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 core::fmt::Write;

use embassy_time::{with_timeout, Duration};
use esp32s2_hal::{
    clock::ClockControl,
    embassy::{self, executor::Executor},
    interrupt,
    peripherals::{Interrupt, Peripherals, UART0},
    prelude::*,
    Uart,
};
use esp_backtrace as _;
use esp_hal_common::uart::config::AtCmdConfig;
use heapless::Vec;
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 run(mut uart: Uart<'static, UART0>) {
    // max message size to receive
    // leave some extra space for AT-CMD characters
    const MAX_BUFFER_SIZE: usize = 10 * READ_BUF_SIZE + 16;
    // timeout read
    const READ_TIMEOUT: Duration = Duration::from_secs(10);

    let mut rbuf: Vec<u8, MAX_BUFFER_SIZE> = Vec::new();
    let mut wbuf: Vec<u8, MAX_BUFFER_SIZE> = Vec::new();
    loop {
        if rbuf.is_empty() {
            embedded_io_async::Write::write(
                &mut uart,
                b"Hello async serial. Enter something ended with EOT (CTRL-D).\r\n",
            )
            .await
            .unwrap();
        } else {
            wbuf.clear();
            write!(&mut wbuf, "\r\n-- received {} bytes --\r\n", rbuf.len()).unwrap();
            embedded_io_async::Write::write(&mut uart, wbuf.as_slice())
                .await
                .unwrap();
            embedded_io_async::Write::write(&mut uart, rbuf.as_slice())
                .await
                .unwrap();
            embedded_io_async::Write::write(&mut uart, b"\r\n")
                .await
                .unwrap();
        }
        embedded_io_async::Write::flush(&mut uart).await.unwrap();

        // set rbuf full capacity
        rbuf.resize_default(rbuf.capacity()).ok();
        let mut offset = 0;
        loop {
            match with_timeout(
                READ_TIMEOUT,
                embedded_io_async::Read::read(&mut uart, &mut rbuf[offset..]),
            )
            .await
            {
                Ok(r) => {
                    if let Ok(len) = r {
                        offset += len;
                        if offset == 0 {
                            rbuf.truncate(0);
                            break;
                        }
                        // if set_at_cmd is used than stop reading
                        if len < READ_BUF_SIZE {
                            rbuf.truncate(offset);
                            break;
                        }
                    } else {
                        // buffer is full or rx fifo overflow
                        break;
                    }
                }
                Err(_) => {
                    // Timeout
                    rbuf.truncate(offset);
                    break;
                }
            }
        }
    }
}

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

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

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

    interrupt::enable(Interrupt::UART0, interrupt::Priority::Priority1).unwrap();

    let executor = make_static!(Executor::new());
    executor.run(|spawner| {
        spawner.spawn(run(uart0)).ok();
    });
}