Last modified on 25 August 2019, at 07:28

Fitlet GPIO usage manual in Linux environment

  • This application notes applies to fitlet1 models running Linux environment.
  • It provides instructions to install the dkms kernel module to enable GPIO functionality.


  • Download and install the package:
$ wget
$ sudo dpkg -i gpio-fch-dkms_1.01.deb
  • Verify the installation:
$ modinfo gpio-fch
filename:       /lib/modules/4.15.0-20-generic/extra/gpio-fch.ko
license:        GPL
description:    GPIO interface for AMD Mullins FCH (Fusion Controller Hub)
author:         Denis Turischev <>
srcversion:     606B1C81CF1D962BE0B5C92
alias:          pci:v00001022d0000780Esv*sd*bc*sc*i*
retpoline:      Y
name:           gpio_fch
vermagic:       4.15.0-20-generic SMP mod_unload

GPIO connector Pinout

Pin Number Color Code GPIO name Power domain HW source Notes
1 Brown GPIO89 3.3V SoC
2 Red GPIO132 3.3V SoC
3 Orange GPIO65 3.3V SoC
4 Yellow GPIO66 3.3V SoC
5 Green GPIO29 1.5V SoC
6 Blue I2C Clock 3.3V SoC
7 Purple I2C Data 3.3V SoC
8 Grey GPIO73 3.3V SoC
9 White GPIO27 1.5V SoC
10 Black GPIO28 1.5V SoC
11 Brown GPIO12 3.3V SoC
12 Red UART Rx 3.3V SuperIO
13 Orange UART Tx 3.3V SuperIO
14 Yellow GND

Usage example

$ sudo -i
$ modprobe gpio_fch
$ 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 (Brown) should give 3.3V
$ echo 0 > /sys/class/gpio/gpio89/value
## at this point voltage measuring on P-1 (Brown) should give 0.0V

$ echo in > /sys/class/gpio/gpio89/direction
$ cat /sys/class/gpio/gpio89/value
## at this point cat command will print 0 or 1 depending if voltage measuring on P-1 (Brown) was 0V or 3.3V

$ echo 89 > /sys/class/gpio/unexport