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Setting up a SeeedStudios GPRS board (v2)

These little boards give your Arduino the ability to send and receive phone calls and texts! Here are the original instructions. I've added to them and cleaned things up for readability. I'm working in OSX.

Activate GSM card

I got mine through Adafruit, but it looks like you can order straight through Ting too.
ting.com/go
Enter IMEI number from GPRS (on SIM900 chip)
Enter number on back of sim

Board preparation

Insert activated SIM card into GPRS
Upload default.ino to Arduino
Attach GPRS to Arduino

Serial monitor

I couldn't do everything the Seeed tutorial asked me to do with the Arduino IDE serial monitor, so I downloaded Coolterm (free). I'll include my Coolterm profile, though you may have to go in and reset the port anyway.

Options

  • Serial Port
    • Baud = 19200
    • Port = usbmodemXXXX
  • Terminal
    • Line mode
    • Enter Key Emulation = cf+lf

Power on the Seeed board by holding down the power button for a second or two. Select Connect in Coolterm. You should get some confirmation text from the board. If you get a clipped response, you may have to increase the serial buffer size. This can't be done from the IDE, rather, you have to edit the following files:
/Applications/Arduino.app/Contents/Java/hardware/arduino/avr/cores/arduino/HardwareSerial.h
/Applications/Arduino.app/Contents/Java/hardware/arduino/avr/libraries/SoftwareSerial.h
Look for all instances of buffers set to 64 and replace with 256. Note that this takes up a lot of memory, so make sure to change back when you move on to a new project.

Sending your first text

Enter AT+CMGS="XXXXXXXXXXX" where the XX's are the phone number you want to dial. In the US I included a 1 before the area code. Hit enter. Type in the text you want to send and hit enter. Now select Connection > Send String. Change the mode to Hex, type 1A, and hit enter.

AT commands

I don't know if you call this a language or syntax or what, but the attached AT Commands PDF lists all the different things you can talk to the board about. Here are some useful ones:

Command

  • AT+CMGR=1 | print first SMS in memory
  • AT+CMGD=1,4 | delete all SMS messages

Response

  • +CMTI: "SM",1 = text received, memory location

Gotchas

Quotes indicate string start/stop to the Arduino, so including AT commands with internal quotes can be tricky. You're supposed to be able to do \" to make a quotation mark work within a string, but I couldn't make the GPRS understand it.

Now have fun

Please send me a note or some photos if you use this in a project. Enjoy!