opi5: leds

content/blog/opi5u-review/index.md

@@ -143,6 +143,25 @@ Please don't judge the soldering, I only used salvaged material:
 
 I made [a program](https://git.txmn.tk/tuxmain/opi-fancontrol) to control the fan depending on the CPU temperature.
 
+## The LEDs
+
+The board has a green LED and a blue LED that can be controlled. By default, they are pulsing heartbeats. That may be convenient as it indicates the system has booted correctly. The heartbeat frequency also depends on the system load.
+
+As they are quite bright, they can get annoying, especially if the server is in the living room where someone may want to watch a movie or sleep on the couch.
+
+The following commands disable the heartbeat behavior, and switches off the LEDs.
+
+```bash
+echo none | sudo tee /sys/class/leds/blue_led/trigger
+echo none | sudo tee /sys/class/leds/green_led/trigger
+echo 1 | sudo tee /sys/class/leds/blue_led/brightness
+echo 1 | sudo tee /sys/class/leds/green_led/brightness
+```
+
+Heartbeat can be enabled again by replacing `none` with `heartbeat`. The LEDs can be switched on by replacing `1` with `0` (I guess it represents the cathode voltage).
+
+These settings are not permanent. To make it persist after reboot, add these commands to `/etc/rc.local`.
+
 ## Remaining problems
 
 I don't have an IPv6 interface? That's probably because of Armbian (or the model mismatch) as it's a nightly community version.

sass/css/_content.scss

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+code {
+	white-space: pre;
+}
+
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