UART GPIOs won't communicate to arduino in General Discussion Posted August 8, 2016 · Report reply I got to the bottom of my issue. Simple fix really. My arduino and pcDuino didn't have a common ground. When i added that it worked fine (using a logic level converter). For extra points, I also found that although my Python script would run fine with no errors, I couldn't get any serial output from it until I ran a serial sketch from the IDE. Another silly NOOB mistake, I had neglected to add echo 3 > /sys/devices/virtual/misc/gpio/mode/gpio0 echo 3 > /sys/devices/virtual/misc/gpio/mode/gpio1 to my /etc/rc.local file so it the Python script would work on bootup without intervention.