diff --git a/embassy-time/src/lib.rs b/embassy-time/src/lib.rs index d27eb92f6..e7efce49c 100644 --- a/embassy-time/src/lib.rs +++ b/embassy-time/src/lib.rs @@ -32,7 +32,7 @@ pub use delay::{block_for, Delay}; pub use duration::Duration; pub use embassy_time_driver::TICK_HZ; pub use instant::Instant; -pub use timer::{with_timeout, Ticker, TimeoutError, Timer}; +pub use timer::{timeout_at, with_timeout, Ticker, TimeoutError, Timer}; const fn gcd(a: u64, b: u64) -> u64 { if b == 0 { diff --git a/embassy-time/src/timer.rs b/embassy-time/src/timer.rs index 565a65cb8..dbce9297c 100644 --- a/embassy-time/src/timer.rs +++ b/embassy-time/src/timer.rs @@ -8,7 +8,7 @@ use futures_util::{pin_mut, Stream}; use crate::{Duration, Instant}; -/// Error returned by [`with_timeout`] on timeout. +/// Error returned by [`with_timeout`] and [`timeout_at`] on timeout. #[derive(Debug, Clone, PartialEq, Eq)] #[cfg_attr(feature = "defmt", derive(defmt::Format))] pub struct TimeoutError; @@ -26,6 +26,19 @@ pub async fn with_timeout(timeout: Duration, fut: F) -> Result(at: Instant, fut: F) -> Result { + let timeout_fut = Timer::at(at); + pin_mut!(fut); + match select(fut, timeout_fut).await { + Either::Left((r, _)) => Ok(r), + Either::Right(_) => Err(TimeoutError), + } +} + /// A future that completes at a specified [Instant](struct.Instant.html). #[must_use = "futures do nothing unless you `.await` or poll them"] pub struct Timer { diff --git a/examples/rp/src/bin/debounce.rs b/examples/rp/src/bin/debounce.rs new file mode 100644 index 000000000..bf1579091 --- /dev/null +++ b/examples/rp/src/bin/debounce.rs @@ -0,0 +1,80 @@ +//! This example shows the ease of debouncing a button with async rust. +//! Hook up a button or switch between pin 9 and ground. + +#![no_std] +#![no_main] + +use defmt::info; +use embassy_executor::Spawner; +use embassy_rp::gpio::{Input, Level, Pull}; +use embassy_time::{timeout_at, Duration, Instant, Timer}; +use {defmt_rtt as _, panic_probe as _}; + +pub struct Debouncer<'a> { + input: Input<'a>, + debounce: Duration, +} + +impl<'a> Debouncer<'a> { + pub fn new(input: Input<'a>, debounce: Duration) -> Self { + Self { input, debounce } + } + + pub async fn debounce(&mut self) -> Level { + loop { + let l1 = self.input.get_level(); + + self.input.wait_for_any_edge().await; + + Timer::after(self.debounce).await; + + let l2 = self.input.get_level(); + if l1 != l2 { + break l2; + } + } + } +} + +#[embassy_executor::main] +async fn main(_spawner: Spawner) { + let p = embassy_rp::init(Default::default()); + let mut btn = Debouncer::new(Input::new(p.PIN_9, Pull::Up), Duration::from_millis(20)); + + info!("Debounce Demo"); + + loop { + // button pressed + btn.debounce().await; + let start = Instant::now(); + info!("Button Press"); + + match timeout_at(start + Duration::from_secs(1), btn.debounce()).await { + // Button Released < 1s + Ok(_) => { + info!("Button pressed for: {}ms", start.elapsed().as_millis()); + continue; + } + // button held for > 1s + Err(_) => { + info!("Button Held"); + } + } + + match timeout_at(start + Duration::from_secs(5), btn.debounce()).await { + // Button released <5s + Ok(_) => { + info!("Button pressed for: {}ms", start.elapsed().as_millis()); + continue; + } + // button held for > >5s + Err(_) => { + info!("Button Long Held"); + } + } + + // wait for button release before handling another press + btn.debounce().await; + info!("Button pressed for: {}ms", start.elapsed().as_millis()); + } +}