Permits the future to be cancelled
Includes documentation
use core::sync::atomic::{compiler_fence, Ordering};
use core::task::Poll;
+use embassy_hal_common::drop::OnDrop;
use embassy_hal_common::{impl_peripheral, into_ref, PeripheralRef};
use embassy_sync::waitqueue::AtomicWaker;
use futures::future::poll_fn;
@@ -225,8 +226,12 @@ impl<'d, const N: usize> Saadc<'d, N> {
/// One shot sampling. The buffer must be the same size as the number of channels configured.
/// The sampling is stopped prior to returning in order to reduce power consumption (power
- /// consumption remains higher if sampling is not stopped explicitly).
+ /// consumption remains higher if sampling is not stopped explicitly). Cancellation will
+ /// also cause the sampling to be stopped.
pub async fn sample(&mut self, buf: &mut [i16; N]) {
+ // In case the future is dropped, stop the task and wait for it to end.
+ let on_drop = OnDrop::new(Self::stop_sampling_immediately);
+
let r = Self::regs();
// Set up the DMA
@@ -259,6 +264,7 @@ impl<'d, const N: usize> Saadc<'d, N> {
})
.await;
+ on_drop.defuse();
Self::stop_sampling().await;
}
@@ -279,6 +285,12 @@ impl<'d, const N: usize> Saadc<'d, N> {
/// taken to acquire the samples into a single buffer. You should measure the
/// time taken by the callback and set the sample buffer size accordingly.
/// Exceeding this time can lead to samples becoming dropped.
+ ///
+ /// The sampling is stopped prior to returning in order to reduce power consumption (power
+ /// consumption remains higher if sampling is not stopped explicitly), and to
+ /// free the buffers from being used by the peripheral. Cancellation will
+ /// also cause the sampling to be stopped.
+
pub async fn run_task_sampler<S, T: TimerInstance, const N0: usize>(
&mut self,
timer: &mut T,
@@ -330,6 +342,9 @@ impl<'d, const N: usize> Saadc<'d, N> {
I: FnMut(),
S: FnMut(&[[i16; N]]) -> SamplerState,
{
+ // In case the future is dropped, stop the task and wait for it to end.
+ let on_drop = OnDrop::new(Self::stop_sampling_immediately);
+
let r = Self::regs();
// Establish mode and sample rate
@@ -413,10 +428,24 @@ impl<'d, const N: usize> Saadc<'d, N> {
})
.await;
+ on_drop.defuse();
Self::stop_sampling().await;
}
- // Stop sampling and wait for it to stop
+ // Stop sampling and wait for it to stop in a blocking fashion
+ fn stop_sampling_immediately() {
+ let r = Self::regs();
+
+ compiler_fence(Ordering::SeqCst);
+
+ r.events_stopped.reset();
+ r.tasks_stop.write(|w| unsafe { w.bits(1) });
+
+ while r.events_stopped.read().bits() == 0 {}
+ r.events_stopped.reset();
+ }
+
+ // Stop sampling and wait for it to stop in a non-blocking fashino
async fn stop_sampling() {
let r = Self::regs();
