OSError: [Errno 5] Input/output error on Raspberry PI GPS shield Python

Question

I have a Raspberry PI 3 and a GSM/GPRS/GNSS HAT.

I want to read the GPS data from the device with Python. I have used the example code from the documentation, and rewrote it a bit. It was working for a couple of hours perfectly, but one time when I rebooted the Raspberry(I have rebooted it before and it was working fine) it started throwing this after a couple of successful reads:

Traceback (most recent call last):
      File "/home/ubuntu/gps.py", line 90, in listenForGpsInfo
        while ser.inWaiting() > 0:
      File "/usr/lib/python3/dist-packages/serial/serialutil.py", line 594, in inWaiting
        return self.in_waiting
      File "/usr/lib/python3/dist-packages/serial/serialposix.py", line 531, in in_waiting
        s = fcntl.ioctl(self.fd, TIOCINQ, TIOCM_zero_str)

OSError: [Errno 5] Input/output error

here is my code:

def listenForGpsInfo(callback):
    ser = serial.Serial("/dev/ttyS0",baudrate=115200)

    W_buff = [b"AT+CGNSPWR=1\r\n", b"AT+CGNSSEQ=\"RMC\"\r\n", b"AT+CGNSINF\r\n", b"AT+CGNSURC=2\r\n", b"AT+CGNSTST=1\r\n"]
    ser.write(W_buff[0])
    ser.flushInput()
    data = ""
    num = 0

    while True:
        time.sleep(utils.GPS_INTERVAL_IN_SECONDS)
        try:
            while ser.inWaiting() > 0:
                data += ser.read(ser.inWaiting()).decode()
                print(data)
            if data != "":
                if  num < len(W_buff)-1:
                    print(num)
                    ser.write(W_buff[num+1])
                    num =num +1
                else:
                    ser.write(W_buff[2])
                    if "+CGNSINF" in data:
                        data = str(data)
                        gpsInfo = parseGpsData(findInfoLine(data))
                        if(gpsInfo is not None):
                            callback(gpsInfo)

                
                data = ""
        except Exception as e:
            if ser != None:
                ser.close()
            traceback.print_exc()
            listenForGpsInfo(callback)
            return

Here is the documentation of the serial commands: https://www.waveshare.com/w/upload/3/3d/SIM868_GNSS_Application_Note_V1.00.pdf

I tried a lot of things, but I couldn't solve it. Couple of things I have tried:

• Restarting the device
• Detaching and Attaching the shield
• Only sending the AT+CGNSPWR=1\r\n and the AT+CGNSINF\r\n commands
• chmod 666 /dev/ttyS0

Answer 1

I had ubuntu on the raspberry and when I installed raspberry os the error went away.