openSUSE:GPIO
To manage GPIO, you can use tools from 'libgpiod' package, available for kernel >= 4.8, which includes Leap 15.0+ and Tumbleweed. You can also use the deprecated 'sysfs' interface.
libgpiod
Installation
To install libgpiod, just install it from main OSS repo. One click installation is also available : https://software.opensuse.org/package/libgpiod
Check available GPIO: gpiodetect
gpiodetect will list all GPIO chips, print their labels and number of GPIO lines.
gpiodetect
will return for the RPi2:
gpiochip0 [pinctrl-bcm2835] (54 lines)
Get information of current GPIO: gpioinfo
gpioinfo gpiochip0
will list all lines of specified gpiochips (here, gpiochip0), their names, consumers, direction, active state and additional flags. For RPi2, it returns:
gpiochip0 - 54 lines:
line 0: unnamed unused input active-high
line 1: unnamed unused input active-high
line 2: unnamed unused input active-high
line 3: unnamed unused input active-high
line 4: unnamed unused input active-high
line 5: unnamed unused input active-high
line 6: unnamed unused input active-high
line 7: unnamed unused input active-high
line 8: unnamed unused input active-high
line 9: unnamed unused input active-high
line 10: unnamed unused input active-high
line 11: unnamed unused input active-high
line 12: unnamed unused input active-high
line 13: unnamed unused input active-high
line 14: unnamed unused input active-high
line 15: unnamed unused input active-high
line 16: unnamed unused input active-high
line 17: unnamed unused input active-high
line 18: unnamed unused input active-high
line 19: unnamed unused input active-high
line 20: unnamed unused input active-high
line 21: unnamed unused input active-high
line 22: unnamed unused input active-high
line 23: unnamed unused input active-high
line 24: unnamed unused input active-high
line 25: unnamed unused input active-high
line 26: unnamed unused input active-high
line 27: unnamed unused input active-high
line 28: unnamed unused input active-high
line 29: unnamed unused input active-high
line 30: unnamed unused input active-high
line 31: unnamed unused input active-high
line 32: unnamed unused input active-high
line 33: unnamed unused input active-high
line 34: unnamed unused input active-high
line 35: unnamed "led1" output active-high [used]
line 36: unnamed unused input active-high
line 37: unnamed unused input active-high
line 38: unnamed unused input active-high
line 39: unnamed unused input active-high
line 40: unnamed unused input active-high
line 41: unnamed unused input active-high
line 42: unnamed unused input active-high
line 43: unnamed unused input active-high
line 44: unnamed unused input active-high
line 45: unnamed unused input active-high
line 46: unnamed unused input active-high
line 47: unnamed "led0" output active-high [used]
line 48: unnamed unused input active-high
line 49: unnamed unused input active-high
line 50: unnamed unused input active-high
line 51: unnamed unused input active-high
line 52: unnamed unused input active-high
line 53: unnamed unused input active-high
Read values (input): gpioget
gpioget gpiochip0 4
will read value of gpio 4 from gpiochip0 and will returns:
1
gpioget gpiochip0 4 5
will read value of gpio 4 and 5, from gpiochip0 and will returns:
1 1
Write values (output): gpioset
gpioset --mode=wait gpiochip0 4=1
will set the value of GPIO 4 to 1 and wait you hit ctrl-c to exit and stop setting the value.
gpioset --mode=wait gpiochip0 4=1 5=0
will set the value of GPIO 4 to 1 and GPIO 5 to 0 and wait you hit ctrl-c to exit and stop setting the value.
With --mode= option, you can wait for ctrl-c (as above), wait for a signal, or an amount of time before exiting (and releasing the GPIO).
The release of the GPIO may reset it to an high-impedance (unconnected) state or leave the last value. It depends on the GPIO chip. Most SoC GPIO will reset to high impedance, whereas I2C GPIO chips will keep the last value set.
libgpiod bindings (C++ and Python)
You can use C++ binding. Examples are provided here: https://git.kernel.org/pub/scm/libs/libgpiod/libgpiod.git/tree/bindings/cxx/examples
For Python binding, you need to install python-libgpiod. Examples are here: https://git.kernel.org/pub/scm/libs/libgpiod/libgpiod.git/tree/bindings/python/examples
python3-gpiod
python3-gpiod package contains the python binding from libgpiod to access GPIO from python3.
Installation
To install python3-gpiod, you just need to use zypper or YaST as it is part of openSUSE distributions repositories.
One click installation is also available : https://software.opensuse.org/package/python3-gpiod
Example
You have lots of example on https://git.kernel.org/pub/scm/libs/libgpiod/libgpiod.git/tree/bindings/python/examples:
sysfs interface (deprecated)
This old (deprecated) interface is still working so far, but is not recommended.
export: get access to your GPIO
echo 229 > /sys/class/gpio/export
will get access to GPIO 229.
Note that the base, which is the N from /sys/class/gpio/gpiochipN, must be added to the GPIO number. This is never mentioned because on Raspbian N is 0.
There may be more than one chip providing GPIO. Try looking in /sys/class/gpio/gpiochipN/label to find out which is which.
direction: choose input or output pin
echo in > /sys/class/gpio/gpio229/direction
will set GPIO 229 to input.
echo out > /sys/class/gpio/gpio229/direction
will set GPIO 229 to out, with initial value of 0, otherwise, use high value to set as out, default to 1.
value: read/write value
cat /sys/class/gpio/gpio229/value
will output the current value of GPIO 229.
echo 1 > /sys/class/gpio/gpio229/value
will set GPIO 229 to 1.
unexport: release access to GPIO
Once done, release access to GPIO with:
echo 229 > /sys/class/gpio/unexport