Abstract: This project presents a prototype security door that can be remotely controlled by a GSM phone set acting as the transmitter and another GSM phone set with a dual tone multi-frequency (DTMF) connected to the door motor through a DTMF decoder interfaced with micro controller unit and a stepper motor. The design is composed of four main functional modules, namely; the GSM module, the IR SENSOR module, GAS SENSOR module and the FIRE SENSOR module. The GSM module act as both transmitting and receiving unit employs the use of a mobile phone set serving as the communication device between the user at one end and the object of access (i.e. the door) at the other receiving end. The codes for this project was written in Embedded C language with Android application compiled by visual studio and keil software , the program run without error before it was burn onto the micro controller using a device called the programmer by placing the micro controller on it socket equal to the pin number.

Keywords: GSM, Microcontroller, IR sensor, Security, Gas sensor, Fire sensor, Buzzer, Android application.