main.rs

fn main() {
    // setup serial port
    let port_name = "/dev/cu.usbmodem21301";
    let mut port = serialport::new(port_name, 115_200)
        .timeout(std::time::Duration::from_millis(10))
        .open()
        .expect("Failed to open port");

    loop {
        // start timer
        let start = std::time::Instant::now();
        // send a byte and read the response
        port.write(&[0x01]).unwrap();
        // flush the buffer
        port.flush().unwrap();
        let mut response: Vec<u8> = vec![0; 1];
        port.read(response.as_mut_slice()).expect("Found no data!");

        let elapsed = start.elapsed();
        println!(
            "Round trip time: {:?} (sent 0x01, received 0x{:02X})",
            elapsed, response[0]
        );

        // busy wait in tight loop
        let wait_ms = 50 - elapsed.as_millis() as u64;
        while (start.elapsed().as_millis() as u64) < wait_ms {
            // do nothing
        }

        // print actual time waited
        println!("Waited for: {:?}", start.elapsed());
    }
}