8 Devices Controlled Thru SMS Message

The project illustrates how the SMS message is used to control 8 devices through relays with only few components required.

An old Ericsson mobile phone is used to connect to AT90S2313 and has a communication port operating at 5V with AT commands such as modem commands for mobile phones. By sending a specific message with any mobile phone, the 8 relays can be activated along with the ON/OFF command and the device number. Other applications include restarting some water pumps, ADSL modems, printers, garage doors, Linux servers, door with electric lock, or block the engine of the motorcycle or car.

The circuit works on both AT90S2313 and ATtiny2313 microcontroller although the firmware is very complicated since it involves the septets of the phone being converted to octets. This is due to the bytes with 8 bits length needed by the AVR because the septet is 1 byte with 7 bits length and octet is 1 byte with 8 bits length. To decode the message from SMS, all these processes are essential. The message must have only 8 numbers and the message format must be only 1 (for enable) or 0 (for disable).

Rest of the project