Interface GSM With PIC


GSM stands for Global System for Mobile communication. It is a digital cellular technology used for transmitting voice and data services.GSM operates on a mobile communication band 900mhz and 1800mhz, it operates on 850mhz and 1900mhz.GSM uses narrowband Time Division Multiple Access (TDMA) technique for transmitting signals.

  • GSM has a different configuration :
    1. Sim300.
    2. Sim900.
    3. Sim900A.
  • Sim300 is a triband GSM modem it can operate at three frequency 900mhz,1800mhz,1900mhz band.
  • Sim900 is a quadband GSM mode it can operate at four frequency 850mhz, 900mhz,1800mhz,1900mhz.
  • Sim900a is a dual-band GSM mode it can operate at two frequency 900mhz,1800mhz.
  • AT commands used to control the modem.
  • In GSM mode for each function like make a call and to send the message, to access the internet, there is a set of AT commands used to activate the function.

AT Commands

AT SMS Commands

Hardware Required

  • GSM Module.
  • PIC16f877a MicroController.

GSM Pinout

  • Vin= +5V.
  • Tx= Rx of Microcontroller.
  • Rx= Tx of Microcontroller.
  • Gnd= Ground.


Virtual Circuit