[s-ol] designed the rotary-encoder based boards around an FPGA ... The FPGA communicates via SPI with an Arduino master controller which communicates to a PC using a serial interface.

An Arduino Due forms the heart of the project, controlling a TEA5767 module, an SH1106 128×64 pixel OLED display and a rotary encoder. The sound signal is passed through an LM4811 headphone ...