How to code to control GPIO from python

[KNaka.6]

Hello, I have a question.

What are some ways to control GPIO from python?

I want to do that with a starter package.

Best Regards!

[Pavel A.]

Does this Linux expose GPIOs in sysfs? /sys/class/... ?

Is this an interview question? 🙂

[Tesla DeLorean]

On the RPi I use this, I'd imagine ST has something similar for a GPIO library

https://pypi.org/project/RPi.GPIO/

[Olivier GALLIEN]

Hi @KNaka.6​ ,

OpenSTLinux is not supporting "/sys/class/gpio" but only the /dev/gpiochip* devices together with libgpiod.

See https://wiki.st.com/stm32mpu/wiki/How_to_control_a_GPIO_in_userspace

Then for Python, interfacing with libgpiod command might be straightforward, or eventually using python3-gpiod.

Olivier

[KNaka.6]

Thank you for your reply. I'm a Linux beginner and I'm sorry I couldn't explain it well. I'm using OpenStLinux-5.10-dunfell

​I have tried the following but I get a permission error. I don't know how to resolve. Or is this the wrong way?

root@stm32mp1:/dev# sudo apt install python3-libgpiod

>>> import gpiod

>>> chip=gpiod.chip('gpiochip0')

>>> prt=chip.get_lines([14])

>>> prt.set_values([1])

Traceback (most recent call last):

 File "<stdin>", line 1, in <module>

 File "/home/root/.local/lib/python3.8/site-packages/gpiod/libgpiodcxx/__init__.py", line 1083, in set_values

  self._m_bulk[i].set_value(values[i])

 File "/home/root/.local/lib/python3.8/site-packages/gpiod/libgpiodcxx/__init__.py", line 629, in set_value

  raise OSError(

PermissionError: [Errno 1] Operation not permitted: 'error setting GPIO line value'

Best Regards!

K-Naka

[Olivier GALLIEN]

Hi @KNaka.6​ ,

Please confirm first that playing with libgpiod works as explained in wiki :

Board $>gpioset gpiochip0 14=0  -->to set GPIO PA14 low // green led on
 
Board $>gpioset gpiochip0 14=1  -->to set GPIO PA14 high // green led off

Then @PatrickF​  just tell me he successfully tested this on DK2 out of the box ( and connected to network) :

python3 -m pip install -U --user pip gpiod 
 
python3 -m gpiod.test.button gpiochip0 14 both
 
-> button user1 is ok 
 
 python3 -m gpiod.test.blink gpiochip0 14
 
-> led blink ok 

Hope it help,

Olivier