How can I query pull state of GPIO pin?

Question

I am writing a script that should query if an input pin is configured as pull-up or pull-down using the RPi.GPIO package.

When configuring each output I can call

GPIO.setup(11, GPIO.IN, pull_up_down=GPIO.PUD_UP)
  # or
GPIO.setup(12, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)

This is done by user input at runtime. After that my application needs to check if the user configured everything properly (one can never be sure!). Is there anything like GPIO.gpio_function(pin) but that will output the pull state of the input? (It would be a plus if it also returned the initial state of an output.)

Thanks in advance for taking the time to read!

Answer 1

It is impossible to determine the pull state of GPIO on most Pi (except by measurement).

It is possible with the BCM2711 used by Pi4 and I have written a Python3 library (based on RPi.GPIO) which does this and a program gpioread which shows this and the actual programmed function/state.

See https://raspberrypi.stackexchange.com/a/117593/8697

Corrupted git repository fixed. This can be downloaded

git clone https://github.com/Milliways2/Pi.GPIO.git

And installed with

sudo apt install python-dev python3-dev
sudo python3 setup.py install

NOTE you can also get pull using the raspi-gpio utility.

Answer 2

You can't query the pull state with RPi.GPIO.

In fact you can only query the pulls in software in the latest Pi models based on the BCM2711. I'm not sure if any of the mainstream GPIO libraries actually provide support for doing so.