Merge #612

612: Add button_events example for stm32f3 r=Dirbaio a=ceigel

This is a more elaborate example of using buttons and leds. 
Tested on STM32F3DISCOVERY

Co-authored-by: Cristian Eigel <cristian.eigel@esrlabs.com>

examples/stm32f3/src/bin/button_events.rs

@@ -0,0 +1,163 @@
+//! This example showcases channels and timing utilities of embassy.
+//!
+//! This example works best on STM32F3DISCOVERY board. It flashes a single LED, then if the USER
+//! button is pressed the next LED is flashed (in clockwise fashion). If the USER button is double
+//! clicked, then the direction changes. If the USER button is pressed for 1 second, then all the
+//! LEDS flash 3 times.
+//!
+
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+#[path = "../example_common.rs"]
+mod example_common;
+use embassy::blocking_mutex::kind::Noop;
+use embassy::channel::mpsc::{self, Channel, Receiver, Sender};
+use embassy::executor::Spawner;
+use embassy::time::{with_timeout, Duration, Timer};
+use embassy::util::Forever;
+use embassy_stm32::exti::ExtiInput;
+use embassy_stm32::gpio::{AnyPin, Input, Level, Output, Pin, Pull, Speed};
+use embassy_stm32::peripherals::PA0;
+use embassy_stm32::Peripherals;
+use example_common::*;
+
+struct Leds<'a> {
+    leds: [Output<'a, AnyPin>; 8],
+    direction: i8,
+    current_led: usize,
+}
+
+impl<'a> Leds<'a> {
+    fn new(pins: [Output<'a, AnyPin>; 8]) -> Self {
+        Self {
+            leds: pins,
+            direction: 1,
+            current_led: 0,
+        }
+    }
+
+    fn change_direction(&mut self) {
+        self.direction *= -1;
+    }
+
+    fn move_next(&mut self) {
+        if self.direction > 0 {
+            self.current_led = (self.current_led + 1) & 7;
+        } else {
+            self.current_led = (8 + self.current_led - 1) & 7;
+        }
+    }
+
+    async fn blink(&mut self) {
+        self.leds[self.current_led].set_high();
+        Timer::after(Duration::from_millis(500)).await;
+        self.leds[self.current_led].set_low();
+        Timer::after(Duration::from_millis(200)).await;
+    }
+
+    async fn flash(&mut self) {
+        for _ in 0..3 {
+            for led in &mut self.leds {
+                led.set_high();
+            }
+            Timer::after(Duration::from_millis(500)).await;
+            for led in &mut self.leds {
+                led.set_low();
+            }
+            Timer::after(Duration::from_millis(200)).await;
+        }
+    }
+}
+
+enum ButtonEvent {
+    SingleClick,
+    DoubleClick,
+    Hold,
+}
+
+static BUTTON_EVENTS_QUEUE: Forever<Channel<Noop, ButtonEvent, 4>> = Forever::new();
+
+#[embassy::main]
+async fn main(spawner: Spawner, p: Peripherals) {
+    let button = Input::new(p.PA0, Pull::Down);
+    let button = ExtiInput::new(button, p.EXTI0);
+    info!("Press the USER button...");
+    let leds = [
+        Output::new(p.PE9.degrade(), Level::Low, Speed::Low),
+        Output::new(p.PE10.degrade(), Level::Low, Speed::Low),
+        Output::new(p.PE11.degrade(), Level::Low, Speed::Low),
+        Output::new(p.PE12.degrade(), Level::Low, Speed::Low),
+        Output::new(p.PE13.degrade(), Level::Low, Speed::Low),
+        Output::new(p.PE14.degrade(), Level::Low, Speed::Low),
+        Output::new(p.PE15.degrade(), Level::Low, Speed::Low),
+        Output::new(p.PE8.degrade(), Level::Low, Speed::Low),
+    ];
+    let leds = Leds::new(leds);
+
+    let buttons_queue = BUTTON_EVENTS_QUEUE.put(Channel::new());
+    let (sender, receiver) = mpsc::split(buttons_queue);
+    spawner.spawn(button_waiter(button, sender)).unwrap();
+    spawner.spawn(led_blinker(leds, receiver)).unwrap();
+}
+
+#[embassy::task]
+async fn led_blinker(mut leds: Leds<'static>, queue: Receiver<'static, Noop, ButtonEvent, 4>) {
+    loop {
+        leds.blink().await;
+        match queue.try_recv() {
+            Ok(ButtonEvent::SingleClick) => leds.move_next(),
+            Ok(ButtonEvent::DoubleClick) => {
+                leds.change_direction();
+                leds.move_next()
+            }
+            Ok(ButtonEvent::Hold) => leds.flash().await,
+            _ => {}
+        }
+    }
+}
+
+#[embassy::task]
+async fn button_waiter(
+    mut button: ExtiInput<'static, PA0>,
+    queue: Sender<'static, Noop, ButtonEvent, 4>,
+) {
+    const DOUBLE_CLICK_DELAY: u64 = 250;
+    const HOLD_DELAY: u64 = 1000;
+
+    button.wait_for_rising_edge().await;
+    loop {
+        if with_timeout(
+            Duration::from_millis(HOLD_DELAY),
+            button.wait_for_falling_edge(),
+        )
+        .await
+        .is_err()
+        {
+            info!("Hold");
+            if queue.send(ButtonEvent::Hold).await.is_err() {
+                break;
+            }
+            button.wait_for_falling_edge().await;
+        } else if with_timeout(
+            Duration::from_millis(DOUBLE_CLICK_DELAY),
+            button.wait_for_rising_edge(),
+        )
+        .await
+        .is_err()
+        {
+            if queue.send(ButtonEvent::SingleClick).await.is_err() {
+                break;
+            }
+            info!("Single click");
+        } else {
+            info!("Double click");
+            if queue.send(ButtonEvent::DoubleClick).await.is_err() {
+                break;
+            }
+            button.wait_for_falling_edge().await;
+        }
+        button.wait_for_rising_edge().await;
+    }
+}