A MIDI controller for the Digitech Whammy IV effects pedal.

Demo on Youtube

Pedal externals Pedal guts

The implementation currently provides these modes:

  • Saw up: / / / / / / /
  • Saw down: \ \ \ \ \ \ \
  • Triangle: / \ / \ / \ /
  • Sine: like triangle but curvier.
  • Square: _ – _ – _ – _
  • “Map of the Problematique” sequencer.
  • Randomisers:
    • Quantized to a musical mode e.g. Phrygian, Lydian…
    • Unquantized, any pedal position. Bleep bloop.
    • Unquantized, any pedal position, any patch.
    • Chaos randomiser, applying any of the other modes randomly.


  • Arduino Nano clone
  • 3 momentary buttons
  • One linear potentiometer
  • MIDI port
  • LED
  • A few resistors, wire, case, etc.


On/off: activate the pedal. Modifier + On/off: Toggle between momentary and latching activation. Default: momentary.

Mode: move to the next pedal mode. Modifier + Mode: move to previous mode.

Tempo potentiometer: Turn to change speed of all pedal functions. Modifier + Tempo potentiometer: Limit the maximum range of the pedal position for tasteful vibrato-like operation [citation needed].

Modifier: Tap to change the musical mode used in ‘quantized scale’ mode.

In all modes, the LED brightness indicates the effective position of the pedal – brighter means toe-down, darker means heel-down.


If you want to work on this project without going mad from constant atonal wee-woo noises, open monitor.pd with Pure Data to see a visualisation of the MIDI messages instead.

Visualisation with Pure Data

This project kept me busy while isolating with Covid 19 in April 2022. The illness provided some gnarly headaches and this project did not help with that whatsoever. Fun though.


View Github