Writing New Firmware for SIM900A

[noureldeen]

I want to use the GPIO pins of the SIM900A, so I need to write new firmware for it. I am looking for the source code of the current version of the SIM900A firmware to modify it and utilize its GPIO pins. How can I find the source code, and how should I start this project?

 

[FvM]

Review SIM900 Embedded AT application note. https://simcom.ee/documents/SIM900/SIM900_Embedded AT Application Note_V1.02.pdf
The toolset can be probably only obtained from an authorized SIMCOM distributor.