Add read_bytes method to uart (#1784)

* Add read_bytes method to uart

* Changelog

esp-hal/CHANGELOG.md

@@ -24,6 +24,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `#[ram(persistent)]` option to replace the unsound `uninitialized` option (#1677)
 - uart: Make `rx_timeout` optional in Config struct (#1759)
 - Add interrupt related functions to `PeriodicTimer`/`OneShotTimer`, added `ErasedTimer` (#1753)
+- Added blocking `read_bytes` method to `Uart` and `UartRx` (#1784)
 
 ### Fixed
 

esp-hal/src/uart.rs

@@ -519,6 +519,30 @@ where
         self
     }
 
+    /// Fill a buffer with received bytes
+    pub fn read_bytes(&mut self, mut buf: &mut [u8]) -> Result<(), Error> {
+        if buf.is_empty() {
+            return Ok(());
+        }
+        let cap = buf.len();
+        let mut total = 0;
+        loop {
+            while T::get_rx_fifo_count() == 0 {
+                // Block until we received at least one byte
+            }
+            let read = self.drain_fifo(buf);
+            total += read;
+            // drain_fifo only drains bytes that will fit in buf,
+            // so we will always have an exact total
+            if total == cap {
+                break;
+            }
+            // update the buffer position based on the bytes read
+            buf = &mut buf[read..];
+        }
+        Ok(())
+    }
+
     /// Read a byte from the UART
     pub fn read_byte(&mut self) -> nb::Result<u8, Error> {
         // On the ESP32-S2 we need to use PeriBus2 to read the FIFO:
@@ -832,6 +856,11 @@ where
         self.tx.write_bytes(data)
     }
 
+    /// Fill a buffer with received bytes
+    pub fn read_bytes(&mut self, buf: &mut [u8]) -> Result<(), Error> {
+        self.rx.read_bytes(buf)
+    }
+
     /// Configures the AT-CMD detection settings
     #[allow(clippy::useless_conversion)]
     pub fn set_at_cmd(&mut self, config: config::AtCmdConfig) {
@@ -1681,7 +1710,7 @@ where
     M: Mode,
 {
     fn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error> {
-        if buf.len() == 0 {
+        if buf.is_empty() {
             return Ok(0);
         }
 

hil-test/tests/uart_tx_rx.rs

@@ -67,4 +67,18 @@ mod tests {
 
         assert_eq!(read, Ok(0x42));
     }
+
+    #[test]
+    #[timeout(3)]
+    fn test_send_receive_bytes(mut ctx: Context) {
+        let bytes = [0x42, 0x43, 0x44];
+        let mut buf = [0u8; 3];
+
+        ctx.tx.flush_tx().unwrap();
+        ctx.tx.write_bytes(&bytes).unwrap();
+
+        ctx.rx.read_bytes(&mut buf).unwrap();
+
+        assert_eq!(buf, bytes);
+    }
 }