stm32f3xx_hal serial reading sample

stm32f3xx_hal_serial_read_sample.rs

let ( _tx, mut rx)  = serial_port.split();

rprintln!("loopstart!");
loop {
  let mut err_count = 0;
  let mut block_count = 0;
  let mut burst_count = 0;
  loop {
      let rc = rx.read();

      match rc {
          Ok(byte) => {
              rprint!("{:x},",last_char);
              last_char = byte;
              err_count = 0;
              block_count = 0;
              burst_count += 1;
          }
          Err(nb::Error::WouldBlock) => {
              if burst_count > 10 {
                  rprintln!("");
              }
              burst_count = 0;
              block_count += 1;
          }
          Err(nb::Error::Other(foo)) => {
              err_count += 1;
              if err_count > 100 {
                  rprintln!("err: {:?}",foo);
                  delay_source.delay_ms(100u8);
              }
          }
      }
  }
}

In practice, at low baud rates, we get nb::Error::WouldBlock frequently between characters.