My aim is to control the GPIO pins in Peppermint 4 Linux (Kernel version 3.8.0) on an Intel motherboard (NM70 chipset with C1037U processor).
How can you check whether your kernel supports GPIO on your hardware?
Background
- Motherboard: Intel with NM70 chipset
- Processor: C1037U processor
- OS: Peppermint 4 Linux
- Kernel version: 3.8.0
- GPIO interface: sysfs
I'm attempting to use the sysfs interface, which allows GPIO pins to be accessed from userspace through the filesystem.
I’ve successfully followed the "Alternate Build Method: The Old-Fashioned Debian Way" section of https://help.ubuntu.com/community/Kernel/Compile to recompile the kernel in order to expose GPIO access in user space and to turn on debug mode for GPIO:
Once the new kernel was compiled, I was able to see the GPIO folder in /sys/class/gpio for the first time. Then, in theory, it should be a case of being able to turn GPIO ports ON/OFF by writing to the filesystem. This approach is outlined at http://falsinsoft.blogspot.co.uk/2012/11/access-gpio-from-linux-user-space.html.
When attempting to export pins 0 to 255 by
echo XX > /sys/class/gpio/export
for XX from 0 to 255, I get the following error message
echo: write error: No such device
When attempting to export pins outside the range 0 to 255 by
echo XX > /sys/class/gpio/export
I get the following error message
echo: write error: Invalid argument
The tutorial suggests this could be because the GPIO ports are reserved for another program and that, if so, the debug file (/sys/kernel/debug/gpio) would be able to show where they are reserved.
However, /sys/kernel/debug/gpio is empty.
I can see and control the GPIO pins in the BIOS (change pins to be input or output HIGH/LOW).
Related questions
Under what conditions would /sys/kernel/debug/gpio be empty?
