Difference between revisions of "Rock/LED"

Latest revision as of 05:23, 6 January 2015

The Radxa Rock has 3 LEDs on board.

All are programmable using either LEDs class devices or GPIOs.

LEDs as class devices

On the latest kernel images (Ubuntu 14.04 server/desktop), the 3 LEDs are configured as LED class devices.

You can control them via /sys/class/leds/

Read the documentation for more information: https://www.kernel.org/doc/Documentation/leds/leds-class.txt

The default status of the three on board leds are:

• Red: On when there is power
• Green: Flash twice per second after the kernel booting, it's called heartbeat.
• Blue: Flash when the uSD card is reading/writing.

You can change the behaviour of each LED by using the echo command on their trigger property.

   root@radxa:~ # echo none > /sys/class/leds/red/trigger
   root@radxa:~ # echo default-on > /sys/class/leds/red/trigger
   root@radxa:~ # echo timer > /sys/class/leds/red/trigger
   root@radxa:~ # echo heartbeat > /sys/class/leds/red/trigger

You can use cat on the trigger property to list all the available values.

   root@radxa:~ # cat /sys/class/leds/red/trigger
   none test_ac-online test_battery-charging-or-full test_battery-charging test_battery-full test_battery-charging-blink-full-solid mmc0 mmc1 timer [heartbeat] backlight gpio default-on sleep rfkill0

Here is the list of current triggers:

• none
• test_ac-online
• test_battery-charging-or-full
• test_battery-charging
• test_battery-full
• test_battery-charging-blink-full-solid
• mmc0
• mmc1
• timer
• heartbeat
• backlight
• gpio
• default-on
• sleep
• rfkill0

The GPIO control external LEDs is moved to GPIO page.

turn off LEDs

use "none" trigger for triggered LEDs or just turn off for non-triggered LEDs.

e.g.

   echo none > /sys/class/leds/blue/trigger
   echo none > /sys/class/leds/green/trigger
   echo 0 > /sys/class/leds/red/brightness

you can modify kernel to change default state at boot.