Gizmo is the codename for an open source MIDI utility device which targets the Arduino Uno or Mega. It can do at least this:


  • Full-featured Arpeggiator
  • Full-featured Step Sequencer (16, 24, 32, 48, 64 steps)
  • Small Note Recorder
  • Capable MIDI Gauge or Monitor
  • Small two-button, two-pot MIDI Controller
  • (On the Arduino Mega) 8-stage Loopable Control Envelope and Random/S&H LFO
  • (On the Arduino Mega) Keyboard Splitter
  • (On the Arduino Mega) Channel Merging, Chord Memory, Debouncing, Multichannel Note Distribution, Channel Blocking, and Note Replication
  • (On the Arduino Mega) Measure and Beat Counter
  • (On the Arduino Mega) MIDI NRPN/CC/Sysex Converters for Blofeld, Matrix 1000, Microsampler, and TX81Z


  • MIDI In and Out
  • NRPN, CC, and by-Note Control of Gizmo
  • Swing
  • Bypass
  • Tempo and Note Speed
  • MIDI Clock Control, Filtering, and Division
  • Click Tracks
  • (On the Arduino Mega) Transposition and Volume Modulation
  • (On the Arduino Mega) Output to 0-5V DC Control Voltage (V/Octave with Gate and auxillary voltage for velocity or pressure)
  • Storage for 10 Arpeggios and 2 (Uno) or 9 (Mega) Sequences / Recordings
Have an Uno but want a feature only available on the Mega? No problem! Gizmo is fully modular: you can customize the board to add or remove applications or features as you like.


Gizmo's LED display is rock-solid, steady bright red. But in these videos it looks like flickery, junky yellow due to the camera. :-( Annoying. Note: these demos were of Version 1: there have been improvements since.

Introduction and Arpeggiator

Step Sequencer

MIDI Gauge, Controller, and Note Recorder

Obtaining Gizmo

Development Ideas

I'm making Gizmo available in the hopes that people will do fun things with it. Ideas I've had include porting it to the E-licktronic MIDI shield family, extending the interface to include the 16x8 Unztrument or even just the Trellis Keypad, upgrading to an OLED (though it may be too slow), attaching a synthesizer shield, and of course making a decent case for this thing.

If you're thinking of doing development for the Gizmo, you should do it on an Arduino Mega. At present Gizmo takes up all but just a few bytes of the Arduino Uno's memory: there's no space left to code.

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