I2C, other shield on top of GPRS shield v1.2.

First of all, here’s my setup :
Arduino UNO rev2 cms + SeeedStudio gprs shield + SnootLab deuligne shield.

This Lcd shield is great because it has an LCD display and a 5dof joystick and uses only Analog pins 0, 4 and 5.
Arduino communicates with deuligne’s LCD via the Wire Library (I2C on pins 4 and 5) and reads joystick’s value via Analog pin 0.

All of this powered with a USB cable plugged to Arduino, GPRS shield is set to communicate via Software serial on pins 7 and 8.

Deuligne shield works without problem when I stack it directly on Arduino.
Gprs Shield works without problems too.

Problem begins when I stack Deuligne on top of GPRS shield, Deuligne doesn’t respond anymore.
Sometimes, when I press the power button on gprs shield, Deuligne executes some instructions but freezes immediatly.
Another strange thing is that when i plug the stack to usb to power it, status and netlight leds turn on. If I press the power button, these leds turn back to their normal behavior.

My current sketches doesn’t sends anything to GPRS Shield, I’m just uploading example sketches from snootlab. (these sketches works perfectly when I stack Deuligne directly on Arduino, problem is with GPRS shield between Deuligne and Arduino).

Did I miss something ? Does Gprs shield modify I2C behavior ?

I think maybe the GPRS “SCL”“SDA” pin and the LCD display conflicts , you can try not connect GPRS"SCL"“SDA” pin to the seeeduino . Only use serial communication can also use GPRS shield.


Thank you,
That’s what I did, I removed the analog pin headers on top/bottom of the Gprs Shield and connected directly Deuligne’s analog pins to Arduino. Everything works fine now :slight_smile: !