Remote Control of Electrical Appliances by Mobile SMS Using STC89C52RC Microcontroller

The aim of this project is to control home electrical appliances utilising the Global System for Mobile Communications (GSM) hand phones we are using every day. This can be achieved by sending Short Message Service (SMS) from the authorized cell phone to the GSM SIM modem which in turn, commands the microcontroller (MCU) to carry out the switching by mean of power relays. This setup is useful for controlling devices where no wired connection to the place is available. To implement the setup, a GSM modem is connected to a programmed microcontroller which would receive SMS from authorized cell phone. The received SMS is then extracted out and processed by the microcontroller-preferred format. Commands are used for controlling the functionality of the GSM hand phone. Utilising low-cost STC89C52RCMCU to read the SMS coding from GSM hand phone and able to translate the coding to switching commands by means of C programming language. A USB to RS232 interface converter connected to computer is used to monitor the transmission between the cell phone and the microcontroller.