Low Voltage Indications

[John BOSSERT]

I recently discovered that dmesg has been filling with "low voltage," "voltage ok," messages. Pi 3B+, fed by an Official Pi power supply via the microUSB connector on the Pi.

Tried a Pi 5 Official power supply (with USB-C adaptor). Same problem.

Detached the Pi from the PiDP-11 PCB. Voltage complaints ended.

So, it would appear that there's an issue with the PCB. The archives discuss this from an anecdotal perspective, but I'm not finding a "here's how to fix..." Hoping that there's a recommended resolution for this issue. Thanks for any guidance...

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John Bossert

[Alan B]

Perhaps the additional load of the PiDP-11 is overloading this particular Pi power supply? Try a higher current Pi supply. The best ones have slightly higher voltages as well. Pi's are sensitive to voltage.

Regards, Alan

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[Whit Turner]

The official PI 5 supply should be way more than enough for a 3B+ unless the micro USB connector is flakey. It is also possible to power a Pi via the GPIO pins, which is one possible way to narrow down the issue.

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[Anton Lavrentiev]

I had problems with the "official" Pi power supply, which was constantly causing under-voltage in my 3B+, and ended up using a 5.25V (5.35V actually) 3A power supply from Amazon -- haven't seen the issues since...

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[Michael Harpe]

I bought a 5V/5A power supply that had a coaxial plug on it. Used a microUSB adapter and hooked up and it works fine on a souped up 3B2 with a SSD on it. Did the same for my PiDP-11. I think Raspberry Pi tends to lean a little bit optimistic with their power supply requirements. 

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[oscarv]

John,

Because you used the 'official' Pi power supply and the problem goed away when unplugging the Pi from the PiDP, it looks like some current leak on the PiDP board.

Because the PiDP hardware hardly adds to the power consumption (IIRC, 4mA pre LED times 16 LEDs at the same time, plus a marginal bit for the onboard IC). Unless there's something wrong with the soldering of the board.

I would:

1) reheat/reflow the pins on the GPIO connector. Then, clean between them with alcohol (or vodka etc, proven just as effective in a couple of cases)

If that does not solve the problem, 

2) look for solder bridges or crusty smudges of flux on the board. I used to think that flux remains were never a problem, and normally they are not. But I've seen a few cases where that was the issue

Use a multimeter to check for resistance between 5V and GND on the board. Alas, I do not have a PiDP-11 at hand here, so I can't tell you what is the normal reading. But it should be so low as not to cause the power problem you have.

Please let me know. Always interesting to go on a bug hunt!

Kind regards,

Oscar.

[stephan küppers]

Hello!
I use a raspberry pi 4 with the PiDP-11 and an original Raspi power supply with 5.35V and 2.5A. I also often have an undervoltage message. Direct voltage measurement on the GPIO between +5V and GND results in a voltage between 4.75V and 4.85V. This indicates that the PiDP-11 is under too much strain. I will now test a direct power supply with 5V on the GPIO connections.
Stephan

[Marco]

The following is *NOT* the proper way to "solve" undervolt warnings, you should solve the issue and not hide it...but...there is a way to get rid of the warnings (and the yellow lightning bolt on screen):

Add the line "avoid_warnings=1" to /boot/config.txt at the bottom (under "[all]"). Note that low voltages can lead to system crashes and/or corrupt SD cards. I'm not quite sure if this works for all RPI's (like the 5) but you'll find that out easily enough.

There also used to be an "avoid_warnings=2" option which allows (allowed?) an undervolted system to stil run in turbo mode, but that's strongly discouraged if still valid at all.

I use the "1" option on some of my RPI's when I am very sure the occasional undervolt warning is harmless.

Op zaterdag 17 augustus 2024 om 11:38:01 UTC+2 schreef stephank...@gmail.com: