NCT5104D GPIO Linux Driver
Preconditions (Compile):
you should have the following packages installed:
- linux-headers-$(uname -r)
- build-essential
- make
- git (you can also download the repo as zip)
apt-get install -y linux-headers-$(uname -r) build-essential make git
git clone <this repo url>
Compile:
run make in the driver folder on the target machine
(otherwise your driver gets compiled for a different kernal version)
Load the driver:
insmod gpio-nct5104d.ko
Unload the driver:
unexport all the used GPIO Pins first, then run
rmmod gpio-nct5104d.ko
Export a GPIO Pin:
echo 0 > /sys/class/gpio/export will export/reserve/setup the gpio pin 0
Unexport a GPIO Pin:
echo 0 > /sys/class/gpio/unexport will unexport/free the gpio pin 0
Set GPIO Pin as output:
echo out > /sys/class/gpio/gpio0/direction
Set GPIO Pin output value:
echo 1 > /sys/class/gpio/gpio0/value
Read GPIO Pin value:
cat /sys/class/gpio/gpio0/value
Invert GPIO Pin logic:
echo 1 > /sys/class/gpio/gpio0/active_low
Using the Kernel interrupt system for GPIO Pins:
echo <TRIGGER_TYPE> >/sys/class/gpio/gpio0/edge
TRIGGER_TYPE can be one of the following values:
- none
- falling
- rising
- both
Show GPIO states using kernal debug information:
cat /sys/kernel/debug/gpio
this has to be enabled in your kernal
Additional informatio:
see those pages for some c-code examples:
http://wiki.gnublin.org/index.php/GPIO
http://falsinsoft.blogspot.de/2012/11/access-gpio-from-linux-user-space.html
see the Kernel documentation for more details:
https://www.kernel.org/doc/Documentation/gpio/sysfs.txt
https://www.kernel.org/doc/Documentation/gpio/gpio-legacy.txt
and so on...