GM862-GPS Hardware User Guide
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GM862-GPS Hardware User Guide
Telit GM862-GPS modules
Telit GM862-GPS modules
NOTE: In this document all the hardware solution are referenced to the GM862-GPS.
NOTE
The information presented in this document is believed to be accurate and reliable. However, no responsibility is
assumed by Telit Communications S.p.A. for its use, nor any infringement of patents or other rights of third
parties which may result from its use. No license is granted by implication or otherwise under any patent rights of
Telit Communications S.p.A. other than for circuitry embodied in Telit products. This document is subject to
change without notice.
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GM862-GPS Hardware User Guide
ON#
R1
Q1
Power ON impulse
R2
GND
NOTE: don't use any pull up resistor on the ON# line, it is internally pulled up. Using pull up resistor may bring to
latch up problems on the GM862-GPS power regulator and improper power on/off of the module. The line ON# must
be connected only in open collector configuration.
NOTE: In this document all the lines that are inverted, hence have active low signals are labeled with a name that
ends with a "#" or with a bar over the name.
TIP: To check if power has raised it is possible to monitor the START line, when this line goes high the module is
powered on, but before it remains on the device needs other 900 ms for software startup. Hence check the PWRCTL
line and 900 ms after its transition to high it is possible to release the ON# pin.
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TIP: To check if the device has powered off, the hardware line PWRCTL should be monitored. When PWRCTL goes
low, the device has powered off.
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RESET#
Unconditional Power OFF
impulse
GND
NOTE: don't use any pull up resistor on the RESET# line nor any totem pole digital output. Using pull up resistor
may bring to latch up problems on the GM862-GPS power regulator and improper functioning of the module. The
line RESET# must be connected only in open collector configuration.
TIP: The unconditional hardware reset should be always implemented on the boards and software should use it as
an emergency exit procedure.
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GM862-GPS Hardware User Guide
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Nominal Supply Voltage:
Max Supply Voltage:
Supply voltage range:
Max Peak current consumption (impulsive):
Max Average current consumption during GPRS transmission (rms):
Max Average current consumption during VOICE/CSD transmission (rms):
Average current during Power Saving:
Average current during idle (Power Saving disabled)
GPS Max Peak current consumption:
GPS Max Average current consumption during Tracking:
GPS Average current during Power Saving:
GPS antenna consumption (external active antenna)
3.8 V
4.2 V
3.4 V - 4.2 V
1.9 A
500 mA
270 mA
≈ 4 mA
≈ 19 mA
80 mA
60 mA
≈ 1 mA
≈ 20 mA
TIP: The electrical design for the Power supply should be made ensuring it will be capable of a peak current output
of at least 2 A.
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μ
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GM862-GPS Hardware User Guide
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GM862-GPS Hardware User Guide
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NOTE: DON'T USE any Ni-Cd, Ni-MH, and Pb battery types. Their use can lead to overvoltage on the GM862-GPS
and damage it. USE ONLY Rechargeable Li-Ion battery types.
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GM862-GPS Hardware User Guide
NOTE: In this particular application the battery charger input current must be limited to less than 1A. This can be
done by using a current limited wall adapter as the power source.
For your convenience in the EVK there's also a current unlimited input, where the input source is not limited in
current and the drawn current is limited to about 0,5A by a MOSFET in the EVK.
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Average current consumption during transmission @PWR level max (rms):
Average current consumption during transmission @ PWR level min (rms):
Average current during Power Saving:
Average current during idle (Power Saving disabled)
Average GPS current during Power Saving:
Average GPS current during Tracking (Power Saving disabled)
500mA
100mA
4mA
19mA
1mA
60mA
NOTE: The average consumption during transmissions depends on the power level at which the device is requested
to transmit by the network. The average current consumption hence varies significantly.
TIP: The thermal design for the Power supply should be made keeping a average consumption at the max
transmitting level during calls of 350mA rms.
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Absolute Maximum Ratings -Not Functional
Parameter Min Max
Operating Range - Interface levels (2.8V CMOS)
Level Min Max
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GM862-GPS Hardware User Guide
NOTE: According to V.24, RX/TX signal names are referred to the application side, therefore on the GM862-GPS side
these signal are on the opposite direction: TXD on the application side will be connected to the receive line (here
named TXD/ rx_uart ) of the GM862-GPS serial port and viceversa for RX.
TIP: For a minimum implementation, only the TXD and RXD lines can be connected, the other lines can be left open
provided a software flow control is implemented.
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GM862-GPS Hardware User Guide
NOTE: The digital input lines working at 2.8VCMOS have an absolute maximum input voltage of 3,75V; therefore the
level translator IC shall not be powered by the +3.8V supply of the module. Instead it shall be powered from a +2.8V /
+3.0V (dedicated) power supply.
This is because in this way the level translator IC outputs on the module side (i.e. GM862-GPS inputs) will work at
+3.8V interface levels, stressing the module inputs at its maximum input voltage.
This can be acceptable for evaluation purposes, but not on production devices.
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GM862-GPS Hardware User Guide
NOTE: The UART input line TXD (rx_uart) of the GM862-GPS is NOT internally pulled up with a resistor, so there
may be the need to place an external 47KΩ pull-up resistor, either the DTR (dtr_uart) and RTS (rts_uart) input lines
are not pulled up internally, so an external pull-up resistor of 47KΩ may be required.
Ω
NOTE: The input lines working at 2.8VCMOS can be pulled-up with 47KΩ resistors that can be connected directly to
the PWRCTL line provided they are connected as in this example.
NO OTHER devices should be powered with the PWRCTL line, otherwise the module functionality may be
compromised.
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GM862-GPS Hardware User Guide
Uplink
Downlink
MT lines
HF lines
AXE
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GM862-GPS Hardware User Guide
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line coupling
line type
AC
balanced
≥ 100nF
50kΩ
≤ 1,03Vpp (365mVrms
-45 dBVrms/Pa
+ 20dB
coupling capacitor
differential input resistance
differential input voltage
microphone nominal sensitivity
analog gain suggested
echo canceller type
)
handset
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line coupling
line type
coupling capacitor
differential input resistance
differential input voltage
microphone nominal sensitivity
AC
balanced
≥ 100nF
50kΩ
≤ 65mVpp (23mVrms
-45 dBVrms/Pa
)
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analog gain suggested
echo canceller type
+10dB
car kit hands-free
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TIP: definition of the nominal sensitivity of the microphone lines .
normal spoken
normal spoken”
-4,7dBPa @1kHz
normal spoken
45dBVrms/Pa
MicLevel = ( -45) + (-4.7) = -49.7 dBVrms
MicVoltage = 10 ( -49.7 / 20 ) = 3.3* 10 -3 Vrms
strongest voice level
lowest voice level
1stdifferential
.
Mic_MT
[(
MicLevel + 20dB
)
+ GA = −8,76dBV
]
[
− 49,7 + 20 + GA = −8,76
]
− 40,9 + 20 = −GA
GA = 20,94dB
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hands-free/car kit
10dB
40/50cm
20dB
The voice signal , that in the "normal spoken” conditions produces on the microphone membrane an
acoustic pressure of -4,7dBPa at 1kHz , will have a further attenuation of 20dB due the 50cm distance
.
Therefore a microphone having the suggested nominal sensitivity of -45dBVrms/Pa,will produce a lower
electrical
MicLevel = ( -45) + (-4.7)-20 = -69.7
equivalent signal :
that means :
MicVoltage = 10 ( -49.7 / 20 ) = 0,33* 10 -3
Setting the “microphone gain” at +10dB (3 times), the signal in the nominal conditions on the
“Mic_HF” inputs s of GM862-GPS Telit Module will be :
“
” Level = 0,33* 10 -3 * 3=1* 10 -3
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216
Hz
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Ω
Ω
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Ω
Ω
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GM862-GPS Hardware User Guide
270pF
270pF
(-45 dBVrms/Pa
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GM862-GPS Hardware User Guide
R604 R606
=
Gain =
R605 R607
1
1
freq. =
=
2π *R604*C637 2π *R606*C636
Let's assume you have a microphone with a sensitivity of -45 dBVrms/Pa and you want to use it in 1st
differential microphone path (“
-4.7dBPa.
” inputs) in "normal spoken" conditions at acoustic pressure of
As reported at page 33 , the electrical level output from the microphone will be :
MicLevel = ( -45) + (-4.7) = -49.7 dBVrms
MicVoltage = 10 ( -49.7 / 20 ) = 3.3* 10 -3 Vrms
corresponding to:
When the talker is screaming ,we will have a signal of 330 mVrms on the
gain GA :
inputs for a buffer
=20 log (AmplifierOutput / MicVoltage) =20 log (330 * 10 -3 )/( 3.3 * 10 -3 ) = 20 log 10=
The corresponding values for the resistors on the buffer could be ( if we keep the input resistance
10kΩ )
R604 = R606 = gain* R603= gain* R605 = 10* 15 = 150 kΩ
The commercial values of 150kΩ & 15kΩ are then chosen.
As a consequence the values of the capacitors C636 and C637 shall be:
C636=C637= 1/ (2π*4000*R606)= 265 *10 -12
F
A commercial value of 270pF gives a cutoff frequency of 3931Hz with an errorless than 1,8% .
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buffered unbalanced
R719
R711
Gain
(
not inverting buffer
)
= 1+
Gain
(
inverting buffer
)
=
R720
R708
1
1
freq. =
=
2π *R719*C726 2π *R711*C727
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GM862-GPS Hardware User Guide
Ω
Llet's assume you have a microphone with a sensitivity of -45dBVrms/Pa and you want to use it in 2nd
differential microphone path (“
of -4.7dBPa.
” inputs) in "normal spoken" conditions at acoustic pressure
As reported at page XX , the electrical level output from the microphone will be :
MicLevel = ( -45) + (-4.7) = -49.7 dBVrms
but we have to consider 20dB loss due to the higher distance from the mouth of the talker ( 50cm ) .
MicLevel = ( -49.7) + (-20) = -69.7 dBVrms
corresponding to
MicVoltage = 10 ( -69.7 / 20 ) = 0,33* 10 -3
In order to have a signal of 1 mVrms at the
“,
inputs , as suggested at
“
/MicVoltage = (1*10 -3)/(0,33*10
the buffer must have a gain
= “
10 dB
Keeping in mind that “ balancing the line will double the signal”, to calculate the resistor values assign
half of required gain to each amplifier section . And therefore =1,5times (or +3,52dB) .
Choosing as 10kΩ as the input resistance , the corresponding values for the resistors on the buffer will
be :
=
* R708= 1.5*10 =
= ( -1) * R720 = (1.5 -1)*10 =
Ω and Ω be accepted .
Ω
Ω
The commercial values of
As a consequence of the assigned values of the resistors, the nominal values of C726 and C727 are
:
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= 1/ (2π*4000*R719)= 7.10 *10 -9
= 1/ (2π*4000*R711)= 2,65 *10 -9
F
F
modified in
(fc1=4181Hz ) and
(fc2=3931Hz) because of commercial values .
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GM862-GPS Hardware User Guide
AXE
Æ
Æ
“
”
EPN1
EPP1
Differential Line-Out Drivers
Ω
”
EPPA1_2
EPPA2
balanced
Fully Differential Power Buffers ;
unbalanced
16Ω speaker
FS
“
Full Scale.
”
”
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≥
Ω
Ω
Ω
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≥
Ω
Ω
Ω
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Π
39pF -
0603
1nF - 0603
39μH
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Ω
GM862-GPS
Ω
GM862-GPS
Ω
GM862-GPS
GM862-GPS
GM862-GPS
GM862-GPS
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R3
Gain =
R2
1
freq. =
2π * R3*C4
00nF
15Ω
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GM862-GPS
GM862-GPS
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GM862-GPS
GM862-GPS
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Ω
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μ
NOTE: To correctly drive a buzzer a driver must be provided, its characteristics depend on the Buzzer and for them
refer to your buzzer vendor.
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ANTENNA REQUIREMENTS
Frequency range
Bandwidth
Gain
Impedance
Amplification
Supply voltage
Current
consumption
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GM862-GPS Hardware User Guide
Type:
TRANSCHIP TC5747
Technology:
Max picture size:
Output format:
Sensitivity:
CMOS COLOR camera
VGA 480x640 pixels landscape
JPEG
4 Lux
Molex 52991-0508 GM862
TC5747MF24L
Signal I/O
Pin
Signal
I/O
Notes
Pin
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I2C bus serial data
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NOTE: The Philips 74LVC1G08GW must be placed close to the GM862 connector; the length of the line between
CAMERA connector and MOLEX 50 PIN of GM862 must be max 5cm anyway.
NOTE: The CMOS cameras must be removed when the GPIO pins are used for I/O purpose.
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Camera Socket Connector
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Camera setting: (shown here are the defaults ones)
Taking an reading a photo:
#OBJL: Snapshot,38900
…data…..
38900
…data…
…data…..
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GM862-GPS Hardware User Guide
Revision
Date
Changes
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