This sounds like an awesome project ! Congratulations on getting things to work. Any photos? Video?
[quote user="rumpus"] The circuit plugs in to various ribbon cables inside the FX-20 and does not make any other changes to the FX-20. The program in the interface can be uploaded via a serial port.[/quote]
So is this an off-the-shelf circut board that connects to organ keyboards?
The circuit provides unlimited polyphony on all keyboards and pedals, tailorable MIDI messages for any button push, button release and/or slider movement, and also MIDI messages for expression changes and pressure sensor changes.
That part sounds very interesting.