mideej

A class-compliant USB MIDI fader box, built on Zephyr RTOS and an ESP32-S3.

Status

Early.

Working:

• Enumerates as a class-compliant USB MIDI 2.0 device
• Sends MIDI control-change messages that arrive on a Linux host with no host-side driver or configuration

Not yet:

• More channels. The firmware currently drives a single control change.
• External ADC. An 8-channel I2C ADC (TI ADS7830) is the current intended input, to be implemented later.
• Hardware. There is no PCB yet; this runs on an ESP32-S3 DevKitC.

Why MIDI instead of a serial protocol

This project is heavily inspired by deej, which solves the same problem and solved it first.

However, using a serial port implementation seems like a less appropriate means to accomplish the same effect.

• No companion software to install or keep running. Anything MIDI-aware consumes it directly. Examples include OBS via a MIDI plugin, a DAW, etc.
• No custom protocol to specify or maintain. MIDI CC is a defined wire format with decades of tooling behind it.
• No serial port to find. No /dev/ttyUSB* enumeration order, no dialout group, no COM port number that changes when you use a different socket.
• Cross-platform for free. Class-compliant means every major OS binds it without a driver, because the descriptors say what it is.

Hardware

Bear in mind that hardware is considered both early, and subject to change or configuration.

• ESP32-S3-DevKitC
• TI ADS7830: 8-channel, 8-bit I2C ADC
• Eight slide potentiometers

Building

Currently requires a Zephyr development environment and west.

west build -p always -b esp32s3_devkitc/esp32s3/procpu .
west flash

Acknowledgements

deej by Omri Harel: the original, and the project that made the idea obvious.

Licence

Apache-2.0. See LICENSE.