LED documentation

#1

Hello - can’t find any info on Rock Pi 4 LEDs.

I have tried to modify

/sys/class/leds/status/max_brightness

but even root cannot change this value from 255.

I am using Rock Pi 4B+ in my bedroom and the green LED is VERY bright at night. Would like to turn off so I can sleep!

#2

Please try the following commands:

sudo -i
echo 124 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio124/direction
echo 1 > /sys/class/gpio/gpio124/value
#3

Unfortunately didn’t work. I rebooted, and tried on a fresh reboot:

Welcome to Ubuntu 20.04.4 LTS (GNU/Linux 5.10.103+ aarch64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage
Last login: Thu Jun  2 05:32:20 2022 from 10.162.110.109
andrew@rock01:~$ sudo -i
[sudo] password for andrew:
root@rock01:~# echo 124 > /sys/class/gpio/export
root@rock01:~# echo out > /sys/class/gpio/gpio124/direction
root@rock01:~# echo 1 > /sys/class/gpio/gpio124/value
#4

When I cat these files (as root):

root@rock01:~# cat /sys/class/gpio/export
cat: /sys/class/gpio/export: Permission denied
root@rock01:~# cat /sys/class/gpio/gpio124/direction
out
root@rock01:~# cat /sys/class/gpio/gpio124/value
1
#5

After some testing it seems that those commands only work for 4C, and due to design difference GPIO control for 4B is not working at the moment. I think you have to use physical means to solve this issue, ex. using opaque tape to cover the led.

1 Like
#6

Thanks for fast response!