B4R Question Help with schematics (Arduino-SIM900)


Licensed User
I have successfully used a different GSM shield with ESP8266 and I remember it was tricky.
First lesson learned, don't power the GSM module from the Uno, it draws too much current and you may fry the Uno.
The Comms are simple TX-Rx but there the CS pin that need to be pulled up during initialization.

It's all I remember, and I no longer have code to share...


Licensed User
Both Ground are comman...means connected with each other

Transmitter of GSM....Receiver of Arduino
Receiver of GSM.....Transmitter of Arduino

Both having separate power supply....in this scenario