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RPi 3B+ green LED 4 fast blinks continuous but normal boot

Posted: Fri Sep 14, 2018 4:01 pm
by kevin.shumaker
I have purchased a RPi 3 B+ from Element14. I have several of every other model made, so not a complete noob.
I have noticed that it blinks rapidly 4 times, pauses, then repeats. I have checked it with SD cards and USB boot.
I have used the 4/2018 and 6/2018 Raspbian Stretch & Lite images from this site.
I have tested with several known good power supplies.
I have tested the images on 2B and 3B devices using the same boot media on the 3s, and the SD only on the 2s, and it doesn't occur there.
The system seems to be working fine, it boots and runs 'normally' but the flashing (very rapid blink, blink, blink, blink, pause, repeat)
is disconcerting. Is this an error condition? Element14 wasn't able to assist, either with 'yes' or 'no'. My google-fu is only able to find comments about if it doesn't boot with this blinking sequence.

Thanks for any assistance you can provide.

Re: RPi 3B+ green LED 4 fast blinks continuous but normal boot

Posted: Fri Sep 14, 2018 8:06 pm
by LTolledo
the green LED blink symptom is usually present in no-microSD USB-boot RPi3B and RPi3B+. Its due to the RPi trying to look for the microSD card

to "silence it" add this to the config.txt file

Code: Select all

dtoverlay=sdtweak,poll_once
and reboot.

On my microSD boot Raspbian Lite RPi3B, (updated and upgraded just now ) the symptom is not present.

Re: RPi 3B+ green LED 4 fast blinks continuous but normal boot

Posted: Fri Sep 14, 2018 8:25 pm
by HawaiianPi
LTolledo wrote:
Fri Sep 14, 2018 8:06 pm
the green LED blink symptom is usually present in no-microSD USB-boot RPi3B and RPi3B+.
Its due to the RPi trying to look for the microSD card...
That's normally only a single blink each second (not 4 blinks).

4 blinks is a error with start.elf, but that usually results in no boot. :?

Re: RPi 3B+ green LED 4 fast blinks continuous but normal boot

Posted: Fri Sep 14, 2018 10:35 pm
by jbudd
to "silence it" add this to the config.txt file

dtoverlay=sdtweak,poll_once

and reboot.
That green LED on my USB boot Pi 3 has been driving me round the bend. Thanks!

Re: RPi 3B+ green LED 4 fast blinks continuous but normal boot

Posted: Sat Sep 15, 2018 12:02 am
by kevin.shumaker
Yay! <sorta 8-) > That cured the 4 rapid blinks.

Are there any docs for this, or to have the ACTIVITY light work as an ACTIVITY light? Which was the disk access indicator?

Re: RPi 3B+ green LED 4 fast blinks continuous but normal boot

Posted: Sat Sep 15, 2018 12:25 am
by HawaiianPi
kevin.shumaker wrote:
Sat Sep 15, 2018 12:02 am
... or to have the ACTIVITY light work as an ACTIVITY light? Which was the disk access indicator?
Technically, it's an SD card access indicator.

It also serves as a shutdown indicator by blinking 10 times after shutdown is complete, with the last flash being longer than the rest. So after issuing a shutdown command, watch that green LED, and when you see nine evenly spaced flashes followed by a tenth longer flash, it's safe to turn off the power.

And, of course, there are the blink error codes, which yours seemed to be doing, so I was surprised when you said it fixed your issue. I thought it only blinked once every second when polling the card slot, but I usually leave an empty SD card in the system to shorten USB boot time, so I don't really have that problem. Guess I remembered it wrong.

Glad you got it fixed.

Re: RPi 3B+ green LED 4 fast blinks continuous but normal boot

Posted: Sat Sep 15, 2018 1:41 am
by LTolledo
jbudd wrote:
Fri Sep 14, 2018 10:35 pm
That green LED on my USB boot Pi 3 has been driving me round the bend. Thanks!
kevin.shumaker wrote:Yay! <sorta > That cured the 4 rapid blinks.


Glad to be of service :D