Merge #1121

1121: Add examples for stm32f0 r=lulf a=imrank03

Hello `@lulf,`

I added some more examples to stm32f0 and tested on hardware.

With love,
Imran

Co-authored-by: @imrank03 <immu0396@gmail.com>

examples/stm32f0/Cargo.toml

@@ -15,5 +15,5 @@ panic-probe = "0.3"
 embassy-sync = { version = "0.1.0", path = "../../embassy-sync", features = ["defmt"] }
 embassy-executor = { version = "0.1.0", path = "../../embassy-executor", features = ["defmt", "integrated-timers"] }
 embassy-time = { version = "0.1.0", path = "../../embassy-time", features = ["defmt", "defmt-timestamp-uptime", "tick-hz-32_768"] }
-embassy-stm32 = { version = "0.1.0", path = "../../embassy-stm32", features = ["nightly", "defmt", "memory-x", "stm32f091rc", "time-driver-any"] }
-
+embassy-stm32 = { version = "0.1.0", path = "../../embassy-stm32", features = ["nightly", "defmt", "memory-x", "stm32f091rc", "time-driver-any", "exti"] }
+static_cell = "1.0"

examples/stm32f0/src/bin/button_controlled_blink.rs

@@ -0,0 +1,64 @@
+//! This example showcases how to create task
+
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use core::sync::atomic::{AtomicU32, Ordering};
+
+use defmt::info;
+use embassy_executor::Spawner;
+use embassy_stm32::exti::ExtiInput;
+use embassy_stm32::gpio::{AnyPin, Input, Level, Output, Pin, Pull, Speed};
+use embassy_time::{Duration, Timer};
+use {defmt_rtt as _, panic_probe as _};
+
+static BLINK_MS: AtomicU32 = AtomicU32::new(0);
+
+#[embassy_executor::task]
+async fn led_task(led: AnyPin) {
+    // Configure the LED pin as a push pull ouput and obtain handler.
+    // On the Nucleo F091RC theres an on-board LED connected to pin PA5.
+    let mut led = Output::new(led, Level::Low, Speed::Low);
+
+    loop {
+        let del = BLINK_MS.load(Ordering::Relaxed);
+        info!("Value of del is {}", del);
+        Timer::after(Duration::from_millis(del.into())).await;
+        info!("LED toggling");
+        led.toggle();
+    }
+}
+
+#[embassy_executor::main]
+async fn main(spawner: Spawner) {
+    // Initialize and create handle for devicer peripherals
+    let p = embassy_stm32::init(Default::default());
+
+    // Configure the button pin and obtain handler.
+    // On the Nucleo F091RC there is a button connected to pin PC13.
+    let button = Input::new(p.PC13, Pull::None);
+    let mut button = ExtiInput::new(button, p.EXTI13);
+
+    // Create and initialize a delay variable to manage delay loop
+    let mut del_var = 2000;
+
+    // Blink duration value to global context
+    BLINK_MS.store(del_var, Ordering::Relaxed);
+
+    // Spawn LED blinking task
+    spawner.spawn(led_task(p.PA5.degrade())).unwrap();
+
+    loop {
+        // Check if button got pressed
+        button.wait_for_rising_edge().await;
+        info!("rising_edge");
+        del_var = del_var - 200;
+        // If updated delay value drops below 200 then reset it back to starting value
+        if del_var < 200 {
+            del_var = 2000;
+        }
+        // Updated delay value to global context
+        BLINK_MS.store(del_var, Ordering::Relaxed);
+    }
+}

examples/stm32f0/src/bin/button_exti.rs

@@ -0,0 +1,27 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_stm32::exti::ExtiInput;
+use embassy_stm32::gpio::{Input, Pull};
+use {defmt_rtt as _, panic_probe as _};
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    // Initialize and create handle for devicer peripherals
+    let p = embassy_stm32::init(Default::default());
+    // Configure the button pin and obtain handler.
+    // On the Nucleo F091RC there is a button connected to pin PC13.
+    let button = Input::new(p.PC13, Pull::Down);
+    let mut button = ExtiInput::new(button, p.EXTI13);
+
+    info!("Press the USER button...");
+    loop {
+        button.wait_for_falling_edge().await;
+        info!("Pressed!");
+        button.wait_for_rising_edge().await;
+        info!("Released!");
+    }
+}

examples/stm32f0/src/bin/priority.rs

@@ -0,0 +1,139 @@
+//! This example showcases how to create multiple Executor instances to run tasks at
+//! different priority levels.
+//!
+//! Low priority executor runs in thread mode (not interrupt), and uses `sev` for signaling
+//! there's work in the queue, and `wfe` for waiting for work.
+//!
+//! Medium and high priority executors run in two interrupts with different priorities.
+//! Signaling work is done by pending the interrupt. No "waiting" needs to be done explicitly, since
+//! when there's work the interrupt will trigger and run the executor.
+//!
+//! Sample output below. Note that high priority ticks can interrupt everything else, and
+//! medium priority computations can interrupt low priority computations, making them to appear
+//! to take significantly longer time.
+//!
+//! ```not_rust
+//!     [med] Starting long computation
+//!     [med] done in 992 ms
+//!         [high] tick!
+//! [low] Starting long computation
+//!     [med] Starting long computation
+//!         [high] tick!
+//!         [high] tick!
+//!     [med] done in 993 ms
+//!     [med] Starting long computation
+//!         [high] tick!
+//!         [high] tick!
+//!     [med] done in 993 ms
+//! [low] done in 3972 ms
+//!     [med] Starting long computation
+//!         [high] tick!
+//!         [high] tick!
+//!     [med] done in 993 ms
+//! ```
+//!
+//! For comparison, try changing the code so all 3 tasks get spawned on the low priority executor.
+//! You will get an output like the following. Note that no computation is ever interrupted.
+//!
+//! ```not_rust
+//!         [high] tick!
+//!     [med] Starting long computation
+//!     [med] done in 496 ms
+//! [low] Starting long computation
+//! [low] done in 992 ms
+//!     [med] Starting long computation
+//!     [med] done in 496 ms
+//!         [high] tick!
+//! [low] Starting long computation
+//! [low] done in 992 ms
+//!         [high] tick!
+//!     [med] Starting long computation
+//!     [med] done in 496 ms
+//!         [high] tick!
+//! ```
+//!
+
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use cortex_m_rt::entry;
+use defmt::*;
+use embassy_stm32::executor::{Executor, InterruptExecutor};
+use embassy_stm32::interrupt;
+use embassy_stm32::interrupt::InterruptExt;
+use embassy_time::{Duration, Instant, Timer};
+use static_cell::StaticCell;
+use {defmt_rtt as _, panic_probe as _};
+
+#[embassy_executor::task]
+async fn run_high() {
+    loop {
+        // info!("        [high] tick!");
+        Timer::after(Duration::from_ticks(27374)).await;
+    }
+}
+
+#[embassy_executor::task]
+async fn run_med() {
+    loop {
+        let start = Instant::now();
+        info!("    [med] Starting long computation");
+
+        // Spin-wait to simulate a long CPU computation
+        cortex_m::asm::delay(8_000_000); // ~1 second
+
+        let end = Instant::now();
+        let ms = end.duration_since(start).as_ticks() / 33;
+        info!("    [med] done in {} ms", ms);
+
+        Timer::after(Duration::from_ticks(23421)).await;
+    }
+}
+
+#[embassy_executor::task]
+async fn run_low() {
+    loop {
+        let start = Instant::now();
+        info!("[low] Starting long computation");
+
+        // Spin-wait to simulate a long CPU computation
+        cortex_m::asm::delay(16_000_000); // ~2 seconds
+
+        let end = Instant::now();
+        let ms = end.duration_since(start).as_ticks() / 33;
+        info!("[low] done in {} ms", ms);
+
+        Timer::after(Duration::from_ticks(32983)).await;
+    }
+}
+
+static EXECUTOR_HIGH: StaticCell<InterruptExecutor<interrupt::USART1>> = StaticCell::new();
+static EXECUTOR_MED: StaticCell<InterruptExecutor<interrupt::USART2>> = StaticCell::new();
+static EXECUTOR_LOW: StaticCell<Executor> = StaticCell::new();
+
+#[entry]
+fn main() -> ! {
+    // Initialize and create handle for devicer peripherals
+    let _p = embassy_stm32::init(Default::default());
+
+    // High-priority executor: USART1, priority level 6
+    let irq = interrupt::take!(USART1);
+    irq.set_priority(interrupt::Priority::P6);
+    let executor = EXECUTOR_HIGH.init(InterruptExecutor::new(irq));
+    let spawner = executor.start();
+    unwrap!(spawner.spawn(run_high()));
+
+    // Medium-priority executor: USART2, priority level 7
+    let irq = interrupt::take!(USART2);
+    irq.set_priority(interrupt::Priority::P7);
+    let executor = EXECUTOR_MED.init(InterruptExecutor::new(irq));
+    let spawner = executor.start();
+    unwrap!(spawner.spawn(run_med()));
+
+    // Low priority executor: runs in thread mode, using WFE/SEV
+    let executor = EXECUTOR_LOW.init(Executor::new());
+    executor.run(|spawner| {
+        unwrap!(spawner.spawn(run_low()));
+    });
+}

examples/stm32f0/src/bin/wdg.rs

@@ -0,0 +1,25 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_stm32::wdg::IndependentWatchdog;
+use embassy_time::{Duration, Timer};
+use {defmt_rtt as _, panic_probe as _};
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    // Initialize and create handle for devicer peripherals
+    let p = embassy_stm32::init(Default::default());
+    // Configure the independent watchdog  timer
+    let mut wdg = IndependentWatchdog::new(p.IWDG, 20_000_00);
+
+    info!("Watchdog start");
+    unsafe { wdg.unleash() };
+
+    loop {
+        Timer::after(Duration::from_secs(1)).await;
+        unsafe { wdg.pet() };
+    }
+}