# pico-pi-midi (Rust)

BLE-MIDI keypad firmware for the Raspberry Pi Pico W (RP2040 + CYW43439), written in Rust using [embassy](https://embassy.dev), the [cyw43](https://crates.io/crates/cyw43) driver (Bluetooth), and the [TrouBLE](https://github.com/embassy-rs/trouble) BLE host.

This is the Rust port of the original C/BTstack firmware (now kept separately as `pico-pi-midi-c`). It talks BLE-MIDI 1.0 to iOS / macOS Core MIDI, turning the Pimoroni Pico RGB Keypad into a 16-pad wireless MIDI controller.

## What it does

- **16-pad keypad** (Pimoroni RGB Keypad Base): reads buttons over I²C (GPIO expander @ 0x20) and drives APA102 RGB LEDs over SPI (CS=17, SCK=18, MOSI=19).
- **BLE-MIDI 1.0** GATT server (MIDI Service `03B80E5A-…`), advertised so Core MIDI discovers it as a MIDI device. Pad presses → Note On/Off over Bluetooth; incoming Note On lights the pad.
- **Octave display**: the BOOTSEL button cycles the keypad's note offset by +12 and flashes the active octave as a digit on the 4×4 grid for 500 ms.
- **Onboard LED** heartbeat (driven via the CYW43 chip — the Pico W's LED is on the wireless chip, not an RP2040 pin).
- **USB serial logging** via `embassy-usb-logger` — connect and read with `screen /dev/cu.usbmodem* 115200` to see boot/advertising logs.

## Roadmap

This is v1: a BLE-MIDI keypad. The goal is a **flexible MIDI router** — MIDI over USB, BLE, keypad, TRS, and 4 stereo CV outputs, with channels configurable at runtime via an LCD. See the architecture notes (kept in the session memory) for the plan.

## Building

Requires Rust stable (≥1.93) and the `thumbv6m-none-eabi` target:

```sh
rustup target add thumbv6m-none-eabi
cargo build --release
```

The CYW43 firmware blobs (`cyw43-firmware/*.bin`) are committed here so no network access is needed at build time. They are redistributable under the permissive binary license in the upstream [`embassy cyw43-firmware`](https://github.com/embassy-rs/embassy/tree/main/cyw43-firmware) directory.

## Flashing

```sh
cargo build --release
elf2uf2-rs convert target/thumbv6m-none-eabi/release/rgb-keypad target/uf2/rgb-keypad.uf2
# hold BOOTSEL + plug in the Pico W, then:
picotool load target/uf2/rgb-keypad.uf2 -x
```

## License

GPL-3.0-or-later (see [`LICENSE`](LICENSE)).

`src/codec.rs` is a Rust port of the BLE-MIDI 1.0 packet codec from
[rppicomidi/pico-w-ble-midi-lib](https://github.com/rppicomidi/pico-w-ble-midi-lib),
which is MIT-licensed; that attribution is retained in the file header. MIT is
GPL-3.0-compatible, so the repository as a whole is GPL-3.0-or-later while that
file preserves its MIT provenance.