The Radxa Rock has 3 LEDs on board.

LED	GPIO ref.	GPIO number
Green	GPIO0_B4	172
Blue	GPIO0_B6	174
Red	GPIO0_B7	175

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.

Rock/LED

Contents

LEDs as class devices