esp-hal/examples/src/bin/embassy_usb_serial.rs

//! CDC-ACM serial port example using embassy.
//!
//! This example should be built in release mode.
//!
//! The following wiring is assumed:
//! - DP => GPIO20
//! - DM => GPIO19

//% CHIPS: esp32s2 esp32s3
//% FEATURES: async embassy embassy-generic-timers

#![no_std]
#![no_main]

use embassy_executor::Spawner;
use embassy_futures::join::join;
use embassy_usb::{
    class::cdc_acm::{CdcAcmClass, State},
    driver::EndpointError,
    Builder,
};
use esp_backtrace as _;
use esp_hal::{
    clock::ClockControl,
    gpio::Io,
    otg_fs::{
        asynch::{Config, Driver},
        Usb,
    },
    peripherals::Peripherals,
    system::SystemControl,
    timer::{timg::TimerGroup, ErasedTimer, OneShotTimer},
};

// When you are okay with using a nightly compiler it's better to use https://docs.rs/static_cell/2.1.0/static_cell/macro.make_static.html
macro_rules! mk_static {
    ($t:ty,$val:expr) => {{
        static STATIC_CELL: static_cell::StaticCell<$t> = static_cell::StaticCell::new();
        #[deny(unused_attributes)]
        let x = STATIC_CELL.uninit().write(($val));
        x
    }};
}

#[esp_hal_embassy::main]
async fn main(_spawner: Spawner) -> () {
    esp_println::println!("Init!");
    let peripherals = Peripherals::take();
    let system = SystemControl::new(peripherals.SYSTEM);
    let clocks = ClockControl::boot_defaults(system.clock_control).freeze();

    let timg0 = TimerGroup::new(peripherals.TIMG0, &clocks);
    esp_hal_embassy::init(
        &clocks,
        mk_static!(
            [OneShotTimer<ErasedTimer>; 1],
            [OneShotTimer::new(timg0.timer0.into())]
        ),
    );

    let io = Io::new(peripherals.GPIO, peripherals.IO_MUX);

    let usb = Usb::new(peripherals.USB0, io.pins.gpio20, io.pins.gpio19);

    // Create the driver, from the HAL.
    let mut ep_out_buffer = [0u8; 1024];
    let config = Config::default();

    let driver = Driver::new(usb, &mut ep_out_buffer, config);

    // Create embassy-usb Config
    let mut config = embassy_usb::Config::new(0x303A, 0x3001);
    config.manufacturer = Some("Espressif");
    config.product = Some("USB-serial example");
    config.serial_number = Some("12345678");

    // Required for windows compatibility.
    // https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.9.1/kconfig/CONFIG_CDC_ACM_IAD.html#help
    config.device_class = 0xEF;
    config.device_sub_class = 0x02;
    config.device_protocol = 0x01;
    config.composite_with_iads = true;

    // Create embassy-usb DeviceBuilder using the driver and config.
    // It needs some buffers for building the descriptors.
    let mut config_descriptor = [0; 256];
    let mut bos_descriptor = [0; 256];
    let mut control_buf = [0; 64];

    let mut state = State::new();

    let mut builder = Builder::new(
        driver,
        config,
        &mut config_descriptor,
        &mut bos_descriptor,
        &mut [], // no msos descriptors
        &mut control_buf,
    );

    // Create classes on the builder.
    let mut class = CdcAcmClass::new(&mut builder, &mut state, 64);

    // Build the builder.
    let mut usb = builder.build();

    // Run the USB device.
    let usb_fut = usb.run();

    // Do stuff with the class!
    let echo_fut = async {
        loop {
            class.wait_connection().await;
            esp_println::println!("Connected");
            let _ = echo(&mut class).await;
            esp_println::println!("Disconnected");
        }
    };

    // Run everything concurrently.
    // If we had made everything `'static` above instead, we could do this using separate tasks instead.
    join(usb_fut, echo_fut).await;
}

async fn echo<'d>(class: &mut CdcAcmClass<'d, Driver<'d>>) -> Result<(), Disconnected> {
    let mut buf = [0; 64];
    loop {
        let n = class.read_packet(&mut buf).await?;
        // Echo back in upper case
        for c in buf[0..n].iter_mut() {
            if 0x61 <= *c && *c <= 0x7a {
                *c &= !0x20;
            }
        }
        let data = &buf[..n];
        class.write_packet(data).await?;
    }
}

struct Disconnected {}

impl From<EndpointError> for Disconnected {
    fn from(val: EndpointError) -> Self {
        match val {
            EndpointError::BufferOverflow => panic!("Buffer overflow"),
            EndpointError::Disabled => Disconnected {},
        }
    }
}