stm32/can: bxcan async enable

embassy-stm32/src/can/bxcan.rs

@@ -161,6 +161,18 @@ impl<'d, T: Instance> Can<'d, T> {
             .leave_disabled();
     }
 
+    /// Enables the peripheral and synchronizes with the bus.
+    ///
+    /// 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() {
+            // 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;
+        }
+    }
+
     /// Queues the message to be sent but exerts backpressure
     pub async fn write(&mut self, frame: &Frame) -> bxcan::TransmitStatus {
         poll_fn(|cx| {

examples/stm32f4/src/bin/can.rs

@@ -40,10 +40,13 @@ async fn main(_spawner: Spawner) {
 
     can.as_mut()
         .modify_config()
-        .set_bit_timing(0x001c0003) // http://www.bittiming.can-wiki.info/
         .set_loopback(true) // Receive own frames
         .set_silent(true)
-        .enable();
+        .leave_disabled();
+
+    can.set_bitrate(1_000_000);
+
+    can.enable().await;
 
     let mut i: u8 = 0;
     loop {