I am using Arduino Mega 2560 and GSM module SIM900A. I have connected module with 12V adapter which can provide 2A. I have connecte RX and TX to pin 50 and 51. Gnd to Gnd of module. Some time its work fine but some time it does not give any responce. I am trying to read meassage through arduino using 16x2 LCD.
Hi,
Your details are a bit strange as we do not know which Sim900A module you are refering to when you say you connected to pin 50 and 51 ?
Also a lot of the common Sim modules work off 5v or less, not 12v ?
Can you first give the make and model of your Sim900a board and a picture or link to the boards site.
Assume you are in India /Asia as that A version is locked to those areas ?