How To Control LEDs

Switch to root user

Only the root user has the authority to control and modify the node status of the LEDs

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khadas@Khadas:~$ su
Password:
root@Khadas:/home/khadas#

Confirm led node

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root@Khadas:/home/khadas# cd /sys/class/leds/
root@Khadas:/sys/class/leds# ls
mmc1::  read_led  sys_led

How To Use

Here takes sys_led as an example:

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root@Khadas:/sys/class/leds# cd sys_led
root@Khadas:/sys/class/leds/sys_led# ls
brightness  device  invert  max_brightness  power  subsystem  trigger  uevent

View all configurable parameters.

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root@Khadas:/sys/class/leds/sys_led# cat trigger
none rc-feedback kbd-scrolllock kbd-numlock kbd-capslock kbd-kanalock kbd-shiftlock kbd-altgrlock kbd-ctrllock kbd-altlock kbd-shiftllock kbd-shiftrlock kbd-ctrlllock kbd-ctrlrlock mmc0 mmc1 timer oneshot [heartbeat] backlight gpio cpu0 cpu1 cpu2 cpu3 cpu4 cpu5 default-on transient flash torch rfkill0 mmc2 rfkill1 rfkill2

Turn off

Enter none parameter to turn off the LED

1	root@Khadas:/sys/class/leds/sys_led# echo none > trigger

Turn on

Enter default-on parameter to turn off the LED

1	root@Khadas:/sys/class/leds/sys_led# echo default-on >trigger

Set heartbeat can make the LED flash

1	root@Khadas:/sys/class/leds/sys_led# echo heartbeat > trigger

You can also try other parameters.