midi2.diy: A Portable MIDI 2.0 Stack for Embedded Systems

A new wave of MIDI 2.0 devices is coming, and the midi2 stack for embedded systems is here to power it.

midi2 is the common foundation: a small, portable C core that speaks the full MIDI 2.0 protocol and fits any board, from hobby projects to professional Zephyr/RTOS firmware.

midi2cpp is where the fun starts. Plug in a board, write five lines of C++, flash, and you have a real MIDI 2.0 instrument, with 32-bit resolution and per-note control. 29+ ready-to-run recipes cover the Raspberry Pi Pico, Teensy 4.1, Daisy Seed, the ESP32 family and more.

Along the way we contributed the USB MIDI 2.0 device and host drivers to TinyUSB, now merged upstream, so the whole embedded community benefits, whether or not it uses our stack. Both libraries are free and MIT licensed, one install away on the Arduino, PlatformIO and Espressif registries. The full story, the architecture and every recipe live at midi2.diy. Come build the next instrument.

Our innovation is bringing a proven embedded model to MIDI 2.0: one small, shared C core that any board and any language can build on, the same approach that made TinyUSB and FreeRTOS the backbone of embedded development. We built it upstream-first: instead of keeping the USB transport in a private fork, we contributed the MIDI 2.0 device and host class drivers to TinyUSB itself, so the entire ecosystem gained the wire, not just our stack.

The architecture is four clean layers: transport, infrastructure, platform, and application. Each layer has one job and a clear contract, so a transport can be swapped, a new language wrapper added, or an application rewritten without touching the rest. That is what makes it a community foundation: anyone can contribute one piece (a new transport, a wrapper for their favorite language, a recipe for their board) and every other user benefits. To our knowledge, this is the first open-source stack that takes a hobby board from blank flash to a discoverable MIDI 2.0 endpoint, host, or bridge in a few lines of code.

A $4 Raspberry Pi Pico or ESP32 becomes a full MIDI 2.0 instrument in five lines of C++. That price changes who gets to contribute to the new protocol: students, teachers, accessibility researchers, and makers, not just established manufacturers.

Our favorite demo is an ESP32 acting as a MIDI 2.0 host with a whole band plugged in: a Teensy, a Daisy Seed, and a Pico, all speaking MIDI 2.0, alongside a classic MIDI 1.0 keyboard playing together. Per-note control and 32-bit expression flowing through hardware anyone on the planet can afford.