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08:52, 26 October 2015 == fitlet GPIO SDK for Linux ==
* [http://fit-pc.com/download/fitlet/sw/fitlet-gpio-sdk-for-linux.zip fitlet GPIO SDK for Linux]
== Installation ==
1. Download the custom kernel image and headers <LINK_TO_DEB_FILES_HERE> to the fitlet.
2. Open the terminal and install the new linux-*.deb packages:
$ sudo dpkg -i /path/to/linux-*.deb
3. Reboot the system:
$ sudo reboot -f
=== fitlet GPIO ===
(based on http://droid/mirror/mediawiki/index.php/CM-iGT:_Linux:_Mint#GPIO)
1. GPIO interface on fitlet consists of 9 I/Os provided by AMD FCH (Fusion Controller Hub)
2. The responsible kernel module is gpio_fch
3. The kernel modules uses the following pin naming convention:
P-1, GPIO89
P-2, GPIO132
P-3, GPIO65
P-4, GPIO66
P-5, GPIO29 Vout 1.5V
P-8, GPIO73
P-9, GPIO27 Vout 1.5V
P-10, GPIO28 Vout 1.5V
P-11, GPIO12
4. The GPIO sysfs interface allows users to manipulate any GPIO from userspace dynamically.
5. A basic example of GPIO usage (as root user):
$ modprobe fch_gpio
$ echo 89 > /sys/class/gpio/export
$ echo out > /sys/class/gpio/gpio89/direction
$ echo 1 > /sys/class/gpio/gpio89/value
## at this point voltage measuring on P-1 should give 3.3V
$ echo 0 > /sys/class/gpio/gpio89/value
## at this point voltage measuring on P-1 should give 0.0V
$ echo 89 > /sys/class/gpio/unexport
6. The source code of gpio_fch driver <LINK_TO_DIFF_FILE_HERE>
7. The GPIO framework and GPIO sysfs interface are documented in Linux Kernel Documentation