Creation of a digital button accordion. EK could mean :

• The author's initials.
• Electronic Keyboard.

• Right hand PCB
  • 35 Cherry MX switches
  • 5 shift registers (74hc165)
  • Daisy-chain : not implemented
  • 6 pin connector to be connected to a micro-controller (Arduino, ESP32, ...)
  • Pull-down resistors : pushing buttons means high level
• Left hand PCB :
  • 24 Cherry MX switches
  • 3 shift registers (74hc165)
  • Daisy-chain : available
  • 7 pin output connector to be connected to a micro-controller (Arduino, ESP32, ...) or another PCB
  • Jumper for CLK INH pull-down
  • 6 pin input connector to be connected to another PCB
  • Jumper for serial input pull-up
  • Pull-up resistors : pushing buttons means low level.

• Right hand
  • 35 button caps to fit the Cherry MX switches
• Left hand
  • 24 button caps to fit the CHerry MX switches with offset to allow the required layout.
  • laser cutted grid

Polyphonic sound synthesizer.

• Keyboard inputs via GPIOs
• Sound output via I2S protocol and external DAC.
• Control of synthesis parameters via classic bluetooth
• Synthesis engine :
  • Three instruments : bass, chords, lead
  • Wavetable synthesis
  • 10 polyphonic sounds (may be more)
  • Vibrato
  • Small reverberation

• Control of synthesis parameters via classic bluetooth