Communication with arduino sometime error

[wiryonolau]

Hi, I've been testing arduino communication with serial. during running it always connected , buy sometime the read is incorrect python in run in version 3.9 in Debian 11

This is the python code

import serial
import aioserial
import asyncio
import time
import sys
import logging

class SerialListener:
    def __init__(self, port="/dev/ttyUSB0", baudrate=9600):
        self._port = port
        self._baud_rate = baudrate
        self._run = True
        self._serial = None
        self._logger = logging.getLogger()

    async def stop(self):
        self._run = False

    async def start(self):
        await self.reconnect()
        await self.listen()

    async def disconnect(self):
        self._logger.info("Cleanup serial {}".format(self._port))
        if self._serial is not None:
            try:
                self._serial.close()
            except:
                self._logger.info(sys.exc_info())
        self._serial = None

    async def reconnect(self):
        await self.disconnect()

        while self._serial is None:
            try:
                self._serial = aioserial.AioSerial(
                    port=self._port, baudrate=self._baud_rate
                )
                self._logger.info("Connected to {}".format(self._port))
            except serial.serialutil.SerialException:
                self._logger.info("{} not ready".format(self._port))
            except:
                self._logger.info(sys.exc_info())
            await asyncio.sleep(1)

    async def listen(self):
        while self._run:
            try:
                data = await self._serial.read_until_async()
                code = data.decode(errors="ignore").strip()
                self._logger.info("Receive {}".format(code))
            except asyncio.CancelledError:
                break
            except serial.serialutil.SerialException:
                # Blocking call
                await self.reconnect()
            except:
                self._logger.info(sys.exc_info())
            await asyncio.sleep(0.1)


def main():
    logging.basicConfig(
        level=logging.DEBUG,
        format="%(asctime)s %(levelname)s %(name)s : %(message)s",
        handlers=[logging.StreamHandler(sys.stdout)],
    )
    logger = logging.getLogger()

    serial_listener = SerialListener(port="/dev/ttyUSB0", baudrate=9600)

    loop = asyncio.get_event_loop()

    try:
        asyncio.ensure_future(serial_listener.start())
        loop.run_forever()
    except asyncio.CancelledError:
        logger.info("Receive Cancel")
    except KeyboardInterrupt:
        logger.info("Receive Keyboard Interrupt")
    except:
        logger.info("Unknown Error")
        logger.info(sys.exc_info())
    finally:
        logger.info("Stop application")

    loop.run_until_complete(asyncio.wait([serial_listener.stop()]))

if __name__ == "__main__":
    main()

This is arduino part

const int buttonPin = 4;

int buttonState = 0;
int value = 0;

void setup() {
  Serial.begin(9600);
  pinMode(buttonPin, INPUT_PULLUP);
}

void loop() {
  buttonState = digitalRead(4);

  if (buttonState == HIGH) 
  {
    value = 0x01;
  } else if (buttonState == LOW) 
  {
    value = 0x00;
  }

  if (Serial.available()) {
    // Sending value to python
    Serial.println(value);
  }

  delay(500);
}

It is very simple code, basically the arduino will send a value 0x01 when button is press and 0x00 when not every .5 second

When starting the python script, sometime the delay is lower then .5 second, and any button press in the arduino will not send the correct value , it kept sending the default value.

On re-connection either by repluging the usb cable or restarting the script might cause the same problem. The most visible is when I clear the terminal. Testing same script in windows 10 with port COM3 ( using pyserial ) the problem doesn't seem to occur

Any idea what the cause ?