Odroid C2: Change the Function of the blue LED

[Odroid C2] Change the Function of the blue Status LED:

Normally the blue LED of the Odroid C2 is used to show a kernel „Heartbeat“ which represents the cpu, but the Linux kernel also offers you possibilities to change this behaviour (for example: showing sd activity, blinking or deactivate it completley)

When you want to change the LED Behaviour you have to follow these steps:

1: Change into the Directory that represents the led:

cd /sys/class/leds/blue:heartbeat

2: Change to root user, so that you can write the device file:

sudo su

For a list of all supported led modes and the one that is currently used, you can use this command:

cat trigger

If you want to set a led mode you use a command like this (without quotes) „echo [your led mode] > trigger“. For example if you want to set the original heartbeat mode again you would use this command:

echo heartbeat > trigger

Some of the supported Led Modes Explained:

    • heartbeat: The default used mode. It blinks like a „heartbeat“ when the kernel is active. The frequency of the beat depends on cpu load
    • none: Deactivate the led completly.
    • sd / emmc: The led shows access to the sd card respectivley the emmc memory
    • blink: The LED starts to blink. You can control on and off times with writing the times in milliseconds into delay_on and delay_off
    •  cpu0/cpu1 … : This trigger should show cpu activity on the selected core [not tested]
    • torch: With this trigger selected, the LEDs is permanent on, but you can set the brightness with writing into the brightness file (0 is no light, 255 is max brightness). For example when you want to set the led to the half brightness you would use this command:
echo 127 > brightness

Make these settings happen on start up (permanently)

When you want these setting permanentley you only have to edit the file /etc/rc.local. You have to put the command from above with full path before the „exit 0“ line. For Example

echo sd > /sys/class/leds/blue:heartbeat/trigger

 

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Ein Gedanke zu “Odroid C2: Change the Function of the blue LED

  1. Great little tutorial! I have been trying to figure out how to disable the incredibly annoying LED for the past hour and a half. I am so glad I stumbled across this post! Great job!

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