I needed a 6 note poly controller for a new hardware synth I was building and this is it.
It works, but as I'm using a teensy 3.6 and the orginal was based on a 5v Teensy 2.0 so the DAC output is 3.3v max. Also the Pitchbend, CC, gates and triggers will all need some level conversion in hardware which I've covered in the schematic PDF. I've used matching 10k resistors on the DAC level converters to give 2x conversion and this gives 1v/octave, the triggers and gates are currently +5v.
6 note polyphonic
6 velocity outputs
6 gate outputs
6 trigger outputs
Pitchbend and CC outputs
MIDI Channel selection or Omni
Poly/Unison/Mono modes
Transpose Mode +/- one Octave
Octave shift 0 to -3 Octaves to give 0V on bottom C
Scaling on individual notes to improve tuning
Up/Down/Select buttons for menu
USB MIDI Host support as well as 5 pin DIN