Application note - fitlet2 controlling front LEDs on Linux

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Revision as of 07:38, 9 October 2018 by Tamir (Talk | contribs) (Tamir moved page Controlling LED1 and LED2 to Application note - fitlet2 controlling front LEDs on Linux)

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  • This document provides an example to control the fitlet2's front LEDs.
  • fitlet2 has 2 LEDs, LED1 and LED2. Each of them has GREEN and YELLOW parts that can be controlled separately.
  • This document is applicable to fitlet2 running Linux.

Linux

In Linux kernel there are 4 related GPIOs: GPIO435, GPIO436, GPIO437, GPIO438.

  • GPIO435 - LED1 GREEN
  • GPIO436 - LED1 YELLOW
  • GPIO437 - LED2 GREEN
  • GPIO438 - LED2 YELLOW

To control the GPIOs need to login as root (root password required):

$ su
Password:

To control for example LED1 GREEN part:

$ echo 435 > /sys/class/gpio/export
$ echo out > /sys/class/gpio/gpio435/direction
$ echo 1 > /sys/class/gpio/gpio435/value
# LED1 should be GREEN now
$ echo 0 > /sys/class/gpio/gpio435/value
# LED1 should be OFF now
$ echo 435 > /sys/class/gpio/unexport

The GPIO framework and GPIO sysfs interface are documented in https://www.kernel.org/doc/Documentation/gpio/gpio.txt