Prototype #3

Design started:

  • April 2019

Build completed:

  • May 2019

Destruction date:

  • November 2019

Goals of this project:

  • Improve upon the design blunders of the Melodicade Prototype #2 by moving all control inputs back to the top deck.

  • Reduce complication further by streamlining or outright removing all unnecessary inputs.

  • Experiment with piezo sensors for detecting expression level.

  • Add outputs for serial DIN MIDI to allow for interoperability with more devices.

What was learned from this prototype:

  • Piezo sensors do work for expression detection, but are not accurate enough for a finished product, at least not without adding more than 5 for an entire deck.

  • With all of the meta keys, the control inputs are still a bit too complicated to use, at least without a cheat sheet.

  • This was an amazing test bed for a number of new features that will carry forward into future designs.

  • 80% of the way there, and the last 20% is definitely most of the work.


I was happy enough with this design to build a second device, and spent a good portion of summer 2019 playing both of them. Having so much time on one design allowed for a number of software refinements that have made this both a fun instrument for playing by itself, and a useful tool for practicing with other instruments; features like a drone mode for helping keep proper intonation when playing my viola, a looper function to record and playback rhythm or harmonies for playing over, or even just quick access to a simple metronome.

Part way through the summer, one of the devices had it's Arduino Due replaced with a Teensy 2.0. The paltry 2KB of SRAM severely limited the looper function (despite some creative efficiency improvements in the code), but the lower energy usage allows an iPad to bus-power the device making iOS GarageBand a lot more portable, and the AVR microcontroller is unaffected by a particularly annoying bug in the MIDIUSB library that causes dropped notes on ARM devices like the Due. This will likely be the preferred path forward.