Problems interfacing with Libelium GPRS / GPS


Firstly I am relatively new to Arduino. I have got my hands on one of Libelium’s GPRS/GPS shields for a university project (my final year project to be precise). I am having major issues with working it. I don’t know where to start really…I understand that serial communication for the GPRS module is done over pins 0 and 1. I have tried sending various AT commands via the Serial.println (for example Serial.println(“AT”) to initiate the device) and it doesn’t seem to work.

I am also having issues with knowing if the module is responding…it says in the documentation that the module will respond with “OK” to any AT command if it is successful but how do I know this? If I use the serial monitor in the arduino environment I just get the AT commands that I have tried to send to the device (naturally) and no response what so ever from the device.

My main aim is to send a SMS message when a button is pressed…that’s all I want to do! but I am really struggling and I am getting nowhere with it.

Has anyone got any code or a tutorial somewhere that may help me?

Please Please Please can anyone help??


How are you checking for the response from the GPRS module? If you’re receiving on using (pin 0, RX), you won’t see that in the serial monitor. You could try removing the ATmega from the Arduino and talking to the GPRS module directly from the serial monitor. Or using the SoftwareSerial library to talk to the GPRS module and the regular serial to send debugging data to the computer.

Well thats the problem...I don't know how to go about checking the response! I cant really remove the ATmega because it has to run standalone in the end. Can I handle the responses, because if it comes back with "ok" am I going to have issues checking it as it is a string?

Sorry to seem a bit dumb with this one...but I am! :)

Thankyou very much for you help

I have looked into using softwareSerial but I don't think it will work because the library can only communicate upto 9600 baud and the recommended rate for the GPRS/GPS is 38400 baud. Also I need to communicate over pin 0 and 1 as these are what the shield's RXD and TXD plug into so surely that's a job for the in built serial library. I have tried numerous things so far and haven't got anywhere with it...

Please Help


You might try removing the chip on the Diecimila temporarily, so that you can send commands directly to the module from the serial monitor - just to check that the GPS / GPRS module is working and that you understand exactly how it behaves. Then, you can try writing some code for the Arduino that will handle those responses - and check that code by talking to it from the serial monitor. Then hopefully you can connect that code to the module.