diff --git a/embassy-stm32/src/usart/mod.rs b/embassy-stm32/src/usart/mod.rs index 6f838cce5..333e01e36 100644 --- a/embassy-stm32/src/usart/mod.rs +++ b/embassy-stm32/src/usart/mod.rs @@ -69,6 +69,12 @@ unsafe fn on_interrupt(r: Regs, s: &'static State) { // disable idle line detection w.set_idleie(false); }); + } else if cr1.tcie() && sr.tc() { + // Transmission complete detected + r.cr1().modify(|w| { + // disable Transmission complete interrupt + w.set_tcie(false); + }); } else if cr1.rxneie() { // We cannot check the RXNE flag as it is auto-cleared by the DMA controller @@ -420,7 +426,7 @@ impl<'d> UartTx<'d, Async> { /// Wait until transmission complete pub async fn flush(&mut self) -> Result<(), Error> { - self.blocking_flush() + flush(&self.info, &self.state).await } } @@ -531,16 +537,40 @@ impl<'d, M: Mode> UartTx<'d, M> { } } +/// Wait until transmission complete +async fn flush(info: &Info, state: &State) -> Result<(), Error> { + let r = info.regs; + if r.cr1().read().te() && !sr(r).read().tc() { + r.cr1().modify(|w| { + // enable Transmission Complete interrupt + w.set_tcie(true); + }); + + compiler_fence(Ordering::SeqCst); + + // future which completes when Transmission complete is detected + let abort = poll_fn(move |cx| { + state.rx_waker.register(cx.waker()); + + let sr = sr(r).read(); + if sr.tc() { + // Transmission complete detected + return Poll::Ready(()); + } + + Poll::Pending + }); + + abort.await; + } + + Ok(()) +} + fn blocking_flush(info: &Info) -> Result<(), Error> { let r = info.regs; - while !sr(r).read().tc() {} - - // Disable Transmitter and enable receiver after transmission complete for Half-Duplex mode - if r.cr3().read().hdsel() { - r.cr1().modify(|reg| { - reg.set_te(false); - reg.set_re(true); - }); + if r.cr1().read().te() { + while !sr(r).read().tc() {} } Ok(()) @@ -621,7 +651,13 @@ impl<'d> UartRx<'d, Async> { // Call flush for Half-Duplex mode if some bytes were written and flush was not called. // It prevents reading of bytes which have just been written. if r.cr3().read().hdsel() && r.cr1().read().te() { - blocking_flush(self.info)?; + flush(&self.info, &self.state).await?; + + // Disable Transmitter and enable Receiver after flush + r.cr1().modify(|reg| { + reg.set_re(true); + reg.set_te(false); + }); } // make sure USART state is restored to neutral state when this future is dropped @@ -960,6 +996,12 @@ impl<'d, M: Mode> UartRx<'d, M> { // It prevents reading of bytes which have just been written. if r.cr3().read().hdsel() && r.cr1().read().te() { blocking_flush(self.info)?; + + // Disable Transmitter and enable Receiver after flush + r.cr1().modify(|reg| { + reg.set_re(true); + reg.set_te(false); + }); } for b in buffer { @@ -1155,6 +1197,11 @@ impl<'d> Uart<'d, Async> { self.tx.write(buffer).await } + /// Wait until transmission complete + pub async fn flush(&mut self) -> Result<(), Error> { + self.tx.flush().await + } + /// Perform an asynchronous read into `buffer` pub async fn read(&mut self, buffer: &mut [u8]) -> Result<(), Error> { self.rx.read(buffer).await @@ -1733,7 +1780,7 @@ impl embedded_io_async::Write for Uart<'_, Async> { } async fn flush(&mut self) -> Result<(), Self::Error> { - self.blocking_flush() + self.flush().await } } @@ -1744,7 +1791,7 @@ impl embedded_io_async::Write for UartTx<'_, Async> { } async fn flush(&mut self) -> Result<(), Self::Error> { - self.blocking_flush() + self.flush().await } }