pub fn write_byte(&mut self, byte: u8) -> nb::Result<(), Error> {
        if self.tx_fifo_count() < UART_FIFO_SIZE {
            self.uart
                .fifo()
                .write(|w| unsafe { w.rxfifo_rd_byte().bits(byte) });
            Ok(())
        } else {
            Err(nb::Error::WouldBlock)
        }
    }
Write a single byte to the UART in a non-blocking manner.
esp-lp-hal/src/uart.rs