APM => Arduino Uno => GSM 900

Hello guys,

I have done that set-up, and I believe I am doing something wrong. Basically the APM should talk using TTL to the Arduino which should talk to the GSM900

Arduino and GSM talk well together, but somehow I cannot send and receive TTL data between the Arduino and the APM.

It is like I connected wrongly the APM and the Arduino Uno.

Do you see anything wrong in the connections I am doing ?


Thank you