usbd-midi/README.md

usbd-midi
=========

A simple usb midi device class for [usb-device](https://crates.io/crates/usb-device).

Currently this aims to be a very simple implementation, that allows the micro
controller to send MIDI information to the PC and also receive MIDI information.

This crate requires the use of a hardware driver, that implements the
usb-device traits.

## Example

### Receive MIDI
Turn on the integrated LED of a STM32 BluePill board as long as C2 is pressed
```rust
fn main() -> ! {
    let dp = pac::Peripherals::take().unwrap();

    let mut rcc = dp.RCC.constrain();

    let mut gpioa = dp.GPIOA.split(&mut rcc.apb2);
    let mut gpioc = dp.GPIOC.split(&mut rcc.apb2);

    let mut led = gpioc.pc13.into_push_pull_output(&mut gpioc.crh);
    led.set_high().unwrap();

    let mut usb_dp = gpioa.pa12.into_push_pull_output(&mut gpioa.crh);

    let usb = Peripheral {
        usb: dp.USB,
        pin_dm: gpioa.pa11,
        pin_dp: usb_dp.into_floating_input(&mut gpioa.crh),
    };

    let usb_bus = UsbBus::new(usb);

    let mut midi = MidiClass::new(&usb_bus);

    let mut usb_dev = UsbDeviceBuilder::new(&usb_bus, UsbVidPid(0x16c0, 0x5e4))
        .product("MIDI Test")
        .device_class(USB_AUDIO_CLASS)
        .device_sub_class(USB_MIDISTREAMING_SUBCLASS)
        .build();

    loop {
        if !usb_dev.poll(&mut [&mut midi]) {
            continue;
        }

        let mut buffer = [0; 64];

        if let Ok(size) = midi.read(&mut buffer) {
            let buffer_reader = MidiPacketBufferReader::new(&buffer, size);
            for packet in buffer_reader.into_iter() {
                if let Ok(packet) = packet {
                    match packet.message {
                        Message::NoteOn(Channel1, Note::C2, ..) => {
                            led.set_low().unwrap();
                        },
                        Message::NoteOff(Channel1, Note::C2, ..) => {
                            led.set_high().unwrap();
                        },
                        _ => {}
                    }
                }
            }
        }
    }
}
```