The project consists planning a complete lighting system which includes a master and some slave modules. The task is that we can choose a lighting modul, and can control its brightness. These options are stored in the master control module which has a simple interface for the user. We can choose the correct unit, and set its parameters. These datas are showed on a simple display of the master unit.
The system uses SPI communication protocol for delivering data bytes. In this communication protocol the master module is the main unit which provided user interface. The slave modules are the concrete illuminators. The communication is built up by the products of AVR family which are exactly the ATMega 8 and ATMega 16. These microcontrollers are appropriates to built up this communication protocol and these have got enough I/O ports.
The controlling of the brightness of lighting units are made by modifying the PWM (Pulse Width Modulation) signal. The concrete driving signal and the control signal are separated with opto join up, avaid the unnecessary noise and levelmatching problems.