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Author Topic: Meaning of LED blinking  (Read 798 times)

Offline pintman

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Meaning of LED blinking
« on: April 02, 2018, 08:30:47 AM »
Hi!

I installed picore on a RaspberryPi 3 and wonder what the blinking of the LEDs means. The red Power LED seems to be on when there is nothing going on and turns of if the CPU has some workload. The green activity LED on the other hand blinks now and then - maybe it has something to do with the networking?!

Can anyone point me to some clarification about this blinking?

Thanks für help. :)

Online Rich

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Re: Meaning of LED blinking
« Reply #1 on: April 02, 2018, 09:17:05 AM »
Hi pintman
Quote
In the later models (A+, B+, Pi 2 & Pi 3) the power LED is slightly more intelligent. it is connected to the 5V and will flash if
the voltage drops below 4.63V.
From:
https://www.raspberrypi-spy.co.uk/2013/02/raspberry-pi-status-leds-explained/

Offline pintman

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Re: Meaning of LED blinking
« Reply #2 on: April 02, 2018, 11:44:09 AM »
Thank you for the link. Therefore, I assume that no modifications have been made for the picore distribution to change the default behavior?

Online Rich

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Re: Meaning of LED blinking
« Reply #3 on: April 02, 2018, 11:49:50 AM »
Hi pintman
The blinking suggests to me that your power supply voltage is dropping too low when you make the Pi do some work. Could
be a weak power supply or maybe excessive wire length between the Pi and power supply.

Offline Misalf

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Re: Meaning of LED blinking
« Reply #4 on: April 02, 2018, 02:23:14 PM »
The green LED mostly indicates reads/writes to the µSD card.
It's used to indicate other things as well. Like blinking 10 times when the RPi shuts down or different "blink-codes" to indicate things like boot errors. Like "beep-codes" on traditional PCs.
I believe the OS doesn't have much control over the status LEDs or it would be pointless anyway, because the LEDs are controlled by the hardware/firmware to indicate hardware stuff.
Download a copy and keep it handy: Core book ;)

Offline bmarkus

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Re: Meaning of LED blinking
« Reply #5 on: April 02, 2018, 07:31:38 PM »
You can modify how LED(s) are working in config.txt or via /sys/class/leds For details read

https://monkeyinmysoup.gitbooks.io/raspberry-pi/content/5.2-leds.html

Béla
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"Amateur Radio: The First Technology-Based Social Network."

Offline pintman

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Re: Meaning of LED blinking
« Reply #6 on: April 02, 2018, 11:42:08 PM »
Thanks for you answers. I powered the Pi with a Powerbank - maybe this could be the source of an error and lead to the blinking of the red LED.

I thought that picore boots into RAM completely. Therefor I was surprised to see the green LED blinking.

Offline bmarkus

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Re: Meaning of LED blinking
« Reply #7 on: April 03, 2018, 12:59:50 AM »
I thought that picore boots into RAM completely. Therefor I was surprised to see the green LED blinking.

piCore itself runs in RAM but by default extensions are loop mounted and not copied to RAM.
Béla
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"Amateur Radio: The First Technology-Based Social Network."

Offline pintman

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Re: Meaning of LED blinking
« Reply #8 on: April 03, 2018, 01:29:07 AM »
Thanks for clarifying the loop-mount. Is it possible to boot extensions into the RAM, too?

When using a power plug instead of the powerbank the red LED now stays red. :)

Offline Juanito

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Re: Meaning of LED blinking
« Reply #9 on: April 03, 2018, 02:36:15 AM »
yes, you can use the copy2fs flag