4 Replies Latest reply on Oct 25, 2014 6:07 AM by mhahn

    GPIO pullup/pulldowns

    faceplant

      I figured out how to enable and change the pullup/puldown on the GPIO pins, including I2C, etc.  It's actually very easy and straightforward.

      If you look in /sys/kernel/debug/gpio_debug/gpio* you will see a whole slew of pseudo-files.  Two of those are current_pullmode and current_pullstrength.  To turn on e.g. a 2k pullup, you just do:

      echo "pullup" > current_pullmode
      echo "2k" > current_pullstrength

       

      You can get a list of the values that are accepted by catting e.g. available_pullstrength.

       

      I tested this with a volt meter (both the voltage for pullmode and current for pullstrength), and it appears to work as expected.