Refer below links

[Vivekanand]

You can refer below links for kind of your information

http://www.engineersgarage.com/microcontroller/8051projects/interface-rfid-AT89C51-circuit

http://www.engineersgarage.com/microcontroller/8051projects/gsm-interface-8051-microcontroller-circuit-code

http://www.engineersgarage.com/microcontroller/8051projects/gps-interface-8051-microcontroller-circuit

All circuits are working fine…