I have bought SIM 900A GSM MODEM. It is working perfectly on serial interface but it require an extra Serial to USB converter module. So I want to interface it with my Raspberry Pi 2 Model B via I2C Interface.

enter image description here

I am new to I2C Interface. Please suggest the connections/schematic or if I require to add any other module (Isolation system) in order to connect via I2C Interface as mentioned in (https://) youtube.com/watch?v=oTOIzdwE84k video.

  • Most likely, you will need 5v to 3.3v converter in between. There is no data sheet / manual available on that site and hence I can't say for sure. Also on their blog, they have used serial / UART to demonstrate how to make this module work with arduino / rpi. Commented Sep 26, 2015 at 6:23
  • @dastaan I have successfully tested it via serial / UART module. But I want to remove this dependency. Let me ask the seller for the datasheet. Between please check above posted image there is a 3 pin port named I2C. I found this schematic, please suggest if this is correct schematic. Commented Sep 26, 2015 at 6:34
  • This is how level shifting is done usually. playground.arduino.cc/uploads/Main/i2c-level-shift-mosfet.png Commented Sep 26, 2015 at 6:37
  • I got an another Idea to connect serial (Rx Tx) TTL output directly to RPi's GPIO (Rx Tx) as discussed here. Correct if I am wrong. Commented Sep 26, 2015 at 6:51
  • 1
    You need to find the specification of the I2C messages. There is little point in connecting the unit to the Raspberry Pi with I2C unless you know the I2C command/data messages needed to communicate with the device.
    – joan
    Commented Sep 26, 2015 at 8:13

1 Answer 1


You can interface gsm module to Raspberry pi using rs232 to usb convertor.. the below tutorial shows how to do the same.. http://learnraspberrypieasily.blogspot.in/2016/09/raspberry-pi-tutorial-part-10-how-to.html?m=1

  • The question does indicate specifically that the point of the exercise is to avoid using an extra converter.
    – goobering
    Commented Sep 27, 2016 at 12:00

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.