buffered generalized working

usart_async_buffered_generalized/src/bin/main.rs

@@ -5,15 +5,23 @@
 use defmt::*;
 use embassy_executor::Spawner;
 use embassy_time::{Duration, Timer};
-use embassy_stm32::usart::{Config, Uart};
 use embassy_stm32::bind_interrupts;
-use embassy_stm32::usart::{BufferedUart, BufferedInterruptHandler};
-use embassy_stm32::mode::Async;
-use embedded_io_async::{Read, Write};
 use embassy_stm32::peripherals;
+use embassy_stm32::usart::{BufferedInterruptHandler, BufferedUart, Config};
+use embedded_io_async::{Read, Write};
 use static_cell::StaticCell;
 use {defmt_rtt as _, panic_probe as _};
 
+// Select + channel + heapless Vec
+use embassy_futures::select::{select, Either};
+use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
+use embassy_sync::channel::Channel;
+use heapless::Vec;
+
+const MAX_MSG: usize = 64;
+const QSIZE: usize = 4;
+static UART_TX: Channel<CriticalSectionRawMutex, Vec<u8, MAX_MSG>, QSIZE> = Channel::new();
+
 bind_interrupts!(
     struct Irqs {
         USART1 => BufferedInterruptHandler<peripherals::USART1>;
@@ -21,14 +29,38 @@ bind_interrupts!(
 );
 
 #[embassy_executor::task]
-async fn receive_uart(mut uart: BufferedUart<'static>) {
+async fn uart_task(mut uart: BufferedUart<'static>) {
     let mut buf = [0u8; 1];
+
     loop {
-        unwrap!(uart.read(&mut buf).await);
+        let rx_fut = uart.read(&mut buf);
+        let tx_fut = UART_TX.receive();
+
+        match select(rx_fut, tx_fut).await {
+            // Incoming RX byte
+            Either::First(res) => {
+                if let Ok(_) = res {
+                    // Echo and log
                     unwrap!(uart.write(&buf).await);
                     unwrap!(uart.write(b"a\r\n").await);
                     info!("uart received {}", buf[0]);
+                    unwrap!(uart.flush().await);
                 }
+            }
+            // Outgoing TX request from main
+            Either::Second(msg) => {
+                unwrap!(uart.write(&msg).await);
+                unwrap!(uart.flush().await);
+                info!("sent {} bytes", msg.len());
+            }
+        }
+    }
+}
+
+pub async fn send_uart(data: &[u8]) {
+    let mut v: Vec<u8, MAX_MSG> = Vec::new();
+    let _ = v.extend_from_slice(data); // truncate if too long
+    UART_TX.send(v).await;
 }
 
 #[embassy_executor::main]
@@ -44,7 +76,6 @@ async fn main(spawner: Spawner) {
     let mut cfg = Config::default();
     cfg.baudrate = 230_400;
 
-    let config = Config::default();
     let usart = BufferedUart::new(
         p.USART1,
         p.PA10, // RX
@@ -53,15 +84,22 @@ async fn main(spawner: Spawner) {
         rx_buf,
         Irqs,
         cfg,
-    ).unwrap();
+    )
+    .unwrap();
 
-    info!("starting echo");
+    info!("starting uart task");
-    spawner.spawn(receive_uart(usart)).unwrap();
+    spawner.spawn(uart_task(usart)).unwrap();
 
-    let mut counter: u8 = 230;
+    let mut counter: u32 = 230;
     loop {
         counter = counter.wrapping_add(1);
+
+        if counter % 10000 == 0 {
             info!("CPU doing other work: {}", counter);
-        Timer::after(Duration::from_millis(300)).await;
+        }
+        if counter % 100000 == 0 {
+            // Send whenever you want; the UART task performs the actual write.
+            send_uart(b"Hello\r\n").await;
+        }
     }
 }