Superpi
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(solved) Disable red power led on 3B+

Mon Aug 13, 2018 8:12 pm

Hello,
I am looking for a way to switch off the red power led on a Raspberry Pi 3B+. It seems this was possible on previous models but the option no longer exists on the 3B+.

I am embedding the Pi in a light-art project and the red glow in some circumstances is rather visible. Covering the led (in black paint) is an option I would rather not take. I am looking for a way to disable the led temporarily thru software.

For reference: https://www.jeffgeerling.com/blogs/jeff ... spberry-pi

Any help appreciated.
Last edited by Superpi on Tue Aug 14, 2018 7:30 pm, edited 1 time in total.

hippy
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Re: Disable red power led on 3B+

Mon Aug 13, 2018 8:44 pm

The power LED on the Pi 3B+ is connected across 5V and 0V so lights up whenever power is supplied, whether through the micro-USB connector, GPIO or test points. The LED can however be shorted out and turned off by using the STATUS_LED_R control line.

Unfortunately the full Pi 3B+ circuit diagrams are not available and the reduced schematic does not show where the STATUS_LED_R signal originates from.

Only someone from the RPT engineering team or with access to the full circuit diagrams or internal Pi information will be able to help further.

Added: Or someone who has the skills and patience to reverse engineer or figure things out anyway ...

viewtopic.php?f=72&t=208381

"The PWD_LED, it is still connected to the GPIO expander that is only available using the mailbox interface.

We posted some info last year about the GPIO expander, that interface still works on the Pi 3B+ except the red LED has moved to pin 2 and is now active low instead."

Superpi
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Re: Disable red power led on 3B+

Mon Aug 13, 2018 9:57 pm

Thanks, hippy, for a knowledgable and quick answer. I take that as "No, not with a few hours of work and certainly not using Ruby".

I'll have to resort to some kind of hardware hack.

That led is rather annoying and useless to me.

Cheers

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Imperf3kt
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Re: Disable red power led on 3B+

Mon Aug 13, 2018 11:46 pm

Why is the red light annoying? I'd expect the green ACT light to be more annoying.

Blue tack works wonders for silencing LEDs.
Stop plugging your fan directly into the GPIO 5v
https://www.electronics-tutorials.ws/power/transient-suppression.html

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Burngate
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Re: Disable red power led on 3B+

Tue Aug 14, 2018 8:54 am

The trouble with the BluTack method is applying / removing it in software.

If you're willing to hack the board, there's a pad, PP10, at the top of the LED.
A FET from that to ground could be controlled by a normal GPIO - choose one that defaults to pull-down (so not GPIOs 0-8) and it should work normally until you switch the FET on.

6by9
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Re: Disable red power led on 3B+

Tue Aug 14, 2018 9:15 am

Same as for (I believe) all previous models.

Code: Select all

sudo su -
echo none > /sys/class/leds/led1/trigger
echo "default-on" to reset it back to being on.

(Yes there are single line alternatives without starting a root shell. but I can never remember them)
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LTolledo
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Re: Disable red power led on 3B+

Tue Aug 14, 2018 9:17 am

If not available in software, how about covering it up with generous amount of black colored hot-glue
"Don't come to me with 'issues' for I don't know how to deal with those
Come to me with 'problems' and I'll help you find solutions"

Some people be like:
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hippy
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Re: Disable red power led on 3B+

Tue Aug 14, 2018 10:18 am

Superpi wrote:
Mon Aug 13, 2018 9:57 pm
Thanks, hippy, for a knowledgable and quick answer. I take that as "No, not with a few hours of work and certainly not using Ruby".
I wouldn't be that absolute. If the LED can be controlled through the mailbox interface then it should be possible to control it from Ruby or anything else.

Superpi
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Re: Disable red power led on 3B+

Tue Aug 14, 2018 2:38 pm

6by9's answer worked like a charm. Thank you!

Sadly I acted too hastily in applying 6 coats of L'Oreal Color Riche No. 674 "noir".
However, the effect is still clearly visible.

Thanks everybody who replied. Onwards and upwards.

desperado
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Joined: Fri Oct 26, 2018 4:44 pm

Re: (solved) Disable red power led on 3B+

Fri Oct 26, 2018 5:13 pm

This worked for me for a while but has stopped. Not sure why.
I had a script which runs on boot with the following

Code: Select all

#Power LED off
sudo sh -c 'echo 0 > /sys/class/leds/led1/brightness'
sudo sh -c 'echo none > /sys/class/leds/led1/trigger'
#Activity LED off
sudo sh -c 'echo 0 > /sys/class/leds/led0/brightness'
But it no longer works for the power LED on my Pi3B+.
If I sudo and edit the brightness with vi changing 255 to 0 and then save. It's still 255 when I cat it out.
Something just writes the original values back into the place.

Any thoughts on why this is happening?
Led0 works LED1 (Power) doesn't and it's crazy bright. I am using this for an install of hassbian and have it in a main room to control my home automation. So the light is quite distracting.

Next step will be to replace my clear case with a solid one but I was hoping to not spend money to fix. Seems there should be a way to solve my the software solution isn't working for me anymore.

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