esp-hal/esp32s2-hal/examples/embassy_serial.rs

//! embassy serial
//!
//! This is an example of running the embassy executor and asynchronously
//! writing to and reading from uart

#![no_std]
#![no_main]
#![feature(type_alias_impl_trait)]

use embassy_executor::Spawner;
use embassy_sync::{blocking_mutex::raw::NoopRawMutex, signal::Signal};
use esp32s2_hal::{
    clock::ClockControl,
    embassy,
    peripherals::{Peripherals, UART0},
    prelude::*,
    uart::{config::AtCmdConfig, UartRx, UartTx},
    Uart,
};
use esp_backtrace as _;
use static_cell::make_static;

// rx_fifo_full_threshold
const READ_BUF_SIZE: usize = 64;
// EOT (CTRL-D)
const AT_CMD: u8 = 0x04;

#[embassy_executor::task]
async fn writer(mut tx: UartTx<'static, UART0>, signal: &'static Signal<NoopRawMutex, usize>) {
    use core::fmt::Write;
    embedded_io_async::Write::write(
        &mut tx,
        b"Hello async serial. Enter something ended with EOT (CTRL-D).\r\n",
    )
    .await
    .unwrap();
    embedded_io_async::Write::flush(&mut tx).await.unwrap();
    loop {
        let bytes_read = signal.wait().await;
        signal.reset();
        write!(&mut tx, "\r\n-- received {} bytes --\r\n", bytes_read).unwrap();
        embedded_io_async::Write::flush(&mut tx).await.unwrap();
    }
}

#[embassy_executor::task]
async fn reader(mut rx: UartRx<'static, UART0>, signal: &'static Signal<NoopRawMutex, usize>) {
    const MAX_BUFFER_SIZE: usize = 10 * READ_BUF_SIZE + 16;

    let mut rbuf: [u8; MAX_BUFFER_SIZE] = [0u8; MAX_BUFFER_SIZE];
    let mut offset = 0;
    loop {
        let r = embedded_io_async::Read::read(&mut rx, &mut rbuf[offset..]).await;
        match r {
            Ok(len) => {
                offset += len;
                esp_println::println!("Read: {len}, data: {:?}", &rbuf[..offset]);
                offset = 0;
                signal.signal(len);
            }
            Err(e) => esp_println::println!("RX Error: {:?}", e),
        }
    }
}

#[main]
async fn main(spawner: Spawner) {
    esp_println::println!("Init!");
    let peripherals = Peripherals::take();
    let system = peripherals.SYSTEM.split();
    let clocks = ClockControl::boot_defaults(system.clock_control).freeze();

    #[cfg(feature = "embassy-time-systick")]
    embassy::init(
        &clocks,
        esp32s2_hal::systimer::SystemTimer::new(peripherals.SYSTIMER),
    );

    #[cfg(feature = "embassy-time-timg0")]
    {
        let timer_group0 = esp32s2_hal::timer::TimerGroup::new(peripherals.TIMG0, &clocks);
        embassy::init(&clocks, timer_group0.timer0);
    }

    let mut uart0 = Uart::new(peripherals.UART0, &clocks);
    uart0.set_at_cmd(AtCmdConfig::new(None, None, None, AT_CMD, None));
    uart0
        .set_rx_fifo_full_threshold(READ_BUF_SIZE as u16)
        .unwrap();
    let (tx, rx) = uart0.split();

    let signal = &*make_static!(Signal::new());

    spawner.spawn(reader(rx, &signal)).ok();
    spawner.spawn(writer(tx, &signal)).ok();
}