I'm having some trouble getting my arduino uno to communicate with a simple python script through pyserial.

Lets start with my arduino sketch:

void setup() {

byte i = 0;
void loop() {
  i = i + 1;

Really dead simple. It just spews the numbers from 0 to 255 over and over again. It works fine in the arduino serial monitor and gets me the expected result.

The python script comes from:


import serial
ser = serial.Serial('/dev/ttyUSB0', 9600)
while True:
    print ser.readline()

However running this script gets me:

$ python test.py 
Traceback (most recent call last):
  File "test.py", line 4, in <module>
    print ser.readline()
  File "/usr/lib/python2.7/dist-packages/serial/serialposix.py", line 460, in read
    raise SerialException('device reports readiness to read but returned no data (device disconnected?)')
serial.serialutil.SerialException: device reports readiness to read but returned no data (device disconnected?)

I am using ubuntu 14.04 and python-serial_2.6-1build1_all.deb

1 Answer 1


This may be a kernel bug. See here: https://bugs.launchpad.net/ubuntu/+source/python2.7/+bug/1501240

The workaround it seems is to use kernel 3.13.0-63-generic.

You can change the kernel for a one-time boot by holding shift while starting up. To make the change persistent, you need to edit /etc/default/grub: https://askubuntu.com/questions/262965/grub-timeout-set-to-0-cant-access-grub-menu-anymore?rq=1

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