Tangible Interactions Workshop - Week 3 - Chord Builder MIDI Device


This two week assignment was to build a tangible MIDI interface which would either send MIDI data to a synthesizer or via USB to a software synth. Because I was interested in working with the MKRZero for the first time, I decided to make a MIDI USB controller since that particular microcontroller has built in MIDI functionality.

This particular idea for the Chord Builder grew out of an interest in exploring the MIDI pitch bend command and using that to create harmonies and chords outside of the traditional European musical scale. Using the little bit of music theory I absorbed during my middle school piano lessons I concluded that in order to be able to play appropriately expressive chords, there would need to be four possible note inputs (the 1,3,5 and 7 notes in a traditional maj7 chord). I settled on using joysticks as the note control because of their distinct ability to offer consistent, subtle analog outputs but also, significantly, because they return to their same original position when you release them. This was a key part of the design because what I was imagining was that each joystick, when untouched, would play the same note (in this case a C) and then the user would bend each joystick individually up or down to tune that note anywhere within a half octave up or down. This way they could very precisely bend from the base note of C smoothly into any four note chord or dissonant harmony. I also deliberately chose joysticks with a center click so that each note could be turned off or on allowing for less that four notes if desired.

Considering I was imagining this potential product as a tool in the arsenal of a music producer, the design of the UI and enclosure took general inspiration from other such synthesizers and devices. Thus the form was relatively conservative, and I chose to simply use LED’s as the necessary affordances to indicate which notes were activated. It was only in the shape of the enclosure that I decided to be a bit creative. By creating a slight “V” shape rather than simple a rectangle, I imagined it would make the device easier to play with one hand by making access to all four joysticks at once much easier. And while I think I achieved that, what I learned after putting together this first prototype is that if the device is rotated 180 degrees, it actually becomes very ergonomic to play with two hands and on a later version of this I would imagine flipping the UI so that it could be played the other way around.

I started the fabrication of the Chord Builder by buying a bamboo drawer organizer from the Container Store. I then cut out a 30 degree triangle from the middle of the box and glued the two pieces together to create the specific angled shape. Making the lid took a bit of trail and error with the laser cutter in order to get the shape and placement of the components just right, but once it fit well, I was able to simply mount the joysticks and LEDs right to the panel.

The code for this device proved to be a bit more of a challenge, due largely to the peculiarities of working with MIDI and the Arduino MIDI library. And while I was able to eventually wrangle the basic functionality of turning on each note and bending it up and down, I was unable to successfully achieve the use of pitch bend to seamlessly transition from one note to the next. However with the wiring and enclosure securely built, I look forward to continuing to manipulate the code to achieve the full functionality I initially envisioned.