eokic
Posts: 2
Joined: Sat Jul 27, 2019 11:17 pm

[SOLVED] Pi 4: Red light (but working normally?)

Sat Jul 27, 2019 11:32 pm

Newbie here,

This is probably a dumb question but I can't find a definitive answer/documentation on the Raspberry Pi 4 (first time tinkering with a Pi either way).

As far as I can tell, my Raspberry Pi works perfectly fine, but the red light is always on. Can someone please confirm this is expected behaviour or if I should be debugging it?

In case it's supposed to be ON: perhaps you could just point me in the direction as to whether I can turn it off or lower the brightness of it (it's quite bright).

In case it's supposed to be OFF: I know this much:
  • Raspberry Pi 4 (4GB)
  • SanDisk Extreme 128GB microSDXC
  • I've installed the "Raspbian Buster with desktop and recommended software" following Method 2 of this guide https://medium.com/@maheshsenni/setting ... 59e0926807
  • Had no issues booting, installing or anything really
  • The red light is on from the very beginning, probably from the very second I turned it on

Thanks!
Last edited by eokic on Mon Jul 29, 2019 8:35 am, edited 1 time in total.

hippy
Posts: 6069
Joined: Fri Sep 09, 2011 10:34 pm
Location: UK

Re: Pi 4: Red light (but working normally?)

Sun Jul 28, 2019 7:19 pm

Yes, the red LED is meant to be always on, but it will be turned off if voltage is low. There may be some software trick to keep the LED permanently off or means to bit-bang PWM to it to dim it.

Physical removal will ensure it cannot be turned on, and sticky tap can reduce its brightness.

dgordon42
Posts: 764
Joined: Tue Aug 13, 2013 6:55 pm
Location: Dublin, Ireland

Re: Pi 4: Red light (but working normally?)

Sun Jul 28, 2019 7:36 pm

See the file '/boot/overlays/README' on your Pi.

The dtoverlay 'pwr_led_activelow' will allow you to change the action of the red power LED, you can have it off when the power is OK instead of the default on.

Hope this helps,
Dave.

eokic
Posts: 2
Joined: Sat Jul 27, 2019 11:17 pm

Re: Pi 4: Red light (but working normally?)

Mon Jul 29, 2019 8:34 am

Got it, thank you!

For any other newbies that stumble on this post, I've successfully turned off the Power LED on Pi 4 by adding the following to /boot/config.txt

Code: Select all

# Disable the PWR LED.
dtparam=pwr_led_trigger=none
dtparam=pwr_led_activelow=off

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