UART with IRQ + Embassy example

examples/embassy/src/bin/uart-echo-with-irq.rs

@@ -0,0 +1,164 @@
+//! This is an example of using the UART HAL abstraction with the IRQ support and embassy.
+//!
+//! It uses the UART0 for communication with another MCU or a host computer (recommended).
+//! You can connect a USB-to-Serial converter to the UART0 pins and then use a serial terminal
+//! application like picocom to send data to the microcontroller, which should be echoed
+//! back to the sender.
+//!
+//! This application uses the interrupt support of the VA416xx to read the data arriving
+//! on the UART without requiring polling.
+#![no_std]
+#![no_main]
+use core::cell::RefCell;
+
+use embassy_example::EXTCLK_FREQ;
+use embassy_executor::Spawner;
+use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
+use embassy_sync::blocking_mutex::Mutex;
+use embassy_time::{Duration, Ticker};
+use embedded_hal::digital::StatefulOutputPin;
+use embedded_io::Write;
+use panic_rtt_target as _;
+use ringbuf::{
+    traits::{Consumer, Observer, Producer},
+    StaticRb,
+};
+use rtt_target::{rprintln, rtt_init_print};
+use va416xx_hal::{
+    gpio::{OutputReadablePushPull, Pin, PinsG, PG5},
+    pac::{self, interrupt},
+    prelude::*,
+    time::Hertz,
+    uart,
+};
+
+pub type SharedUart = Mutex<CriticalSectionRawMutex, RefCell<Option<uart::RxWithIrq<pac::Uart0>>>>;
+static RX: SharedUart = Mutex::new(RefCell::new(None));
+
+const BAUDRATE: u32 = 115200;
+
+// Ring buffer size.
+const RING_BUF_SIZE: usize = 2048;
+
+pub type SharedRingBuf =
+    Mutex<CriticalSectionRawMutex, RefCell<Option<StaticRb<u8, RING_BUF_SIZE>>>>;
+// Ring buffers to handling variable sized telemetry
+static RINGBUF: SharedRingBuf = Mutex::new(RefCell::new(None));
+
+// See https://embassy.dev/book/#_sharing_using_a_mutex for background information about sharing
+// a peripheral with embassy.
+#[embassy_executor::main]
+async fn main(spawner: Spawner) {
+    rtt_init_print!();
+    rprintln!("VA416xx UART-Embassy Example");
+
+    let mut dp = pac::Peripherals::take().unwrap();
+
+    // Initialize the systick interrupt & obtain the token to prove that we did
+    // Use the external clock connected to XTAL_N.
+    let clocks = dp
+        .clkgen
+        .constrain()
+        .xtal_n_clk_with_src_freq(Hertz::from_raw(EXTCLK_FREQ))
+        .freeze(&mut dp.sysconfig)
+        .unwrap();
+    // Safety: Only called once here.
+    unsafe {
+        embassy_example::init(
+            &mut dp.sysconfig,
+            &dp.irq_router,
+            dp.tim15,
+            dp.tim14,
+            &clocks,
+        )
+    };
+
+    let portg = PinsG::new(&mut dp.sysconfig, dp.portg);
+
+    let tx = portg.pg0.into_funsel_1();
+    let rx = portg.pg1.into_funsel_1();
+
+    let uart0 = uart::Uart::new(
+        dp.uart0,
+        (tx, rx),
+        Hertz::from_raw(BAUDRATE),
+        &mut dp.sysconfig,
+        &clocks,
+    );
+    let (mut tx, rx) = uart0.split();
+    let mut rx = rx.to_rx_with_irq();
+    rx.start();
+    RX.lock(|static_rx| {
+        static_rx.borrow_mut().replace(rx);
+    });
+    RINGBUF.lock(|static_rb| {
+        static_rb.borrow_mut().replace(StaticRb::default());
+    });
+
+    let led = portg.pg5.into_readable_push_pull_output();
+    let mut ticker = Ticker::every(Duration::from_millis(50));
+    let mut processing_buf: [u8; RING_BUF_SIZE] = [0; RING_BUF_SIZE];
+    let mut read_bytes = 0;
+    spawner.spawn(blinky(led)).expect("failed to spawn blinky");
+    loop {
+        RINGBUF.lock(|static_rb| {
+            let mut rb_borrow = static_rb.borrow_mut();
+            let rb_mut = rb_borrow.as_mut().unwrap();
+            read_bytes = rb_mut.occupied_len();
+            rb_mut.pop_slice(&mut processing_buf[0..read_bytes]);
+        });
+        // Simply send back all received data.
+        tx.write_all(&processing_buf[0..read_bytes])
+            .expect("sending back read data failed");
+        ticker.next().await;
+    }
+}
+
+#[embassy_executor::task]
+async fn blinky(mut led: Pin<PG5, OutputReadablePushPull>) {
+    let mut ticker = Ticker::every(Duration::from_millis(500));
+    loop {
+        led.toggle().ok();
+        ticker.next().await;
+    }
+}
+
+#[interrupt]
+#[allow(non_snake_case)]
+fn UART0_RX() {
+    let mut buf: [u8; 16] = [0; 16];
+    let mut read_len: usize = 0;
+    let mut irq_error = None;
+    RX.lock(|static_rx| {
+        let mut rx_borrow = static_rx.borrow_mut();
+        let rx_mut_ref = rx_borrow.as_mut().unwrap();
+        match rx_mut_ref.irq_handler(&mut buf) {
+            Ok(result) => {
+                read_len = result.bytes_read;
+            }
+            Err(e) => {
+                irq_error = Some(e);
+            }
+        }
+    });
+    let mut ringbuf_full = false;
+    if read_len > 0 {
+        // Send the received buffer to the main thread for processing via a ring buffer.
+        RINGBUF.lock(|static_rb| {
+            let mut rb_borrow = static_rb.borrow_mut();
+            let rb_mut_ref = rb_borrow.as_mut().unwrap();
+            if rb_mut_ref.vacant_len() < read_len {
+                ringbuf_full = true;
+                for _ in rb_mut_ref.pop_iter() {}
+            }
+            rb_mut_ref.push_slice(&buf[0..read_len]);
+        });
+    }
+
+    if irq_error.is_some() {
+        rprintln!("error in IRQ handler: {:?}", irq_error);
+    }
+    if ringbuf_full {
+        rprintln!("ringbuffer is full, deleted oldest data");
+    }
+}

examples/embassy/src/lib.rs

@@ -1,4 +1,6 @@
 #![no_std]
 pub mod time_driver;
 
+pub const EXTCLK_FREQ: u32 = 40_000_000;
+
 pub use time_driver::init;

examples/embassy/src/main.rs

@@ -1,5 +1,6 @@
 #![no_std]
 #![no_main]
+use embassy_example::EXTCLK_FREQ;
 use embassy_executor::Spawner;
 use embassy_time::{Duration, Instant, Ticker};
 use embedded_hal::digital::StatefulOutputPin;
@@ -7,8 +8,6 @@ use panic_rtt_target as _;
 use rtt_target::{rprintln, rtt_init_print};
 use va416xx_hal::{gpio::PinsG, pac, prelude::*, time::Hertz};
 
-const EXTCLK_FREQ: u32 = 40_000_000;
-
 // main is itself an async function.
 #[embassy_executor::main]
 async fn main(_spawner: Spawner) {

examples/embassy/src/time_driver.rs

@@ -17,7 +17,7 @@ use va416xx_hal::{
     enable_interrupt,
     irq_router::enable_and_init_irq_router,
     pac::{self, interrupt},
-    pwm::{assert_tim_reset_for_two_cycles, enable_tim_clk, ValidTim},
+    timer::{assert_tim_reset_for_two_cycles, enable_tim_clk, ValidTim},
 };
 
 pub type TimekeeperClk = pac::Tim15;