Using the GPRS section on Terra board

A Quectel M95 quad band GPRS module is mounted on TERRA-M board. It comunicates with the Aria G25 Linux module through a serial port mapped to /dev/ttyS1. All the modem function can be controlled using the Quectel AT commands set.

Before sending any AT message to the modem it's requested to turn-on the power section that provides the 4.4 volt to the pin VIN of the modem module.

At startup this section is in off state. To turn it on we have to set the Aria G25 W10 line (Atmel PA23 GPIO line) as output and put it in hi-state using these commands:

echo 23 > /sys/class/gpio/export
echo out > /sys/class/gpio/pioA23/direction
echo 1 > /sys/class/gpio/pioA23/value

The green led labeled 4V4 will turn on.

In this state we have to send an hi pulse to the modem PWRKEY line. This pin is wired on Aria G25 E10 gpio (Atmel PC30 GPIO line).

Configure this pin as output and send a 1 second hi pulse using these commands:

echo 94 > /sys/class/gpio/export
echo out > /sys/class/gpio/pioC30/direction
echo 1 > /sys/class/gpio/pioC30/value
sleep 1
echo 0 > /sys/class/gpio/pioC30/value

Check the green led labeled GSM, it will start to blink. If a GSM antenna is plugged and a valid SIM in inserted the blink will become to be slower after a while to indicate that the modem is registered to the GSM network.

In this state it is possible to send the AT commends to the serial port /dev/ttyS1.

GPRS link examples

Wirings between the Quectel M95 quad band GPRS modem and the Aria G25 module

Following is the pinout of Quectel modem:

and this is the wirings between it and the Aria G25:

Quectel pin # I/O Quectel signal Aria G25 pin # Aria G25 signal Notes
21 I RXD S23 (PA0) /dev/ttyS1 TXD0
22 O TXD S22 (PA1) /dev/ttyS1 RXD0
23 I CTS S20 (PA3) /dev/ttyS1 CTS0
24 O RTS S21 (PA2) /dev/ttyS1 RTS0
10 I PWRKEY E10 (PC30) GPIO (126) Normal state Low
11 I EMERG_OFF E11 (PC31) GPIO (127) Normal state Low
12 O STATUS N6 (PC4) GPIO (100)
Power supply W10 (PA23) GPIO (55) 0=Power off, 1=Power on

Please note that Ring Indicator (RI) and Data Carrier Detect (DCD) are not connected to the Aria pins.

Related link


EUR 249.00

Linux embedded board for fast prototyping

TERRA is a carrier board conceived both to evaluate the Aria G25 SoM and to make prototypes or small production batches of OEM equipments using the Daisy cabling system.

The TERRA-M variation is equiped with a GSM/GPRS Quectel M95 quad band modem, a SIM holder and a SMA connector for an external GSM antenna.

| Product description | Terra catalog |