Fitlet GPIO SDK for Linux

Installation

• Download the kernel image and kernel headers to the fitlet.

• Open the terminal and install the new linux-*.deb packages:

$ sudo dpkg -i /path/to/linux-*.deb

• Reboot the system:

$ sudo reboot -f

fitlet GPIO

• GPIO interface on fitlet consists of 9 I/Os provided by AMD FCH (Fusion Controller Hub)
• The responsible kernel module is gpio_fch
• The kernel modules uses the following pin naming convention:

GPIO pin naming convention on fitlet

GPIO name	HW source	Pin on GPIO Connector	Notes
GPIO89	FCH	P-1
GPIO132	FCH	P-2
GPIO65	FCH	P-3
GPIO66	FCH	P-4
GPIO29	FCH	P-5	Vout 1.5V
GPIO73	FCH	P-8
GPIO27	FCH	P-9	Vout 1.5V
GPIO28	FCH	P-10	Vout 1.5V
GPIO12	FCH	P-11

• The GPIO sysfs interface allows users to manipulate any GPIO from userspace dynamically.
• 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

• The source code of gpio_fch driver fitlet.gpio.3.16.diff
• The GPIO framework and GPIO sysfs interface are documented in Linux Kernel Documentation :: GPIO