chrisfenton
Posts: 3
Joined: Thu Aug 10, 2017 2:31 pm

Power supply undervoltage monitoring

Thu Aug 10, 2017 3:02 pm

My question is simple, how can I programatically monitor my power supply input voltage? I know that it turns on the yellow lightning bolt on my desktop when there is a problem, but most of my Raspberry PIs don't have monitors attached to them. All the results from vcgencmd show no difference, except "vcgencmd get_throttled" that shows:

Bad PI: throttled=0x50005
vs
Good PI: throttled=0x50000

Is there another command that I should be using to monitor power supply quality?

A little background on my situation, if anyone is interested. The problem PI is using a power supply that I reused from my original PI 1, which I accidentally killed. When I was doing testing of compression and encryption on a usb thumb drive, at random points the mount would go read only. In my online research I discovered the meaning of the lightning bolt on my desktop, and my solution was to order a new power supply with more than adequate capacity. I would like to setup monitoring of this condition on all my PIs, and if anyone knows of any other PI internals that I can monitor, please chime in. Also, I currently have 1 PI2 running with a NOOBS 2.4 build installed, and 4 of the latest PI3's, all but this one quietly doing their thing in the background.

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davidcoton
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Joined: Mon Sep 01, 2014 2:37 pm
Location: Cambridge, UK

Re: Power supply undervoltage monitoring

Thu Aug 10, 2017 7:11 pm

"vcgencmd get_throttled" tells you (amongst other things) all the Pi knows about the quality of its power. To get any more you need an analogue to digital convertor to measure the key voltages -- mainly the 5V rail, possibly battery if you run from one.
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pcmanbob
Posts: 11937
Joined: Fri May 31, 2013 9:28 pm
Location: Mansfield UK

Re: Power supply undervoltage monitoring

Fri Aug 11, 2017 11:43 am

chrisfenton wrote:
Thu Aug 10, 2017 3:02 pm
My question is simple, how can I programatically monitor my power supply input voltage?
You can monitor it using some simple python which mikerr posted in this thread viewtopic.php?f=29&t=82373&start=75
you could modify that code to do what ever you wanted with the result.
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