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Sorry for the very basic question. I am trying to set a built-in pullup on GPIO pins and it doesn't seem to be working. Hardware is Pi 3B and 4B (I tried on both), OS is Raspbian 10 (buster). The wiringPi pin 0 (BCM pin 17) is not connected to anything:

% gpio mode 0 input 
% gpio mode 0 up 
% gpio read 0 
0 
%

Should this pin not be reading back a 1 due to the pull-up? What am I missing?

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  • Which model Pi? Which distribution? – joan Oct 31 '19 at 19:45
  • Pi 4B and 3B. I tried on both. Current Raspbian (version 10 buster) OS. – Jabberwock Oct 31 '19 at 21:24
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    You should edit your question and/or the tags to include that information. – joan Oct 31 '19 at 21:41
  • Have you tried gpio mode 0 in instead of input? wiringpi.com/the-gpio-utility lists in as the command for reading a pin. – Fred Nov 2 '19 at 8:57
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wiringPi pull-ups and pull-downs do not work on the Pi4B. The ways the pulls work has changed in the new BCM2711 SoC used in the Pi4B.

See this question.

As far as I know they do work correctly on the Pi3B (but I have not tested recently).

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set the pullups in config.txt or use raspi-gpio command.

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  • It'd be helpful if you'd explain how in more detail. – user96931 Mar 23 '20 at 18:23
  • This link contains the info on how to set up gpio pins at boot time y /boot/config.txt file. raspberrypi.org/documentation/configuration/config-txt/gpio.md – Arístides Bouza Mar 24 '20 at 23:30
  • other way that worked to me was explained at wiring.org. cd /tmp wget project-downloads.drogon.net/wiringpi-latest.deb sudo dpkg -i wiringpi-latest.deb (wiringpi.com/wiringpi-updated-to-2-52-for-the-raspberry-pi-4b) apliying this method you will end up with 2.62 version instead of 2.52. But I hope 2.62 will solve your problems and you will get everything working just using Gordon Henderson's great library. (Please do not send questions to his mail). – Arístides Bouza Mar 24 '20 at 23:39
  • the third option si to use raspi-gpio tool. The raspi-gpio tool is designed to help hack / debug BCM283x GPIO. Running raspi-gpio with the help argument prints this help. raspi-gpio can get and print the state of a GPIO (or all GPIOs) and can be used to set the function, pulls and value of a GPIO. raspi-gpio must be run as root. Use: raspi-gpio get [GPIO] OR raspi-gpio set <GPIO> [options] OR raspi-gpio funcs [GPIO] OR raspi-gpio raw – Arístides Bouza Mar 24 '20 at 23:49
  • hope this may be useful for you. I' bored making quarantine here in Argentina!!! – Arístides Bouza Mar 24 '20 at 23:50

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