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. – dhruvvyas90 Sep 26 '15 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. – Karan S. Sisodia Sep 26 '15 at 6:34
  • This is how level shifting is done usually. playground.arduino.cc/uploads/Main/i2c-level-shift-mosfet.png – dhruvvyas90 Sep 26 '15 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. – Karan S. Sisodia Sep 26 '15 at 6:51
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    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 Sep 26 '15 at 8:13

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 Sep 27 '16 at 12:00

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