GSM modules has only 3 pins | Projects › Projects › problem on gsm with 8051 › GSM modules has only 3 pins January 29, 2015 at 9:58 am #12550 Ashutosh BhattParticipant GSM modules has only 3 pins to be connected with micro controller 1 Tx 2 Rx 3 Gnd see the datasheet of max232 chip to get the idea to connect micro contoller and gsm module through RS232
