Espruino-based square wave synth

This keyboard experiment, again, derives much from recycled parts: keys and plywood from a defunct Rheem Mark VII combo organ, other hardware from old organs and oscilloscopes and the like. But the brains of the operation this time is the Espruino 1.4, a JavaScript-enabled microcontroller.

I have only just begun to appreciate this device. For example, in the Espruino forums, I received remarkable assistance on the MPR121 capacitive sensor module. And, for that matter, I have only just begun to appreciate the complexities of device design in general.

Nonetheless, I feel Graiboi is at least ready to look at - even if its sounds are still unremarkable. Gray fabric covers the '60s plywood base, gray and white keys from the Mark VII's bass section attach internally, and grayscale knobs from my collection of salvage cover two as-yet un-activated features: a) a rotary encoder and b) a 12-position rotary switch.

Here's a glimpse at the rudimentary code as of the time of this writing:

graiboi code, page 1 of 2

graiboi code, page 2 of 2

In all of these kinds of projects, I am fascinated by the 'keying' technologies. Here's a glimpse at the Rheem-salvaged 1-octave device I re-used. Notice it has three layers of contact: one for the individual notes and two for other functions.

Rheem Keyboard mechanics module

Code also available on GitHub.