1 files changed, 180 insertions, 0 deletions

diff --git a/embassy-stm32/src/adc/ringbuffered.rs b/embassy-stm32/src/adc/ringbuffered.rs
new file mode 100644
index 000000000..242a1a89c
--- /dev/null
+++ b/embassy-stm32/src/adc/ringbuffered.rs
@@ -0,0 +1,180 @@
+use core::marker::PhantomData;
+use core::sync::atomic::{Ordering, compiler_fence};
+
+#[allow(unused_imports)]
+use embassy_hal_internal::Peri;
+
+use super::AdcRegs;
+#[allow(unused_imports)]
+use crate::adc::{Instance, RxDma};
+#[allow(unused_imports)]
+use crate::dma::{ReadableRingBuffer, TransferOptions};
+use crate::rcc;
+
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct OverrunError;
+
+pub struct RingBufferedAdc<'d, T: Instance> {
+    _phantom: PhantomData<T>,
+    ring_buf: ReadableRingBuffer<'d, u16>,
+}
+
+impl<'d, T: Instance> RingBufferedAdc<'d, T> {
+    pub(crate) fn new(dma: Peri<'d, impl RxDma<T>>, dma_buf: &'d mut [u16]) -> Self {
+        //dma side setup
+        let opts = TransferOptions {
+            half_transfer_ir: true,
+            circular: true,
+            ..Default::default()
+        };
+
+        // Safety: we forget the struct before this function returns.
+        let request = dma.request();
+
+        let ring_buf = unsafe { ReadableRingBuffer::new(dma, request, T::regs().data(), dma_buf, opts) };
+
+        Self {
+            _phantom: PhantomData,
+            ring_buf,
+        }
+    }
+
+    /// Turns on ADC if it is not already turned on and starts continuous DMA transfer.
+    pub fn start(&mut self) {
+        compiler_fence(Ordering::SeqCst);
+        self.ring_buf.start();
+
+        T::regs().start();
+    }
+
+    pub fn stop(&mut self) {
+        self.ring_buf.request_pause();
+
+        compiler_fence(Ordering::SeqCst);
+    }
+
+    pub fn clear(&mut self) {
+        self.ring_buf.clear();
+    }
+
+    /// Reads measurements from the DMA ring buffer.
+    ///
+    /// This method fills the provided `measurements` array with ADC readings from the DMA buffer.
+    /// The length of the `measurements` array should be exactly half of the DMA buffer length.
+    /// Because interrupts are only generated if half or full DMA transfer completes.
+    ///
+    /// Each call to `read` will populate the `measurements` array in the same order as the channels
+    /// defined with `sequence`. There will be many sequences worth of measurements in this array
+    /// because it only returns if at least half of the DMA buffer is filled. For example if 2
+    /// channels are sampled `measurements` contain: `[sq0 sq1 sq0 sq1 sq0 sq1 ..]`.
+    ///
+    /// Note that the ADC Datarate can be very fast, it is suggested to use DMA mode inside tightly
+    /// running tasks. Otherwise, you'll see constant Overrun errors occurring, this means that
+    /// you're sampling too quickly for the task to handle, and you may need to increase the buffer size.
+    /// Example:
+    /// ```rust,ignore
+    /// const DMA_BUF_LEN: usize = 120;
+    /// use embassy_stm32::adc::{Adc, AdcChannel}
+    ///
+    /// let mut adc = Adc::new(p.ADC1);
+    /// let mut adc_pin0 = p.PA0.degrade_adc();
+    /// let mut adc_pin1 = p.PA1.degrade_adc();
+    /// let adc_dma_buf = [0u16; DMA_BUF_LEN];
+    ///
+    /// let mut ring_buffered_adc: RingBufferedAdc<embassy_stm32::peripherals::ADC1> = adc.into_ring_buffered(
+    ///     p.DMA2_CH0,
+    ///      adc_dma_buf, [
+    ///         (&mut *adc_pin0, SampleTime::CYCLES160_5),
+    ///         (&mut *adc_pin1, SampleTime::CYCLES160_5),
+    ///     ].into_iter());
+    ///
+    ///
+    /// let mut measurements = [0u16; DMA_BUF_LEN / 2];
+    /// loop {
+    ///     match ring_buffered_adc.read(&mut measurements).await {
+    ///         Ok(_) => {
+    ///             defmt::info!("adc1: {}", measurements);
+    ///         }
+    ///         Err(e) => {
+    ///             defmt::warn!("Error: {:?}", e);
+    ///         }
+    ///     }
+    /// }
+    /// ```
+    ///
+    ///
+    /// [`teardown_adc`]: #method.teardown_adc
+    /// [`start_continuous_sampling`]: #method.start_continuous_sampling
+    pub async fn read(&mut self, measurements: &mut [u16]) -> Result<usize, OverrunError> {
+        assert_eq!(
+            self.ring_buf.capacity() / 2,
+            measurements.len(),
+            "Buffer size must be half the size of the ring buffer"
+        );
+
+        if !self.ring_buf.is_running() {
+            self.start();
+        }
+
+        //        #[cfg(adc_v2)]
+        //        {
+        //            // Clear overrun flag if set.
+        //            if T::regs().sr().read().ovr() {
+        //                self.stop();
+        //
+        //                return Err(OverrunError);
+        //            }
+        //        }
+
+        self.ring_buf.read_exact(measurements).await.map_err(|_| OverrunError)
+    }
+
+    /// Read bytes that are readily available in the ring buffer.
+    /// If no bytes are currently available in the buffer the call waits until the some
+    /// bytes are available (at least one byte and at most half the buffer size)
+    ///
+    /// Background receive is started if `start_continuous_sampling()` has not been previously called.
+    ///
+    /// Receive in the background is terminated if an error is returned.
+    /// It must then manually be started again by calling `start_continuous_sampling()` or by re-calling `blocking_read()`.
+    pub fn blocking_read(&mut self, buf: &mut [u16]) -> Result<usize, OverrunError> {
+        if !self.ring_buf.is_running() {
+            self.start();
+        }
+
+        //        #[cfg(adc_v2)]
+        //        {
+        //            // Clear overrun flag if set.
+        //            if T::regs().sr().read().ovr() {
+        //                self.stop();
+        //
+        //                return Err(OverrunError);
+        //            }
+        //        }
+
+        loop {
+            match self.ring_buf.read(buf) {
+                Ok((0, _)) => {}
+                Ok((len, _)) => {
+                    return Ok(len);
+                }
+                Err(_) => {
+                    self.ring_buf.request_pause();
+
+                    return Err(OverrunError);
+                }
+            }
+        }
+    }
+}
+
+impl<T: Instance> Drop for RingBufferedAdc<'_, T> {
+    fn drop(&mut self) {
+        T::regs().stop();
+
+        compiler_fence(Ordering::SeqCst);
+
+        self.ring_buf.request_pause();
+        rcc::disable::<T>();
+    }
+}