I've done connecting the gsm sim900d to my arduino and it works fine i can send & receive message. Now what I am trying to do is I will light up a led with a text message is there any code for that?
Given the fact that you can read the received SMS, you can do everything you want. All you have to do is to compare the SMS content with the string you decide that will light on the led :
say if the SMS content is "ledon" (just an example
), then set the output driving the led HIGH :
, if the SMS is "ledoff" , set the output LOW:
If you don't know how t compare strings in C, it is a programming question. If you google "compare strings C" , you'll get tons of answers, one of these is here http://www.programmingsimplified.com/c-program-compare-two-strings