feat: Block on twai calls, remove Option<> results

esp-hal/src/twai/mod.rs

@@ -1194,10 +1194,7 @@ where
             return Err(EspTwaiError::BusOff);
         }
         // Check that the peripheral is not already transmitting a packet.
-        if !status.tx_buf_st().bit_is_set() {
-            return Err(EspTwaiError::WouldBlock); // TODO: Is this the right
-                                                  // error?
-        }
+        while !status.tx_buf_st().bit_is_set() {}
 
         write_frame(register_block, frame);
 
@@ -1227,9 +1224,7 @@ where
         }
 
         // Check that we actually have packets to receive.
-        if !status.rx_buf_st().bit_is_set() {
-            return Err(EspTwaiError::WouldBlock);
-        }
+        while !status.rx_buf_st().bit_is_set() {}
 
         // Check if the packet in the receive buffer is valid or overrun.
         if status.miss_st().bit_is_set() {
@@ -1252,8 +1247,6 @@ pub enum EspTwaiError {
     NonCompliantDlc(u8),
     /// Encapsulates errors defined by the embedded-hal crate.
     EmbeddedHAL(ErrorKind),
-    /// This operation requires blocking behavior to complete
-    WouldBlock,
 }
 
 #[cfg(any(doc, feature = "unstable"))]

examples/src/bin/twai.rs

@@ -81,7 +81,7 @@ fn main() -> ! {
         // Send a frame to the other ESP
         // Use `new_self_reception` if you want to use self-testing.
         let frame = EspTwaiFrame::new(StandardId::ZERO, &[1, 2, 3]).unwrap();
-        while twai.transmit(&frame).is_err() {}
+        twai.transmit(&frame).unwrap();
 
         println!("Sent a frame");
     }
@@ -89,18 +89,14 @@ fn main() -> ! {
     let delay = Delay::new();
     loop {
         // Wait for a frame to be received.
-        let frame = loop {
-            if let Ok(frame) = twai.receive() {
-                break frame;
-            }
-        };
+        let frame = twai.receive().unwrap();
 
         println!("Received a frame: {frame:?}");
         delay.delay_millis(250);
 
         let frame = EspTwaiFrame::new(StandardId::ZERO, &[1, 2, 3]).unwrap();
         // Transmit a new frame back to the other ESP
-        while twai.transmit(&frame).is_err() {}
+        twai.transmit(&frame).unwrap();
         println!("Sent a frame");
     }
 }

hil-test/tests/twai.rs

@@ -51,13 +51,9 @@ mod tests {
     #[test]
     fn test_send_receive(mut ctx: Context) {
         let frame = EspTwaiFrame::new_self_reception(StandardId::ZERO, &[1, 2, 3]).unwrap();
-        while ctx.twai.transmit(&frame).is_err() {}
+        ctx.twai.transmit(&frame).unwrap();
 
-        let frame = loop {
-            if let Ok(frame) = ctx.twai.receive() {
-                break frame;
-            }
-        };
+        let frame = ctx.twai.receive().unwrap();
 
         assert_eq!(frame.data(), &[1, 2, 3])
     }