1 Reply Latest reply on Jan 23, 2015 7:38 AM by DiegoV_Intel

    Changing internal pullup resistors

    Yodal

      I have looked over all of the documentation I have been able to get my hands on and I have not found a way to change what value of internal pullup is used. In the Edison Module Hardware Guide it is mentioned that 2, 20, and 50 kohm values are available for internal pullups and I have found how to enable the pullups in a few locations, but I have found no place where there is mention of how to change the value used for the pullup resistor. How would the value be selected, either through mraa or directly through the gpio device? Thank you in advance.

        • 1. Re: Changing internal pullup resistors
          DiegoV_Intel

          Hi Yodal,

           

          To change the value of the internal pull-up resistors you should go to the following directory:

           

          /sys/kernel/debug/gpio_debug/gpio*

           

          In there you will find, among others settings, the option to change the pull-up resistor value. For example, to change the value of the pull-up resistor for the GPIO49, which is the IO8 in the Arduino Expansion Board, you have to use the following commands:

           

          cd /sys/kernel/debug/gpio_debug/gpio49
          echo "2k" > current_pullstrength
          

           

          You can check what the available values are with the following command:

           

          cd /sys/kernel/debug/gpio_debug/gpio49
          cat available_pullstrength
          

           

          I hope you find this information useful. There are more settings that you can check. I think you will find them interesting.

           

          Regards,

          Diego.