The AVR SYNTH is a monophonic "virtual analog" synth based, originally, on the Atmel AT90S8535 microcontroller and was designed by Jarek Ziembicki. His aim was to check to see if a simple micro could be used for sound synthesis purposes. And the result? The AT90S8535 managed to do all the tasks: service front panel switches and pots, receive and process MIDI messages, and sound generation!
Mk 1 - Uses a PCB Front and Rear PanelAVRSynth Datasheet and Build Guide
Mk 2 - Uses an aluminium Front and Rear Panel