transmitting device
The 16-bit length/type field containing the value 88.08h
The 16-bit pause opcode equal to 00.01h
The 16-bit pause time. A pause-quantum is 512 bit-times
Padding to 64-byte data length
The 32-bit frame-check sequence (CRC word)
All quantities are hexadecimal and are transmitted most-significant-byte first. The least-significant-bit
(LSB) is transferred first in each byte.
The padding is required to make up the frame to a minimum of 64 bytes. The standard allows pause
frames longer than 64 bytes to be discarded or interpreted as valid pause frames. The EMAC recognizes
any pause frame between 64 bytes and RXMAXLEN bytes in length.
2.9.2.7
Speed, Duplex, and Pause Frame Support
The MAC can operate in half-duplex or full-duplex mode at 10 Mbps or 100 Mbps, and can operate in full
duplex only in 1000 Mbps. Pause frame support is included in 10/100/1000 Mbps modes as configured by
the host.
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2.10 Packet Receive Operation
2.10.1 Receive DMA Host Configuration
To configure the receive DMA for operation, the host must perform the following actions:
•
•
•
•
Initialize the receive addresses
Initialize the RXnHDP registers to zero
Write the MACHASH1 and MACHASH2 registers, if hash matching multicast addressing is desired
Initialize the RXnFREEBUFFER, RXnFLOWTHRESH, and RXFILTERLOWTHRESH registers, if flow
control is to be enabled
•
•
•
•
•
•
Enable the desired receive interrupts using the RXINTMASKSET and RXINTMASKCLEAR registers
Set the appropriate configuration bits in the MACCONTROL register
Write the RXBUFFEROFFSET register value (typically zero)
Set up the receive channel(s) buffer descriptors and initialize the RXnHDP registers
Enable the receive DMA controller by setting the RXEN bit in the RXCONTROL register
Configure and enable the receive operation, as desired, in the RXMBPENABLE register and by using
the RXUNICASTSET and RXUNICASTCLEAR registers
2.10.2 Receive Channel Enabling
Each of the eight receive channels has an enable bit (RXCHnEN) in the RXUNICASTSET register that is
controlled using the RXUNICASTSET and RXUNICASTCLEAR registers. The RXCHnEN bits determine
whether the given channel is enabled (when set to 1) to receive frames with a matching unicast or
multicast destination address.
The RXBROADEN bit in the RXMBPENABLE register determines if broadcast frames are enabled or
filtered. If broadcast frames are enabled, then they are copied to only a single channel selected by the
RXBROADCH field of RXMBPENABLE register.
The RXMULTEN bit in the RXMBPENABLE register determines if hash matching multicast frames are
enabled or filtered. Incoming multicast addresses (group addresses) are hashed into an index in the hash
table. If the indexed bit is set, the frame hash will match and it will be transferred to the channel selected
by the RXMULTCH field when multicast frames are enabled. The multicast hash bits are set in the
MACHASH1 and MACHASH2 registers.
The RXPROMCH bits in the RXMBPENABLE register select the promiscuous channel to receive frames
selected by the RXCMFEN, RXCSFEN, RXCEFEN, and RXCAFEN bits. These four bits allow reception of
MAC control frames, short frames, error frames, and all frames (promiscuous), respectively.
The address RAM can be configured to set multiple unicast and/or multicast addresses to a given channel
(if the match bit is set in the RAM). Multicast addresses in the RAM are enabled by the RXUNICASTSET
register and not by the RXMULTEN bit in the RXMBPENABLE register. The RXMULTEN bit enables the
hash multicast match only. The address RAM takes precedence over the hash match.
If a multicast packet is received that hash matches (multicast packets enabled), but is filtered in the RAM,
then the packet is filtered. If a multicast packet does not hash match, regardless of whether or not hash
matching is enabled, but matches an enabled multicast address in the RAM, then the packet will be
transferred to the associated channel.
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2.10.3 Receive Channel Addressing
The receive address block can store up to 32 addresses to be filtered or matched. Before enabling packet
reception, all the address RAM locations should be initialized, including locations to be unused. The
system software is responsible for adding and removing addresses from the RAM.
A MAC address location in RAM is 53 bits wide and consists of:
•
•
48 bits of the MAC address
3 bits for the channel to which a valid address match will be transferred. The channel is a don’t care if
MATCHFILT bit is cleared.
•
•
A valid bit
A match or filter bit
First, write the index into the address RAM in the MACINDEX register to start writing a MAC address.
Then write the upper 32 bits of the MAC address (MACADDRHI register), and then the lower 16 bits of
MAC address with the VALID and MATCHFILT control bits (MACADDRLO). The valid bit should be
cleared for the unused locations in the receive address RAM.
The most common uses for the receive address sub-module are:
•
Set EMAC in promiscuous mode, using RXCAFEN and RXPROMCH bits in the RXMBPENABLE
register. Then filter up to 32 individual addresses, which can be both unicast and/or multicast.
•
Disable the promiscuous mode (RXCAFEN = 0) and match up to 32 individual addresses, multicast
and/or unicast.
2.10.4 Hardware Receive QOS Support
Hardware receive quality of service (QOS) is supported, when enabled, by the Tag Protocol Identifier
format and the associated Tag Control Information (TCI) format priority field. When the incoming frame
length/type value is equal to 81.00h, the EMAC recognizes the frame as an Ethernet Encoded Tag
Protocol Type. The two octets immediately following the protocol type contain the 16-bit TCI field. Bits
15-13 of the TCI field contain the received frames priority (0 to 7). The received frame is a low-priority
frame if the priority value is 0 to 3. The received frame is a high-priority frame if the priority value is 4 to 7.
All frames that have a length/type field value not equal to 81.00h are low-priority frames.
Received frames that contain priority information are determined by the EMAC as:
•
A 48-bit (6 bytes) destination address equal to:
–
–
–
The destination station’s individual unicast address
The destination station’s multicast address (MACHASH1 and MACHASH2 registers)
The broadcast address of all ones
•
•
•
•
•
A 48-byte (6 bytes) source address
The 16-bit (2 bytes) length/type field containing the value 81.00h
The 16-bit (2 bytes) TCI field with the priority field in the upper 3 bits
Data bytes
The 4-bytes CRC
The RXFILTERLOWTHRESH and the RXnFREEBUFFER registers are used in conjunction with the
priority information to implement receive hardware QOS. Low-priority frames are filtered if the number of
free buffers (RXnFREEBUFFER) for the frame channel is less than or equal to the filter low threshold
(RXFILTERLOWTHRESH) value. Hardware QOS is enabled by the RXQOSEN bit in the RXMBPENABLE
register.
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2.10.5 Host Free Buffer Tracking
The host must track free buffers for each enabled channel (including unicast, multicast, broadcast, and
promiscuous) if receive QOS or receive flow control is used. Disabled channel free buffer values are don’t
cares. During initialization, the host should write the number of free buffers for each enabled channel to
the appropriate RXnFREEBUFFER register. The EMAC decrements the appropriate channel’s free buffer
value for each buffer used. When the host reclaims the frame buffers, the host should write the channel
free buffer register with the number of reclaimed buffers (write to increment). There are a maximum of 65
535 free buffers available. The RXnFREEBUFFER registers only need to be updated by the host if receive
QOS or flow control is used.
2.10.6 Receive Channel Teardown
The host commands a receive channel teardown by writing the channel number to the RXTEARDOWN
register. When a teardown command is issued to an enabled receive channel, the following occurs:
•
•
•
•
•
•
Any current frame in reception completes normally.
The TDOWNCMPLT flag is set in the next buffer descriptor in the chain, if there is one.
The channel head descriptor pointer is cleared.
A receive interrupt for the channel is issued to the host.
The corresponding RXnCP register contains the value FFFF FFFCh.
The host should acknowledge a teardown interrupt with an FFFF FFFCh acknowledge value.
Channel teardown may be commanded on any channel at any time. The host is informed of the teardown
completion by the set teardown complete buffer descriptor bit. The EMAC does not clear any channel
enables due to a teardown command. A teardown command to an inactive channel issues an interrupt
that software should acknowledge with an FFFF FFFCh acknowledge value to RXnCP (note that there is
no buffer descriptor in this case). Software may read RXnCP to determine if the interrupt was due to a
commanded teardown. The read value is FFFF FFFCh if the interrupt was due to a teardown command.
2.10.7 Receive Frame Classification
Received frames are proper, or good, frames if they are between 64 and RXMAXLEN in length (inclusive)
and contain no code, align, or CRC errors.
Received frames are long frames if their frame count exceeds the value in the RXMAXLEN register. The
RXMAXLEN register default reset value is 5EEh (1518 in decimal). Long received frames are either
oversized or jabber frames. Long frames with no errors are oversized frames; long frames with CRC,
code, or alignment errors are jabber frames.
Received frames are short frames if their frame count is less than 64 bytes. Short frames that address
match and contain no errors are undersized frames; short frames with CRC, code, or alignment errors are
fragment frames. If the frame length is less than or equal to 20, then the frame CRC is passed regardless
of whether the RXPASSCRC bit is set or cleared in the RXMBPENABLE register.
A received long packet always contains RXMAXLEN number of bytes transferred to memory (if the
RXCEFEN bit is set in RXMBPENABLE) regardless of the value of the RXPASSCRC bit. Following is an
example with RXMAXLEN set to 1518:
•
•
•
•
•
If the frame length is 1518, then the packet is not a long packet and there are 1514 or 1518 bytes
transferred to memory depending on the value of the RXPASSCRC bit.
If the frame length is 1519, there are 1518 bytes transferred to memory regardless of the
RXPASSCRC bit value. The last three bytes are the first three CRC bytes.
If the frame length is 1520, there are 1518 bytes transferred to memory regardless of the
RXPASSCRC bit value. The last two bytes are the first two CRC bytes.
If the frame length is 1521, there are 1518 bytes transferred to memory regardless of the
RXPASSCRC bit value. The last byte is the first CRC byte.
If the frame length is 1522, there are 1518 bytes transferred to memory. The last byte is the last data
byte.
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2.10.8 Promiscuous Receive Mode
When the promiscuous receive mode is enabled by setting the RXCAFEN bit in the RXMBPENABLE
register, non-address matching frames that would normally be filtered are transferred to the promiscuous
channel. Address matching frames that would normally be filtered due to errors are transferred to the
address match channel when RXCAFEN and RXCEFEN bits are set. Address matching frames with the
filter bit set (MATCHFILT = 0) are always filtered regardless of the RXCAFEN and RXCEFEN bit setting. A
frame is considered to be an address matching frame only if it is enabled to be received on a unicast,
multicast, or broadcast channel. Frames received to disabled unicast, multicast, or broadcast channels are
considered non-address matching.
MAC control frames address match only if RXCMFEN bit is set. RXCEFEN and RXCSFEN determine
whether error frames are transferred to memory or not, but they do not determine whether error frames
are address matching or not. Short frames are a special type of error frames.
A single channel is selected as the promiscuous channel by the RXPROMCH field in the RXMBPENABLE
register. The promiscuous receive mode is enabled by the RXCMFEN, RXCEFEN, RXCSFEN, and
frames are frames that are between 64 and RXMAXLEN bytes in length inclusive and contain no code,
align, or CRC errors.
Table 8. Receive Frame Treatment Summary
RXMBPENABLE Bits
ADDRESS MATCH
RXCAFEN RXCEFEN RXCMFEN RXCSFEN Frame treatment
0
0
0
1
X
0
X
0
X
0
No frames transferred.
Proper frames transferred to promiscuous
channel.
0
0
0
0
1
1
1
1
0
0
0
1
0
1
1
0
1
0
1
0
Proper/undersized data frames transferred to
promiscuous channel.
Proper data and control frames transferred to
promiscuous channel.
Proper/undersized data and control frames
transferred to promiscuous channel.
Proper/oversize/jabber/code/align/CRC data
frames transferred to promiscuous channel. No
control or undersized/fragment frames are
transferred.
0
1
1
0
1
Proper/undersized/fragment/oversize/jabber/cod
e/align/CRC data frames transferred to
promiscuous channel. No control frames are
transferred.
0
0
1
1
1
1
1
1
0
1
Proper/oversize/jabber/code/align/CRC data and
control frames transferred to promiscuous
channel. No undersized frames are transferred.
All non-address matching frames with and
without errors transferred to promiscuous
channel.
1
1
1
1
1
X
X
X
X
X
0
0
0
0
1
0
0
1
1
0
0
1
0
1
0
Proper data frames transferred to address
match channel.
Proper/undersized data frames transferred to
address match channel.
Proper data and control frames transferred to
address match channel.
Proper/undersized data and control frames
transferred to address match channel.
Proper/oversize/jabber/code/align/CRC data
frames transferred to address match channel.
No control or undersized frames are transferred.
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Table 8. Receive Frame Treatment Summary (continued)
RXMBPENABLE Bits
ADDRESS MATCH
RXCAFEN RXCEFEN RXCMFEN RXCSFEN Frame treatment
1
X
X
X
1
1
1
0
1
1
1
0
1
Proper/oversize/jabber/fragment/undersized/cod
e/align/CRC data frames transferred to address
match channel. No control frames are
transferred.
1
1
Proper/oversize/jabber/code/align/CRC data and
control frames transferred to address match
channel. No undersized/fragment frames are
transferred.
All address matching frames with and without
errors transferred to the address match channel.
2.10.9 Receive Overrun
The types of receive overrun are:
•
•
•
•
FIFO start of frame overrun (FIFO_SOF)
FIFO middle of frame overrun (FIFO_MOF)
DMA start of frame overrun (DMA_SOF)
DMA middle of frame overrun (DMA_MOF)
The statistics counters used to track these types of receive overrun are:
•
•
•
Receive Start of Frame Overruns Register (RXSOFOVERRUNS)
Receive Middle of Frame Overruns Register (RXMOFOVERRUNS)
Receive DMA Overruns Register (RXDMAOVERRUNS)
Start of frame overruns happen when there are no resources available when frame reception begins. Start
of frame overruns increment the appropriate overrun statistic(s) and the frame is filtered.
Middle of frame overruns happen when there are some resources to start the frame reception, but the
resources run out during frame reception. In normal operation, a frame that overruns after starting the
frame reception is filtered and the appropriate statistic(s) are incremented; however, the RXCEFEN bit in
the RXMBPENABLE register affects overrun frame treatment. Table 9 shows how the overrun condition is
handled for the middle of frame overrun.
Table 9. Middle of Frame Overrun Treatment
ADDRESS MATCH
RXCAFEN
RXCEFEN
Middle of frame overrun treatment
Overrun frame filtered.
0
0
0
0
1
1
X
0
1
Overrun frame filtered.
As much frame data as possible is transferred to the promiscuous
channel until overrun. The appropriate overrun statistic(s) is
incremented and the OVERRUN and NOMATCH flags are set in the
SOP buffer descriptor. Note that the RXMAXLEN number of bytes
cannot be reached for an overrun to occur (it would be truncated and
be a jabber or oversize).
1
1
X
X
0
1
Overrun frame filtered with the appropriate overrun statistic(s)
incremented.
As much frame data as possible is transferred to the address match
channel until overrun. The appropriate overrun statistic(s) is
incremented and the OVERRUN flag is set in the SOP buffer
descriptor. Note that the RXMAXLEN number of bytes cannot be
reached for an overrun to occur (it would be truncated).
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2.11 Packet Transmit Operation
The transmit DMA is an eight channel interface. Priority between the eight queues may be either fixed or
round robin as selected by the TXPTYPE bit in the MACCONTROL register. If the priority type is fixed,
then channel 7 has the highest priority and channel 0 has the lowest priority. Round robin priority
proceeds from channel 0 to channel 7.
2.11.1 Transmit DMA Host Configuration
To configure the transmit DMA for operation, the host must perform the following:
•
•
•
•
•
•
•
Write the MACSRCADDRLO and MACSRCADDRHI registers (used for pause frames on transmit).
Initialize the TXnHDP registers to zero.
Enable the desired transmit interrupts using the TXINTMASKSET and TXINTMASKCLEAR registers.
Set the appropriate configuration bits in the MACCONTROL register.
Set up the transmit channel(s) buffer descriptors in host memory.
Enable the transmit DMA controller by setting the TXEN bit in the TXCONTROL register.
Write the appropriate TXnHDP registers with the pointer to the first descriptor to start transmit
operations.
2.11.2 Transmit Channel Teardown
The host commands a transmit channel teardown by writing the channel number to the TXTEARDOWN
register. When a teardown command is issued to an enabled transmit channel, the following occurs:
•
•
•
•
•
•
Any frame currently in transmission completes normally.
The TDOWNCMPLT flag is set in the next SOP buffer descriptor in the chain, if there is one.
The channel head descriptor pointer is cleared.
A transmit interrupt is issued, informing the host of the channel teardown.
The corresponding TXnCP register contains the value FFFF FFFCh.
The host should acknowledge a teardown interrupt with an FFFF FFFCh acknowledge value.
Channel teardown may be commanded on any channel at any time. The host is informed of the teardown
completion by the set teardown complete buffer descriptor bit (TDOWNCMPLT). The EMAC does not
clear any channel enables due to a teardown command. A teardown command to an inactive channel
issues an interrupt that software should acknowledge with an FFFF FFFCh acknowledge value to TXnCP
(note that there is no buffer descriptor). Software may read the interrupt acknowledge location (TXnCP) to
determine if the interrupt was due to a commanded teardown. The read value is FFFF FFFCh if the
interrupt was due to a teardown command.
2.12 Receive and Transmit Latency
The transmit FIFO contains twenty four 64-byte cells, and the receive FIFO contains sixty eight 64-byte
cells. The EMAC begins transmission of a packet on the wire after TXCELLTHRESH cells (configurable
through the FIFOCONTROL register) or a complete packet are available in the FIFO.
Transmit under-run cannot occur for packet sizes of TXCELLTHRESH times 64 bytes (or less). For larger
packet sizes, transmit under-run can occur if the memory latency is greater than the time required to
transmit a 64-byte cell on the wire; this is 0.512 µs in 1 Gbit mode, 5.12 µs in 100 Mbps mode, and 51.2
µs in 10 Mbps mode. The memory latency time includes all buffer descriptor reads for the entire cell data.
The EMAC transmit FIFO uses 24 cells; thus, under-run cannot happen for a normal size packet (less
than 1536 packet bytes). Cell transmission can be configured to start only after an entire packet is
contained in the FIFO; for a maximum-size packet, set the TXCELLTHRESH field to the maximum
possible value of 24.
Receive overrun is prevented if the receive memory cell latency is less than the time required to transmit a
64-byte cell on the wire (0.512 µs in 1 Gbps mode, 5.12 µs in 100 Mbps mode, or 51.2µs in 10 Mbps
mode). The latency time includes any required buffer descriptor reads for the cell data.
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Latency to system’s internal and external RAM can be controlled through the use of the transfer node
priority allocation register in the C645x devices. Latency to descriptor RAM is low because RAM is local to
the EMAC, as it is part of the EMAC control module.
2.13 Transfer Node Priority
The C645x devices contain a system level priority allocation register (PRI_ALLOC) that sets the priority of
the transfer node used in issuing memory transfer requests to system memory.
Although the EMAC has internal FIFOs to help alleviate memory transfer arbitration problems, the average
transfer rate of data read and written by the EMAC to internal or external DSP memory must be at least
equal to the Ethernet wire rate. In addition, the internal FIFO system can not withstand a single memory
latency event greater than the time it takes to fill or empty a TXCELLTHRESH number of internal 64-byte
FIFO cells.
For example, for 1000 Mbps operation, these restrictions translate into the following rules:
•
For the short-term average, each 64-byte memory read/write request from the EMAC must be serviced
in no more than 0.512 µs.
•
Any single latency event in request servicing can be no longer than (0.512 * TXCELLTHRESH) µs.
Bits [0-2] of the PRI_ALLOC register set the transfer node priority for all the master peripherals in the
device, including EMAC. A value of 000b will have the highest priority, while 111b will have the lowest.
The default priority assigned to EMAC is 001b. It is important to have a balance between all peripherals.
In most cases, the default priorities will not need adjustment.
2.14 Reset Considerations
2.14.1 Software Reset Considerations
For information on the chip level reset capabilities of various peripherals, see the device-specific data
manual.
Within the peripheral itself, the EMAC component of the Ethernet MAC peripheral can be placed in a reset
state by writing to the SOFTRESET register located in EMAC memory map. Writing a one to bit 0 of this
register causes the EMAC logic to be reset, and the register values to be set to their default values.
Software reset occurs when the receive and transmit DMA controllers are in an idle state to avoid locking
up the configuration bus; it is the responsibility of the software to verify that there are no pending frames to
be transferred. After writing a one to this bit, it may be polled to determine if the reset has occurred. A
value of one indicates that the reset has not yet occurred. A value of zero indicates that a reset has
occurred.
After a software reset operation, all the EMAC registers need to be re-initialized for proper data
transmission.
Unlike the EMAC module, the MDIO and EMAC control modules cannot be placed in reset from a register
inside their memory map.
2.14.2 Hardware Reset Considerations
When a hardware reset occurs, the EMAC peripheral will have its register values reset, and all the
sub-modules will return to their default state. After the hardware reset, the EMAC needs to be initialized
A hardware reset is the only means of recovering from the error interrupts (HOSTPEND), which are
triggered by errors in packet buffer descriptors. Before doing a hardware reset, you should inspect the
error codes in the MACSTATUS register. This register provides information about the software error type
that needs correction. For more information on error interrupts, see Section 2.16.1.4.
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2.15 Initialization
2.15.1 Enabling the EMAC/MDIO Peripheral
When the device is powered on, the EMAC peripheral is disabled. Prior to EMAC-specific initialization, the
EMAC must be enabled; otherwise its registers cannot be written, and the reads will all return a value of
zero. The interface to be used (MII, RMII, GMII, or RGMII) is automatically selected at power-on reset,
based on the state of the MACSEL configuration pins.
EMAC/MDIO is enabled through the chip level module state control register 0 (MDCTL0) and module
status register 0 (MDSTAT0). For detailed information on the programming sequence, see the
device-specific data manual. This sequence will enable the EMAC peripheral, and the register values are
reset to default. Module-specific initialization may proceed.
2.15.2 EMAC Control Module Initialization
The EMAC control module is used for global interrupt enable, and to pace back-to-back interrupts using
an interrupt re-trigger count based on the peripheral clock (CPUclk/6). There is also an 8K block of RAM
local to the EMAC that holds packet buffer descriptors.
Note that although the EMAC control module and the EMAC module have slightly different functions, in
practice, the type of maintenance performed on the EMAC control module is more commonly conducted
from the EMAC module software (as opposed to the MDIO module).
The initialization of the EMAC control module consists of two parts:
1. Configuration of the interrupt on the DSP.
2. Initialization of the EMAC control module:
–
–
–
Setting the interrupt pace count (using EWINTTCNT)
Initializing the EMAC and MDIO modules
Enabling interrupts in the EMAC control module (using EWCTL)
See Example 4 to view example code used to perform the actions associated with the second part of the
EMAC control module initialization when using the register-level CSL.
Use the system’s interrupt controller to map the EMAC interrupts to one of the CPU’s interrupts. Once the
interrupt is mapped to a CPU interrupt, general masking and unmasking of the interrupt (to control
reentrancy) should be done at the chip level by manipulating the interrupt enable mask. The EMAC control
module control register (EWCTL) should only enable and disable interrupts from within the EMAC interrupt
service routine (ISR), as disabling and re-enabling the interrupt in EWCTL also resets the interrupt pace
counter.
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Example 4. EMAC Control Module Initialization Code
Uint32 tmpval;
/*
// Globally disable EMAC/MDIO interrupts in the control module
/*
CSL_FINST(ECTL_REGS->EWCTL, ECTL_EWCTL_INTEN, DISABLE );
/* Wait about 100 cycles */
for( I=0; i<5; I++ )
tmpval = ECTL_REGS->EWCTL;
/* Set Interrupt Timer Count (CPUclk/6) */
ECTL_REGS->EWINTTCNT = 1500 ;
/*
// Initialize MDIO and EMAC Module
*/
[Discussed Later in this document]
/* Enable global interrupt in the control module */
CSL_FINST(ECTL_REGS->EWCTL, ECTL_EWCTL_INTEN, ENABLE );
2.15.3 MDIO Module Initialization
The MDIO module initially configures and monitors one or more external PHY devices. Other than
initializing the software state machine (details on the MDIO state machine can be found in the IEEE 802.3
standard), the MDIO module only needs the MDIO engine enabled and the clock divider configured. To
set the clock divider, supply an MDIO clock of 1 MHz. As the peripheral clock is used as the base clock
(CPUclk/6), the divider can be set to 125 for a 750 MHz device. Slower MDIO clocks for slower CPU
frequencies are acceptable.
Both the state machine enable and the MDIO clock divider are controlled through the MDIO control
register (CONTROL). If none of the potentially connected PHYs require the access preamble, the
example of the code for initialization.
Example 5. MDIO Module Initialization Code
#define PCLK 125
...
/* Enable MDIO and setup divider */
MDIO_REGS->CONTROL = CSL_FMKT( MDIO_CONTROL_ENABLE, YES) |
CSL_FMK( MDIO_CONTROL_CLKDIV, PCLK ) ;
If the MDIO module must operate on an interrupt basis, the interrupts can be enabled at this time using
the USERINTMASKSET register for register access and the USERPHYSELn register if a target PHY is
already known.
Once the MDIO state machine has been initialized and enabled, it starts polling all 32 PHY addresses on
the MDIO bus, looking for active PHYs. Since it can take up to 50 µs to read one register, the MDIO
module provides an accurate representation of all the PHYs available after a reasonable interval. Also, a
PHY can take up to 3 seconds to negotiate a link. Thus, it is advisable to run the MDIO software off a
time-based event rather than polling.
For more information on PHY control registers, see your PHY device documentation.
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EMAC Functional Architecture
2.15.4 EMAC Module Initialization
The EMAC module sends and receives data packets over the network by maintaining up to 8 transmit and
receive descriptor queues. The EMAC module configuration must also be kept current based on the PHY
negotiation results returned from the MDIO module. Programming this module is the most time-consuming
aspect of developing an application or device driver for Ethernet.
A device drive should follow this initialization procedure to get the EMAC to the state where it is ready to
receive and send Ethernet packets. Some of these steps are not necessary when performed immediately
after device reset.
1. If enabled, clear the device interrupt enable in EWCTL.
2. Clear the MACCONTROL, RXCONTROL, and TXCONTROL registers (not necessary immediately
after reset).
3. Initialize all 16 Head Descriptor Pointer registers (RXnHDP and TXnHDP) to 0.
4. Clear all 36 statistics registers by writing 0 (not necessary immediately after reset).
5. Initialize all 32 receive address RAM locations to 0. Set up the addresses to be matched to the eight
receive channels and the addresses to be filtered, through programming the MACINDEX,
MACADDRHI, and MACADDRLO registers.
6. Initialize the RXnFREEBUFFER, RXnFLOWTHRESH, and RXFILTERLOWTHRESH registers, if buffer
flow control is to be enabled. Program the FIFOCONTROL register is FIFO flow control is desired.
7. Most device drivers open with no multicast addresses, so clear the MACHASH1 and MACHASH2
registers.
8. Write the RXBUFFEROFFSET register value (typically zero).
9. Initially clear all unicast channels by writing FFh to the RXUNICASTCLEAR register. If unicast is
desired, it can be enabled now by writing the RXUNICASTSET register. Some drivers will default to
unicast on device open while others will not.
10. If you desire to transfer jumbo frames, set the RXMAXLEN register to the maximum frame length you
want to allow to be received.
11. Set up the RXMBPENABLE register with an initial configuration. The configuration is based on the
current receive filter settings of the device driver. Some drivers may enable things like broadcast and
multicast packets immediately, while others may not.
12. Set the appropriate configuration bits in the MACCONTROL register (do not set the GMIIEN bit yet).
13. Clear all unused channel interrupt bits by writing RXINTMASKCLEAR and TXINTMASKCLEAR.
14. Enable the receive and transmit channel interrupt bits in RXINTMASKSET and TXINTMASKSET for
the channels to be used, and enable the HOSTMASK and STATMASK bits using the
MACINTMASKSET register.
15. Initialize the receive and transmit descriptor list queues using the 8K descriptor memory block
contained in the EMAC control module.
16. Prepare receive by writing a pointer to the head of the receive buffer descriptor list to RXnHDP.
17. Enable the receive and transmit DMA controllers by setting the RXEN bit in the RXCONTROL register
and the TXEN bit in the TXCONTROL register. Then set the GMIIEN bit in MACCONTROL.
18. If the gigabit mode is desired (available only if using GMII or RGMII interface), set the GIG bit in the
MACCONTROL register.
19. When using RMII, release the interface logic from reset by clearing the RMII_RST field of the EMAC
Configuration register (EMACCFG), found at device level.
20. Enable the device interrupt in EWCTL.
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2.16 Interrupt Support
2.16.1 EMAC Module Interrupt Events and Requests
The EMAC/MDIO generates 18 interrupt events, as follows:
•
•
•
•
TXPENDn: Transmit packet completion interrupt for transmit channels 7 through 0
RXPENDn: Receive packet completion interrupt for receive channels 7 through 0
STATPEND: Statistics interrupt
HOSTPEND: Host error interrupt
2.16.1.1 Transmit Packet Completion Interrupts
The transmit DMA engine has eight channels, and each channel has a corresponding interrupt
(TXPENDn). The transmit interrupts are level interrupts that remain asserted until cleared by the CPU.
Each of the eight transmit channel interrupts may be individually enabled by setting the appropriate bit in
the TXINTMASKSET register. Each of the eight transmit channel interrupts may be individually disabled
by clearing the appropriate bit in the TXINTMASKCLEAR register. The raw and masked transmit interrupt
status may be read by reading the TXINTSTATRAW and TXINTSTATMASKED registers, respectively.
When the EMAC completes the transmission of a packet, the EMAC issues an interrupt to the CPU by
writing the packet’s last buffer descriptor address to the appropriate channel queue’s TX completion
pointer located in the state RAM block. The write generates the interrupt when enabled by the interrupt
mask, regardless of the value written.
Upon interrupt reception, the CPU processes one or more packets from the buffer chain and then
acknowledges an interrupt by writing the address of the last buffer descriptor processed to the queue’s
associated TX completion pointer in the transmit DMA state RAM.
The data written by the host (buffer descriptor address of the last processed buffer) is compared to the
data in the register written by the EMAC port (address of last buffer descriptor used by the EMAC). If the
two values are not equal, indicating that the EMAC has transmitted more packets than the CPU has
processed interrupts for, then the transmit packet completion interrupt signal remains asserted. If the two
values are equal, indicating that the host has processed all packets that the EMAC has transferred, then
the pending interrupt is cleared. Reading the TXnCP register displays the value that the EMAC is
expecting.
The EMAC write to the completion pointer stores the value in the state RAM. The CPU written value does
not change the register value. The host-written value is compared to the register content, which was
written by the EMAC. If the two values are equal, then the interrupt is removed; otherwise the interrupt
remains asserted. The host may process multiple packets prior to acknowledging an interrupt, or the host
may acknowledge interrupts for every packet.
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2.16.1.2 Receive Packet Completion Interrupts
The receive DMA engine has eight channels, and each channel has a corresponding interrupt
(RXPENDn). The receive interrupts are level interrupts that remain asserted until cleared by the CPU.
Each of the eight receive channel interrupts may be individually enabled by setting the appropriate bit in
the RXINTMASKSET register. Each of the eight receive channel interrupts may be individually disabled by
clearing the appropriate bit in the RXINTMASKCLEAR register. The raw and masked receive interrupt
status may be read by reading the RXINTSTATRAW and RXINTSTATMASKED registers, respectively.
When the EMAC completes a packet reception, the EMAC issues an interrupt to the CPU by writing the
packet’s last buffer descriptor address to the appropriate channel queue’s RX completion pointer located
in the state RAM block. The write generates the interrupt when enabled by the interrupt mask, regardless
of the value written.
Upon interrupt reception, the CPU processes one or more packets from the buffer chain and then
acknowledges one or more interrupt(s) by writing the address of the last buffer descriptor processed to the
queue’s associated RX completion pointer in the receive DMA state RAM.
The data written by the host (buffer descriptor address of the last processed buffer) is compared to the
data in the register written by the EMAC (address of last buffer descriptor used by the EMAC). If the two
values are not equal, indicating that the EMAC has received more packets than the CPU has processed
interrupts for, the receive packet completion interrupt signal remains asserted. If the two values are equal,
indicating that the host has processed all packets that the EMAC has received, the pending interrupt is
de-asserted. Reading the RXnCP register displays the value that the EMAC is expecting .
The EMAC write to the completion pointer stores the value in the state RAM. The CPU written value does
not change the register value. The host-written value is compared to the register content, which was
written by the EMAC. If the two values are equal, then the interrupt is removed; otherwise the interrupt
remains asserted. The host may process multiple packets prior to acknowledging an interrupt, or the host
may acknowledge interrupts for every packet.
2.16.1.3 Statistics Interrupt
The statistics level interrupt (STATPEND) is issued when any statistics value is greater than or equal to
8000 0000h, if it has been enabled by the STATMASK bit in the MACINTMASKSET register. The statistics
interrupt is removed by writing to decrement any statistics value greater than 8000 0000h. The interrupt
remains asserted as long as the most-significant-bit of any statistics value is set.
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2.16.1.4 Host Error Interrupt
The host error interrupt (HOSTPEND) is issued, if enabled, under error conditions due to the handling of
buffer descriptors detected during transmit or receive DMA transactions. The failure of the software
application to supply properly formatted buffer descriptors results in this error. The error bit can only be
cleared by resetting the EMAC module in hardware.
The host error interrupt is enabled by setting the HOSTMASK bit in the MACINTMASKSET register. The
host error interrupt is disabled by clearing the appropriate bit in the MACINTMASKCLEAR register. The
raw and masked host error interrupt status may be read by reading the MACINTSTATRAW and
MACINTSTATMASKED registers, respectively.
Transmit host error conditions include:
•
•
•
•
•
•
SOP error
Ownership bit not set in SOP buffer
Zero next buffer descriptor pointer without EOP
Zero buffer pointer
Zero buffer length
Packet length error
Receive host error conditions include:
•
•
Ownership bit not set in input buffer
Zero buffer pointer
2.16.2 MDIO Module Interrupt Events and Requests
The MDIO module generates two interrupt events, as follows:
•
•
LINKINT: Serial interface link change interrupt. Indicates a change in the state of the PHY link.
USERINT: Serial interface user command event complete interrupt.
2.16.2.1 Link Change Interrupt
The MDIO module asserts a link change interrupt (LINKINT) if there is a change in the link state of the
PHY corresponding to the address in the PHYADRMON bits in the USERPHYSELn register, and if the
LINKINTENB bit is also set in USERPHYSELn. This interrupt event is also captured in the LINKINTRAW
bits of the LINKINTRAW register. The LINKINTRAW bits 0 and 1 correspond to USERPHYSEL0 and
USERPHYSEL1, respectively.
When the interrupt is enabled and generated, the corresponding bit is also set in the LINKINTMASKED
register. The interrupt is cleared by writing back the same bit to LINKINTMASKED (write to clear).
2.16.2.2 User Access Completion Interrupt
A user access completion interrupt (USERINT) is asserted when the GO bit in one of the USERACCESSn
registers transitions from 1 to 0 (indicating completion of a user access) and the bit in the
USERINTMASKSET register corresponding to USERACCESS0 or USERACCESS1 is set. This interrupt
event is also captured in bits 0 and 1 of the USERINTRAW register. USERINTRAW bits 0 and bit 1
correspond to USERACCESS0 and USERACCESS1, respectively.
When the interrupt is enabled and generated, the corresponding USERINTMASKED bit is also set in the
USERINTMASKED register. The interrupt is cleared by writing back the same bit to USERINTMASKED
(write to clear).
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2.16.3 Proper Interrupt Processing
All the interrupts signaled from the EMAC and MDIO modules are level-driven. If they remain active, their
level remains constant. However, the CPU core requires edge-triggered interrupts. To properly convert the
level-driven interrupt signal to an edge-triggered signal, the application software must use the interrupt
control logic of the EMAC control module.
Section 2.6.3 discusses interrupt control in the EMAC control module. For safe interrupt processing, the
software application should disable interrupts using the EMAC Control Module Interrupt Control (EWCTL)
register upon entry to the ISR, and re-enable them upon leaving the ISR. If any interrupt signals are active
at that time, this creates another rising edge on the interrupt signal routed to the CPU interrupt controller,
thus triggering another interrupt. The EMAC control module also uses the EMAC Control Module Interrupt
Timer Count (EWINTTCNT) register to implement interrupt pacing.
2.16.4 Interrupt Multiplexing
The EMAC control module combines different interrupt signals from both the EMAC and MDIO modules
and generates a single interrupt signal that is wired to the CPU interrupt controller.
Once this interrupt is generated, the reason for the interrupt can be read from the MACINVECTOR
register located in the EMAC memory map. MACINVECTOR combines the status of the following 20
interrupt signals: TXPENDn, RXPENDn, STATPEND, HOSTPEND, LINKINT, and USERINT.
The EMAC and MDIO interrupts are combined within the EMAC control module and mapped to system
event 17 through the use of the enhanced interrupt selector within the C64x+ core. For more details, see
the Interrupt Controller chapter in the TMS320C64x+ Megamodule Peripherals Reference Guide
SPRU871.
2.17 Power Management
The power saver module integrated in this device allows the clock going to different peripherals to be shut
down when that peripheral is not being used. For more information on the power conservation modes
available for the EMAC/MDIO peripheral, see the device-specific data manual.
2.18 Emulation Considerations
EMAC emulation control is implemented for compatibility with other peripherals. The SOFT and FREE bits
from the EMCONTROL register allow EMAC operation to be suspended.
When the emulation suspend state is entered, the EMAC will stop processing receive and transmit frames
at the next frame boundary. Any frame currently in reception or transmission will be completed normally
without suspension. For transmission, any complete or partial frame in the transmit cell FIFO will be
transmitted. For receive, frames that are detected by the EMAC after the suspend state is entered are
ignored. No statistics will be kept for ignored frames.
Table 10. Emulation Control
SOFT
FREE
Description
0
1
X
0
0
1
Normal operation
Emulation suspend
Normal operation
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EMAC Control Module Registers
3
EMAC Control Module Registers
3.1 Introduction
Table 11 lists the memory-mapped registers for the EMAC Control Module. See the device-specific data
manual for the memory address of these registers.
Table 11. EMAC Control Module Registers
Offset
4h
Acronym
EWCTL
Register Description
Section
EMAC Control Module Interrupt Control Register
EMAC Control Module Interrupt Timer Count Register
Section 3.2
Section 3.3
8h
EWINTTCNT
3.2 EMAC Control Module Interrupt Control Register (EWCTL)
The EMAC control module interrupt control register (EWCTL) is used to enable and disable the central
interrupt from the EMAC and MDIO modules.
It is expected that any time the EMAC and MDIO interrupt is being serviced, the software disables the
INTEN bit in EWCTL. This ensures that the interrupt line goes back to zero. The software reenables the
INTEN bit after clearing all the pending interrupts and before leaving the interrupt service routine. At this
point, if the EMAC control module monitors any interrupts still pending, it reasserts the interrupt line, and
generates a new edge that the DSP can recognize.
Figure 14. EMAC Control Module Interrupt Control Register (EWCTL)
31
15
16
Reserved
R-0
1
0
Reserved
R-0
INTEN
R/W-0
LEGEND: R = Read only; R/W = Read/Write; -n = value after reset
Table 12. EMAC Control Module Interrupt Control Register (EWCTL) Field Descriptions
Bit
31-1
0
Field
Value Description
Reserved
INTEN
0
Reserved
Controls the EMAC_MDIO_INT interrupt generation to the CPU. Any time the INTEN bit in the
EWCTL register is 0, the EMAC_MDIO_INT signal to the CPU is kept de-asserted. If the INTEN bit
in the EWCTL register is 1, then the interrupt control logic checks all the interrupt lines from EMAC
and MDIO. If any of these interrupt lines are active, the EMAC_MDIO_INT signal is asserted.
Assertion of this signal generates an edge, which can then be recognized as a valid interrupt by the
CPU. The INTEN bit takes care of two problems associated with level interrupts from the EMAC
and the MDIO modules. One, it makes sure that none of interrupts are missed, and second, it
makes sure that only the required number of interrupts are sent to the CPU.
0
1
EMAC and MDIO interrupts are disabled
EMAC and MDIO interrupts are enabled
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3.3 EMAC Control Module Interrupt Timer Count Register (EWINTTCNT)
The EMAC control module interrupt timer count register (EWINTTCNT) is used to control the generation of
back-to-back interrupts from the EMAC and MDIO modules. The value of this timer count is loaded into an
internal counter every time interrupts are enabled using EWCTL. A second interrupt cannot be generated
until this count reaches 0. The counter is decremented at a frequency of CPU clock/6; its default reset
count is 0 (inactive), its maximum value is 1 FFFFh (131 071).
Figure 15. EMAC Control Module Interrupt Timer Count Register (EWINTTCNT)
31
17
16
Reserved
R-0
EWINT
TCNT
R/W-0
0
15
EWINTTCNT
R/W-0
LEGEND: R = Read only; R/W = Read/Write; -n = value after reset
Table 13. EMAC Control Module Interrupt Timer Count Register (EWINTTCNT) Field Descriptions
Bit
Field
Value Description
31-17 Reserved
0
Reserved
16-0
EWINTTCNT
Interrupt timer count. EWINTTCNT is a 17-bit interrupt timer count that is used to control the
generation of back-to-back interrupts from the EMAC and MDIO modules. The value of
EWINTTCNT is loaded in an internal time counter every time interrupts are enabled using EWCTL
register by writing a '1' to INTEN bit. (Note the INTEN bit must transition from '0' to '1' to initialize
the internal time counter.) Once initialized, the time counter will count down with each peripheral
clock till it reaches zero. A second interrupt cannot be generated until this counter reaches 0. Any
time the time counter has a non-zero value, the interrupt logic will block the EMAC_MDIO_INT
interrupt to the CPU. Thus, if any of the interrupts coming to the EMAC control module is asserted,
the interrupt logic will assert the EMAC_MDIO_INT signal to the CPU, provided the INTEN bit in the
EWCTL register is set, and the time counter value is zero.
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MDIO Registers
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MDIO Registers
4.1 Introduction
device-specific data manual for the memory address of these registers.
Table 14. Management Data Input/Output (MDIO) Registers
Offset
0h
Acronym
Register Description
Section
VERSION
MDIO Version Register
Section 4.2
Section 4.3
Section 4.4
Section 4.5
Section 4.6
Section 4.7
Section 4.8
Section 4.9
Section 4.10
Section 4.11
Section 4.12
Section 4.13
Section 4.14
Section 4.15
4h
CONTROL
MDIO Control Register
8h
ALIVE
PHY Alive Status register
Ch
LINK
PHY Link Status Register
10h
14h
20h
24h
28h
2Ch
80h
84h
88h
8Ch
LINKINTRAW
LINKINTMASKED
USERINTRAW
USERINTMASKED
USERINTMASKSET
USERINTMASKCLEAR
USERACCESS0
USERPHYSEL0
USERACCESS1
USERPHYSEL1
MDIO Link Status Change Interrupt (Unmasked) Register
MDIO Link Status Change Interrupt (Masked) Register
MDIO User Command Complete Interrupt (Unmasked) Register
MDIO User Command Complete Interrupt (Masked) Register
MDIO User Command Complete Interrupt Mask Set Register
MDIO User Command Complete Interrupt Mask Clear Register
MDIO User Access Register 0
MDIO User PHY Select Register 0
MDIO User Access Register 1
MDIO User PHY Select Register 1
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4.2 MDIO Version Register (VERSION)
Figure 16. MDIO Version Register (VERSION)
31
16
0
MODID
R-7
15
8
7
REVMAJ
R-1
REVMIN
R-3
LEGEND: R = Read only; R/W = Read/Write; -n = value after reset
Table 15. MDIO Version Register (VERSION) Field Descriptions
Bit
Field
Value Description
31-16 MODID
Identifies the type of peripheral
15-8
7-0
REVMAJ
REVMIN
Management Interface Module major revision value
Management Interface Module minor revision value
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MDIO Registers
4.3 MDIO Control Register (CONTROL)
Figure 17. MDIO Control Register (CONTROL)
31
30
29
28
24
23
21
20
19
18
17
16
IDLE ENABLE Reserved
HIGHEST_USER_CHANNEL
Reserved
R-0
PREAMBLE
FAULT
FAULT
ENB
Reserved
R-1
15
R/W-0
R-0
R-1
R/W-0
R/WC-0
R/W-0
R-0
0
CLKDIV
R/W-255
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 16. MDIO Control Register (CONTROL) Field Descriptions
Bit
Field
Value Description
31
IDLE
State machine IDLE status bit
0
1
State machine is not in idle state
State machine is in idle state
30
29
ENABLE
Reserved
State machine enable control bit. . If the MDIO state machine is active at the time it is disabled, it
will complete the current operation before halting and setting the idle bit.
0
1
0
Disables the MDIO state machine
Enable the MDIO state machine
Reserved
28-24 HIGHEST_USER
_CHANNEL
Highest user channel that is available in the module. It is currently set to 1. This implies that
MDIOUserAccess1 is the highest available user access channel.
23-21 Reserved
0
Reserved
20
PREAMBLE
Preamble disable
0
1
Standard MDIO preamble is used
Disables this device from sending MDIO frame preambles
19
FAULT
Fault indicator. This bit is set to 1 if the MDIO pins fail to read back what the device is driving onto
them. This indicates a physical layer fault and the module state machine is reset. Writing a 1 to it
clears this bit.
0
1
No failure
Physical layer fault; the MDIO state machine is reset
Fault detect enable. This bit has to be set to 1 to enable the physical layer fault detection.
Disables the physical layer fault detection
18
FAULTENB
0
1
0
Enables the physical layer fault detection
17-16 Reserved
15-0 CLKDIV
Reserved
Clock Divider bits. This field specifies the division ratio between VBUS peripheral clock and the
frequency of MDCLK. MDCLK is disabled when CLKDIV is set to 0. MDCLK frequency = peripheral
clock frequency/(CLKDIV + 1).
68
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MDIO Registers
4.4 PHY Acknowledge Status Register (ALIVE)
Figure 18. PHY Acknowledge Status Register (ALIVE)
31
15
16
0
ALIVE
R/WC-0
ALIVE
R/WC-0
LEGEND: R/W = Read/Write; R/WC = Read/Write 1 to clear; -n = value after reset
Table 17. PHY Acknowledge Status Register (ALIVE) Field Descriptions
Bit
Field
Value Description
31-0
ALIVE
MDIO Alive bits. Each of the 32 bits of this register is set if the most recent access to the PHY with
address corresponding to the register bit number was acknowledged by the PHY; the bit is reset if
the PHY fails to acknowledge the access. Both the user and polling accesses to a PHY will cause
the corresponding alive bit to be updated. The alive bits are only meant to be used to give an
indication of the presence or not of a PHY with the corresponding address. Writing a 1 to any bit
will clear it, writing a 0 has no effect.
0
1
The PHY fails to acknowledge the access
The most recent access to the PHY with an address corresponding to the register bit number was
acknowledged by the PHY.
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MDIO Registers
4.5 PHY Link Status Register (LINK)
Figure 19. PHY Link Status Register (LINK)
31
16
LINK
R-0
15
0
LINK
R-0
LEGEND: R = Read only; -n = value after reset
Table 18. PHY Link Status Register (LINK) Field Descriptions
Bit
Field
Value Description
31-0
LINK
MDIO Link state bits. This register is updated after a read of the Generic Status Register of a PHY.
The bit is set if the PHY with the corresponding address has link and the PHY acknowledges the
read transaction. The bit is reset if the PHY indicates it does not have link or fails to acknowledge
the read transaction. Writes to the register have no effect.
0
1
The PHY indicates it does not have a link or fails to acknowledge the read transaction
The PHY with the corresponding address has a link and the PHY acknowledges the read
transaction
70
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MDIO Registers
4.6 MDIO Link Status Change Interrupt (Unmasked) Register (LINKINTRAW)
Figure 20. MDIO Link Status Change Interrupt (Unmasked) Register (LINKINTRAW)
31
15
16
0
Reserved
R-0
2
1
Reserved
R-0
LINKINTRAW
R/WC-0
LEGEND: R = Read only; R/WC = Read/Write 1 to clear; -n = value after reset
Table 19. MDIO Link Status Change Interrupt (Unmasked) Register (LINKINTRAW) Field
Descriptions
Bit
31-2
1-0
Field
Value Description
Reserved
0
Reserved
LINKINTRAW
MDIO Link change event, raw value. When asserted, a bit indicates that there was an MDIO link
change event (i.e. change in the LINK register) corresponding to the PHY address in the
USERPHYSEL register. LINKINTRAW[0] and LINKINTRAW[1] correspond to USERPHYSEL0 and
USERPHYSEL1, respectively. Writing a 1 will clear the event and writing 0 has no effect.
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MDIO Registers
4.7 MDIO Link Status Change Interrupt (Masked) Register (LINKINTMASKED)
Figure 21. MDIO Link Status Change Interrupt (Masked) Register (LINKINTMASKED)
31
15
16
Reserved
R-0
2
1
0
Reserved
R-0
LINKINT
MASKED
R/WC-0
LEGEND: R = Read only; R/WC = Read/Write 1 to clear; -n = value after reset
Table 20. MDIO Link Status Change Interrupt (Masked) Register (LINKINTMASKED) Field
Descriptions
Bit
31-2
1-0
Field
Value Description
Reserved
0
Reserved
LINKINTMASKED
MDIO Link change interrupt, masked value. . When asserted, a bit indicates that there was an
MDIO link change event (i.e. change in the LINK register) corresponding to the PHY address in the
USERPHYSEL register and the corresponding LINKINTENB bit was set. LINKINTRAW[0] and
LINKINTRAW[1] correspond to USERPHYSEL0 and USERPHYSEL1, respectively. Writing a 1 will
clear the event and writing 0 has no effect.
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MDIO Registers
4.8 MDIO User Command Complete Interrupt (Unmasked) Register (USERINTRAW)
Figure 22. MDIO User Command Complete Interrupt (Unmasked) Register (USERINTRAW)
31
15
16
Reserved
R-0
2
1
0
Reserved
R-0
LEGEND: R = Read only; R/WC = Read/Write 1 to clear; -n = value after reset
USERINTRAW
R/WC-0
Table 21. MDIO User Command Complete Interrupt (Unmasked) Register (USERINTRAW) Field
Descriptions
Bit
31-2
1-0
Field
Value Description
Reserved
USERINTRAW
0
Reserved
MDIO User command complete event bits. When asserted, a bit indicates that the previously
scheduled PHY read or write command using that particular USERACCESS register has
completed. Writing a 1 will clear the event and writing 0 has no effect.
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MDIO Registers
4.9 MDIO User Command Complete Interrupt (Masked) Register (USERINTMASKED)
The MDIO user command complete interrupt (Masked) register (USERINTMASKED) is shown in
Figure 23. MDIO User Command Complete Interrupt (Masked) Register (USERINTMASKED)
31
15
16
0
Reserved
R-0
2
1
Reserved
R-0
USERINT
MASKED
R/WC-0
LEGEND: R = Read only; R/WC = Read/Write 1 to clear; -n = value after reset
Table 22. MDIO User Command Complete Interrupt (Masked) Register (USERINTMASKED) Field
Descriptions
Bit
31-2
1-0
Field
Value Description
Reserved
0
Reserved
USERINTMASKED
Masked value of MDIO User command complete interrupt. When asserted, a bit indicates that
the previously scheduled PHY read or write command using that particular USERACCESS
register has completed and the corresponding USERINTMASKSET bit is set to 1. Writing a 1
will clear the interrupt and writing 0 has no effect.
74
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MDIO Registers
4.10 MDIO User Command Complete Interrupt Mask Set Register (USERINTMASKSET)
The MDIO user command complete interrupt mask set register (USERINTMASKSET) is shown in
Figure 24. MDIO User Command Complete Interrupt Mask Set Register (USERINTMASKSET)
31
15
16
Reserved
R-0
2
1
0
Reserved
R-0
USERINT
MASKSET
R/WC-0
LEGEND: R = Read only; R/WC = Read/Write 1 to clear; -n = value after reset
Table 23. MDIO User Command Complete Interrupt Mask Set Register (USERINTMASKSET) Field
Descriptions
Bit
31-2
1-0
Field
Value Description
Reserved
0
Reserved
USERINTMASKSET
MDIO user interrupt mask set for USERINTMASKED[1:0] respectively. Setting a bit to 1 will
enable MDIO user command complete interrupts for that particular USERACCESS register.
MDIO user interrupt for a particular USERACCESS register is disabled if the corresponding bit
is 0. Writing a 0 to this register has no effect.
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MDIO Registers
4.11 MDIO User Command Complete Interrupt Mask Clear Register (USERINTMASKCLEAR)
The MDIO user command complete interrupt mask clear register (USERINTMASKCLEAR) is shown in
Figure 25. MDIO User Command Complete Interrupt Mask Clear Register (USERINTMASKCLEAR)
31
15
16
Reserved
R-0
2
1
0
Reserved
R-0
USERINTMASK
CLEAR
R/WC-0
LEGEND: R = Read only; R/WC = Read/Write 1 to clear; -n = value after reset
Table 24. MDIO User Command Complete Interrupt Mask Clear Register (USERINTMASKCLEAR)
Field Descriptions
Bit
31-2
1-0
Field
Value Description
Reserved
0
Reserved
USERINTMASK
CLEAR
MDIO user command complete interrupt mask clear for USERINTMASKED[1:0] respectively.
Setting a bit to 1 will disable further user command complete interrupts for that particular
USERACCESS register. Writing a 0 to this register has no effect.
76
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MDIO Registers
4.12 MDIO User Access Register 0 (USERACCESS0)
Figure 26. MDIO User Access Register 0 (USERACCESS0)
31
GO
30
29
28
26
25
21
20
16
0
WRITE
R/W-0
ACK
Reserved
R-0
REGADR
R/W-0
PHYADR
R/W-0
R/WS-0
R/W-0
15
DATA
R/W-0
LEGEND: R = Read only; R/W = Read/Write; R/WS = Read/Write 1 to set; -n = value after reset
Table 25. MDIO User Access Register 0 (USERACCESS0) Field Descriptions
Bit
Field
Value Description
31
GO
Go bit. Writing a 1 to this bit causes the MDIO state machine to perform an MDIO access when it is
convenient for it to do so; this is not an instantaneous process. Writing a 0 to this bit has no effect.
This bit is writeable only if the MDIO state machine is enabled. This bit will self clear when the
requested access has been completed. Any writes to the USERACCESS0 register are blocked
when the GO bit is 1.
30
29
WRITE
ACK
Write enable bit. Setting this bit to a 1 causes the MDIO transaction to be a register write, otherwise
it is a register read.
0
1
The user command is a read operation
The user command is a write operation
Acknowledge bit. This bit is set if the PHY acknowledged the read transaction.
Reserved
28-26 Reserved
25-21 REGADR
20-16 PHYADR
0
Register address bits. This field specifies the PHY register to be accessed for this transaction
PHY address bits. This field specifies the PHY to be accesses for this transaction
15-0
DATA
User data bits. These bits specify the data value read from or to be written to the specified PHY
register.
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MDIO Registers
4.13 MDIO User PHY Select Register 0 (USERPHYSEL0)
Figure 27. MDIO User PHY Select Register 0 (USERPHYSEL0)
31
16
Reserved
R-0
15
8
7
6
5
4
0
Reserved
R-0
LINKSEL
R/W-0
LINKINTENB
R/W-0
Reserved
R-0
PHYADRMON
R/W-0
LEGEND: R = Read only; R/W = Read/Write; -n = value after reset
Table 26. MDIO User PHY Select Register 0 (USERPHYSEL0) Field Descriptions
Bit
31-8
7
Field
Value Description
Reserved
LINKSEL
0
Reserved
Link status determination select bit. Default value is 0 which implies that the link status is
determined by the MDIO state machine. This is the only option supported on this device.
6
LINKINTENB
Link change interrupt enable. Set to 1 to enable link change status interrupts for PHY address
specified in PHYADRMON. Link change interrupts are disabled if this bit is set to 0.
0
1
0
Link change interrupts are disabled
Link change status interrupts for PHY address specified in PHYADDRMON bits are enabled
Reserved
5
Reserved
4-0
PHYADRMON
PHY address whose link status is to be monitored
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MDIO Registers
4.14 MDIO User Access Register 1 (USERACCESS1)
Figure 28. MDIO User Access Register 1 (USERACCESS1)
31
GO
30
29
28
26
25
21
20
16
0
WRITE
R/W-0
ACK
Reserved
R-0
REGADR
R/W-0
PHYADR
R/W-0
R/WS-0
R/W-0
15
DATA
R/W-0
LEGEND: R = Read only; R/W = Read/Write; R/WS = Read/Write 1 to set; -n = value after reset
Table 27. MDIO User Access Register 1 (USERACCESS1) Field Descriptions
Bit
Field
Value Description
31
GO
Go bit. Writing a 1 to this bit causes the MDIO state machine to perform an MDIO access when it is
convenient for it to do so, this is not an instantaneous process. Writing a 0 to this bit has no effect.
This bit is write able only if the MDIO state machine is enabled. This bit will self clear when the
requested access has been completed. Any writes to the USERACCESS0 register are blocked
when the go bit is 1.
30
29
WRITE
ACK
Write enable bit. Setting this bit to a 1 causes the MDIO transaction to be a register write, otherwise
it is a register read.
0
1
The user command is a read operation
The user command is a write operation
Acknowledge bit. This bit is set if the PHY acknowledged the read transaction.
Reserved
28-26 Reserved
25-21 REGADR
20-16 PHYADR
0
Register address bits. This field specifies the PHY register to be accessed for this transaction
PHY address bits. This field specifies the PHY to be accesses for this transaction
15-0
DATA
User data bits. These bits specify the data value read from or to be written to the specified PHY
register.
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MDIO Registers
4.15 MDIO User PHY Select Register 1 (USERPHYSEL1)
Figure 29. MDIO User PHY Select Register 1 (USERPHYSEL1)
31
16
Reserved
R-0
15
8
7
6
5
4
0
Reserved
R-0
LINKSEL
R/W-0
LINKINTENB
R/W-0
Reserved
R-0
PHYADRMON
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 28. MDIO User PHY Select Register 1 (USERPHYSEL1) Field Descriptions
Bit
31-8
7
Field
Value Description
Reserved
LINKSEL
0
Reserved
Link status determination select bit. Default value is 0 which implies that the link status is
determined by the MDIO state machine. This is the only option supported on this device.
6
LINKINTENB
Link change interrupt enable. Set to 1 to enable link change status interrupts for PHY address
specified in PHYADRMON. Link change interrupts are disabled if this bit is set to 0.
0
1
0
Link change interrupts are disabled
Link change status interrupts for PHY address specified in PHYADDRMON bits are enabled
PHY address whose link status is to be monitored
5
Reserved
4-0
PHYADRMON
PHY address whose link status is to be monitored
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EMAC Port Registers
5
EMAC Port Registers
5.1 Introduction
device-specific data manual for the memory address of these registers.
Table 29. Ethernet Media Access Controller (EMAC) Registers
Offset
0h
Acronym
Register Description
Section
TXIDVER
Transmit Identification and Version Register
Transmit Control Register
Section 5.2
Section 5.3
Section 5.4
Section 5.5
Section 5.6
Section 5.7
Section 5.8
Section 5.9
Section 5.10
Section 5.11
Section 5.12
Section 5.13
Section 5.14
Section 5.15
Section 5.16
Section 5.17
Section 5.18
Section 5.19
Section 5.20
Section 5.21
4h
TXCONTROL
8h
TXTEARDOWN
RXIDVER
Transmit Teardown Register
10h
14h
18h
80h
84h
88h
8Ch
90h
A0h
A4h
A8h
ACh
B0h
B4h
B8h
BCh
100h
Receive Identification and Version Register
Receive Control Register
RXCONTROL
RXTEARDOWN
TXINTSTATRAW
TXINTSTATMASKED
TXINTMASKSET
TXINTMASKCLEAR
MACINVECTOR
RXINTSTATRAW
RXINTSTATMASKED
RXINTMASKSET
RXINTMASKCLEAR
MACINTSTATRAW
MACINTSTATMASKED
MACINTMASKSET
MACINTMASKCLEAR
RXMBPENABLE
Receive Teardown Register
Transmit Interrupt Status (Unmasked) Register
Transmit Interrupt Status (Masked) Register
Transmit Interrupt Mask Set Register
Transmit Interrupt Clear Register
MAC Input Vector Register
Receive Interrupt Status (Unmasked) Register
Receive Interrupt Status (Masked) Register
Receive Interrupt Mask Set Register
Receive Interrupt Mask Clear Register
MAC Interrupt Status (Unmasked) Register
MAC Interrupt Status (Masked) Register
MAC Interrupt Mask Set Register
MAC Interrupt Mask Clear Register
Receive Multicast/Broadcast/Promiscuous Channel Enable
Register
104h
108h
10Ch
110h
114h
120h
124h
128h
12Ch
130h
134h
138h
13Ch
140h
144h
148h
14Ch
150h
154h
158h
RXUNICASTSET
Receive Unicast Enable Set Register
Section 5.22
Section 5.23
Section 5.24
Section 5.25
Section 5.26
Section 5.27
Section 5.27
Section 5.27
Section 5.27
Section 5.27
Section 5.27
Section 5.27
Section 5.27
Section 5.28
Section 5.28
Section 5.28
Section 5.28
Section 5.28
Section 5.28
Section 5.28
RXUNICASTCLEAR
RXMAXLEN
Receive Unicast Clear Register
Receive Maximum Length Register
RXBUFFEROFFSET
RXFILTERLOWTHRESH
RX0FLOWTHRESH
RX1FLOWTHRESH
RX2FLOWTHRESH
RX3FLOWTHRESH
RX4FLOWTHRESH
RX5FLOWTHRESH
RX6FLOWTHRESH
RX7FLOWTHRESH
RX0FREEBUFFER
RX1FREEBUFFER
RX2FREEBUFFER
RX3FREEBUFFER
RX4FREEBUFFER
RX5FREEBUFFER
RX6FREEBUFFER
Receive Buffer Offset Register
Receive Filter Low Priority Frame Threshold Register
Receive Channel 0 Flow Control Threshold Register
Receive Channel 1 Flow Control Threshold Register
Receive Channel 2 Flow Control Threshold Register
Receive Channel 3 Flow Control Threshold Register
Receive Channel 4 Flow Control Threshold Register
Receive Channel 5 Flow Control Threshold Register
Receive Channel 6 Flow Control Threshold Register
Receive Channel 7 Flow Control Threshold Register
Receive Channel 0 Free Buffer Count Register
Receive Channel 1 Free Buffer Count Register
Receive Channel 2 Free Buffer Count Register
Receive Channel 3 Free Buffer Count Register
Receive Channel 4 Free Buffer Count Register
Receive Channel 5 Free Buffer Count Register
Receive Channel 6 Free Buffer Count Register
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EMAC Port Registers
Table 29. Ethernet Media Access Controller (EMAC) Registers (continued)
Offset
15Ch
160h
164h
168h
16Ch
170h
174h
1D0h
1D4h
1D8h
1DCh
1E0h
1E4h
1E8h
1ECh
500h
Acronym
Register Description
Section
RX7FREEBUFFER
MACCONTROL
MACSTATUS
EMCONTROL
FIFOCONTROL
MACCONFIG
SOFTRESET
MACSRCADDRLO
MACSRCADDRHI
MACHASH1
Receive Channel 7 Free Buffer Count Register
MAC Control Register
Section 5.28
Section 5.29
Section 5.30
Section 5.31
Section 5.32
Section 5.33
Section 5.34
Section 5.35
Section 5.36
Section 5.37
Section 5.38
Section 5.39
Section 5.40
Section 5.41
Section 5.42
Section 5.43
MAC Status Register
Emulation Control Register
FIFO Control Register
MAC Configuration Register
Soft Reset Register
MAC Source Address Low Bytes Register
MAC Source Address High Bytes Register
MAC Hash Address Register 1
MAC Hash Address Register 2
Back Off Test Register
MACHASH2
BOFFTEST
TPACETEST
RXPAUSE
Transmit Pacing Algorithm Test Register
Receive Pause Timer Register
Transmit Pause Timer Register
TXPAUSE
MACADDRLO
MAC Address Low Bytes Register, Used in Receive Address
Matching
504h
MACADDRHI
MAC Address High Bytes Register, Used in Receive Address
Matching
Section 5.44
508h
600h
604h
608h
60Ch
610h
614h
618h
61Ch
620h
624h
628h
62Ch
630h
634h
638h
63Ch
640h
MACINDEX
TX0HDP
TX1HDP
TX2HDP
TX3HDP
TX4HDP
TX5HDP
TX6HDP
TX7HDP
RX0HDP
RX1HDP
RX2HDP
RX3HDP
RX4HDP
RX5HDP
RX6HDP
RX7HDP
TX0CP
MAC Index Register
Section 5.45
Section 5.46
Section 5.46
Section 5.46
Section 5.46
Section 5.46
Section 5.46
Section 5.46
Section 5.46
Section 5.47
Section 5.47
Section 5.47
Section 5.47
Section 5.47
Section 5.47
Section 5.47
Section 5.47
Section 5.48
Transmit Channel 0 DMA Head Descriptor Pointer Register
Transmit Channel 1 DMA Head Descriptor Pointer Register
Transmit Channel 2 DMA Head Descriptor Pointer Register
Transmit Channel 3 DMA Head Descriptor Pointer Register
Transmit Channel 4 DMA Head Descriptor Pointer Register
Transmit Channel 5 DMA Head Descriptor Pointer Register
Transmit Channel 6 DMA Head Descriptor Pointer Register
Transmit Channel 7 DMA Head Descriptor Pointer Register
Receive Channel 0 DMA Head Descriptor Pointer Register
Receive Channel 1 DMA Head Descriptor Pointer Register
Receive Channel 2 DMA Head Descriptor Pointer Register
Receive Channel 3 DMA Head Descriptor Pointer Register
Receive Channel 4 DMA Head Descriptor Pointer Register
Receive Channel 5 DMA Head Descriptor Pointer Register
Receive Channel 6 DMA Head Descriptor Pointer Register
Receive Channel 7 DMA Head Descriptor Pointer Register
Transmit Channel 0 Completion Pointer (Interrupt
Acknowledge) Register
644h
648h
64Ch
650h
654h
TX1CP
TX2CP
TX3CP
TX4CP
TX5CP
Transmit Channel 1 Completion Pointer (Interrupt
Acknowledge) Register
Section 5.48
Section 5.48
Section 5.48
Section 5.48
Section 5.48
Transmit Channel 2 Completion Pointer (Interrupt
Acknowledge) Register
Transmit Channel 3 Completion Pointer (Interrupt
Acknowledge) Register
Transmit Channel 4 Completion Pointer (Interrupt
Acknowledge) Register
Transmit Channel 5 Completion Pointer (Interrupt
Acknowledge) Register
82
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EMAC Port Registers
Table 29. Ethernet Media Access Controller (EMAC) Registers (continued)
Offset
Acronym
Register Description
Section
658h
65Ch
660h
664h
668h
66Ch
670h
674h
678h
67Ch
TX6CP
Transmit Channel 6 Completion Pointer (Interrupt
Acknowledge) Register
Section 5.48
TX7CP
RX0CP
RX1CP
RX2CP
RX3CP
RX4CP
RX5CP
RX6CP
RX7CP
Transmit Channel 7 Completion Pointer (Interrupt
Acknowledge) Register
Section 5.48
Section 5.49
Section 5.49
Section 5.49
Section 5.49
Section 5.49
Section 5.49
Section 5.49
Section 5.49
Receive Channel 0 Completion Pointer (Interrupt Acknowledge)
Register
Receive Channel 1 Completion Pointer (Interrupt Acknowledge)
Register
Receive Channel 2 Completion Pointer (Interrupt Acknowledge)
Register
Receive Channel 3 Completion Pointer (Interrupt Acknowledge)
Register
Receive Channel 4 Completion Pointer (Interrupt Acknowledge)
Register
Receive Channel 5 Completion Pointer (Interrupt Acknowledge)
Register
Receive Channel 6 Completion Pointer (Interrupt Acknowledge)
Register
Receive Channel 7 Completion Pointer (Interrupt Acknowledge)
Register
Network Statistics Registers
Good Receive Frames
200h
204h
208h
20ch
210h
214h
218h
21ch
220h
224h
228h
22Ch
230h
234h
238h
23Ch
240h
244h
248h
24Ch
250h
254h
258h
25Ch
260h
264h
268h
26Ch
RXGOODFRAMES
RXBCASTFRAMES
RXMCASTFRAMES
RXPAUSEFRAMES
RXCRCERRORS
Section 5.50.1
Section 5.50.2
Section 5.50.3
Section 5.50.4
Section 5.50.5
Section 5.50.6
Section 5.50.7
Section 5.50.8
Section 5.50.9
Section 5.50.10
Section 5.50.11
Section 5.50.12
Section 5.50.13
Section 5.50.14
Section 5.50.15
Section 5.50.16
Section 5.50.17
Section 5.50.18
Section 5.50.19
Section 5.50.20
Section 5.50.21
Section 5.50.22
Section 5.50.23
Section 5.50.24
Section 5.50.25
Section 5.50.26
Section 5.50.27
Section 5.50.28
Total number of good broadcast frames received
Total number of good multicast frames received
Pause Receive Frames Register
Total number of frames received with CRC errors
RXALIGNCODEERRORS Total number of frames received with alignment/code errors
RXOVERSIZED
RXJABBER
Total number of oversized frames received
Total number of jabber frames received
Total number of undersized frames received
Receive Frame Fragments Register
RXUNDERSIZED
RXFRAGMENTS
RXFILTERED
Filtered Receive Frames
RXQOSFILTERED
RXOCTETS
Received Frames Filtered by QOS
Total number of received bytes in good frames
Total number of good frames transmitted
Broadcast Transmit Frames Register
Multicast Transmit Frames Register
TXGOODFRAMES
TXBCASTFRAMES
TXMCASTFRAMES
TXPAUSEFRAMES
TXDEFERRED
TXCOLLISION
TXSINGLECOLL
TXMULTICOLL
TXEXCESSIVECOLL
TXLATECOLL
Pause Transmit Frames Register
Deferred Transmit Frames Register
Transmit Collision Frames Register
Transmit Single Collision Frames Register
Transmit Multiple Collision Frames Register
Transmit Excessive Collision Frames Register
Transmit Late Collision Frames Register
Transmit Underrun Error Register
TXUNDERRUN
TXCARRIERSENSE
TXOCTETS
Transmit Carrier Sense Errors Register
Transmit Octet Frames Register
FRAME64
Transmit and Receive 64 Octet Frames Register
Transmit and Receive 65 to 127 Octet Frames Register
FRAME65T127
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EMAC Port Registers
Table 29. Ethernet Media Access Controller (EMAC) Registers (continued)
Offset
270h
274h
278h
27Ch
Acronym
Register Description
Section
FRAME128T255
FRAME256T511
FRAME512T1023
FRAME1024TUP
Transmit and Receive 128 to 255 Octet Frames Register
Transmit and Receive 256 to 511 Octet Frames Register
Transmit and Receive 512 to 1023 Octet Frames Register
Section 5.50.29
Section 5.50.30
Section 5.50.31
Section 5.50.32
Transmit and Receive 1024 to RXMAXLEN Octet Frames
Register
280h
284h
288h
28Ch
NETOCTETS
Network Octet Frames Register
Section 5.50.33
Section 5.50.34
Section 5.50.35
Section 5.50.36
RXSOFOVERRUNS
RXMOFOVERRUNS
RXDMAOVERRUNS
Receive FIFO or DMA Start of Frame Overruns Register
Receive FIFO or DMA Middle of Frame Overruns Register
Receive DMA Start of Frame and Middle of Frame Overruns
Register
84
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EMAC Port Registers
5.2 Transmit Identification and Version Register (TXIDVER)
Figure 30. Transmit Identification and Version Register (TXIDVER)
31
15
16
0
TXIDENT
R-12
8
7
TXMAJORVER
R-10
TXMINORVER
R-7
LEGEND: R = Read only; -n = value after reset
Table 30. Transmit Identification and Version Register (TXIDVER) Field Descriptions
Bit
Field
Value Description
31-16 TXIDENT
Transmit identification value
Transmit major version value
Transmit minor version value
15-8
7-0
TXMAJORVER
TXMINORVER
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EMAC Port Registers
5.3 Transmit Control Register (TXCONTROL)
Figure 31. Transmit Control Register (TXCONTROL)
31
16
Reserved
R-0
15
1
0
Reserved
TXEN
R/W-0
R-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 31. Transmit Control Register (TXCONTROL) Field Descriptions
Bit
31-1
0
Field
Value Description
Reserved
TXEN
0
Reserved
Transmit enable
Transmit is disabled
Transmit is enabled
0
1
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EMAC Port Registers
5.4 Transmit Teardown Register (TXTEARDOWN)
Figure 32. Transmit Teardown Register (TXTEARDOWN)
31
15
16
0
Reserved
R-0
3
2
Reserved
R-0
TXTDNCH
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 32. Transmit Teardown Register (TXTEARDOWN) Field Descriptions
Bit
31-3
2-0
Field
Value Description
Reserved
TXTDNCH
0
Reserved
0-3h
Transmit teardown channel. Transmit channel teardown is commanded by writing the encoded
value of the transmit channel to be torn down. The teardown register is read as zero.
0
Teardown transmit channel 0
Teardown transmit channel 1
Teardown transmit channel 2
Teardown transmit channel 3
Teardown transmit channel 4
Teardown transmit channel 5
Teardown transmit channel 6
Teardown transmit channel 7
1h
2h
3h
4h
5h
6h
7h
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EMAC Port Registers
5.5 Receive Identification and Version Register (RXIDVER)
Figure 33. Receive Identification and Version Register (RXIDVER)
31
15
16
0
RXIDENT
R-12
8
7
RXMAJORVER
R-10
RXMINORVER
R-7
LEGEND: R = Read only; -n = value after reset
Table 33. Receive Identification and Version Register (RXIDVER) Field Descriptions
Bit
Field
Value Description
31-16 RXIDENT
Receive identification value
Receive major version value
Receive minor version value
15-8
7-0
RXMAJORVER
RXMINORVER
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EMAC Port Registers
5.6 Receive Control Register (RXCONTROL)
Figure 34. Receive Control Register (RXCONTROL)
31
15
16
Reserved
R-0
1
0
Reserved
R-0
RXEN
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 34. Receive Control Register (RXCONTROL) Field Descriptions
Bit
31-1
0
Field
Value Description
Reserved
RXEN
0
Reserved
Receive DMA enable
Receive is disabled
Receive is enabled
0
1
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EMAC Port Registers
5.7 Receive Teardown Register (RXTEARDOWN)
Figure 35. Receive Teardown Register (RXTEARDOWN)
31
15
16
0
Reserved
R-0
3
2
Reserved
R-0
RXTDNCH
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 35. Receive Teardown Register (RXTEARDOWN) Field Descriptions
Bit
31-3
2-0
Field
Value Description
Reserved
RXTDNCH
0
Reserved
0-3h
Receive teardown channel. Receive channel teardown is commanded by writing the encoded value
of the receive channel to be torn down. The teardown register is read as zero.
0
Teardown receive channel 0
Teardown receive channel 1
Teardown receive channel 2
Teardown receive channel 3
Teardown receive channel 4
Teardown receive channel 5
Teardown receive channel 6
Teardown receive channel 7
1h
2h
3h
4h
5h
6h
7h
90
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EMAC Port Registers
5.8 Transmit Interrupt Status (Unmasked) Register (TXINTSTATRAW)
The transmit interrupt status (unmasked) register (TXINTSTATRAW) is shown in Figure 36 and described
Figure 36. Transmit Interrupt Status (Unmasked) Register (TXINTSTATRAW)
31
15
16
Reserved
R-0
8
7
6
5
4
3
2
1
0
Reserved
R-0
TX7
TX6
TX5
TX4
TX3
TX2
TX1
TX0
PEND PEND PEND PEND PEND PEND PEND PEND
R-0 R-0 R-0 R-0 R-0 R-0 R-0 R-0
LEGEND: R = Read only; -n = value after reset
Table 36. Transmit Interrupt Status (Unmasked) Register (TXINTSTATRAW) Field Descriptions
Bit
31-8
7
Field
Value Description
Reserved
TX7PEND
TX6PEND
TX5PEND
TX4PEND
TX3PEND
TX2PEND
TX1PEND
TX0PEND
0
Reserved
TX7PEND raw interrupt read (before mask)
TX6PEND raw interrupt read (before mask)
TX5PEND raw interrupt read (before mask)
TX4PEND raw interrupt read (before mask)
TX3PEND raw interrupt read (before mask)
TX2PEND raw interrupt read (before mask)
TX1PEND raw interrupt read (before mask)
TX0PEND raw interrupt read (before mask)
6
5
4
3
2
1
0
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EMAC Port Registers
5.9 Transmit Interrupt Status (Masked) Register (TXINTSTATMASKED)
Figure 37. Transmit Interrupt Status (Masked) Register (TXINTSTATMASKED)
31
15
16
Reserved
R-0
8
7
6
5
4
3
2
1
0
Reserved
R-0
TX7
TX6
TX5
TX4
TX3
TX2
TX1
TX0
PEND PEND PEND PEND PEND PEND PEND PEND
R-0 R-0 R-0 R-0 R-0 R-0 R-0 R-0
LEGEND: R/W = R = Read only; -n = value after reset
Table 37. Transmit Interrupt Status (Masked) Register (TXINTSTATMASKED) Field Descriptions
Bit
31-8
7
Field
Value Description
Reserved
TX7PEND
TX6PEND
TX5PEND
TX4PEND
TX3PEND
TX2PEND
TX1PEND
TX0PEND
0
Reserved
TX7PEND masked interrupt read
TX6PEND masked interrupt read
TX5PEND masked interrupt read
TX4PEND masked interrupt read
TX3PEND masked interrupt read
TX2PEND masked interrupt read
TX1PEND masked interrupt read
TX0PEND masked interrupt read
6
5
4
3
2
1
0
92
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EMAC Port Registers
5.10 Transmit Interrupt Mask Set Register (TXINTMASKSET)
Figure 38. Transmit Interrupt Mask Set Register (TXINTMASKSET)
31
16
Reserved
R-0
15
8
7
6
5
4
3
2
1
0
Reserved
R-0
TX7
MASK
TX6
MASK
TX5
MASK
TX4
MASK
TX3
MASK
TX2
MASK
TX1
MASK
TX0
MASK
R/WS-0 R/WS-0 R/WS-0 R/WS-0 R/WS-0 R/WS-0 R/WS-0 R/WS-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 38. Transmit Interrupt Mask Set Register (TXINTMASKSET) Field Descriptions
Bit
31-8
7
Field
Value Description
Reserved
Reserved
TX7MASK
TX6MASK
TX5MASK
TX4MASK
TX3MASK
TX2MASK
TX1MASK
TX0MASK
0
Transmit channel 7 interrupt mask set bit. Write 1 to enable interrupt, a write of 0 has no effect.
Transmit channel 6 interrupt mask set bit. Write 1 to enable interrupt, a write of 0 has no effect.
Transmit channel 5 interrupt mask set bit. Write 1 to enable interrupt, a write of 0 has no effect.
Transmit channel 4 interrupt mask set bit. Write 1 to enable interrupt, a write of 0 has no effect.
Transmit channel 3 interrupt mask set bit. Write 1 to enable interrupt, a write of 0 has no effect.
Transmit channel 2 interrupt mask set bit. Write 1 to enable interrupt, a write of 0 has no effect.
Transmit channel 1 interrupt mask set bit. Write 1 to enable interrupt, a write of 0 has no effect.
Transmit channel 0 interrupt mask set bit. Write 1 to enable interrupt, a write of 0 has no effect.
6
5
4
3
2
1
0
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EMAC Port Registers
5.11 Transmit Interrupt Mask Clear Register (TXINTMASKCLEAR)
Figure 39. Transmit Interrupt Mask Clear Register (TXINTMASKCLEAR)
31
16
Reserved
R-0
15
8
7
6
5
4
3
2
1
0
Reserved
R-0
TX7
MASK
TX6
MASK
TX5
MASK
TX4
MASK
TX3
MASK
TX2
MASK
TX1
MASK
TX0
MASK
R/WS-0 R/WS-0 R/WS-0 R/WS-0 R/WS-0 R/WS-0 R/WS-0 R/WS-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 39. Transmit Interrupt Mask Clear Register (TXINTMASKCLEAR) Field Descriptions
Bit
31-8
7
Field
Value Description
Reserved
TX7MASK
TX6MASK
TX5MASK
TX4MASK
TX3MASK
TX2MASK
TX1MASK
TX0MASK
0
Reserved
Transmit channel 7 interrupt mask clear bit. Write 1 to disable interrupt, a write of 0 has no effect.
Transmit channel 6 interrupt mask clear bit. Write 1 to disable interrupt, a write of 0 has no effect.
Transmit channel 5 interrupt mask clear bit. Write 1 to disable interrupt, a write of 0 has no effect.
Transmit channel 4 interrupt mask clear bit. Write 1 to disable interrupt, a write of 0 has no effect.
Transmit channel 3 interrupt mask clear bit. Write 1 to disable interrupt, a write of 0 has no effect.
Transmit channel 2 interrupt mask clear bit. Write 1 to disable interrupt, a write of 0 has no effect.
Transmit channel 1 interrupt mask clear bit. Write 1 to disable interrupt, a write of 0 has no effect.
Transmit channel 0 interrupt mask clear bit. Write 1 to disable interrupt, a write of 0 has no effect.
6
5
4
3
2
1
0
94
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EMAC Port Registers
5.12 MAC Input Vector Register (MACINVECTOR)
Figure 40. MAC Input Vector Register (MACINVECTOR)
31
30
29
18
17
16
USER LINK
Reserved
R-0
HOST STAT
PEND PEND
INT
R-0
INT
R-0
R-0
R-0
0
15
RXPEND
R-0
TXPEND
R-0
LEGEND: R = Read only; -n = value after reset
Table 40. MAC Input Vector Register (MACINVECTOR) Field Descriptions
Bit
31
30
Field
Value Description
USERINT
LINKINT
MDIO module user interrupt (USERINT) pending status bit
MDIO module link change interrupt (LINKINT) pending status bit
29-18 Reserved
0
Reserved
17
16
HOSTPEND
STATPEND
RXPEND
EMAC module host error interrupt (HOSTPEND) pending status bit
EMAC module statistics interrupt (STATPEND) pending status bit
15-8
7-0
Receive channels 0-7 interrupt (RXnPEND) pending status bit. Bit 8 is receive channel 0.
TXPEND
Transmit channels 0-7 interrupt (TXnPEND) pending status bit. Bit 0 is transmit channel 0.
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EMAC Port Registers
5.13 Receive Interrupt Status (Unmasked) Register (RXINTSTATRAW)
Figure 41. Receive Interrupt Status (Unmasked) Register (RXINTSTATRAW)
31
15
16
Reserved
R-0
8
7
6
5
4
3
2
1
0
Reserved
R-0
RX7
RX6
RX5
RX4
RX3
RX2
RX1
RX0
PEND PEND PEND PEND PEND PEND PEND PEND
R-0 R-0 R-0 R-0 R-0 R-0 R-0 R-0
LEGEND: R = Read only; -n = value after reset
Table 41. Receive Interrupt Status (Unmasked) Register (RXINTSTATRAW) Field Descriptions
Bit
31-8
7
Field
Value Description
Reserved
RX7PEND
RX6PEND
RX5PEND
RX4PEND
RX3PEND
RX2PEND
RX1PEND
RX0PEND
0
Reserved
RX7PEND raw interrupt read (before mask)
RX6PEND raw interrupt read (before mask)
RX5PEND raw interrupt read (before mask)
RX4PEND raw interrupt read (before mask)
RX3PEND raw interrupt read (before mask)
RX2PEND raw interrupt read (before mask)
RX1PEND raw interrupt read (before mask)
RX0PEND raw interrupt read (before mask)
6
5
4
3
2
1
0
96
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EMAC Port Registers
5.14 Receive Interrupt Status (Masked) Register (RXINTSTATMASKED)
Figure 42. Receive Interrupt Status (Masked) Register (RXINTSTATMASKED)
31
15
16
Reserved
R-0
8
7
6
5
4
3
2
1
0
Reserved
R-0
RX7
RX6
RX5
RX4
RX3
RX2
RX1
RX0
PEND PEND PEND PEND PEND PEND PEND PEND
R-0 R-0 R-0 R-0 R-0 R-0 R-0 R-0
LEGEND: R = Read only; -n = value after reset
Table 42. Receive Interrupt Status (Masked) Register (RXINTSTATMASKED) Field Descriptions
Bit
31-8
7
Field
Value Description
Reserved
RX7PEND
RX6PEND
RX5PEND
RX4PEND
RX3PEND
RX2PEND
RX1PEND
RX0PEND
0
Reserved
RX7PEND masked interrupt read
RX6PEND masked interrupt read
RX5PEND masked interrupt read
RX4PEND masked interrupt read
RX3PEND masked interrupt read
RX2PEND masked interrupt read
RX1PEND masked interrupt read
RX0PEND masked interrupt read
6
5
4
3
2
1
0
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EMAC Port Registers
5.15 Receive Interrupt Mask Set Register (RXINTMASKSET)
Figure 43. Receive Interrupt Mask Set Register (RXINTMASKSET)
31
16
Reserved
R-0
15
8
7
6
5
4
3
2
1
0
Reserved
R-0
RX7
MASK
RX6
MASK
RX5
MASK
RX4
MASK
RX3
MASK
RX2
MASK
RX1
MASK
RX0
MASK
R/WS-0 R/WS-0 R/WS-0 R/WS-0 R/WS-0 R/WS-0 R/WS-0 R/WS-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 43. Receive Interrupt Mask Set Register (RXINTMASKSET) Field Descriptions
Bit
31-8
7
Field
Value Description
Reserved
Reserved
0
RX7MASK
RX6MASK
RX5MASK
RX4MASK
RX3MASK
RX2MASK
RX1MASK
RX0MASK
Receive channel 7 mask set bit. Write 1 to enable interrupt, a write of 0 has no effect.
Receive channel 6 mask set bit. Write 1 to enable interrupt, a write of 0 has no effect.
Receive channel 5 mask set bit. Write 1 to enable interrupt, a write of 0 has no effect.
Receive channel 4 mask set bit. Write 1 to enable interrupt, a write of 0 has no effect.
Receive channel 3 mask set bit. Write 1 to enable interrupt, a write of 0 has no effect.
Receive channel 2 mask set bit. Write 1 to enable interrupt, a write of 0 has no effect.
Receive channel 1 mask set bit. Write 1 to enable interrupt, a write of 0 has no effect.
Receive channel 0 mask set bit. Write 1 to enable interrupt, a write of 0 has no effect.
6
5
4
3
2
1
0
98
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EMAC Port Registers
5.16 Receive Interrupt Mask Clear Register (RXINTMASKCLEAR)
Figure 44. Receive Interrupt Mask Clear Register (RXINTMASKCLEAR)
31
16
Reserved
R-0
15
8
7
6
5
4
3
2
1
0
Reserved
R-0
RX7
MASK
RX6
MASK
RX5
MASK
RX4
MASK
RX3
MASK
RX2
MASK
RX1
MASK
RX0
MASK
R/WC-0 R/WC-0 R/WC-0 R/WC-0 R/WC-0 R/WC-0 R/WC-0 R/WC-0
LEGEND: R = Read only; R/W = Read/Write; R/WC = Read/Write 1 to clear; -n = value after reset
Table 44. Receive Interrupt Mask Clear Register (RXINTMASKCLEAR) Field Descriptions
Bit
31-8
7
Field
Value Description
Reserved
RX7MASK
RX6MASK
RX5MASK
RX4MASK
RX3MASK
RX2MASK
RX1MASK
RX0MASK
0
Reserved
Receive channel 7 mask clear bit. Write 1 to disable interrupt, a write of 0 has no effect.
Receive channel 6 mask clear bit. Write 1 to disable interrupt, a write of 0 has no effect.
Receive channel 5 mask clear bit. Write 1 to disable interrupt, a write of 0 has no effect.
Receive channel 4 mask clear bit. Write 1 to disable interrupt, a write of 0 has no effect.
Receive channel 3 mask clear bit. Write 1 to disable interrupt, a write of 0 has no effect.
Receive channel 2 mask clear bit. Write 1 to disable interrupt, a write of 0 has no effect.
Receive channel 1 mask clear bit. Write 1 to disable interrupt, a write of 0 has no effect.
Receive channel 0 mask clear bit. Write 1 to disable interrupt, a write of 0 has no effect.
6
5
4
3
2
1
0
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EMAC Port Registers
5.17 MAC Interrupt Status (Unmasked) Register (MACINTSTATRAW)
Figure 45. MAC Interrupt Status (Unmasked) Register (MACINTSTATRAW)
31
15
16
Reserved
R-0
2
1
0
Reserved
R-0
HOST STAT
PEND PEND
R-0
R-0
LEGEND: R = Read only; -n = value after reset
Table 45. MAC Interrupt Status (Unmasked) Register (MACINTSTATRAW) Field Descriptions
Bit
31-2
1
Field
Value Description
Reserved
0
Reserved
HOSTPEND
STATPEND
Host pending interrupt (HOSTPEND); raw interrupt read (before mask)
Statistics pending interrupt (STATPEND); raw interrupt read (before mask)
0
100
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EMAC Port Registers
5.18 MAC Interrupt Status (Masked) Register (MACINTSTATMASKED)
Figure 46. MAC Interrupt Status (Masked) Register (MACINTSTATMASKED)
31
15
16
Reserved
R-0
2
1
0
Reserved
R-0
HOST STAT
PEND PEND
R-0
R-0
LEGEND: R/W = R = Read only; -n = value after reset
Table 46. MAC Interrupt Status (Masked) Register (MACINTSTATMASKED) Field Descriptions
Bit
31-2
1
Field
Value Description
Reserved
0
Reserved
HOSTPEND
STATPEND
Host pending interrupt (HOSTPEND); masked interrupt read
Statistics pending interrupt (STATPEND); masked interrupt read
0
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EMAC Port Registers
5.19 MAC Interrupt Mask Set Register (MACINTMASKSET)
Figure 47. MAC Interrupt Mask Set Register (MACINTMASKSET)
31
15
16
Reserved
R-0
2
1
0
Reserved
R-0
HOST
MASK
STAT
MASK
R/WS-0
R/WS-0
LEGEND: R = Read only; R/W = Read/Write; R/WS = Read/Write 1 to set; -n = value after reset
Table 47. MAC Interrupt Mask Set Register (MACINTMASKSET) Field Descriptions
Bit
31-2
1
Field
Value Description
Reserved
HOSTMASK
STATMASK
0
Reserved
Host error interrupt mask set bit. Write 1 to enable interrupt, a write of 0 has no effect.
Statistics interrupt mask set bit. Write 1 to enable interrupt, a write of 0 has no effect.
0
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EMAC Port Registers
5.20 MAC Interrupt Mask Clear Register (MACINTMASKCLEAR)
Figure 48. MAC Interrupt Mask Clear Register (MACINTMASKCLEAR)
31
15
16
Reserved
R-0
2
1
0
Reserved
R-0
HOST
MASK
STAT
MASK
R/WC-0
R/WC-0
LEGEND: R = Read only; R/W = Read/Write; R/WC = Read/Write 1 to clear; -n = value after reset
Table 48. MAC Interrupt Mask Clear Register (MACINTMASKCLEAR) Field Descriptions
Bit
31-2
1
Field
Value Description
Reserved
0
Reserved
HOSTMASK
STATMASK
Host error interrupt mask clear bit. Write 1 to disable interrupt, a write of 0 has no effect.
Statistics interrupt mask clear bit. Write 1 to disable interrupt, a write of 0 has no effect.
0
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EMAC Port Registers
5.21 Receive Multicast/Broadcast/Promiscuous Channel Enable Register (RXMBPENABLE)
The receive multicast/broadcast/promiscuous channel enable register (RXMBPENABLE) is shown in
Figure 49. Receive Multicast/Broadcast/Promiscuous Channel Enable Register (RXMBPENABLE)
31
Reserved
R-0
30
29
28
27
19
11
3
25
24
RXPASSCRC
R/W-0
RXQOSEN
R/W-0
RXNOCHAIN
R/W-0
Reserved
R-0
RXCMFEN
R/W-0
23
22
21
20
18
10
2
16
RXCSFEN
R/W-0
RXCEFEN
R/W-0
RXCAFEN
R/W-0
Reserved
RXPROMCH
R/W-0
R-0
15
14
13
12
8
Reserved
RXBROADEN
R/W-0
Reserved
R-0
RXBROADCH
R/W-0
R-0
7
6
5
4
0
Reserved
R-0
RXMULTEN
R/W-0
Reserved
R-0
RXMULTCH
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 49. Receive Multicast/Broadcast/Promiscuous Channel Enable Register (RXMBPENABLE)
Field Descriptions
Bit
31
30
Field
Value Description
Reserved
RXPASSCRC
0
Reserved
Pass receive CRC enable bit
0
1
Received CRC is discarded for all channels and is not included in the buffer descriptor packet
length field
Received CRC is transferred to memory for all channels and is included in the buffer descriptor
packet length
29
28
RXQOSEN
Receive quality of service enable bit
Receive QOS is disabled
0
1
Receive QOS is enabled
RXNOCHAIN
Receive no buffer chaining bit
Received frames can span multiple buffers
0
1
Receive DMA controller transfers each frame into a single buffer regardless of the frame or buffer
size. All remaining frame data after the first buffer is discarded. The buffer descriptor buffer length
field will contain the entire frame byte count (up to 65535 bytes).
27-25 Reserved
0
Reserved
24
RXCMFEN
Receive copy MAC control frames enable bit. Enables MAC control frames to be transferred to
memory. MAC control frames are normally acted upon (if enabled), but not copied to memory. MAC
control frames that are pause frames will be acted upon if enabled in MACCONTROL, regardless of
the value of RXCMFEN. Frames transferred to memory due to RXCMFEN will have the CONTROL
bit set in their EOP buffer descriptor.
0
1
MAC control frames are filtered (but acted upon if enabled)
MAC control frames are transferred to memory
23
RXCSFEN
Receive copy short frames enable bit. Enables frames or fragments shorter than 64 bytes to be
copied to memory. Frames transferred to memory due to RXCSFEN will have the FRAGMENT or
UNDERSIZE bit set in their EOP buffer descriptor. Fragments are short frames that contain
CRC/align/code errors and undersized are short frames without errors.
0
1
Short frames are filtered
Short frames are transferred to memory
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EMAC Port Registers
Table 49. Receive Multicast/Broadcast/Promiscuous Channel Enable Register (RXMBPENABLE) Field
Descriptions (continued)
Bit
Field
Value Description
22
RXCEFEN
Receive copy error frames enable bit. Enables frames containing errors to be transferred to
memory. The appropriate error bit will be set in the frame EOP buffer descriptor.
Frames containing errors are filtered
0
1
Frames containing errors are transferred to memory
21
RXCAFEN
Receive copy all frames enable bit. Enables frames that do not address match (includes multicast
frames that do not hash match) to be transferred to the promiscuous channel selected by
RXPROMCH bits. Such frames will be marked with the NOMATCH bit in their EOP buffer
descriptor.
0
1
Frames that do not address match are filtered
Frames that do not address match are transferred to the promiscuous channel selected by
RXPROMCH bits
20-19 Reserved
0
0-3h
0
Reserved
18-16 RXPROMCH
Receive promiscuous channel select
Select channel 0 to receive promiscuous frames
Select channel 1 to receive promiscuous frames
Select channel 2 to receive promiscuous frames
Select channel 3 to receive promiscuous frames
Select channel 4 to receive promiscuous frames
Select channel 5 to receive promiscuous frames
Select channel 6 to receive promiscuous frames
Select channel 7 to receive promiscuous frames
Reserved
1h
2h
3h
4h
5h
6h
7h
0
15-14 Reserved
13
RXBROADEN
Receive broadcast enable. Enable received broadcast frames to be copied to the channel selected
by RXBROADCH bits.
0
1
Broadcast frames are filtered
Broadcast frames are copied to the channel selected by RXBROADCH bits
Reserved
12-11 Reserved
0
10-8
RXBROADCH
0-3h
0
Receive broadcast channel select
Select channel 0 to receive broadcast frames
Select channel 1 to receive broadcast frames
Select channel 2 to receive promiscuous frames
Select channel 3 to receive broadcast frames
Select channel 4 to receive broadcast frames
Select channel 5 to receive broadcast frames
Select channel 6 to receive broadcast frames
Select channel 7 to receive broadcast frames
Reserved
1h
2h
3h
4h
5h
6h
7h
0
7-6
5
Reserved
RXMULTEN
RX multicast enable. Enable received hash matching multicast frames to be copied to the channel
selected by RXMULTCH bits.
0
1
0
Multicast frames are filtered
Multicast frames are copied to the channel selected by RXMULTCH bits
Reserved
4-3
Reserved
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EMAC Port Registers
Table 49. Receive Multicast/Broadcast/Promiscuous Channel Enable Register (RXMBPENABLE) Field
Descriptions (continued)
Bit
Field
Value Description
2-0
RXMULTCH
0-3h
0
Receive multicast channel select
Select channel 0 to receive multicast frames
Select channel 1 to receive multicast frames
Select channel 2 to receive promiscuous frames
Select channel 3 to receive multicast frames
Select channel 4 to receive multicast frames
Select channel 5 to receive multicast frames
Select channel 6 to receive multicast frames
Select channel 7 to receive multicast frames
1h
2h
3h
4h
5h
6h
7h
5.22 Receive Unicast Enable Set Register (RXUNICASTSET)
Figure 50. Receive Unicast Enable Set Register (RXUNICASTSET)
31
16
Reserved
R-0
15
8
7
6
5
4
3
2
1
0
Reserved
R-0
RXCH7EN RXCH6EN RXCH5EN RXCH4EN RXCH3EN RXCH2EN RXCH1EN RXCH0EN
R/WS-0 R/WS-0 R/WS-0 R/WS-0 R/WS-0 R/WS-0 R/WS-0 R/WS-0
LEGEND: R = Read only; R/W = Read/Write; R/WS = Read/Write 1 to set; -n = value after reset
Table 50. Receive Unicast Enable Set Register (RXUNICASTSET) Field Descriptions
Bit
31-8
7
Field
Value Description
Reserved
0
Reserved
RXCH7EN
Receive channel 7 unicast enable set bit. Write 1 to set the enable, a write of 0 has no effect. May
be read.
6
5
4
3
2
1
0
RXCH6EN
RXCH5EN
RXCH4EN
RXCH3EN
RXCH2EN
RXCH1EN
RXCH0EN
Receive channel 6 unicast enable set bit. Write 1 to set the enable, a write of 0 has no effect. May
be read.
Receive channel 5 unicast enable set bit. Write 1 to set the enable, a write of 0 has no effect. May
be read.
Receive channel 4 unicast enable set bit. Write 1 to set the enable, a write of 0 has no effect. May
be read.
Receive channel 3 unicast enable set bit. Write 1 to set the enable, a write of 0 has no effect. May
be read.
Receive channel 2 unicast enable set bit. Write 1 to set the enable, a write of 0 has no effect. May
be read.
Receive channel 1 unicast enable set bit. Write 1 to set the enable, a write of 0 has no effect. May
be read.
Receive channel 0 unicast enable set bit. Write 1 to set the enable, a write of 0 has no effect. May
be read.
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EMAC Port Registers
5.23 Receive Unicast Clear Register (RXUNICASTCLEAR)
The receive unicast clear register (RXUNICASTCLEAR) is shown in Figure 51 and described in Table 51.
Figure 51. Receive Unicast Clear Register (RXUNICASTCLEAR)
31
16
Reserved
R-0
15
8
7
6
5
4
3
2
1
0
Reserved
R-0
RXCH7EN RXCH6EN RXCH5EN RXCH4EN RXCH3EN RXCH2EN RXCH1EN RXCH0EN
R/WC-0 R/WC-0 R/WC-0 R/WC-0 R/WC-0 R/WC-0 R/WC-0 R/WC-0
LEGEND: R = Read only; R/W = Read/Write; R/WC = Read/Write 1 to clear; -n = value after reset
Table 51. Receive Unicast Clear Register (RXUNICASTCLEAR) Field Descriptions
Bit
31-8
7
Field
Value Description
Reserved
RXCH7EN
RXCH6EN
RXCH5EN
RXCH4EN
RXCH3EN
RXCH2EN
RXCH1EN
RXCH0EN
0
Reserved
Receive channel 7 unicast enable clear bit. Write 1 to clear the enable, a write of 0 has no effect.
Receive channel 6 unicast enable clear bit. Write 1 to clear the enable, a write of 0 has no effect.
Receive channel 5 unicast enable clear bit. Write 1 to clear the enable, a write of 0 has no effect.
Receive channel 4 unicast enable clear bit. Write 1 to clear the enable, a write of 0 has no effect.
Receive channel 3 unicast enable clear bit. Write 1 to clear the enable, a write of 0 has no effect.
Receive channel 2 unicast enable clear bit. Write 1 to clear the enable, a write of 0 has no effect.
Receive channel 1 unicast enable clear bit. Write 1 to clear the enable, a write of 0 has no effect.
Receive channel 0 unicast enable clear bit. Write 1 to clear the enable, a write of 0 has no effect.
6
5
4
3
2
1
0
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EMAC Port Registers
5.24 Receive Maximum Length Register (RXMAXLEN)
Figure 52. Receive Maximum Length Register (RXMAXLEN)
31
15
16
0
Reserved
R-0
RXMAXLEN
R/W-1518
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 52. Receive Maximum Length Register (RXMAXLEN) Field Descriptions
Bit
31-16 Reserved
15-0 RXMAXLEN
Field
Value Description
Reserved
0
Receive maximum frame length. These bits determine the maximum length of a received frame.
The reset value is 5EEh (1518). Frames with byte counts greater than RXMAXLEN are long
frames. Long frames with no errors are oversized frames. Long frames with CRC, code, or
alignment error are jabber frames.
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EMAC Port Registers
5.25 Receive Buffer Offset Register (RXBUFFEROFFSET)
The receive buffer offset register (RXBUFFEROFFSET) is shown in Figure 53 and described in Table 53.
Figure 53. Receive Buffer Offset Register (RXBUFFEROFFSET)
31
15
16
Reserved
R-0
0
RXBUFFEROFFSET
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 53. Receive Buffer Offset Register (RXBUFFEROFFSET) Field Descriptions
Bit
Field
Value Description
Reserved
31-16 Reserved
0
15-0
RXBUFFER
OFFSET
Receive buffer offset value. These bits are written by the EMAC into each frame SOP buffer
descriptor Buffer Offset field. The frame data begins after the RXBUFFEROFFSET value of bytes.
A value of 0 indicates that there are no unused bytes at the beginning of the data and that valid
data begins on the first byte of the buffer. A value of Fh (15) indicates that the first 15 bytes of the
buffer are to be ignored by the EMAC and that valid buffer data starts on byte 16 of the buffer. This
value is used for all channels.
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EMAC Port Registers
5.26 Receive Filter Low Priority Frame Threshold Register (RXFILTERLOWTHRESH)
Figure 54. Receive Filter Low Priority Frame Threshold Register (RXFILTERLOWTHRESH)
31
15
16
Reserved
R-0
8
7
0
Reserved
R-0
RXFILTERTHRESH
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 54. Receive Filter Low Priority Frame Threshold Register (RXFILTERLOWTHRESH) Field
Descriptions
Bit
31-8
7-0
Field
Value Description
Reserved
0
Reserved
RXFILTERTHRESH
Receive filter low threshold. These bits contain the free buffer count threshold value for filtering
low priority incoming frames. This field should remain zero, if no filtering is desired.
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EMAC Port Registers
5.27 Receive Channel 0-7 Flow Control Threshold Register (RXnFLOWTHRESH)
Figure 55. Receive Channel n Flow Control Threshold Register (RXnFLOWTHRESH)
31
15
16
Reserved
R-0
8
7
0
Reserved
R-0
RXnFLOWTHRESH
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 55. Receive Channel n Flow Control Threshold Register (RXnFLOWTHRESH) Field
Descriptions
Bit
31-8
7-0
Field
Value Description
Reserved
0
Reserved
RXnFLOW
Receive flow threshold. These bits contain the threshold value for issuing flow control on incoming
THRESH
frames for channel n (when enabled).
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EMAC Port Registers
5.28 Receive Channel 0-7 Free Buffer Count Register (RXnFREEBUFFER)
Figure 56. Receive Channel n Free Buffer Count Register (RXnFREEBUFFER)
31
15
16
0
Reserved
R-0
RXnFREEBUF
WI-0
tLEGEND: R = Read only; R/W = Read/Write; WI = Write to increment; -n = value after reset
Table 56. Receive Channel n Free Buffer Count Register (RXnFREEBUFFER) Field Descriptions
Bit
31-16 Reserved
15-0 RXnFREEBUF
Field
Value Description
0
Reserved
Receive free buffer count. These bits contain the count of free buffers available. The
RXFILTERTHRESH value is compared with this field to determine if low priority frames should be
filtered. The RXnFLOWTHRESH value is compared with this field to determine if receive flow
control should be issued against incoming packets (if enabled). This is a write-to-increment field.
This field rolls over to zero on overflow. If hardware flow control or QOS is used, the host must
initialize this field to the number of available buffers (one register per channel). The EMAC
decrements (by the number of buffers in the received frame) the associated channel register for
each received frame. The host must write this field with the number of buffers that have been freed
due to host processing.
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EMAC Port Registers
5.29 MAC Control Register (MACCONTROL)
Figure 57. MAC Control Register (MACCONTROL)
31
23
24
16
Reserved
R-0
19
18
17
Reserved
RGMIIEN
GIGFORCE
RMIIDUPLEX-
MODE
R-0
13
R/W-0
R/W-0
R/W-0
15
14
12
11
10
9
8
RMIISPEED RXOFFLENBLOCK RXOWNERSHIP
RXFIFO
CMDIDLE
Reserved
TXPTYPE
Reserved
FLOWEN
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R-0
R/W-0
R-0
7
6
5
4
3
2
1
0
GIG
TXPACE
R/W-0
GMIIEN
R/W-0
TXFLOWEN
R/W-0
RXBUFFERFLOWEN
R/W-0
Reserved
R-0
LOOPBACK
R/W-0
FULLDUPLEX
R/W-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 57. MAC Control Register (MACCONTROL) Field Descriptions
Bit
Field
Value Description
31-19 Reserved
0
Reserved
18
RGMIIEN
RGMII enable bit. Enables the fullduplex and gigabit mode to be selected from the
RGMIIFULLDUPLEX and RGMIIGIG input signals and not from the FULLDUPLEX and GIG bits
contained in this register. This bit is directly connected to the RXINBAND input on the RGMII
module.
0
1
The RGMII interface is in forced link mode. The duplexity is determined by the FULLDUPLEX
bit, and the speed is determined by the GIG bit. The speed is either 1 Gbps or 100 Mbps; 10
Mbps is not supported in forced link mode.
The RGMII interface requires and uses the in-band signals coming in on its receive.
17
16
GIGFORCE
Gigabit force mode. This bit is used to force the EMAC into gigabit mode if the input MTCLK
signal has been stopped by the PHY.
RMIIDUPLEXMODE
Duplex mode for the RMII interface.
0
1
The RMII operates in half duplex mode
The RMII operates in full duplex mode. This mode is not supported in the C645x devices.
Operating speed for the RMII interface
15
14
RMIISPEED
0
1
The RMII operates at 2.5 MHz (10Mbps mode)
The RMII operates at 25 MHz (100 Mbps mode)
Receive offset / length word write block
RXOFFLENBLOCK
0
1
Do not block the DMA writes to the receive buffer descriptor offset/buffer length word
Block all EMAC DMA controller writes to the receive buffer descriptor offset/buffer length words
during packet processing. When this bit is set, the EMAC will never write the third word to any
receive buffer descriptor.
13
12
RXOWNERSHIP
RXFIFOFLOWEN
Receive ownership write bit value
0
1
The EMAC writes the Receive ownership bit to zero at the end of packet processing
The EMAC writes the Receive ownership bit to one at the end of packet processing. If you do
not use the ownership mechanism, you can set this mode to preclude the necessity of software
having to set this bit each time the buffer descriptor is used.
Receive FIFO flow control enable
0
Receive flow control disabled. For full-duplex mode, no outgoing pause frames are sent.
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EMAC Port Registers
Table 57. MAC Control Register (MACCONTROL) Field Descriptions (continued)
Bit
Field
Value Description
1
Receive flow control enabled. For full-duplex mode, outgoing pause frames are sent when
receive FIFO flow control is triggered.
11
CMDIDLE
Command Idle bit
0
1
0
Idle not commanded
Idle commanded (read IDLE in the MACSTATUS register)
Reserved
10
9
Reserved
TXPTYPE
Transmit queue priority type
0
1
The queue uses a round-robin scheme to select the next channel for transmission
The queue uses a fixed-priority (channel 7 highest priority) scheme to select the next channel
for transmission
8
7
Reserved
GIG
0
Reserved
Gigabit mode
0
1
Gigabit mode is disabled; 10/100 mode is in operation
Gigabit mode is enabled (full-duplex only)
Transmit pacing enable bit
6
5
4
TXPACE
GMIIEN
0
1
Transmit pacing is disabled
Transmit pacing is enabled
GMII enable bit
0
1
GMII RX and TX are held in reset
GMII RX and TX are enabled for receive and transmit
TXFLOWEN
Transmit flow control enable bit. This bit determines if incoming pause frames are acted upon in
full-duplex mode. Incoming pause frames are not acted upon in half-duplex mode, regardless of
this bit setting. The RXMBPENABLE bits determine whether or not received pause frames are
transferred to memory.
0
1
Transmit flow control is disabled. Full-duplex mode: incoming pause frames are not acted upon.
Transmit flow control is enabled. Full-duplex mode: incoming pause frames are acted upon.
Receive buffer flow control enable bit
3
RXBUFFER
FLOWEN
0
1
Receive flow control is disabled. Half-duplex mode: no flow control generated collisions are
sent. Full-duplex mode: no outgoing pause frames are sent.
Receive flow control is enabled. Half-duplex mode: collisions are initiated when receive buffer
flow control is triggered. Full-duplex mode: outgoing pause frames are sent when receive flow
control is triggered.
2
1
Reserved
0
Reserved
LOOPBACK
Loopback mode. The loopback mode forces internal full-duplex mode regardless of the
FULLDUPLEX bit. The loopback bit should be changed only when GMIIEN bit is de-asserted.
0
1
Loopback mode is disabled
Loopback mode is enabled
0
FULLDUPLEX
Full duplex mode. The gigabit mode forces full duplex mode regardless of whether the
FULLDUPLEX bit is set or not.
0
1
Half-duplex mode is enabled
Full-duplex mode is enabled
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EMAC Port Registers
5.30 MAC Status Register (MACSTATUS)
Figure 58. MAC Status Register (MACSTATUS)
31
IDLE
R-0
30
24
16
8
Reserved
R-0
23
15
7
20
19
18
TXERRCODE
R-0
Reserved
TXERRCH
R-0
R-0
12
11
Reserved
R-0
10
RXERRCODE
R-0
RXERRCH
R-0
5
4
3
RGMIIFULLDUPLEX
R-x
2
1
0
Reserved
RDMIIGIG
R-x
RXQOSACT
R-0
RXFLOWACT
R-0
TXFLOWACT
R-0
R-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 58. MAC Status Register (MACSTATUS) Field Descriptions
Bit
Field
Value Description
31
IDLE
EMAC idle bit. This bit is set to 0 at reset; one clock after reset it goes to 1.
0
1
0
The EMAC is not idle
The EMAC is in the idle state
Reserved
30-24 Reserved
23-20 TXERRCODE
Transmit host error code. These bits indicate that EMAC detected transmit DMA related host errors.
The host should read this field after a host error interrupt (HOSTPEND) to determine the error. Host
error interrupts require hardware reset in order to recover. A zero packet length is an error, but it is
not detected.
0
1h
2h
3h
4h
5h
6h
0
No error
SOP error; the buffer is the first buffer in a packet, but the SOP bit is not set in software.
Ownership bit not set in SOP buffer
Zero next buffer descriptor pointer without EOP
Zero buffer pointer
Zero buffer length
Packet length error (sum of buffers < packet length)
Reserved
19
Reserved
18-16 TXERRCH
0-3h
Transmit host error channel. These bits indicate which transmit channel the host error occurred on.
This field is cleared to 0 on a host read.
0
The host error occurred on transmit channel 0
The host error occurred on transmit channel 1
The host error occurred on transmit channel 2
The host error occurred on transmit channel 3
The host error occurred on transmit channel 4
The host error occurred on transmit channel 5
The host error occurred on transmit channel 6
The host error occurred on transmit channel 7
1h
2h
3h
4h
5h
6h
7h
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EMAC Port Registers
Table 58. MAC Status Register (MACSTATUS) Field Descriptions (continued)
Bit
Field
Value Description
15-12 RXERRCODE
Receive host error code. These bits indicate that EMAC detected receive DMA related host errors.
The host should read this field after a host error interrupt (HOSTPEND) to determine the error. Host
error interrupts require hardware reset in order to recover.
0
2h
4h
0
No error
Ownership bit not set in SOP buffer
Zero buffer pointer
Reserved
11
Reserved
10-8
RXERRCH
0-3h
Receive host error channel. These bits indicate which receive channel the host error occurred on.
This field is cleared to 0 on a host read.
0
The host error occurred on receive channel 0
The host error occurred on receive channel 1
The host error occurred on receive channel 2
The host error occurred on receive channel 3
The host error occurred on receive channel 4
The host error occurred on receive channel 5
The host error occurred on receive channel 6
The host error occurred on receive channel 7
Reserved
1h
2h
3h
4h
5h
6h
7h
0
7-5
4
Reserved
RGMIIGIG
RGMII gigabit. This is the value of RGMIIGIG input.
RGMII full-duplex. This is the value of RGMIIFULLDUPLEX input.
3
RGMIIFULL
DUPLEX
2
1
0
RXQOSACT
RXFLOWACT
TXFLOWACT
Receive Quality of Service (QOS) active bit. When asserted, indicates that receive quality of service
is enabled and that at least one channel freebuffer count (RXnFREEBUFFER) is less than or equal
to the RXFILTERLOWTHRESH value.
0
1
Receive quality of service is disabled.
Receive quality of service is enabled
Receive flow control active bit. When asserted, indicates that at least one channel freebuffer count
(RXnFREEBUFFER) is less than or equal to the channel's corresponding RXnFILTERTHRESH
value.
0
1
Receive flow control is inactive
Receive flow control is active
Transmit flow control active bit. When asserted, this bit indicates that the pause time period is being
observed for a received pause frame. No new transmissions will begin while this bit is asserted
except for the transmission of pause frames. Any transmission in progress when this bit is asserted
will complete.
0
1
Transmit flow control is inactive
Transmit flow control is active
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EMAC Port Registers
5.31 Emulation Control Register (EMCONTROL)
Figure 59. Emulation Control Register (EMCONTROL)
31
15
16
Reserved
R-0
2
1
0
Reserved
R-0
SOFT FREE
R/W-0 R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 59. Emulation Control Register (EMCONTROL) Field Descriptions
Bit
31-2
1
Field
Value Description
Reserved
SOFT
0
Reserved
Emulation soft bit
Emulation free bit
0
FREE
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EMAC Port Registers
5.32 FIFO Control Register (FIFOCONTROL)
Figure 60. FIFO Control Register (FIFOCONTROL)
31
23
22
16
Reserved
R-0
RXFIFOFLOWTHRESH
R/W-2
15
5
4
0
Reserved
R-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
TXCELLTHRESH
R/W-24
Table 60. FIFO Control Register (FIFOCONTROL) Field Descriptions
Bit
Field
Value Description
31-23 Reserved
0
Reserved
22-16 RXFIFOFLOW
THRESH
Receive FIFO flow control threshold. Occupancy of the receive FIFO when Receive FIFO flow
control is triggered (if enabled). The default value is 0x2 which means that receive FIFO flow control
will be triggered when the occupancy of the FIFO reaches two cells.
15-5
4-0
Reserved
0
Reserved
TXCELLTHRESH
Transmit FIFO cell threshold. Indicates the number of 64-byte packet cells required to be in the
transmit FIFO before the packet transfer is initiated. Packets with fewer cells will be initiated when
the complete packet is contained in the FIFO. This value must be greater then or equal to 2 and
less than or equal to 24.
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EMAC Port Registers
5.33 MAC Configuration Register (MACCONFIG)
Figure 61. MAC Configuration Register (MACCONFIG)
31
15
24
8
23
7
16
0
TXCELLDEPTH
R-24
RXCELLDEPTH
R-68
ADDRESSTYPE
R-2
MACCFIG
R-3
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 61. MAC Configuration Register (MACCONFIG) Field Descriptions
Bit
Field
Value Description
31-24 TXCELLDEPTH
23-16 RXCELLDEPTH
Transmit cell depth. These bit indicates the number of cells in the transmit FIFO.
Receive cell depth. These bits indicate the number of cells in the receive FIFO.
Address type
15-8
7-0
ADDRESSTYPE
MACCFIG
MAC configuration value
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EMAC Port Registers
5.34 Soft Reset Register (SOFTRESET)
Figure 62. Soft Reset Register (SOFTRESET)
31
16
Reserved
R-0
15
1
0
Reserved
SOFTRESET
R/W-0
R-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 62. Soft Reset Register (SOFTRESET) Field Descriptions
Bit
31-1
0
Field
Value Description
Reserved
SOFTRESET
0
Reserved
Software reset. Writing a one to this bit causes the EMAC logic to be reset. Software reset occurs
when the receive and transmit DMA controllers are in an idle state to avoid locking up the
Configuration bus. After writing a one to this bit, it may be polled to determine if the reset has
occurred. If a one is read, the reset has not yet occurred. If a zero is read then reset has occurred.
0
1
A software reset has not occurred
A software reset has occurred
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EMAC Port Registers
5.35 MAC Source Address Low Bytes Register (MACSRCADDRLO)
Figure 63. MAC Source Address Low Bytes Register (MACSRCADDRLO)
31
15
16
Reserved
R-0
8
7
0
MACSRCADDR0
R/W-0
MACSRCADDR1
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 63. MAC Source Address Low Bytes Register (MACSRCADDRLO) Field Descriptions
Bit
Field
Value Description
31-16 Reserved
0
Reserved
15-8
7-0
MACSRCADDR0
MACSRCADDR1
MAC source address lower 8 bits (byte 0)
MAC source address bits 15-8 (byte 1)
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EMAC Port Registers
5.36 MAC Source Address High Bytes Register (MACSRCADDRHI)
Figure 64. MAC Source Address High Bytes Register (MACSRCADDRHI)
31
15
24
8
23
7
16
0
MACSRCADDR2
R/W-0
MACSRCADDR3
R/W-0
MACSRCADDR4
R/W-0
MACSRCADDR5
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 64. MAC Source Address High Bytes Register (MACSRCADDRHI) Field Descriptions
Bit
Field
Value Description
MAC source address bits 23-16 (byte 2)
31-24 MACSRCADDR2
23-16 MACSRCADDR3
MAC source address bits 31-24 (byte 3)
MAC source address bits 39-32 (byte 4)
MAC source address bits 47-40 (byte 5)
15-8
7-0
MACSRCADDR4
MACSRCADDR5
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EMAC Port Registers
5.37 MAC Hash Address Register 1 (MACHASH1)
The MAC hash registers allow group addressed frames to be accepted on the basis of a hash function of
the address. The hash function creates a 6-bit data value (hash_fun) from the 48-bit destination address
(DA) as follows:
Hash_fun(0)=DA(0) XOR DA(6) XOR DA(12) XOR DA(18) XOR DA(24) XOR DA(30) XOR DA(36) XOR DA(42);
Hash_fun(1)=DA(1) XOR DA(7) XOR DA(13) XOR DA(19) XOR DA(25) XOR DA(31) XOR DA(37) XOR DA(43);
Hash_fun(2)=DA(2) XOR DA(8) XOR DA(14) XOR DA(20) XOR DA(26) XOR DA(32) XOR DA(38) XOR DA(44);
Hash_fun(3)=DA(3) XOR DA(9) XOR DA(15) XOR DA(21) XOR DA(27) XOR DA(33) XOR DA(39) XOR DA(45);
Hash_fun(4)=DA(4) XOR DA(10) XOR DA(16) XOR DA(22) XOR DA(28) XOR DA(34) XOR DA(40) XOR DA(46);
Hash_fun(5)=DA(5) XOR DA(11) XOR DA(17) XOR DA(23) XOR DA(29) XOR DA(35) XOR DA(41) XOR DA(47);
This function is used as an offset into a 64-bit hash table stored in MACHASH1 and MACHASH2 that
indicates whether a particular address should be accepted or not.
Figure 65. MAC Hash Address Register 1 (MACHASH1)
31
15
16
MACHASH1
R/W-0
0
MACHASH1
R/W-0
LEGEND: R/W = Read/Write; -n = value after reset
Table 65. MAC Hash Address Register 1 (MACHASH1) Field Descriptions
Bit
Field
Value Description
31-0
MACHASH1
Least-significant 32 bits of the hash table corresponding to hash values 0 to 31. If a hash table bit is
set, then a group address that hashes to that bit index is accepted.
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EMAC Port Registers
5.38 MAC Hash Address Register 2 (MACHASH2)
Figure 66. MAC Hash Address Register 2 (MACHASH2)
31
15
16
0
MACHASH2
R/W-0
MACHASH2
R/W-0
LEGEND: R/W = Read/Write; -n = value after reset
Table 66. MAC Hash Address Register 2 (MACHASH2) Field Descriptions
Bit
Field
Value Description
31-0
MACHASH2
Most-significant 32 bits of the hash table corresponding to hash values 32 to 63. If a hash table bit
is set, then a group address that hashes to that bit index is accepted.
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EMAC Port Registers
5.39 Back Off Test Register (BOFFTEST)
Figure 67. Back Off Random Number Generator Test Register (BOFFTEST)
31
15
26
25
9
16
0
Reserved
R-0
RNDNUM
R-0
12
11
10
COLLCOUNT
R-0
LEGEND: R = Read only; -n = value after reset
Reserved
TXBACKOFF
R-0
R-0
Table 67. Back Off Test Register (BOFFTEST) Field Descriptions
Bit
Field
Value Description
31-26 Reserved
25-16 RNDNUM
0
Reserved
Back off random number generator. This field allows the Back off Random Number Generator to be
read. Reading this field returns the generator's current value. The value is reset to zero and begins
counting on the clock after the de-assertion of reset.
15-12 COLLCOUNT
11-10 Reserved
Collision count. These bits indicate the number of collisions the current frame has experienced.
Reserved
0
9-0
TXBACKOFF
Back off count. This field allows the current value of the back off counter to be observed for test
purposes. This field is loaded automatically according to the back off algorithm, and is decremented
by one for each slot time after the collision.
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EMAC Port Registers
5.40 Transmit Pacing Algorithm Test Register (TPACETEST)
Figure 68. Transmit Pacing Algorithm Test Register (TPACETEST)
31
15
16
0
Reserved
R-0
5
4
Reserved
R-0
PACEVAL
R-0
LEGEND: R = Read only; -n = value after reset
Table 68. Transmit Pacing Algorithm Test Register (TPACETEST) Field Descriptions
Bit
31-5
4-0
Field
Value Description
Reserved
PACEVAL
0
Reserved
Pacing register current value. A nonzero value in this field indicates that transmit pacing is active. A
transmit frame collision or deferral causes PACEVAL to be loaded with 1Fh (31); good frame
transmissions (with no collisions or deferrals) cause PACEVAL to be decremented down to 0.
When PACEVAL is nonzero, the transmitter delays four Inter Packet Gaps between new frame
transmissions after each successfully transmitted frame that had no deferrals or collisions. If a
transmit frame is deferred or suffers a collision, the IPG time is not stretched to four times the
normal value. Transmit pacing helps reduce capture effects, which improves overall network
bandwidth.
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EMAC Port Registers
5.41 Receive Pause Timer Register (RXPAUSE)
Figure 69. Receive Pause Timer Register (RXPAUSE)
31
15
16
0
Reserved
R-0
PAUSETIMER
R-0
LEGEND: R = Read only; -n = value after reset
Table 69. Receive Pause Timer Register (RXPAUSE) Field Descriptions
Bit
Field
Value Description
Reserved
Receive pause timer value. These bits allow the contents of the receive pause timer to be
31-16 Reserved
0
15-0
PAUSETIMER
observed. The receive pause timer is loaded with FF00h when the EMAC sends an outgoing pause
frame (with pause time of FFFFh). The receive pause timer is decremented at slot time intervals. If
the receive pause timer decrements to 0, then another outgoing pause frame is sent and the
load/decrement process is repeated.
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EMAC Port Registers
5.42 Transmit Pause Timer Register (TXPAUSE)
Figure 70. Transmit Pause Timer Register (TXPAUSE)
31
15
16
0
Reserved
R-0
PAUSETIMER
R-0
LEGEND: R = Read only; -n = value after reset
Table 70. Transmit Pause Timer Register (TXPAUSE) Field Descriptions
Bit
31-16 Reserved
15-0 PAUSETIMER
Field
Value Description
0
Reserved
Transmit pause timer value. These bits allow the contents of the transmit pause timer to be
observed. The transmit pause timer is loaded by a received (incoming) pause frame, and then
decremented at slot time intervals down to 0 at which time EMAC transmit frames are again
enabled.
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EMAC Port Registers
5.43 MAC Address Low Bytes Register (MACADDRLO)
Figure 71. MAC Address Low Bytes Register (MACADDRLO)
31
15
21
20
19
18
16
0
Reserved
R-0
VALID
MATCH
FILT
CHANNEL
R/W-x
R/W-x
R/W-x
8
7
MACADDR0
R/W-0
MACADDR1
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 71. MAC Address Low Bytes Register (MACADDRLO) Field Descriptions
Bit
Field
Value Description
31-21 Reserved
0
Reserved
20
19
VALID
Address valid bit. This bit should be cleared to zero for unused address RAM locations.
0
1
Address location is not valid and will not be used in determining whether or not an incoming packet
matches or is filtered
Address location is valid and will be used in determining whether or not an incoming packet
matches or is filtered
MATCHFILT
Match or filter bit.
0
1
The address will be used (if VALID is set) to determine if the incoming packet address should be
filtered
The address will be used (if VALID is set) to determine if the incoming packet address is a match
18-16 CHANNEL
Channel bit; determines which receive channel a valid address match will be transferred to. The
channel is a don't care if the MATCHFILT bit is cleared to zero.
15-8
7-0
MACADDR0
MACADDR1
MAC address lower 8 bits (byte 0)
MAC address bits 15-8 (byte 1)
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EMAC Port Registers
5.44 MAC Address High Bytes Register (MACADDRHI)
Figure 72. MAC Address High Bytes Register (MACADDRHI)
31
15
24
8
23
7
16
0
MACADDR2
R/W-0
MACADDR3
R/W-0
MACADDR4
R/W-0
MACADDR5
R/W-0
LEGEND: R/W = Read/Write; -n = value after reset
Table 72. MAC Address High Bytes Register (MACADDRHI) Field Descriptions
Bit
Field
Value Description
31-24 MACADDR2
23-16 MACADDR3
MAC source address bits 23-16 (byte 2)
MAC source address bits 31-24 (byte 3)
15-8
7-0
MACADDR4
MACADDR5
MAC source address bits 39-32 (byte 4)
MAC source address bits 47-40 (byte 5)
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EMAC Port Registers
5.45 MAC Index Register (MACINDEX)
Figure 73. MAC Index Register (MACINDEX)
31
16
0
Reserved
R-0
15
5
4
Reserved
R-0
MACINDEX
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 73. MAC Index Register (MACINDEX) Field Descriptions
Bit
31-5
4-0
Field
Value Description
Reserved
MACINDEX
0
Reserved
MAC address index. The host must write the index into the RX ADDR RAM in the MACINDEX field,
followed by the upper 32-bits of address, followed by the lower 16-bits of address (with control bits).
The 53-bit indexed ram location is written when the low location is written. All 32 address RAM
locations must be initialized prior to enabling packet reception.
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EMAC Port Registers
5.46 Transmit Channel 0-7 DMA Head Descriptor Pointer Register (TXnHDP)
Figure 74. Transmit Channel n DMA Head Descriptor Pointer Register (TXnHDP)
31
15
16
0
TXnHDP
R/W-x
TXnHDP
R/W-x
LEGEND: R/W = Read/Write; -n = value after reset
Table 74. Transmit Channel n DMA Head Descriptor Pointer Register (TXnHDP) Field Descriptions
Bit
Field
Value Description
31-0
TXnHDP
Transmit channel n DMA Head Descriptor pointer. Writing a transmit DMA buffer descriptor address
to a head pointer location initiates transmit DMA operations in the queue for the selected channel.
Writing to these locations when they are nonzero is an error (except at reset). Host software must
initialize these locations to zero on reset.
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EMAC Port Registers
5.47 Receive Channel 0-7 DMA Head Descriptor Pointer Register (RXnHDP)
Figure 75. Receive Channel n DMA Head Descriptor Pointer Register (RXnHDP)
31
15
16
0
RXnHDP
R/W-x
RXnHDP
R/W-x
LEGEND: R/W = Read/Write; -n = value after reset
Table 75. Receive Channel n DMA Head Descriptor Pointer Register (RXnHDP) Field Descriptions
Bit
Field
Value Description
31-0
RXnHDP
Receive channel n DMA Head Descriptor pointer. Writing a receive DMA buffer descriptor address
to this location allows receive DMA operations in the selected channel when a channel frame is
received. Writing to these locations when they are nonzero is an error (except at reset). Host
software must initialize these locations to zero on reset.
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EMAC Port Registers
5.48 Transmit Channel 0-7 Completion Pointer Register (TXnCP)
Figure 76. Transmit Channel n Completion Pointer Register (TXnCP)
31
15
16
TXnCP
R/W-x
0
TXnCP
R/W-x
LEGEND: R/W = Read/Write; -n = value after reset
Table 76. Transmit Channel n Completion Pointer Register (TXnCP) Field Descriptions
Bit
Field
Value Description
31-0
TXnCP
Transmit channel n completion pointer register is written by the host with the buffer descriptor
address for the last buffer processed by the host during interrupt processing. The EMAC uses the
value written to determine if the interrupt should be de-asserted.
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EMAC Port Registers
5.49 Receive Channel 0-7 Completion Pointer Register (RXnCP)
Figure 77. Receive Channel n Completion Pointer Register (RXnCP)
31
15
16
0
RXnCP
R/W-x
RXnCP
R/W-x
LEGEND: R/W = Read/Write; -n = value after reset
Table 77. Receive Channel n Completion Pointer Register (RXnCP) Field Descriptions
Bit
Field
Value Description
31-0
RXnCP
Receive channel n completion pointer register is written by the host with the buffer descriptor
address for the last buffer processed by the host during interrupt processing. The EMAC uses the
value written to determine if the interrupt should be de-asserted.
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EMAC Port Registers
5.50 Network Statistics Registers
The EMAC has a set of statistics that record events associated with frame traffic. The statistics values are
cleared to zero 38 clocks after the rising edge of reset. When the GMIIEN bit in the MACCONTROL
register is set, all statistics registers are write-to-decrement. The value written is subtracted from the
register value with the result stored in the register. If a value greater than the statistics value is written,
then zero is written to the register (writing FFFF FFFFh clears a statistics location). When the GMIIEN bit
is cleared, all statistics registers are read/write (normal write direct, so writing 0000 0000h clears a
statistics location). All write accesses must be 32-bit accesses.
The statistics interrupt (STATPEND) is issued, if enabled, when any statistics value is greater than or
equal to 8000 0000h. The statistics interrupt is removed by writing to decrement any statistics value
greater than 8000 0000h. The statistics are mapped into internal memory space and are 32-bits wide. All
statistics rollover from FFFF FFFFh to 0000 0000h.
Figure 78. Statistics Register
31
15
16
COUNT
R/W-0
0
COUNT
R/W-0
LEGEND: R/W = Read/Write; -n = value after reset
Table 78. Statistics Register Field Descriptions
Bit
Field
Value Description
Count
31-0
COUNT
5.50.1 Good Receive Frames Register (RXGOODFRAMES)
The total number of good frames received on the EMAC. A good frame is defined as having all of the
following:
•
Any data or MAC control frame that matched a unicast, broadcast, or multicast address, or matched
due to promiscuous mode
•
•
Was of length 64 to RXMAXLEN bytes inclusive
Had no CRC error, alignment error, or code error
See Section 2.5.5 for definitions of alignment, code, and CRC errors. Overruns have no effect on this
statistic.
5.50.2 Broadcast Receive Frames Register (RXBCASTFRAMES)
The total number of good broadcast frames received on the EMAC. A good broadcast frame is defined as
having all of the following:
•
•
•
Any data or MAC control frame that was destined for address FF-FF-FF-FF-FF-FFh only
Was of length 64 to RXMAXLEN bytes inclusive
Had no CRC error, alignment error, or code error
See Section 2.5.5 for definitions of alignment, code, and CRC errors. Overruns have no effect on this
statistic.
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EMAC Port Registers
5.50.3 Multicast Receive Frames Register (RXMCASTFRAMES)
The total number of good multicast frames received on the EMAC. A good multicast frame is defined as
having all of the following:
•
Any data or MAC control frame that was destined for any multicast address other than
FF-FF-FF-FF-FF-FFh
•
•
Was of length 64 to RXMAXLEN bytes inclusive
Had no CRC error, alignment error, or code error
See Section 2.5.5 for alignment/code/CRC error definitions. Overruns have no effect on this statistic.
5.50.4 Pause Receive Frames Register (RXPAUSEFRAMES)
The total number of IEEE 802.3X pause frames received by the EMAC (whether acted upon or not). A
pause frame is defined as having all of the following:
•
•
•
•
•
Contained any unicast, broadcast, or multicast address
Contained the length/type field value 88.08h and the opcode 0001h
Was of length 64 to RXMAXLEN bytes inclusive
Had no CRC error, alignment error, or code error
Pause-frames had been enabled on the EMAC (TXFLOWEN bit is set in MACCONTROL).
alignment/code/CRC error definitions. Overruns have no effect on this statistic.
5.50.5 Receive CRC Errors Register (RXCRCERRORS)
The total number of frames received on the EMAC that experienced a CRC error. A frame with CRC
errors is defined as having all of the following:
•
Was any data or MAC control frame that matched a unicast, broadcast, or multicast address, or
matched due to promiscuous mode
•
•
•
Was of length 64 to RXMAXLEN bytes inclusive
Had no alignment or code error
Had a CRC error. A CRC error is defined as having all of the following:
–
–
A frame containing an even number of nibbles
Fails the frame check sequence test
See Section 2.5.5 for definitions of alignment and code errors. Overruns have no effect on this statistic.
5.50.6 Receive Alignment/Code Errors Register (RXALIGNCODEERRORS)
The total number of frames received on the EMAC that experienced an alignment error or code error.
Such a frame is defined as having all of the following:
•
Was any data or MAC control frame that matched a unicast, broadcast, or multicast address, or
matched due to promiscuous mode
•
•
Was of length 64 to RXMAXLEN bytes inclusive
Had either an alignment error or a code error
–
An alignment error is defined as having all of the following:
•
•
A frame containing an odd number of nibbles
Fails the frame check sequence test, if the final nibble is ignored
–
A code error is defined as a frame that has been discarded because the EMACs MRXER pin is
driven with a one for at least one bit-time's duration at any point during the frame's reception.
Overruns have no effect on this statistic.
CRC alignment or code errors can be calculated by summing receive alignment errors, receive code
errors, and receive CRC errors.
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EMAC Port Registers
5.50.7 Receive Oversized Frames Register (RXOVERSIZED)
The total number of oversized frames received on the EMAC. An oversized frame is defined as having all
of the following:
•
Was any data or MAC control frame that matched a unicast, broadcast, or multicast address, or
matched due to promiscuous mode
•
•
Was greater than RXMAXLEN in bytes
Had no CRC error, alignment error, or code error
See Section 2.5.5 for definitions of alignment, code/CRC errors. Overruns have no effect on this statistic.
5.50.8 Receive Jabber Frames Register (RXJABBER)
The total number of jabber frames received on the EMAC. A jabber frame is defined as having all of the
following:
•
Was any data or MAC control frame that matched a unicast, broadcast, or multicast address, or
matched due to promiscuous mode
•
•
Was greater than RXMAXLEN bytes long
Had a CRC error, alignment error, or code error
See Section 2.5.5 for definitions of alignment, code, and CRC errors. Overruns have no effect on this
statistic.
5.50.9 Receive Undersized Frames Register (RXUNDERSIZED)
The total number of undersized frames received on the EMAC. An undersized frame is defined as having
all of the following:
•
Was any data frame that matched a unicast, broadcast, or multicast address, or matched due to
promiscuous mode
•
•
Was less than 64 bytes long
Had no CRC error, alignment error, or code error
See Section 2.5.5 for definitions of alignment, code, and CRC errors. Overruns have no effect on this
statistic.
5.50.10 Receive Frame Fragments Register (RXFRAGMENTS)
The total number of frame fragments received on the EMAC. A frame fragment is defined as having all of
the following:
•
•
•
•
Any data frame (address matching does not matter)
Was less than 64 bytes long
Had a CRC error, alignment error, or code error
Was not the result of a collision caused by half duplex, collision based flow control
See Section 2.5.5 for definitions of alignment, code, and CRC errors. Overruns have no effect on this
statistic.
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EMAC Port Registers
5.50.11 Filtered Receive Frames Register (RXFILTERED)
The total number of frames received on the EMAC that the EMAC address matching process indicated
should be discarded. Such a frame is defined as having all of the following:
•
•
•
Was any data frame (not MAC control frame) destined for any unicast, broadcast, or multicast address
Did not experience any CRC error, alignment error, code error
The address matching process decided that the frame should be discarded (filtered) because it did not
match the unicast, broadcast, or multicast address, and it did not match due to promiscuous mode.
To determine the number of receive frames discarded by the EMAC for any reason, sum the following
statistics (promiscuous mode disabled):
•
•
•
•
•
•
•
Receive fragments
Receive undersized frames
Receive CRC errors
Receive alignment/code errors
Receive jabbers
Receive overruns
Receive filtered frames
This may not be an exact count because the receive overruns statistic is independent of the other
statistics, so if an overrun occurs at the same time as one of the other discard reasons, then the above
sum double-counts that frame.
5.50.12 Receive QOS Filtered Frames Register (RXQOSFILTERED)
The total number of frames received on the EMAC that were filtered due to receive quality of service
(QOS) filtering. Such a frame is defined as having all of the following:
•
Any data or MAC control frame that matched a unicast, broadcast, or multicast address, or matched
due to promiscuous mode
•
The frame destination channel flow control threshold register (RXnFLOWTHRESH) value was greater
than or equal to the channel's corresponding free buffer register (RXnFREEBUFFER) value
•
•
•
Was of length 64 to RXMAXLEN
RXQOSEN bit is set in RXMBPENABLE
Had no CRC error, alignment error, or code error
See Section 2.5.5 for definitions of alignment, code, and CRC errors. Overruns have no effect on this
statistic.
5.50.13 Receive Octet Frames Register (RXOCTETS)
The total number of bytes in all good frames received on the EMAC. A good frame is defined as having all
of the following:
•
Any data or MAC control frame that matched a unicast, broadcast, or multicast address, or matched
due to promiscuous mode
•
•
Was of length 64 to RXMAXLEN bytes inclusive
Had no CRC error, alignment error, or code error
See Section 2.5.5 for definitions of alignment, code, and CRC errors. Overruns have no effect on this
statistic.
5.50.14 Good Transmit Frames Register (TXGOODFRAMES)
The total number of good frames transmitted on the EMAC. A good frame is defined as having all of the
following:
•
•
•
Any data or MAC control frame that was destined for any unicast, broadcast, or multicast address
Was any length
Had no late or excessive collisions, no carrier loss, and no underrun
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EMAC Port Registers
5.50.15 Broadcast Transmit Frames Register (TXBCASTFRAMES)
The total number of good broadcast frames transmitted on the EMAC. A good broadcast frame is defined
as having all of the following:
•
•
•
Any data or MAC control frame destined for address FF-FF-FF-FF-FF-FFh only
Was of any length
Had no late or excessive collisions, no carrier loss, and no underrun
5.50.16 Multicast Transmit Frames Register (TXMCASTFRAMES)
The total number of good multicast frames transmitted on the EMAC. A good multicast frame is defined as
having all of the following:
•
•
•
Any data or MAC control frame destined for any multicast address other than FF-FF-FF-FF-FF-FFh
Was of any length
Had no late or excessive collisions, no carrier loss, and no underrun
5.50.17 Pause Transmit Frames Register (TXPAUSEFRAMES)
The total number of IEEE 802.3X pause frames transmitted by the EMAC. Pause frames cannot underrun
or contain a CRC error because they are created in the transmitting MAC, so these error conditions have
no effect on this statistic. Pause frames sent by software are not included in this count. Since pause
frames are only transmitted in full-duplex mode, carrier loss and collisions have no effect on this statistic.
Transmitted pause frames are always 64-byte multicast frames so appear in the multicast transmit frames
register and 64 octect frames register statistics.
5.50.18 Deferred Transmit Frames Register (TXDEFERRED)
The total number of frames transmitted on the EMAC that first experienced deferment. Such a frame is
defined as having all of the following:
•
•
•
•
•
Was any data or MAC control frame destined for any unicast, broadcast, or multicast address
Was any size
Had no carrier loss and no underrun
Experienced no collisions before being successfully transmitted
Found the medium busy when transmission was first attempted, so had to wait.
CRC errors have no effect on this statistic.
5.50.19 Transmit Collision Frames Register (TXCOLLISION)
The total number of times that the EMAC experienced a collision. Collisions occur under two
circumstances:
•
When a transmit data or MAC control frame has all of the following:
–
–
–
–
Was destined for any unicast, broadcast, or multicast address
Was any size
Had no carrier loss and no underrun
Experienced a collision. A jam sequence is sent for every non-late collision, so this statistic
increments on each occasion if a frame experiences multiple collisions (and increments on late
collisions).
CRC errors have no effect on this statistic.
•
When the EMAC is in half-duplex mode, flow control is active, and a frame reception begins.
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EMAC Port Registers
5.50.20 Transmit Single Collision Frames Register (TXSINGLECOLL)
The total number of frames transmitted on the EMAC that experienced exactly one collision. Such a frame
is defined as having all of the following:
•
•
•
•
Was any data or MAC control frame destined for any unicast, broadcast, or multicast address
Was any size
Had no carrier loss and no underrun
Experienced one collision before successful transmission. The collision was not late.
CRC errors have no effect on this statistic.
5.50.21 Transmit Multiple Collision Frames Register (TXMULTICOLL)
The total number of frames transmitted on the EMAC that experienced multiple collisions. Such a frame is
defined as having all of the following:
•
•
•
•
Was any data or MAC control frame destined for any unicast, broadcast, or multicast address
Was any size
Had no carrier loss and no underrun
Experienced 2 to 15 collisions before being successfully transmitted. None of the collisions were late.
CRC errors have no effect on this statistic.
5.50.22 Transmit Excessive Collision Frames Register (TXEXCESSIVECOLL)
The total number of frames when transmission was abandoned due to excessive collisions. Such a frame
is defined as having all of the following:
•
•
•
•
Was any data or MAC control frame destined for any unicast, broadcast, or multicast address
Was any size
Had no carrier loss and no underrun
Experienced 16 collisions before abandoning all attempts at transmitting the frame. None of the
collisions were late.
CRC errors have no effect on this statistic.
5.50.23 Transmit Late Collision Frames Register (TXLATECOLL)
The total number of frames when transmission was abandoned due to a late collision. Such a frame is
defined as having all of the following:
•
•
•
•
Was any data or MAC control frame destined for any unicast, broadcast, or multicast address
Was any size
Had no carrier loss and no underrun
Experienced a collision later than 512 bit-times into the transmission. There may have been up to 15
previous (non-late) collisions that had previously required the transmission to be re-attempted. The late
collisions statistic dominates over the single, multiple, and excessive collisions statistics. If a late
collision occurs, the frame is not counted in any of these other three statistics.
CRC errors, carrier loss, and underrun have no effect on this statistic.
5.50.24 Transmit Underrun Error Register (TXUNDERRUN)
The number of frames sent by the EMAC that experienced FIFO underrun. Late collisions, CRC errors,
carrier loss, and underrun have no effect on this statistic.
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EMAC Port Registers
5.50.25 Transmit Carrier Sense Errors Register (TXCARRIERSENSE)
The total number of frames on the EMAC that experienced carrier loss. Such a frame is defined as having
all of the following:
•
•
•
Was any data or MAC control frame destined for any unicast, broadcast, or multicast address
Was any size
The carrier sense condition was lost or never asserted when transmitting the frame (the frame is not
re-transmitted)
CRC errors and underrun have no effect on this statistic.
5.50.26 Transmit Octet Frames Register (TXOCTETS)
The total number of bytes in all good frames transmitted on the EMAC. A good frame is defined as having
all of the following:
•
•
•
Any data or MAC control frame that was destined for any unicast, broadcast, or multicast address
Was any length
Had no late or excessive collisions, no carrier loss, and no underrun
5.50.27 Transmit and Receive 64 Octet Frames Register (FRAME64)
The total number of 64-byte frames received and transmitted on the EMAC. Such a frame is defined as
having all of the following:
•
•
•
Any data or MAC control frame that was destined for any unicast, broadcast, or multicast address
Did not experience late collisions, excessive collisions, underrun, or carrier sense error
Was exactly 64-bytes long. (If the frame was being transmitted and experienced carrier loss that
resulted in a frame of this size being transmitted, then the frame is recorded in this statistic).
CRC errors, alignment/code errors, and overruns do not affect the recording of frames in this statistic.
5.50.28 Transmit and Receive 65 to 127 Octet Frames Register (FRAME65T127)
The total number of 65-byte to 127-byte frames received and transmitted on the EMAC. Such a frame is
defined as having all of the following:
•
•
•
Any data or MAC control frame that was destined for any unicast, broadcast, or multicast address
Did not experience late collisions, excessive collisions, underrun, or carrier sense error
Was 65-bytes to 127-bytes long
CRC errors, alignment/code errors, under-runs, and overruns do not affect the recording of frames in this
statistic.
5.50.29 Transmit and Receive 128 to 255 Octet Frames Register (FRAME128T255)
The total number of 128-byte to 255-byte frames received and transmitted on the EMAC. Such a frame is
defined as having all of the following:
•
•
•
Any data or MAC control frame that was destined for any unicast, broadcast, or multicast address
Did not experience late collisions, excessive collisions, underrun, or carrier sense error
Was 128-bytes to 255-bytes long
CRC errors, alignment/code errors, under-runs, and overruns do not affect the recording of frames in this
statistic.
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EMAC Port Registers
5.50.30 Transmit and Receive 256 to 511 Octet Frames Register (FRAME256T511)
The total number of 256-byte to 511-byte frames received and transmitted on the EMAC. Such a frame is
defined as having all of the following:
•
•
•
Any data or MAC control frame that was destined for any unicast, broadcast, or multicast address
Did not experience late collisions, excessive collisions, underrun, or carrier sense error
Was 256-bytes to 511-bytes long
CRC errors, alignment/code errors, under-runs, and overruns do not affect the recording of frames in this
statistic.
5.50.31 Transmit and Receive 512 to 1023 Octet Frames Register (FRAME512T1023)
The total number of 512-byte to 1023-byte frames received and transmitted on the EMAC. Such a frame is
defined as having all of the following:
•
•
•
Any data or MAC control frame that was destined for any unicast, broadcast, or multicast address
Did not experience late collisions, excessive collisions, underrun, or carrier sense error
Was 512-bytes to 1023-bytes long
CRC errors, alignment/code errors, and overruns do not affect the recording of frames in this statistic.
5.50.32 Transmit and Receive 1024 to RXMAXLEN Octet Frames Register (FRAME1024TUP)
The total number of 1024-byte to RXMAXLEN-byte frames received and transmitted on the EMAC. Such a
frame is defined as having all of the following:
•
•
•
Any data or MAC control frame that was destined for any unicast, broadcast, or multicast address
Did not experience late collisions, excessive collisions, underrun, or carrier sense error
Was 1024-bytes to RXMAXLEN-bytes long
CRC/alignment/code errors, under-runs, and overruns do not affect frame recording in this statistic.
5.50.33 Network Octet Frames Register (NETOCTETS)
The total number of bytes of frame data received and transmitted on the EMAC. Each frame counted has
all of the following:
•
Was any data or MAC control frame destined for any unicast, broadcast, or multicast address (address
match does not matter)
•
Was of any size (including less than 64-byte and greater than RXMAXLEN-byte frames)
Also counted in this statistic is:
•
•
•
Every byte transmitted before a carrier-loss was experienced
Every byte transmitted before each collision was experienced (multiple retries are counted each time)
Every byte received if the EMAC is in half-duplex mode until a jam sequence was transmitted to initiate
flow control. (The jam sequence is not counted to prevent double-counting).
Error conditions such as alignment errors, CRC errors, code errors, overruns, and under-runs do not affect
the recording of bytes in this statistic. The objective of this statistic is to give a reasonable indication of
Ethernet utilization.
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EMAC Port Registers
5.50.34 Receive FIFO or DMA Start of Frame Overruns Register (RXSOFOVERRUNS)
The total number of frames received on the EMAC that had either a FIFO or DMA start of frame (SOF)
overrun. An SOF overrun frame is defined as having all of the following:
•
Was any data or MAC control frame that matched a unicast, broadcast, or multicast address, or
matched due to promiscuous mode
•
•
Was of any size (including less than 64-byte and greater than RXMAXLEN-byte frames)
The EMAC was unable to receive it because it did not have the resources to receive it (cell FIFO full or
no DMA buffer available at the start of the frame).
CRC errors, alignment errors, and code errors have no effect on this statistic.
5.50.35 Receive FIFO or DMA Middle of Frame Overruns Register (RXMOFOVERRUNS)
The total number of frames received on the EMAC that had either a FIFO or DMA middle of frame (MOF)
overrun. An MOF overrun frame is defined as having all of the following:
•
Was any data or MAC control frame that matched a unicast, broadcast, or multicast address, or
matched due to promiscuous mode
•
•
Was of any size (including less than 64-byte and greater than RXMAXLEN-byte frames)
The EMAC was unable to receive it because it did not have the resources to receive it (cell FIFO full or
no DMA buffer available after the frame was successfully started, no SOF overrun)
CRC errors, alignment errors, and code errors have no effect on this statistic.
5.50.36 Receive DMA Start of Frame and Middle of Frame Overruns Register (RXDMAOVERRUNS)
The total number of frames received on the EMAC that had either a DMA start of frame (SOF) overrun or
a DMA middle of frame (MOF) overrun. A receive DMA overrun frame is defined as having all of the
following:
•
Was any data or MAC control frame that matched a unicast, broadcast, or multicast address, or
matched due to promiscuous mode
•
•
Was of any size (including less than 64-byte and greater than RXMAXLEN-byte frames)
The EMAC was unable to receive it because it did not have the DMA buffer resources to receive it
(zero head descriptor pointer at the start or during the middle of the frame reception).
CRC errors, alignment errors, and code errors have no effect on this statistic.
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Appendix A
Appendix A Glossary
Broadcast MAC Address —A special Ethernet MAC address used to send data to all Ethernet devices
on the local network. The broadcast address is FFh-FFh-FFh-FFh-FFh-FFh. The LSB of the first
byte is odd, qualifying it as a group address; however, its value is reserved for broadcast. It is
classified separately by the EMAC.
Descriptor (Packet Buffer Descriptor) —A small memory structure that describes a larger block of
memory in terms of size, location, and state. Descriptors are used by the EMAC and application to
describe the memory buffers that hold Ethernet data.
Device —In this document, device refers to the TMS320C645x processor.
Ethernet MAC Address (MAC Address) —A unique 6-byte address that identifies an Ethernet device on
the network. In an Ethernet packet, a MAC address is used twice, first to identify the packet’s
destination, and second to identify the packet’s sender or source. An Ethernet MAC address is
normally specified in hexadecimal, using dashes to separate bytes. For example,
08h-00h-28h-32h-17h-42h.
The first three bytes normally designate the manufacturer of the device. However, when the first
byte of the address is odd (LSB is 1), the address is a group address (broadcast or multicast). The
second bit specifies whether the address is globally or locally administrated (not considered in this
document).
Ethernet Packet (Packet) —An Ethernet packet is the collection of bytes that represents the data portion
of a single Ethernet frame on the wire.
Full Duplex —Full duplex operation allows simultaneous communication between a pair of stations using
point-to-point media (dedicated channel). Full duplex operation does not require that transmitters
defer, nor do they monitor or react to receive activity, as there is no contention for a shared medium
in this mode. Full duplex mode can only be used when all of the following are true:
•
The physical medium is capable of supporting simultaneous transmission and reception without
interference.
•
There are exactly two stations connected with a full duplex point-to-point link. As there is no
contention for use of a shared medium, the multiple access (i.e., CSMA/CD) algorithms are
unnecessary.
•
Both stations on the LAN are capable of, and have been configured to use, full duplex
operation.
The most common configuration envisioned for full duplex operation consists of a central bridge
(also known as a switch) with a dedicated LAN connecting each bridge port to a single device.
Full duplex operation constitutes a proper subset of the MAC functionality required for half duplex
operation.
Half Duplex —In half duplex mode, the CSMA/CD media access method is the means by which two or
more stations share a common transmission medium. To transmit, a station waits (defers) for a
quiet period on the medium, that is, no other station is transmitting. It then sends the intended
message in bit-serial form. If, after initiating a transmission, the message collides with that of
another station, then each transmitting station intentionally transmits for an additional predefined
period to ensure propagation of the collision throughout the system. The station remains silent for a
random amount of time (back off) before attempting to transmit again.
Host — The host is an intelligent system resource that configures and manages each communications
control module. The host is responsible for allocating memory, initializing all data structures, and
responding to port (EMAC) interrupts. In this document, host refers to the TMS320C645x device.
Jabber — A condition wherein a station transmits for a period of time longer than the maximum
permissible packet length, usually due to a fault condition.
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Appendix A
Jumbo Packets —Jumbo frames are defined as those packets whose length exceeds the standard
Ethernet MTU, which is 1500 kbytes. For the C64x+ devices, it is recommended not to use packets
exceeding 35K in length. The PHY that you use can place additional limits on to the length of the
packets that you can transfer in a system.
Link — The transmission path between any two instances of generic cabling.
Multicast MAC Address —A class of MAC address that sends a packet to potentially more than one
recipient. A group address is specified by setting the LSB of the first MAC address byte. Thus,
01h-02h-03h-04h-05h-06h is a valid multicast address. Typically, an Ethernet MAC looks for only
certain multicast addresses on a network to reduce traffic load. The multicast address list of
acceptable packets is specified by the application.
Physical Layer and Media Notation —To identify different Ethernet technologies, a simple, three-field,
type notation is used. The Physical Layer type used by the Ethernet is specified by these fields:
<data rate in Mb/s><medium type><maximum segment length (×100m)>
The definitions for the technologies mentioned in this guide are as follows:
Table A-1. Physical Layer Definitions
Term
Definition
10Base-T
IEEE 802.3 Physical Layer specification for a 10 Mb/s CSMA/CD local area network over two
pairs of twisted-pair telephone wire.
100Base-T
1000Base-T
Twisted pair
IEEE 802.3 Physical Layer specification for a 100 Mb/s CSMA/CD local area network over two
pairs of Category 5 unshielded twisted-pair (UTP) or shielded twisted-pair (STP) wire.
IEEE 802.3 Physical Layer specification for a 1000 Mb/s CSMA/CD LAN using four pairs of
Category 5 balanced copper cabling.
A cable element that consists of two insulated conductors twisted together in a regular fashion to
form a balanced transmission line.
Port — Ethernet device.
Promiscuous Mode —EMAC receives frames that do not match its address.
146
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Appendix B
Appendix B Revision History
Table B-1. Document Revision History
Reference
Section 2.1
Section 2.1.2
Section 2.15.4
Figure 3
Additions/Modifications/Deletions
Table 3
Figure 6
Chapter A
Added the term jumbo packets.
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is an unfair and deceptive business practice. TI is not responsible or liable for any such statements.
Following are URLs where you can obtain information on other Texas Instruments products and application
solutions:
Products
Applications
Audio
Amplifiers
amplifier.ti.com
www.ti.com/audio
Data Converters
dataconverter.ti.com
Automotive
www.ti.com/automotive
DSP
dsp.ti.com
Broadband
Digital Control
Military
www.ti.com/broadband
www.ti.com/digitalcontrol
www.ti.com/military
Interface
Logic
interface.ti.com
logic.ti.com
Power Mgmt
Microcontrollers
power.ti.com
Optical Networking
Security
www.ti.com/opticalnetwork
www.ti.com/security
www.ti.com/telephony
www.ti.com/video
microcontroller.ti.com
Low Power Wireless www.ti.com/lpw
Telephony
Video & Imaging
Wireless
www.ti.com/wireless
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Texas Instruments
Post Office Box 655303 Dallas, Texas 75265
Copyright 2006, Texas Instruments Incorporated
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