Objective:

Design and build a fully functional digital accordion with standard MIDI output.

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Skills and Tools Used:

• Circuit Design

• Arduino Programming

• Fusion 360

• MIDI Protocol Integration

• Breadboarding

• Soldering

• 3D Printing

 

Notable Features:

• Compatible with any standard mechanical keyswitch types

• Removable keycaps allow for custom note layouts

• Expressive analog input via breath pressure transducer

• 168 Button input (120 Bass, 48 Treble)

• Stradella bass read by opto interrupter subassemblies

• Standard MIDI output

 

Details:

As an accordion player, it can be frustrating to practice when the people around you are sleeping. For this reason, I wanted an instrument that could control virtual pitches played though my computer and headphones. Roland makes a MIDI accordion, but even the used chromatic button accordions in their product lineup run over $3000.

 

So like any musical engineer would, I decided to build my solution. I used shift registers, diodes and 48 Gateron Brown mechanical keyswitches to construct a chromatic treble keyboard which only required 14 digital I/O pins on the Arduino. The keys were arranged in the standard B-griff system.  

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The MIDI velocity values are determined in real time by the analog output of a MPXV7002 differential pressure transducer.

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For the bass side, I used 6 subassemblies of my own design (4 opto interrupters each) which read the state of the 24 bass reeds in a Stradella bass assembly. The final part of this project will be to put both sides together in an elegant fashion.

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This project is still a work in progress.