Im working with a SIM900 module bought from SainSmart on a MEGA.
I somehow connected it and it magically "just works"! My sketch that simply sends out and SMS. :-)
Here is my question: Ok, the UNO is a bit different because it only has a dedicated Rx & Tx pin. MEGA has a bunch more. But even so, is there no need to specify the pins you are using for Rx & Tx when using the MEGA?
How does the UNO/MEGA know where to look for outgoing/incoming data?
Is it because those are designated Rx/Tx hardware pins that they don't need software/code specification?