SMS control unit on AT90S8515 and Siemens C45

Control via GSM channel of four actuators (expandable to 8). The command is sent via SMS from your phone, and after it is triggered, a response SMS is sent to your phone. The block is built on a combination of an AT90S8515 microcontroller and a cell phone.

Manufacturing of the control unit

Any MK with a serial port and 8 kilobytes of flash memory will do. Type Atmega8, ATmega8535, Atmega88. Any phone with a built-in modem will do (old push-button Eriksson T10, T18, Siemens C35, C45).

Device diagram

The microcontroller is programmed using the well-known homemade programmer PonyProg or any other programmer for ATMEL microcontrollers. MK firmware in the attached hex file.
The program was written for the Siemens C45 phone; for other phones you need to use the appropriate AT commands. A SIM card from the MEGAFON operator is used.


An SMS message received on the phone is transmitted via the built-in modem to the UART transceiver of the microcontroller. The MK analyzes the phone number from which the SMS came, and if it matches the number stored in the MK’s memory, it executes a command (turn on or off the corresponding channel). After the starter or solid-state relay is triggered, a feedback signal is sent to the input of the MK.The microcontroller generates a response SMS message (it worked - it didn’t work) and sends it to the control phone number.


Optionally, when finalizing the program: Also, other inputs of the MK can receive signals from security sensors, alarms, fire sensors, etc. MK also sends SMS about the event that occurred. The following changes must be made to the firmware file:

You can download the firmware and board here:

Watch the video