ci: cache lockfiles

- Removes the slow "updating crates.io index, updating git" at start of the job.
- Avoids CI being randomly slower if a widely-used dep (like serde) gets bumped causing rebuilding everything.

.github/ci/build-stable.sh

@@ -12,9 +12,19 @@ export CARGO_TARGET_DIR=/ci/cache/target
 # used when pointing stm32-metapac to a CI-built one.
 export CARGO_NET_GIT_FETCH_WITH_CLI=true
 
+# Restore lockfiles
+if [ -f /ci/cache/lockfiles.tar ]; then
+    echo Restoring lockfiles...
+    tar xf /ci/cache/lockfiles.tar
+fi
+
 hashtime restore /ci/cache/filetime.json || true
 hashtime save /ci/cache/filetime.json
 
 sed -i 's/channel.*/channel = "stable"/g' rust-toolchain.toml
 
 ./ci_stable.sh
+
+# Save lockfiles
+echo Saving lockfiles...
+find . -type f -name Cargo.lock -exec tar -cf /ci/cache/lockfiles.tar '{}' \+

.github/ci/build.sh

@@ -18,7 +18,17 @@ fi
 # used when pointing stm32-metapac to a CI-built one.
 export CARGO_NET_GIT_FETCH_WITH_CLI=true
 
+# Restore lockfiles
+if [ -f /ci/cache/lockfiles.tar ]; then
+    echo Restoring lockfiles...
+    tar xf /ci/cache/lockfiles.tar
+fi
+
 hashtime restore /ci/cache/filetime.json || true
 hashtime save /ci/cache/filetime.json
 
 ./ci.sh
+
+# Save lockfiles
+echo Saving lockfiles...
+find . -type f -name Cargo.lock -exec tar -cf /ci/cache/lockfiles.tar '{}' \+

ci.sh

@@ -38,6 +38,7 @@ cargo batch  \
     --- build --release --manifest-path embassy-sync/Cargo.toml --target thumbv6m-none-eabi --features nightly,defmt \
     --- build --release --manifest-path embassy-time/Cargo.toml --target thumbv6m-none-eabi --features nightly,defmt,defmt-timestamp-uptime,tick-hz-32_768,generic-queue-8 \
     --- build --release --manifest-path embassy-net/Cargo.toml --target thumbv7em-none-eabi --features defmt,tcp,udp,dns,proto-ipv4,medium-ethernet \
+    --- build --release --manifest-path embassy-net/Cargo.toml --target thumbv7em-none-eabi --features defmt,tcp,udp,dns,proto-ipv4,igmp,medium-ethernet \
     --- build --release --manifest-path embassy-net/Cargo.toml --target thumbv7em-none-eabi --features defmt,tcp,udp,dns,dhcpv4,medium-ethernet \
     --- build --release --manifest-path embassy-net/Cargo.toml --target thumbv7em-none-eabi --features defmt,tcp,udp,dns,dhcpv4,medium-ethernet,nightly,dhcpv4-hostname \
     --- build --release --manifest-path embassy-net/Cargo.toml --target thumbv7em-none-eabi --features defmt,tcp,udp,dns,proto-ipv6,medium-ethernet \
@@ -110,6 +111,7 @@ cargo batch  \
     --- build --release --manifest-path embassy-stm32/Cargo.toml --target thumbv7em-none-eabi --features nightly,stm32h753zi,defmt,exti,time-driver-any,unstable-traits,time \
     --- build --release --manifest-path embassy-stm32/Cargo.toml --target thumbv7em-none-eabi --features nightly,stm32h735zg,defmt,exti,time-driver-any,unstable-traits,time \
     --- build --release --manifest-path embassy-stm32/Cargo.toml --target thumbv7em-none-eabi --features nightly,stm32h755zi-cm7,defmt,exti,time-driver-any,unstable-traits,time \
+    --- build --release --manifest-path embassy-stm32/Cargo.toml --target thumbv7em-none-eabi --features nightly,stm32h725re,defmt,exti,time-driver-any,unstable-traits,time \
     --- build --release --manifest-path embassy-stm32/Cargo.toml --target thumbv7em-none-eabi --features nightly,stm32h7b3ai,defmt,exti,time-driver-any,unstable-traits,time \
     --- build --release --manifest-path embassy-stm32/Cargo.toml --target thumbv7em-none-eabi --features nightly,stm32l476vg,defmt,exti,time-driver-any,unstable-traits,time \
     --- build --release --manifest-path embassy-stm32/Cargo.toml --target thumbv7em-none-eabi --features nightly,stm32l422cb,defmt,exti,time-driver-any,unstable-traits,time \

cyw43/src/control.rs

@@ -1,4 +1,5 @@
 use core::cmp::{max, min};
+use core::iter::zip;
 
 use embassy_net_driver_channel as ch;
 use embassy_net_driver_channel::driver::{HardwareAddress, LinkState};
@@ -16,6 +17,12 @@ pub struct Error {
     pub status: u32,
 }
 
+#[derive(Debug)]
+pub enum AddMulticastAddressError {
+    NotMulticast,
+    NoFreeSlots,
+}
+
 pub struct Control<'a> {
     state_ch: ch::StateRunner<'a>,
     events: &'a Events,
@@ -316,6 +323,54 @@ impl<'a> Control<'a> {
         self.set_iovar_u32x2("bss", 0, 1).await; // bss = BSS_UP
     }
 
+    /// Add specified address to the list of hardware addresses the device
+    /// listens on. The address must be a Group address (I/G bit set). Up
+    /// to 10 addresses are supported by the firmware. Returns the number of
+    /// address slots filled after adding, or an error.
+    pub async fn add_multicast_address(&mut self, address: [u8; 6]) -> Result<usize, AddMulticastAddressError> {
+        // The firmware seems to ignore non-multicast addresses, so let's
+        // prevent the user from adding them and wasting space.
+        if address[0] & 0x01 != 1 {
+            return Err(AddMulticastAddressError::NotMulticast);
+        }
+
+        let mut buf = [0; 64];
+        self.get_iovar("mcast_list", &mut buf).await;
+
+        let n = u32::from_le_bytes(buf[..4].try_into().unwrap()) as usize;
+        let (used, free) = buf[4..].split_at_mut(n * 6);
+
+        if used.chunks(6).any(|a| a == address) {
+            return Ok(n);
+        }
+
+        if free.len() < 6 {
+            return Err(AddMulticastAddressError::NoFreeSlots);
+        }
+
+        free[..6].copy_from_slice(&address);
+        let n = n + 1;
+        buf[..4].copy_from_slice(&(n as u32).to_le_bytes());
+
+        self.set_iovar_v::<80>("mcast_list", &buf).await;
+        Ok(n)
+    }
+
+    /// Retrieve the list of configured multicast hardware addresses.
+    pub async fn list_mulistcast_addresses(&mut self, result: &mut [[u8; 6]; 10]) -> usize {
+        let mut buf = [0; 64];
+        self.get_iovar("mcast_list", &mut buf).await;
+
+        let n = u32::from_le_bytes(buf[..4].try_into().unwrap()) as usize;
+        let used = &buf[4..][..n * 6];
+
+        for (addr, output) in zip(used.chunks(6), result.iter_mut()) {
+            output.copy_from_slice(addr)
+        }
+
+        n
+    }
+
     async fn set_iovar_u32x2(&mut self, name: &str, val1: u32, val2: u32) {
         let mut buf = [0; 8];
         buf[0..4].copy_from_slice(&val1.to_le_bytes());

cyw43/src/lib.rs

@@ -27,7 +27,7 @@ use ioctl::IoctlState;
 
 use crate::bus::Bus;
 pub use crate::bus::SpiBusCyw43;
-pub use crate::control::{Control, Error as ControlError, Scanner};
+pub use crate::control::{AddMulticastAddressError, Control, Error as ControlError, Scanner};
 pub use crate::runner::Runner;
 pub use crate::structs::BssInfo;
 

docs/modules/ROOT/nav.adoc

@@ -10,3 +10,4 @@
 * xref:examples.adoc[Examples]
 * xref:developer.adoc[Developer]
 ** xref:developer_stm32.adoc[Developer: STM32]
+* xref:faq.adoc[Frequently Asked Questions]

docs/modules/ROOT/pages/faq.adoc

@@ -0,0 +1,25 @@
+= Frequently Asked Questions
+
+These are a list of unsorted, commonly asked questions and answers.
+
+Please feel free to add items to link:https://github.com/embassy-rs/embassy/edit/main/docs/modules/ROOT/pages/faq.adoc[this page], especially if someone in the chat answered a question for you!
+
+== Missing main macro
+
+If you see an error like this:
+
+[source,rust]
+----
+#[embassy_executor::main]
+|                   ^^^^ could not find `main` in `embassy_executor`
+----
+
+You are likely missing some features of the `embassy-executor` crate.
+
+For Cortex-M targets, consider making sure that ALL of the following features are active in your `Cargo.toml` for the `embassy-executor` crate:
+
+* `arch-cortex-m`
+* `executor-thread`
+* `nightly`
+
+For Xtensa ESP32, consider using the executors and `#[main]` macro provided by your appropriate link:https://crates.io/crates/esp-hal-common[HAL crate].

embassy-net/src/lib.rs

@@ -616,9 +616,11 @@ impl<D: Driver> Stack<D> {
         let addr = addr.into();
 
         self.with_mut(|s, i| {
+            let (_hardware_addr, medium) = to_smoltcp_hardware_address(i.device.hardware_address());
             let mut smoldev = DriverAdapter {
                 cx: Some(cx),
                 inner: &mut i.device,
+                medium,
             };
 
             match s
@@ -653,9 +655,11 @@ impl<D: Driver> Stack<D> {
         let addr = addr.into();
 
         self.with_mut(|s, i| {
+            let (_hardware_addr, medium) = to_smoltcp_hardware_address(i.device.hardware_address());
             let mut smoldev = DriverAdapter {
                 cx: Some(cx),
                 inner: &mut i.device,
+                medium,
             };
 
             match s

embassy-stm32/build.rs

@@ -61,6 +61,7 @@ fn main() {
     let mut singletons: Vec<String> = Vec::new();
     for p in METADATA.peripherals {
         if let Some(r) = &p.registers {
+            println!("cargo:rustc-cfg=peri_{}", p.name.to_ascii_lowercase());
             match r.kind {
                 // Generate singletons per pin, not per port
                 "gpio" => {

embassy-stm32/src/can/bxcan.rs

@@ -1,4 +1,3 @@
-use core::cell::{RefCell, RefMut};
 use core::future::poll_fn;
 use core::marker::PhantomData;
 use core::ops::{Deref, DerefMut};
@@ -84,7 +83,7 @@ impl<T: Instance> interrupt::typelevel::Handler<T::SCEInterrupt> for SceInterrup
 }
 
 pub struct Can<'d, T: Instance> {
-    pub can: RefCell<bxcan::Can<BxcanInstance<'d, T>>>,
+    pub can: bxcan::Can<BxcanInstance<'d, T>>,
 }
 
 #[derive(Debug)]
@@ -175,17 +174,12 @@ impl<'d, T: Instance> Can<'d, T> {
         tx.set_as_af(tx.af_num(), AFType::OutputPushPull);
 
         let can = bxcan::Can::builder(BxcanInstance(peri)).leave_disabled();
-        let can_ref_cell = RefCell::new(can);
-        Self { can: can_ref_cell }
+        Self { can }
     }
 
     pub fn set_bitrate(&mut self, bitrate: u32) {
         let bit_timing = Self::calc_bxcan_timings(T::frequency(), bitrate).unwrap();
-        self.can
-            .borrow_mut()
-            .modify_config()
-            .set_bit_timing(bit_timing)
-            .leave_disabled();
+        self.can.modify_config().set_bit_timing(bit_timing).leave_disabled();
     }
 
     /// Enables the peripheral and synchronizes with the bus.
@@ -193,7 +187,7 @@ impl<'d, T: Instance> Can<'d, T> {
     /// This will wait for 11 consecutive recessive bits (bus idle state).
     /// Contrary to enable method from bxcan library, this will not freeze the executor while waiting.
     pub async fn enable(&mut self) {
-        while self.borrow_mut().enable_non_blocking().is_err() {
+        while self.enable_non_blocking().is_err() {
             // SCE interrupt is only generated for entering sleep mode, but not leaving.
             // Yield to allow other tasks to execute while can bus is initializing.
             embassy_futures::yield_now().await;
@@ -202,46 +196,46 @@ impl<'d, T: Instance> Can<'d, T> {
 
     /// Queues the message to be sent but exerts backpressure
     pub async fn write(&mut self, frame: &Frame) -> bxcan::TransmitStatus {
-        CanTx { can: &self.can }.write(frame).await
+        self.split().0.write(frame).await
     }
 
     /// Attempts to transmit a frame without blocking.
     ///
     /// Returns [Err(TryWriteError::Full)] if all transmit mailboxes are full.
     pub fn try_write(&mut self, frame: &Frame) -> Result<bxcan::TransmitStatus, TryWriteError> {
-        CanTx { can: &self.can }.try_write(frame)
+        self.split().0.try_write(frame)
     }
 
     /// Waits for a specific transmit mailbox to become empty
     pub async fn flush(&self, mb: bxcan::Mailbox) {
-        CanTx { can: &self.can }.flush(mb).await
+        CanTx::<T>::flush_inner(mb).await
     }
 
     /// Waits until any of the transmit mailboxes become empty
     pub async fn flush_any(&self) {
-        CanTx { can: &self.can }.flush_any().await
+        CanTx::<T>::flush_any_inner().await
     }
 
     /// Waits until all of the transmit mailboxes become empty
     pub async fn flush_all(&self) {
-        CanTx { can: &self.can }.flush_all().await
+        CanTx::<T>::flush_all_inner().await
     }
 
     /// Returns a tuple of the time the message was received and the message frame
     pub async fn read(&mut self) -> Result<Envelope, BusError> {
-        CanRx { can: &self.can }.read().await
+        self.split().1.read().await
     }
 
     /// Attempts to read a can frame without blocking.
     ///
     /// Returns [Err(TryReadError::Empty)] if there are no frames in the rx queue.
     pub fn try_read(&mut self) -> Result<Envelope, TryReadError> {
-        CanRx { can: &self.can }.try_read()
+        self.split().1.try_read()
     }
 
     /// Waits while receive queue is empty.
     pub async fn wait_not_empty(&mut self) {
-        CanRx { can: &self.can }.wait_not_empty().await
+        self.split().1.wait_not_empty().await
     }
 
     unsafe fn receive_fifo(fifo: RxFifo) {
@@ -385,24 +379,25 @@ impl<'d, T: Instance> Can<'d, T> {
         Some((sjw - 1) << 24 | (bs1 as u32 - 1) << 16 | (bs2 as u32 - 1) << 20 | (prescaler - 1))
     }
 
-    pub fn split<'c>(&'c self) -> (CanTx<'c, 'd, T>, CanRx<'c, 'd, T>) {
-        (CanTx { can: &self.can }, CanRx { can: &self.can })
+    pub fn split<'c>(&'c mut self) -> (CanTx<'c, 'd, T>, CanRx<'c, 'd, T>) {
+        let (tx, rx0, rx1) = self.can.split_by_ref();
+        (CanTx { tx }, CanRx { rx0, rx1 })
     }
 
-    pub fn as_mut(&self) -> RefMut<'_, bxcan::Can<BxcanInstance<'d, T>>> {
-        self.can.borrow_mut()
+    pub fn as_mut(&mut self) -> &mut bxcan::Can<BxcanInstance<'d, T>> {
+        &mut self.can
     }
 }
 
 pub struct CanTx<'c, 'd, T: Instance> {
-    can: &'c RefCell<bxcan::Can<BxcanInstance<'d, T>>>,
+    tx: &'c mut bxcan::Tx<BxcanInstance<'d, T>>,
 }
 
 impl<'c, 'd, T: Instance> CanTx<'c, 'd, T> {
     pub async fn write(&mut self, frame: &Frame) -> bxcan::TransmitStatus {
         poll_fn(|cx| {
             T::state().tx_waker.register(cx.waker());
-            if let Ok(status) = self.can.borrow_mut().transmit(frame) {
+            if let Ok(status) = self.tx.transmit(frame) {
                 return Poll::Ready(status);
             }
 
@@ -415,11 +410,10 @@ impl<'c, 'd, T: Instance> CanTx<'c, 'd, T> {
     ///
     /// Returns [Err(TryWriteError::Full)] if all transmit mailboxes are full.
     pub fn try_write(&mut self, frame: &Frame) -> Result<bxcan::TransmitStatus, TryWriteError> {
-        self.can.borrow_mut().transmit(frame).map_err(|_| TryWriteError::Full)
+        self.tx.transmit(frame).map_err(|_| TryWriteError::Full)
     }
 
-    /// Waits for a specific transmit mailbox to become empty
-    pub async fn flush(&self, mb: bxcan::Mailbox) {
+    async fn flush_inner(mb: bxcan::Mailbox) {
         poll_fn(|cx| {
             T::state().tx_waker.register(cx.waker());
             if T::regs().tsr().read().tme(mb.index()) {
@@ -431,8 +425,12 @@ impl<'c, 'd, T: Instance> CanTx<'c, 'd, T> {
         .await;
     }
 
-    /// Waits until any of the transmit mailboxes become empty
-    pub async fn flush_any(&self) {
+    /// Waits for a specific transmit mailbox to become empty
+    pub async fn flush(&self, mb: bxcan::Mailbox) {
+        Self::flush_inner(mb).await
+    }
+
+    async fn flush_any_inner() {
         poll_fn(|cx| {
             T::state().tx_waker.register(cx.waker());
 
@@ -449,8 +447,12 @@ impl<'c, 'd, T: Instance> CanTx<'c, 'd, T> {
         .await;
     }
 
-    /// Waits until all of the transmit mailboxes become empty
-    pub async fn flush_all(&self) {
+    /// Waits until any of the transmit mailboxes become empty
+    pub async fn flush_any(&self) {
+        Self::flush_any_inner().await
+    }
+
+    async fn flush_all_inner() {
         poll_fn(|cx| {
             T::state().tx_waker.register(cx.waker());
 
@@ -466,11 +468,17 @@ impl<'c, 'd, T: Instance> CanTx<'c, 'd, T> {
         })
         .await;
     }
+
+    /// Waits until all of the transmit mailboxes become empty
+    pub async fn flush_all(&self) {
+        Self::flush_all_inner().await
+    }
 }
 
 #[allow(dead_code)]
 pub struct CanRx<'c, 'd, T: Instance> {
-    can: &'c RefCell<bxcan::Can<BxcanInstance<'d, T>>>,
+    rx0: &'c mut bxcan::Rx0<BxcanInstance<'d, T>>,
+    rx1: &'c mut bxcan::Rx1<BxcanInstance<'d, T>>,
 }
 
 impl<'c, 'd, T: Instance> CanRx<'c, 'd, T> {
@@ -538,7 +546,7 @@ impl<'d, T: Instance> Drop for Can<'d, T> {
 }
 
 impl<'d, T: Instance> Deref for Can<'d, T> {
-    type Target = RefCell<bxcan::Can<BxcanInstance<'d, T>>>;
+    type Target = bxcan::Can<BxcanInstance<'d, T>>;
 
     fn deref(&self) -> &Self::Target {
         &self.can

embassy-stm32/src/i2c/v2.rs

@@ -1,21 +1,16 @@
 use core::cmp;
-#[cfg(feature = "time")]
 use core::future::poll_fn;
 use core::marker::PhantomData;
-#[cfg(feature = "time")]
 use core::task::Poll;
 
 use embassy_embedded_hal::SetConfig;
-#[cfg(feature = "time")]
 use embassy_hal_internal::drop::OnDrop;
 use embassy_hal_internal::{into_ref, PeripheralRef};
 use embassy_sync::waitqueue::AtomicWaker;
 #[cfg(feature = "time")]
 use embassy_time::{Duration, Instant};
 
-use crate::dma::NoDma;
-#[cfg(feature = "time")]
-use crate::dma::Transfer;
+use crate::dma::{NoDma, Transfer};
 use crate::gpio::sealed::AFType;
 use crate::gpio::Pull;
 use crate::i2c::{Error, Instance, SclPin, SdaPin};
@@ -24,6 +19,23 @@ use crate::pac::i2c;
 use crate::time::Hertz;
 use crate::{interrupt, Peripheral};
 
+#[cfg(feature = "time")]
+fn timeout_fn(timeout: Duration) -> impl Fn() -> Result<(), Error> {
+    let deadline = Instant::now() + timeout;
+    move || {
+        if Instant::now() > deadline {
+            Err(Error::Timeout)
+        } else {
+            Ok(())
+        }
+    }
+}
+
+#[cfg(not(feature = "time"))]
+pub fn no_timeout_fn() -> impl Fn() -> Result<(), Error> {
+    move || Ok(())
+}
+
 /// Interrupt handler.
 pub struct InterruptHandler<T: Instance> {
     _phantom: PhantomData<T>,
@@ -260,21 +272,12 @@ impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> {
     }
 
     fn flush_txdr(&self) {
-        //if $i2c.isr.read().txis().bit_is_set() {
-        //$i2c.txdr.write(|w| w.txdata().bits(0));
-        //}
-
         if T::regs().isr().read().txis() {
             T::regs().txdr().write(|w| w.set_txdata(0));
         }
         if !T::regs().isr().read().txe() {
             T::regs().isr().modify(|w| w.set_txe(true))
         }
-
-        // If TXDR is not flagged as empty, write 1 to flush it
-        //if $i2c.isr.read().txe().is_not_empty() {
-        //$i2c.isr.write(|w| w.txe().set_bit());
-        //}
     }
 
     fn wait_txe(&self, check_timeout: impl Fn() -> Result<(), Error>) -> Result<(), Error> {
@@ -437,7 +440,6 @@ impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> {
         result
     }
 
-    #[cfg(feature = "time")]
     async fn write_dma_internal(
         &mut self,
         address: u8,
@@ -528,7 +530,6 @@ impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> {
         Ok(())
     }
 
-    #[cfg(feature = "time")]
     async fn read_dma_internal(
         &mut self,
         address: u8,
@@ -610,42 +611,38 @@ impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> {
 
     // =========================
     //  Async public API
-
     #[cfg(feature = "time")]
     pub async fn write(&mut self, address: u8, write: &[u8]) -> Result<(), Error>
-    where
-        TXDMA: crate::i2c::TxDma<T>,
-    {
-        self.write_timeout(address, write, self.timeout).await
-    }
-
-    #[cfg(feature = "time")]
-    pub async fn write_timeout(&mut self, address: u8, write: &[u8], timeout: Duration) -> Result<(), Error>
     where
         TXDMA: crate::i2c::TxDma<T>,
     {
         if write.is_empty() {
-            self.write_internal(address, write, true, timeout_fn(timeout))
+            self.write_internal(address, write, true, timeout_fn(self.timeout))
         } else {
             embassy_time::with_timeout(
-                timeout,
-                self.write_dma_internal(address, write, true, true, timeout_fn(timeout)),
+                self.timeout,
+                self.write_dma_internal(address, write, true, true, timeout_fn(self.timeout)),
             )
             .await
             .unwrap_or(Err(Error::Timeout))
         }
     }
 
-    #[cfg(feature = "time")]
-    pub async fn write_vectored(&mut self, address: u8, write: &[&[u8]]) -> Result<(), Error>
+    #[cfg(not(feature = "time"))]
+    pub async fn write(&mut self, address: u8, write: &[u8]) -> Result<(), Error>
     where
         TXDMA: crate::i2c::TxDma<T>,
     {
-        self.write_vectored_timeout(address, write, self.timeout).await
+        if write.is_empty() {
+            self.write_internal(address, write, true, no_timeout_fn())
+        } else {
+            self.write_dma_internal(address, write, true, true, no_timeout_fn())
+                .await
+        }
     }
 
     #[cfg(feature = "time")]
-    pub async fn write_vectored_timeout(&mut self, address: u8, write: &[&[u8]], timeout: Duration) -> Result<(), Error>
+    pub async fn write_vectored(&mut self, address: u8, write: &[&[u8]]) -> Result<(), Error>
     where
         TXDMA: crate::i2c::TxDma<T>,
     {
@@ -661,8 +658,8 @@ impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> {
             let is_last = next.is_none();
 
             embassy_time::with_timeout(
-                timeout,
-                self.write_dma_internal(address, c, first, is_last, timeout_fn(timeout)),
+                self.timeout,
+                self.write_dma_internal(address, c, first, is_last, timeout_fn(self.timeout)),
             )
             .await
             .unwrap_or(Err(Error::Timeout))?;
@@ -672,66 +669,79 @@ impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> {
         Ok(())
     }
 
+    #[cfg(not(feature = "time"))]
+    pub async fn write_vectored(&mut self, address: u8, write: &[&[u8]]) -> Result<(), Error>
+    where
+        TXDMA: crate::i2c::TxDma<T>,
+    {
+        if write.is_empty() {
+            return Err(Error::ZeroLengthTransfer);
+        }
+        let mut iter = write.iter();
+
+        let mut first = true;
+        let mut current = iter.next();
+        while let Some(c) = current {
+            let next = iter.next();
+            let is_last = next.is_none();
+
+            self.write_dma_internal(address, c, first, is_last, no_timeout_fn())
+                .await?;
+            first = false;
+            current = next;
+        }
+        Ok(())
+    }
+
     #[cfg(feature = "time")]
     pub async fn read(&mut self, address: u8, buffer: &mut [u8]) -> Result<(), Error>
     where
         RXDMA: crate::i2c::RxDma<T>,
     {
-        self.read_timeout(address, buffer, self.timeout).await
+        if buffer.is_empty() {
+            self.read_internal(address, buffer, false, timeout_fn(self.timeout))
+        } else {
+            embassy_time::with_timeout(
+                self.timeout,
+                self.read_dma_internal(address, buffer, false, timeout_fn(self.timeout)),
+            )
+            .await
+            .unwrap_or(Err(Error::Timeout))
+        }
     }
 
-    #[cfg(feature = "time")]
-    pub async fn read_timeout(&mut self, address: u8, buffer: &mut [u8], timeout: Duration) -> Result<(), Error>
+    #[cfg(not(feature = "time"))]
+    pub async fn read(&mut self, address: u8, buffer: &mut [u8]) -> Result<(), Error>
     where
         RXDMA: crate::i2c::RxDma<T>,
     {
         if buffer.is_empty() {
-            self.read_internal(address, buffer, false, timeout_fn(timeout))
+            self.read_internal(address, buffer, false, no_timeout_fn())
         } else {
-            embassy_time::with_timeout(
-                timeout,
-                self.read_dma_internal(address, buffer, false, timeout_fn(timeout)),
-            )
-            .await
-            .unwrap_or(Err(Error::Timeout))
+            self.read_dma_internal(address, buffer, false, no_timeout_fn()).await
         }
     }
 
     #[cfg(feature = "time")]
     pub async fn write_read(&mut self, address: u8, write: &[u8], read: &mut [u8]) -> Result<(), Error>
-    where
-        TXDMA: super::TxDma<T>,
-        RXDMA: super::RxDma<T>,
-    {
-        self.write_read_timeout(address, write, read, self.timeout).await
-    }
-
-    #[cfg(feature = "time")]
-    pub async fn write_read_timeout(
-        &mut self,
-        address: u8,
-        write: &[u8],
-        read: &mut [u8],
-        timeout: Duration,
-    ) -> Result<(), Error>
     where
         TXDMA: super::TxDma<T>,
         RXDMA: super::RxDma<T>,
     {
         let start_instant = Instant::now();
-        let check_timeout = timeout_fn(timeout);
+        let check_timeout = timeout_fn(self.timeout);
         if write.is_empty() {
             self.write_internal(address, write, false, &check_timeout)?;
         } else {
             embassy_time::with_timeout(
-                timeout,
+                self.timeout,
                 self.write_dma_internal(address, write, true, true, &check_timeout),
             )
             .await
             .unwrap_or(Err(Error::Timeout))?;
         }
 
-        let time_left_until_timeout = timeout - Instant::now().duration_since(start_instant);
+        let time_left_until_timeout = self.timeout - Instant::now().duration_since(start_instant);
 
         if read.is_empty() {
             self.read_internal(address, read, true, &check_timeout)?;
@@ -747,6 +757,28 @@ impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> {
         Ok(())
     }
 
+    #[cfg(not(feature = "time"))]
+    pub async fn write_read(&mut self, address: u8, write: &[u8], read: &mut [u8]) -> Result<(), Error>
+    where
+        TXDMA: super::TxDma<T>,
+        RXDMA: super::RxDma<T>,
+    {
+        let no_timeout = no_timeout_fn();
+        if write.is_empty() {
+            self.write_internal(address, write, false, &no_timeout)?;
+        } else {
+            self.write_dma_internal(address, write, true, true, &no_timeout).await?;
+        }
+
+        if read.is_empty() {
+            self.read_internal(address, read, true, &no_timeout)?;
+        } else {
+            self.read_dma_internal(address, read, true, &no_timeout).await?;
+        }
+
+        Ok(())
+    }
+
     // =========================
     //  Blocking public API
 
@@ -1201,15 +1233,3 @@ impl<'d, T: Instance> SetConfig for I2c<'d, T> {
         Ok(())
     }
 }
-
-#[cfg(feature = "time")]
-fn timeout_fn(timeout: Duration) -> impl Fn() -> Result<(), Error> {
-    let deadline = Instant::now() + timeout;
-    move || {
-        if Instant::now() > deadline {
-            Err(Error::Timeout)
-        } else {
-            Ok(())
-        }
-    }
-}

embassy-stm32/src/opamp.rs

@@ -31,12 +31,9 @@ impl From<OpAmpSpeed> for crate::pac::opamp::vals::OpampCsrOpahsm {
 
 /// OpAmp external outputs, wired to a GPIO pad.
 ///
-/// The GPIO output pad is held by this struct to ensure it cannot be used elsewhere.
-///
 /// This struct can also be used as an ADC input.
-pub struct OpAmpOutput<'d, 'p, T: Instance, P: OutputPin<T>> {
+pub struct OpAmpOutput<'d, T: Instance> {
     _inner: &'d OpAmp<'d, T>,
-    _output: &'p mut P,
 }
 
 /// OpAmp internal outputs, wired directly to ADC inputs.
@@ -54,19 +51,12 @@ pub struct OpAmp<'d, T: Instance> {
 impl<'d, T: Instance> OpAmp<'d, T> {
     /// Create a new driver instance.
     ///
-    /// Enables the OpAmp and configures the speed, but
-    /// does not set any other configuration.
+    /// Does not enable the opamp, but does set the speed mode on some families.
     pub fn new(opamp: impl Peripheral<P = T> + 'd, #[cfg(opamp_g4)] speed: OpAmpSpeed) -> Self {
         into_ref!(opamp);
 
-        #[cfg(opamp_f3)]
-        T::regs().opampcsr().modify(|w| {
-            w.set_opampen(true);
-        });
-
         #[cfg(opamp_g4)]
         T::regs().opamp_csr().modify(|w| {
-            w.set_opaen(true);
             w.set_opahsm(speed.into());
         });
 
@@ -74,24 +64,23 @@ impl<'d, T: Instance> OpAmp<'d, T> {
     }
 
     /// Configure the OpAmp as a buffer for the provided input pin,
-    /// outputting to the provided output pin.
+    /// outputting to the provided output pin, and enable the opamp.
     ///
     /// The input pin is configured for analogue mode but not consumed,
     /// so it may subsequently be used for ADC or comparator inputs.
     ///
     /// The output pin is held within the returned [`OpAmpOutput`] struct,
     /// preventing it being used elsewhere. The `OpAmpOutput` can then be
-    /// directly used as an ADC input.
-    pub fn buffer_ext<'a, 'b, IP, OP>(
-        &'a mut self,
-        in_pin: &IP,
-        out_pin: &'b mut OP,
+    /// directly used as an ADC input. The opamp will be disabled when the
+    /// [`OpAmpOutput`] is dropped.
+    pub fn buffer_ext(
+        &'d mut self,
+        in_pin: impl Peripheral<P = impl NonInvertingPin<T> + crate::gpio::sealed::Pin>,
+        out_pin: impl Peripheral<P = impl OutputPin<T> + crate::gpio::sealed::Pin> + 'd,
         gain: OpAmpGain,
-    ) -> OpAmpOutput<'a, 'b, T, OP>
-    where
-        IP: NonInvertingPin<T> + crate::gpio::sealed::Pin,
-        OP: OutputPin<T> + crate::gpio::sealed::Pin,
-    {
+    ) -> OpAmpOutput<'d, T> {
+        into_ref!(in_pin);
+        into_ref!(out_pin);
         in_pin.set_as_analog();
         out_pin.set_as_analog();
 
@@ -122,24 +111,24 @@ impl<'d, T: Instance> OpAmp<'d, T> {
             w.set_opaen(true);
         });
 
-        OpAmpOutput {
-            _inner: self,
-            _output: out_pin,
-        }
+        OpAmpOutput { _inner: self }
     }
 
     /// Configure the OpAmp as a buffer for the provided input pin,
-    /// with the output only used internally.
+    /// with the output only used internally, and enable the opamp.
     ///
     /// The input pin is configured for analogue mode but not consumed,
     /// so it may be subsequently used for ADC or comparator inputs.
     ///
     /// The returned `OpAmpInternalOutput` struct may be used as an ADC input.
+    /// The opamp output will be disabled when it is dropped.
     #[cfg(opamp_g4)]
-    pub fn buffer_int<'a, P>(&'a mut self, pin: &P, gain: OpAmpGain) -> OpAmpInternalOutput<'a, T>
-    where
-        P: NonInvertingPin<T> + crate::gpio::sealed::Pin,
-    {
+    pub fn buffer_int(
+        &'d mut self,
+        pin: impl Peripheral<P = impl NonInvertingPin<T> + crate::gpio::sealed::Pin>,
+        gain: OpAmpGain,
+    ) -> OpAmpInternalOutput<'d, T> {
+        into_ref!(pin);
         pin.set_as_analog();
 
         let (vm_sel, pga_gain) = match gain {
@@ -163,7 +152,21 @@ impl<'d, T: Instance> OpAmp<'d, T> {
     }
 }
 
-impl<'d, T: Instance> Drop for OpAmp<'d, T> {
+impl<'d, T: Instance> Drop for OpAmpOutput<'d, T> {
+    fn drop(&mut self) {
+        #[cfg(opamp_f3)]
+        T::regs().opampcsr().modify(|w| {
+            w.set_opampen(false);
+        });
+
+        #[cfg(opamp_g4)]
+        T::regs().opamp_csr().modify(|w| {
+            w.set_opaen(false);
+        });
+    }
+}
+
+impl<'d, T: Instance> Drop for OpAmpInternalOutput<'d, T> {
     fn drop(&mut self) {
         #[cfg(opamp_f3)]
         T::regs().opampcsr().modify(|w| {
@@ -203,16 +206,16 @@ macro_rules! impl_opamp_external_output {
     ($inst:ident, $adc:ident, $ch:expr) => {
         foreach_adc!(
             ($adc, $common_inst:ident, $adc_clock:ident) => {
-                impl<'d, 'p, P: OutputPin<crate::peripherals::$inst>> crate::adc::sealed::AdcPin<crate::peripherals::$adc>
-                    for OpAmpOutput<'d, 'p, crate::peripherals::$inst, P>
+                impl<'d> crate::adc::sealed::AdcPin<crate::peripherals::$adc>
+                    for OpAmpOutput<'d, crate::peripherals::$inst>
                 {
                     fn channel(&self) -> u8 {
                         $ch
                     }
                 }
 
-                impl<'d, 'p, P: OutputPin<crate::peripherals::$inst>> crate::adc::AdcPin<crate::peripherals::$adc>
-                    for OpAmpOutput<'d, 'p, crate::peripherals::$inst, P>
+                impl<'d> crate::adc::AdcPin<crate::peripherals::$adc>
+                    for OpAmpOutput<'d, crate::peripherals::$inst>
                 {
                 }
             };

embassy-stm32/src/rcc/h.rs

@@ -168,7 +168,12 @@ impl Default for Config {
             apb4_pre: APBPrescaler::DIV1,
 
             per_clock_source: PerClockSource::HSI,
-            adc_clock_source: AdcClockSource::from_bits(0), // PLL2_P on H7, HCLK on H5
+
+            #[cfg(stm32h5)]
+            adc_clock_source: AdcClockSource::HCLK1,
+            #[cfg(stm32h7)]
+            adc_clock_source: AdcClockSource::PER,
+
             timer_prescaler: TimerPrescaler::DefaultX2,
             voltage_scale: VoltageScale::Scale0,
             ls: Default::default(),

embassy-stm32/src/sai/mod.rs

@@ -207,27 +207,40 @@ impl Protocol {
 }
 
 #[derive(Copy, Clone, PartialEq)]
-pub enum SyncEnable {
-    Asynchronous,
+pub enum SyncInput {
+    /// Not synced to any other SAI unit.
+    None,
     /// Syncs with the other A/B sub-block within the SAI unit
     Internal,
-    /// Syncs with a sub-block in the other SAI unit - use set_sync_output() and set_sync_input()
-    #[cfg(any(sai_v4))]
-    External,
+    /// Syncs with a sub-block in the other SAI unit
+    #[cfg(sai_v4)]
+    External(SyncInputInstance),
 }
 
-impl SyncEnable {
-    #[cfg(any(sai_v1, sai_v2, sai_v3, sai_v4))]
+impl SyncInput {
     pub const fn syncen(&self) -> vals::Syncen {
         match self {
-            SyncEnable::Asynchronous => vals::Syncen::ASYNCHRONOUS,
-            SyncEnable::Internal => vals::Syncen::INTERNAL,
+            SyncInput::None => vals::Syncen::ASYNCHRONOUS,
+            SyncInput::Internal => vals::Syncen::INTERNAL,
             #[cfg(any(sai_v4))]
-            SyncEnable::External => vals::Syncen::EXTERNAL,
+            SyncInput::External(_) => vals::Syncen::EXTERNAL,
         }
     }
 }
 
+#[cfg(sai_v4)]
+#[derive(Copy, Clone, PartialEq)]
+pub enum SyncInputInstance {
+    #[cfg(peri_sai1)]
+    Sai1 = 0,
+    #[cfg(peri_sai2)]
+    Sai2 = 1,
+    #[cfg(peri_sai3)]
+    Sai3 = 2,
+    #[cfg(peri_sai4)]
+    Sai4 = 3,
+}
+
 #[derive(Copy, Clone, PartialEq)]
 pub enum StereoMono {
     Stereo,
@@ -428,8 +441,8 @@ impl MasterClockDivider {
 pub struct Config {
     pub mode: Mode,
     pub tx_rx: TxRx,
-    pub sync_enable: SyncEnable,
-    pub is_sync_output: bool,
+    pub sync_input: SyncInput,
+    pub sync_output: bool,
     pub protocol: Protocol,
     pub slot_size: SlotSize,
     pub slot_count: word::U4,
@@ -459,8 +472,8 @@ impl Default for Config {
         Self {
             mode: Mode::Master,
             tx_rx: TxRx::Transmitter,
-            is_sync_output: false,
-            sync_enable: SyncEnable::Asynchronous,
+            sync_output: false,
+            sync_input: SyncInput::None,
             protocol: Protocol::Free,
             slot_size: SlotSize::DataSize,
             slot_count: word::U4(2),
@@ -608,18 +621,18 @@ impl<'d, T: Instance> Sai<'d, T> {
 
 fn update_synchronous_config(config: &mut Config) {
     config.mode = Mode::Slave;
-    config.is_sync_output = false;
+    config.sync_output = false;
 
     #[cfg(any(sai_v1, sai_v2, sai_v3))]
     {
-        config.sync_enable = SyncEnable::Internal;
+        config.sync_input = SyncInput::Internal;
     }
 
     #[cfg(any(sai_v4))]
     {
         //this must either be Internal or External
-        //The asynchronous sub-block on the same SAI needs to enable is_sync_output
-        assert!(config.sync_enable != SyncEnable::Asynchronous);
+        //The asynchronous sub-block on the same SAI needs to enable sync_output
+        assert!(config.sync_input != SyncInput::None);
     }
 }
 
@@ -866,20 +879,13 @@ impl<'d, T: Instance, C: Channel, W: word::Word> SubBlock<'d, T, C, W> {
 
         #[cfg(any(sai_v4))]
         {
-            // Not totally clear from the datasheet if this is right
-            // This is only used if using SyncEnable::External on the other SAI unit
-            // Syncing from SAIX subblock A to subblock B does not require this
-            // Only syncing from SAI1 subblock A/B to SAI2 subblock A/B
-            let value: u8 = if T::REGS.as_ptr() == stm32_metapac::SAI1.as_ptr() {
-                1 //this is SAI1, so sync with SAI2
-            } else {
-                0 //this is SAI2, so sync with SAI1
-            };
-            T::REGS.gcr().modify(|w| {
-                w.set_syncin(value);
-            });
+            if let SyncInput::External(i) = config.sync_input {
+                T::REGS.gcr().modify(|w| {
+                    w.set_syncin(i as u8);
+                });
+            }
 
-            if config.is_sync_output {
+            if config.sync_output {
                 let syncout: u8 = match sub_block {
                     WhichSubBlock::A => 0b01,
                     WhichSubBlock::B => 0b10,
@@ -903,7 +909,7 @@ impl<'d, T: Instance, C: Channel, W: word::Word> SubBlock<'d, T, C, W> {
                 w.set_ds(config.data_size.ds());
                 w.set_lsbfirst(config.bit_order.lsbfirst());
                 w.set_ckstr(config.clock_strobe.ckstr());
-                w.set_syncen(config.sync_enable.syncen());
+                w.set_syncen(config.sync_input.syncen());
                 w.set_mono(config.stereo_mono.mono());
                 w.set_outdriv(config.output_drive.outdriv());
                 w.set_mckdiv(config.master_clock_divider.mckdiv());

embassy-sync/README.md

@@ -5,6 +5,7 @@ An [Embassy](https://embassy.dev) project.
 Synchronization primitives and data structures with async support:
 
 - [`Channel`](channel::Channel) - A Multiple Producer Multiple Consumer (MPMC) channel. Each message is only received by a single consumer.
+- [`PriorityChannel`](channel::priority::PriorityChannel) - A Multiple Producer Multiple Consumer (MPMC) channel. Each message is only received by a single consumer. Higher priority items are sifted to the front of the channel.
 - [`PubSubChannel`](pubsub::PubSubChannel) - A broadcast channel (publish-subscribe) channel. Each message is received by all consumers.
 - [`Signal`](signal::Signal) - Signalling latest value to a single consumer.
 - [`Mutex`](mutex::Mutex) - Mutex for synchronizing state between asynchronous tasks.

embassy-sync/src/channel.rs

@@ -76,7 +76,7 @@ where
 
 /// Send-only access to a [`Channel`] without knowing channel size.
 pub struct DynamicSender<'ch, T> {
-    channel: &'ch dyn DynamicChannel<T>,
+    pub(crate) channel: &'ch dyn DynamicChannel<T>,
 }
 
 impl<'ch, T> Clone for DynamicSender<'ch, T> {
@@ -176,7 +176,7 @@ where
 
 /// Receive-only access to a [`Channel`] without knowing channel size.
 pub struct DynamicReceiver<'ch, T> {
-    channel: &'ch dyn DynamicChannel<T>,
+    pub(crate) channel: &'ch dyn DynamicChannel<T>,
 }
 
 impl<'ch, T> Clone for DynamicReceiver<'ch, T> {
@@ -321,7 +321,7 @@ impl<'ch, T> Future for DynamicSendFuture<'ch, T> {
 
 impl<'ch, T> Unpin for DynamicSendFuture<'ch, T> {}
 
-trait DynamicChannel<T> {
+pub(crate) trait DynamicChannel<T> {
     fn try_send_with_context(&self, message: T, cx: Option<&mut Context<'_>>) -> Result<(), TrySendError<T>>;
 
     fn try_receive_with_context(&self, cx: Option<&mut Context<'_>>) -> Result<T, TryReceiveError>;

embassy-sync/src/lib.rs

@@ -15,6 +15,7 @@ pub mod blocking_mutex;
 pub mod channel;
 pub mod mutex;
 pub mod pipe;
+pub mod priority_channel;
 pub mod pubsub;
 pub mod signal;
 pub mod waitqueue;

embassy-sync/src/priority_channel.rs

@@ -0,0 +1,613 @@
+//! A queue for sending values between asynchronous tasks.
+//!
+//! Similar to a [`Channel`](crate::channel::Channel), however [`PriorityChannel`] sifts higher priority items to the front of the queue.
+//! Priority is determined by the `Ord` trait. Priority behavior is determined by the [`Kind`](heapless::binary_heap::Kind) parameter of the channel.
+
+use core::cell::RefCell;
+use core::future::Future;
+use core::pin::Pin;
+use core::task::{Context, Poll};
+
+pub use heapless::binary_heap::{Kind, Max, Min};
+use heapless::BinaryHeap;
+
+use crate::blocking_mutex::raw::RawMutex;
+use crate::blocking_mutex::Mutex;
+use crate::channel::{DynamicChannel, DynamicReceiver, DynamicSender, TryReceiveError, TrySendError};
+use crate::waitqueue::WakerRegistration;
+
+/// Send-only access to a [`PriorityChannel`].
+pub struct Sender<'ch, M, T, K, const N: usize>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    channel: &'ch PriorityChannel<M, T, K, N>,
+}
+
+impl<'ch, M, T, K, const N: usize> Clone for Sender<'ch, M, T, K, N>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    fn clone(&self) -> Self {
+        Sender { channel: self.channel }
+    }
+}
+
+impl<'ch, M, T, K, const N: usize> Copy for Sender<'ch, M, T, K, N>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+}
+
+impl<'ch, M, T, K, const N: usize> Sender<'ch, M, T, K, N>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    /// Sends a value.
+    ///
+    /// See [`PriorityChannel::send()`]
+    pub fn send(&self, message: T) -> SendFuture<'ch, M, T, K, N> {
+        self.channel.send(message)
+    }
+
+    /// Attempt to immediately send a message.
+    ///
+    /// See [`PriorityChannel::send()`]
+    pub fn try_send(&self, message: T) -> Result<(), TrySendError<T>> {
+        self.channel.try_send(message)
+    }
+
+    /// Allows a poll_fn to poll until the channel is ready to send
+    ///
+    /// See [`PriorityChannel::poll_ready_to_send()`]
+    pub fn poll_ready_to_send(&self, cx: &mut Context<'_>) -> Poll<()> {
+        self.channel.poll_ready_to_send(cx)
+    }
+}
+
+impl<'ch, M, T, K, const N: usize> From<Sender<'ch, M, T, K, N>> for DynamicSender<'ch, T>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    fn from(s: Sender<'ch, M, T, K, N>) -> Self {
+        Self { channel: s.channel }
+    }
+}
+
+/// Receive-only access to a [`PriorityChannel`].
+pub struct Receiver<'ch, M, T, K, const N: usize>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    channel: &'ch PriorityChannel<M, T, K, N>,
+}
+
+impl<'ch, M, T, K, const N: usize> Clone for Receiver<'ch, M, T, K, N>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    fn clone(&self) -> Self {
+        Receiver { channel: self.channel }
+    }
+}
+
+impl<'ch, M, T, K, const N: usize> Copy for Receiver<'ch, M, T, K, N>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+}
+
+impl<'ch, M, T, K, const N: usize> Receiver<'ch, M, T, K, N>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    /// Receive the next value.
+    ///
+    /// See [`PriorityChannel::receive()`].
+    pub fn receive(&self) -> ReceiveFuture<'_, M, T, K, N> {
+        self.channel.receive()
+    }
+
+    /// Attempt to immediately receive the next value.
+    ///
+    /// See [`PriorityChannel::try_receive()`]
+    pub fn try_receive(&self) -> Result<T, TryReceiveError> {
+        self.channel.try_receive()
+    }
+
+    /// Allows a poll_fn to poll until the channel is ready to receive
+    ///
+    /// See [`PriorityChannel::poll_ready_to_receive()`]
+    pub fn poll_ready_to_receive(&self, cx: &mut Context<'_>) -> Poll<()> {
+        self.channel.poll_ready_to_receive(cx)
+    }
+
+    /// Poll the channel for the next item
+    ///
+    /// See [`PriorityChannel::poll_receive()`]
+    pub fn poll_receive(&self, cx: &mut Context<'_>) -> Poll<T> {
+        self.channel.poll_receive(cx)
+    }
+}
+
+impl<'ch, M, T, K, const N: usize> From<Receiver<'ch, M, T, K, N>> for DynamicReceiver<'ch, T>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    fn from(s: Receiver<'ch, M, T, K, N>) -> Self {
+        Self { channel: s.channel }
+    }
+}
+
+/// Future returned by [`PriorityChannel::receive`] and  [`Receiver::receive`].
+#[must_use = "futures do nothing unless you `.await` or poll them"]
+pub struct ReceiveFuture<'ch, M, T, K, const N: usize>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    channel: &'ch PriorityChannel<M, T, K, N>,
+}
+
+impl<'ch, M, T, K, const N: usize> Future for ReceiveFuture<'ch, M, T, K, N>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    type Output = T;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<T> {
+        self.channel.poll_receive(cx)
+    }
+}
+
+/// Future returned by [`PriorityChannel::send`] and  [`Sender::send`].
+#[must_use = "futures do nothing unless you `.await` or poll them"]
+pub struct SendFuture<'ch, M, T, K, const N: usize>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    channel: &'ch PriorityChannel<M, T, K, N>,
+    message: Option<T>,
+}
+
+impl<'ch, M, T, K, const N: usize> Future for SendFuture<'ch, M, T, K, N>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    type Output = ();
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        match self.message.take() {
+            Some(m) => match self.channel.try_send_with_context(m, Some(cx)) {
+                Ok(..) => Poll::Ready(()),
+                Err(TrySendError::Full(m)) => {
+                    self.message = Some(m);
+                    Poll::Pending
+                }
+            },
+            None => panic!("Message cannot be None"),
+        }
+    }
+}
+
+impl<'ch, M, T, K, const N: usize> Unpin for SendFuture<'ch, M, T, K, N>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+}
+
+struct ChannelState<T, K, const N: usize> {
+    queue: BinaryHeap<T, K, N>,
+    receiver_waker: WakerRegistration,
+    senders_waker: WakerRegistration,
+}
+
+impl<T, K, const N: usize> ChannelState<T, K, N>
+where
+    T: Ord,
+    K: Kind,
+{
+    const fn new() -> Self {
+        ChannelState {
+            queue: BinaryHeap::new(),
+            receiver_waker: WakerRegistration::new(),
+            senders_waker: WakerRegistration::new(),
+        }
+    }
+
+    fn try_receive(&mut self) -> Result<T, TryReceiveError> {
+        self.try_receive_with_context(None)
+    }
+
+    fn try_receive_with_context(&mut self, cx: Option<&mut Context<'_>>) -> Result<T, TryReceiveError> {
+        if self.queue.len() == self.queue.capacity() {
+            self.senders_waker.wake();
+        }
+
+        if let Some(message) = self.queue.pop() {
+            Ok(message)
+        } else {
+            if let Some(cx) = cx {
+                self.receiver_waker.register(cx.waker());
+            }
+            Err(TryReceiveError::Empty)
+        }
+    }
+
+    fn poll_receive(&mut self, cx: &mut Context<'_>) -> Poll<T> {
+        if self.queue.len() == self.queue.capacity() {
+            self.senders_waker.wake();
+        }
+
+        if let Some(message) = self.queue.pop() {
+            Poll::Ready(message)
+        } else {
+            self.receiver_waker.register(cx.waker());
+            Poll::Pending
+        }
+    }
+
+    fn poll_ready_to_receive(&mut self, cx: &mut Context<'_>) -> Poll<()> {
+        self.receiver_waker.register(cx.waker());
+
+        if !self.queue.is_empty() {
+            Poll::Ready(())
+        } else {
+            Poll::Pending
+        }
+    }
+
+    fn try_send(&mut self, message: T) -> Result<(), TrySendError<T>> {
+        self.try_send_with_context(message, None)
+    }
+
+    fn try_send_with_context(&mut self, message: T, cx: Option<&mut Context<'_>>) -> Result<(), TrySendError<T>> {
+        match self.queue.push(message) {
+            Ok(()) => {
+                self.receiver_waker.wake();
+                Ok(())
+            }
+            Err(message) => {
+                if let Some(cx) = cx {
+                    self.senders_waker.register(cx.waker());
+                }
+                Err(TrySendError::Full(message))
+            }
+        }
+    }
+
+    fn poll_ready_to_send(&mut self, cx: &mut Context<'_>) -> Poll<()> {
+        self.senders_waker.register(cx.waker());
+
+        if !self.queue.len() == self.queue.capacity() {
+            Poll::Ready(())
+        } else {
+            Poll::Pending
+        }
+    }
+}
+
+/// A bounded channel for communicating between asynchronous tasks
+/// with backpressure.
+///
+/// The channel will buffer up to the provided number of messages.  Once the
+/// buffer is full, attempts to `send` new messages will wait until a message is
+/// received from the channel.
+///
+/// Sent data may be reordered based on their priorty within the channel.
+/// For example, in a [`Max`](heapless::binary_heap::Max) [`PriorityChannel`]
+/// containing `u32`'s, data sent in the following order `[1, 2, 3]` will be recieved as `[3, 2, 1]`.
+pub struct PriorityChannel<M, T, K, const N: usize>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    inner: Mutex<M, RefCell<ChannelState<T, K, N>>>,
+}
+
+impl<M, T, K, const N: usize> PriorityChannel<M, T, K, N>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    /// Establish a new bounded channel. For example, to create one with a NoopMutex:
+    ///
+    /// ```
+    /// use embassy_sync::priority_channel::{PriorityChannel, Max};
+    /// use embassy_sync::blocking_mutex::raw::NoopRawMutex;
+    ///
+    /// // Declare a bounded channel of 3 u32s.
+    /// let mut channel = PriorityChannel::<NoopRawMutex, u32, Max, 3>::new();
+    /// ```
+    pub const fn new() -> Self {
+        Self {
+            inner: Mutex::new(RefCell::new(ChannelState::new())),
+        }
+    }
+
+    fn lock<R>(&self, f: impl FnOnce(&mut ChannelState<T, K, N>) -> R) -> R {
+        self.inner.lock(|rc| f(&mut *unwrap!(rc.try_borrow_mut())))
+    }
+
+    fn try_receive_with_context(&self, cx: Option<&mut Context<'_>>) -> Result<T, TryReceiveError> {
+        self.lock(|c| c.try_receive_with_context(cx))
+    }
+
+    /// Poll the channel for the next message
+    pub fn poll_receive(&self, cx: &mut Context<'_>) -> Poll<T> {
+        self.lock(|c| c.poll_receive(cx))
+    }
+
+    fn try_send_with_context(&self, m: T, cx: Option<&mut Context<'_>>) -> Result<(), TrySendError<T>> {
+        self.lock(|c| c.try_send_with_context(m, cx))
+    }
+
+    /// Allows a poll_fn to poll until the channel is ready to receive
+    pub fn poll_ready_to_receive(&self, cx: &mut Context<'_>) -> Poll<()> {
+        self.lock(|c| c.poll_ready_to_receive(cx))
+    }
+
+    /// Allows a poll_fn to poll until the channel is ready to send
+    pub fn poll_ready_to_send(&self, cx: &mut Context<'_>) -> Poll<()> {
+        self.lock(|c| c.poll_ready_to_send(cx))
+    }
+
+    /// Get a sender for this channel.
+    pub fn sender(&self) -> Sender<'_, M, T, K, N> {
+        Sender { channel: self }
+    }
+
+    /// Get a receiver for this channel.
+    pub fn receiver(&self) -> Receiver<'_, M, T, K, N> {
+        Receiver { channel: self }
+    }
+
+    /// Send a value, waiting until there is capacity.
+    ///
+    /// Sending completes when the value has been pushed to the channel's queue.
+    /// This doesn't mean the value has been received yet.
+    pub fn send(&self, message: T) -> SendFuture<'_, M, T, K, N> {
+        SendFuture {
+            channel: self,
+            message: Some(message),
+        }
+    }
+
+    /// Attempt to immediately send a message.
+    ///
+    /// This method differs from [`send`](PriorityChannel::send) by returning immediately if the channel's
+    /// buffer is full, instead of waiting.
+    ///
+    /// # Errors
+    ///
+    /// If the channel capacity has been reached, i.e., the channel has `n`
+    /// buffered values where `n` is the argument passed to [`PriorityChannel`], then an
+    /// error is returned.
+    pub fn try_send(&self, message: T) -> Result<(), TrySendError<T>> {
+        self.lock(|c| c.try_send(message))
+    }
+
+    /// Receive the next value.
+    ///
+    /// If there are no messages in the channel's buffer, this method will
+    /// wait until a message is sent.
+    pub fn receive(&self) -> ReceiveFuture<'_, M, T, K, N> {
+        ReceiveFuture { channel: self }
+    }
+
+    /// Attempt to immediately receive a message.
+    ///
+    /// This method will either receive a message from the channel immediately or return an error
+    /// if the channel is empty.
+    pub fn try_receive(&self) -> Result<T, TryReceiveError> {
+        self.lock(|c| c.try_receive())
+    }
+}
+
+/// Implements the DynamicChannel to allow creating types that are unaware of the queue size with the
+/// tradeoff cost of dynamic dispatch.
+impl<M, T, K, const N: usize> DynamicChannel<T> for PriorityChannel<M, T, K, N>
+where
+    T: Ord,
+    K: Kind,
+    M: RawMutex,
+{
+    fn try_send_with_context(&self, m: T, cx: Option<&mut Context<'_>>) -> Result<(), TrySendError<T>> {
+        PriorityChannel::try_send_with_context(self, m, cx)
+    }
+
+    fn try_receive_with_context(&self, cx: Option<&mut Context<'_>>) -> Result<T, TryReceiveError> {
+        PriorityChannel::try_receive_with_context(self, cx)
+    }
+
+    fn poll_ready_to_send(&self, cx: &mut Context<'_>) -> Poll<()> {
+        PriorityChannel::poll_ready_to_send(self, cx)
+    }
+
+    fn poll_ready_to_receive(&self, cx: &mut Context<'_>) -> Poll<()> {
+        PriorityChannel::poll_ready_to_receive(self, cx)
+    }
+
+    fn poll_receive(&self, cx: &mut Context<'_>) -> Poll<T> {
+        PriorityChannel::poll_receive(self, cx)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use core::time::Duration;
+
+    use futures_executor::ThreadPool;
+    use futures_timer::Delay;
+    use futures_util::task::SpawnExt;
+    use heapless::binary_heap::{Kind, Max};
+    use static_cell::StaticCell;
+
+    use super::*;
+    use crate::blocking_mutex::raw::{CriticalSectionRawMutex, NoopRawMutex};
+
+    fn capacity<T, K, const N: usize>(c: &ChannelState<T, K, N>) -> usize
+    where
+        T: Ord,
+        K: Kind,
+    {
+        c.queue.capacity() - c.queue.len()
+    }
+
+    #[test]
+    fn sending_once() {
+        let mut c = ChannelState::<u32, Max, 3>::new();
+        assert!(c.try_send(1).is_ok());
+        assert_eq!(capacity(&c), 2);
+    }
+
+    #[test]
+    fn sending_when_full() {
+        let mut c = ChannelState::<u32, Max, 3>::new();
+        let _ = c.try_send(1);
+        let _ = c.try_send(1);
+        let _ = c.try_send(1);
+        match c.try_send(2) {
+            Err(TrySendError::Full(2)) => assert!(true),
+            _ => assert!(false),
+        }
+        assert_eq!(capacity(&c), 0);
+    }
+
+    #[test]
+    fn send_priority() {
+        // Prio channel with kind `Max` sifts larger numbers to the front of the queue
+        let mut c = ChannelState::<u32, Max, 3>::new();
+        assert!(c.try_send(1).is_ok());
+        assert!(c.try_send(2).is_ok());
+        assert!(c.try_send(3).is_ok());
+        assert_eq!(c.try_receive().unwrap(), 3);
+        assert_eq!(c.try_receive().unwrap(), 2);
+        assert_eq!(c.try_receive().unwrap(), 1);
+    }
+
+    #[test]
+    fn receiving_once_with_one_send() {
+        let mut c = ChannelState::<u32, Max, 3>::new();
+        assert!(c.try_send(1).is_ok());
+        assert_eq!(c.try_receive().unwrap(), 1);
+        assert_eq!(capacity(&c), 3);
+    }
+
+    #[test]
+    fn receiving_when_empty() {
+        let mut c = ChannelState::<u32, Max, 3>::new();
+        match c.try_receive() {
+            Err(TryReceiveError::Empty) => assert!(true),
+            _ => assert!(false),
+        }
+        assert_eq!(capacity(&c), 3);
+    }
+
+    #[test]
+    fn simple_send_and_receive() {
+        let c = PriorityChannel::<NoopRawMutex, u32, Max, 3>::new();
+        assert!(c.try_send(1).is_ok());
+        assert_eq!(c.try_receive().unwrap(), 1);
+    }
+
+    #[test]
+    fn cloning() {
+        let c = PriorityChannel::<NoopRawMutex, u32, Max, 3>::new();
+        let r1 = c.receiver();
+        let s1 = c.sender();
+
+        let _ = r1.clone();
+        let _ = s1.clone();
+    }
+
+    #[test]
+    fn dynamic_dispatch() {
+        let c = PriorityChannel::<NoopRawMutex, u32, Max, 3>::new();
+        let s: DynamicSender<'_, u32> = c.sender().into();
+        let r: DynamicReceiver<'_, u32> = c.receiver().into();
+
+        assert!(s.try_send(1).is_ok());
+        assert_eq!(r.try_receive().unwrap(), 1);
+    }
+
+    #[futures_test::test]
+    async fn receiver_receives_given_try_send_async() {
+        let executor = ThreadPool::new().unwrap();
+
+        static CHANNEL: StaticCell<PriorityChannel<CriticalSectionRawMutex, u32, Max, 3>> = StaticCell::new();
+        let c = &*CHANNEL.init(PriorityChannel::new());
+        let c2 = c;
+        assert!(executor
+            .spawn(async move {
+                assert!(c2.try_send(1).is_ok());
+            })
+            .is_ok());
+        assert_eq!(c.receive().await, 1);
+    }
+
+    #[futures_test::test]
+    async fn sender_send_completes_if_capacity() {
+        let c = PriorityChannel::<CriticalSectionRawMutex, u32, Max, 1>::new();
+        c.send(1).await;
+        assert_eq!(c.receive().await, 1);
+    }
+
+    #[futures_test::test]
+    async fn senders_sends_wait_until_capacity() {
+        let executor = ThreadPool::new().unwrap();
+
+        static CHANNEL: StaticCell<PriorityChannel<CriticalSectionRawMutex, u32, Max, 1>> = StaticCell::new();
+        let c = &*CHANNEL.init(PriorityChannel::new());
+        assert!(c.try_send(1).is_ok());
+
+        let c2 = c;
+        let send_task_1 = executor.spawn_with_handle(async move { c2.send(2).await });
+        let c2 = c;
+        let send_task_2 = executor.spawn_with_handle(async move { c2.send(3).await });
+        // Wish I could think of a means of determining that the async send is waiting instead.
+        // However, I've used the debugger to observe that the send does indeed wait.
+        Delay::new(Duration::from_millis(500)).await;
+        assert_eq!(c.receive().await, 1);
+        assert!(executor
+            .spawn(async move {
+                loop {
+                    c.receive().await;
+                }
+            })
+            .is_ok());
+        send_task_1.unwrap().await;
+        send_task_2.unwrap().await;
+    }
+}

examples/boot/application/rp/memory.x

@@ -5,7 +5,19 @@ MEMORY
   BOOTLOADER_STATE                  : ORIGIN = 0x10006000, LENGTH = 4K
   FLASH                             : ORIGIN = 0x10007000, LENGTH = 512K
   DFU                               : ORIGIN = 0x10087000, LENGTH = 516K
-  RAM                               : ORIGIN = 0x20000000, LENGTH = 256K
+
+  /* Pick one of the two options for RAM layout     */
+
+  /* OPTION A: Use all RAM banks as one big block   */
+  /* Reasonable, unless you are doing something     */
+  /* really particular with DMA or other concurrent */
+  /* access that would benefit from striping        */
+  RAM   : ORIGIN = 0x20000000, LENGTH = 264K
+
+  /* OPTION B: Keep the unstriped sections separate */
+  /* RAM: ORIGIN = 0x20000000, LENGTH = 256K        */
+  /* SCRATCH_A: ORIGIN = 0x20040000, LENGTH = 4K    */
+  /* SCRATCH_B: ORIGIN = 0x20041000, LENGTH = 4K    */
 }
 
 __bootloader_state_start = ORIGIN(BOOTLOADER_STATE) - ORIGIN(BOOT2);

examples/boot/bootloader/rp/memory.x

@@ -6,7 +6,19 @@ MEMORY
   BOOTLOADER_STATE                  : ORIGIN = 0x10006000, LENGTH = 4K
   ACTIVE                            : ORIGIN = 0x10007000, LENGTH = 512K
   DFU                               : ORIGIN = 0x10087000, LENGTH = 516K
-  RAM                               : ORIGIN = 0x20000000, LENGTH = 256K
+
+  /* Pick one of the two options for RAM layout     */
+
+  /* OPTION A: Use all RAM banks as one big block   */
+  /* Reasonable, unless you are doing something     */
+  /* really particular with DMA or other concurrent */
+  /* access that would benefit from striping        */
+  RAM   : ORIGIN = 0x20000000, LENGTH = 264K
+
+  /* OPTION B: Keep the unstriped sections separate */
+  /* RAM: ORIGIN = 0x20000000, LENGTH = 256K        */
+  /* SCRATCH_A: ORIGIN = 0x20040000, LENGTH = 4K    */
+  /* SCRATCH_B: ORIGIN = 0x20041000, LENGTH = 4K    */
 }
 
 __bootloader_state_start = ORIGIN(BOOTLOADER_STATE) - ORIGIN(BOOT2);

examples/rp/memory.x

@@ -1,5 +1,17 @@
 MEMORY {
     BOOT2 : ORIGIN = 0x10000000, LENGTH = 0x100
     FLASH : ORIGIN = 0x10000100, LENGTH = 2048K - 0x100
-    RAM   : ORIGIN = 0x20000000, LENGTH = 256K
-}
+
+    /* Pick one of the two options for RAM layout     */
+
+    /* OPTION A: Use all RAM banks as one big block   */
+    /* Reasonable, unless you are doing something     */
+    /* really particular with DMA or other concurrent */
+    /* access that would benefit from striping        */
+    RAM   : ORIGIN = 0x20000000, LENGTH = 264K
+
+    /* OPTION B: Keep the unstriped sections separate */
+    /* RAM: ORIGIN = 0x20000000, LENGTH = 256K        */
+    /* SCRATCH_A: ORIGIN = 0x20040000, LENGTH = 4K    */
+    /* SCRATCH_B: ORIGIN = 0x20041000, LENGTH = 4K    */
+}

examples/stm32f334/src/bin/opamp.rs

@@ -39,7 +39,7 @@ async fn main(_spawner: Spawner) -> ! {
 
     let mut vrefint = adc.enable_vref(&mut Delay);
     let mut temperature = adc.enable_temperature();
-    let mut buffer = opamp.buffer_ext(&p.PA7, &mut p.PA6, OpAmpGain::Mul1);
+    let mut buffer = opamp.buffer_ext(&mut p.PA7, &mut p.PA6, OpAmpGain::Mul1);
 
     loop {
         let vref = adc.read(&mut vrefint).await;