usbd-serial
===========

CDC-ACM USB serial port implementation for [usb-device](https://crates.io/crates/usb-device).

CDC-ACM is a USB class that's supported out of the box by most operating systems and used for
implementing modems and generic serial ports. The SerialPort class implements a stream-like buffered
serial port that can be used similarly to a normal UART.

The crate also contains CdcAcmClass which is a lower-level implementation that has less overhead,
but requires more care to use correctly.

Example
=======

A full example requires the use of a hardware-driver, but the hardware independent part is as
follows:

```rust
let mut serial = SerialPort::new(&usb_bus);

let mut usb_dev = UsbDeviceBuilder::new(&usb_bus, UsbVidPid(0x16c0, 0x27dd))
    .strings(&[StringDescriptors::new(LangID::EN).product("Serial port")])
    .expect("Failed to set strings")
    .device_class(USB_CLASS_CDC)
    .build();

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

    let mut buf = [0u8; 64];

    match serial.read(&mut buf[..]) {
        Ok(count) => {
            // count bytes were read to &buf[..count]
        },
        Err(UsbError::WouldBlock) => // No data received
        Err(err) => // An error occurred
    };

    match serial.write(&[0x3a, 0x29]) {
        Ok(count) => {
            // count bytes were written
        },
        Err(UsbError::WouldBlock) => // No data could be written (buffers full)
        Err(err) => // An error occurred
    };
}
```