Sunday, April 12, 2015

MIDI2VC+, a MIDI driven Voltage Controller

The MIDI2VC+, v2, is finally finished. These are the implemented features:
MIDI2VC+, v2, primary side.

MIDI2VC+, v2, secondary side.

  • 5 octaves 1V/octave VC output
  • 3V gate output
  • Low note priority
  • Filters channel number, plays any MIDI-note regardless of channel
  • MIDI input and USB-MIDI input. Prioritise USB if both are connected.
  • Reset button
  • Pitch bend, 2 semitones in each direction
  • Input voltage 8-35V (high input voltage may need heat sink on regulators)
  • 5us trigger output
  • Powers USB-keyboard
  • USB interface tested on Korg MicroKEY 25
  • RCA jacks as outputs. Used RCA wires are easy to find very cheap, and jacks can easily be salvaged from scrapped audio equipment.
  • Both code and hardware is open source licensed to CERN OHL v.1.2.
The PCB needs two straps. The MIDI input to the micro controller has no connection. Pin 4 on the optocoupler needs to be strapped to pin 24 on the micro controller. Also, the optocoupler needs to be powered from the 3V3 rail instead of the 5V. Before the optocoupler is mounted, one needs to cut out pin 6 and the pad from the pull-up resistor right besides it. When the optocoupler is mounted, strap a wire from pin 6 to the 3V3 rail.

Cutout below optocoupler.
Anyone is welcome to edit the layout files to fix the straps. I'm not going to do another version of the PCB at the moment. Eagle files and source code is available here.

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