This is an ongoing project of retrofitting a cheap 44-note electronic keyboard with a Teensy 3.2 and Teensy Audio Adaptor. See KeyboardSensor.h for code and documentation regarding the Teensy keyboard sensing interface.
Goals:
- Configurable switch between standard (Equal Temperament) tuning and Just Intonation.
- MIDI input/output.
- Glissando/portamento between keys.
- Electrical connection points such that one can connect an oscilloscope to the right and left channel and visualize the audio.
- Variety of waveforms and samples to choose from.
- Remove all circuit limitations regarding key ghosting. The original keyboard was not very good at this, and you couldn't press two keys simultaneously if they were a multiple of 8 keys apart from each other. Will require some hardware changes (adding diodes next to every key).