4

i have a problem with the gpio sysfs files. when i use cat to get the values of a gpio pin it will always show 0. but after using a python script ( https://github.com/elParaguayo/RPI-Info-Screen/blob/PiTFT/pitftgpio.py ) the pins work normally.

im using the normal commands to adress the gpio: sudo sh -c 'echo 23 > /sys/class/gpio/export' , setting direction and then cat /sys/class/gpio/gpio23/value

closed as unclear what you're asking by goldilocks Jan 5 '15 at 13:55

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • What are you doing to the gpio to make it change value? All the Python code seems to do is open gpio 23 as an input and set a pull-up to 3V3. – joan Apr 16 '14 at 17:00
  • Maybe something like 'echo "in" > /sys/class/gpio/gpio23/direction' to specify pin23 as an input, I'm not sure how to set the pullup. – francis Apr 17 '14 at 9:44
  • thanks, i think its the pull-up. i set the direction,but forgot to mention it ;) – tly Apr 17 '14 at 10:51
  • is it necessesary to set the pull-up? – tly Apr 17 '14 at 13:38
  • It depends on what is connected to the gpio. If nothing is connected it will float randomly between 0 and 1. The pull-up will fix the gpio high unless an external circuit pulls it low. – joan Apr 17 '14 at 17:29

Browse other questions tagged or ask your own question.