⚠️ This kit only includes PCB and front panel.

An open-source, Arduino-powered MIDI to 4x CV/gate interface in 6 HP, with both polyphonic and monophonic voice allocation modes.

• Single MIDI input via DIN or TRS Type A (now the MIDI standard).
• Four 1V/oct CV/gate outputs with gate LEDs.
• Button for cycling through four different modes, with coloured mode LED:
  • Poly (red): four-voices polyphony with priority to last, LRU strategy and voice stealing;
  • Poly-first (green): four-voices polyphony with priority to first and first-available strategy;
  • Split poly+mono (blue): split keyboard with three-voices polyphony on the left, and monophony on the right (priority to last);
  • Split mono+poly (pink): same as above, but flipped;
  • Mono (teal): four independent monophonic allocators, one for each MIDI channel 1 to 4.
• Additional output which can work as one of the following:
  • Gate output that stays high while at least one polyphonic voice is active (logic OR), useful for single-filter setups;
  • Trigger output for MIDI clock, with customizable PPQ (can be enabled in code).
• Voices lock with a long-press of the mode button: all gates of currently held polyphonic voices stay high, ignoring key releases until next reallocation.

The DACs range is 0-4V, so only the 4 center octaves are covered. To get more, it is necessary to add amplifiers on CV outputs. Split modes splits the keyboard on middle C. Both lowest MIDI octave and split octave are easily configurable in code.