Monitoring internal voltages

bob prohaska

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Jun 20, 2018, 5:32:55 PM6/20/18

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Does the Pi (Pi3, in particular) have any ability to report
interal power supply voltages? Spot checks with a voltmeter
on the GPIO header are some help, but a running test that can
be logged over time would be much more informative.

I found a web page suggesting "vcgencmd measure_volts core"
but on my Pi3 it reports VCHI "initialization failed". Apropos
didn't hit on voltage or volt

As it happens I want to do this under FreeBSD, but if it can't
be done under Raspbian there's no hope. If it can, then I'll
look further.

Thanks for reading,

bob prohaska

Rob Morley

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Jun 20, 2018, 7:46:30 PM6/20/18

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That command works on a 3B+ and a Zero W (running a recent Raspbian
Lite headless) although it returns a suspicious looking "volt=1.2000V"
on both of them.

ray carter

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Jun 20, 2018, 8:34:05 PM6/20/18

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From elinux:

vcgencmd measure_volts <id>

Shows voltage. id can be one of core, sdram_c, sdram_i, sdram_p, and
defaults to core if not specified.

root@raspberrypi:~# \
> for id in core sdram_c sdram_i sdram_p ; do \
> echo -e "$id:\t$(vcgencmd measure_volts $id)" ; \
> done
core: volt=1.20V
sdram_c: volt=1.20V
sdram_i: volt=1.20V
sdram_p: volt=1.23V

Jim Jackson

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Jul 2, 2018, 4:35:18 PM7/2/18

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I got initialization failed until I ran it as root (or used sudo)

bob prohaska

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Jul 6, 2018, 10:02:34 PM7/6/18

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Thank you! I shoulda guessed....

bob prohaska

A. Dumas

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Jul 7, 2018, 3:58:42 AM7/7/18

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On 07/07/2018 04:02, bob prohaska wrote:
> Jim Jackson wrote:

>> On 2018-06-20, bob prohaska wrote:
>>> I found a web page suggesting "vcgencmd measure_volts core"
>>

>> I got initialization failed until I ran it as root (or used sudo)
>
> Thank you! I shoulda guessed....

Normally it works without sudo, though. Could be something wrong with
your Raspbian installation or at least s/t non-standard, perhaps like
using a different user account than pi.

bob prohaska

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Jul 7, 2018, 9:23:23 PM7/7/18

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I am using s different account than pi, but I tried my double-damndest
to make all the changes required to get along without the pi account
and _thought_ I'd succeded.

Guess not 8-(

Thanks for writing,

bob prohaska

A. Dumas

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Jul 8, 2018, 1:40:02 AM7/8/18

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bob prohaska <b...@www.zefox.net> wrote:

> A. Dumas <alex...@dumas.fr.invalid> wrote:
>> Normally it works without sudo, though. Could be something wrong with
>> your Raspbian installation or at least s/t non-standard, perhaps like
>> using a different user account than pi.
>
> I am using s different account than pi, but I tried my double-damndest
> to make all the changes required to get along without the pi account
> and _thought_ I'd succeded.
>
> Guess not 8-(

Might not be your fault; apparently user pi is hardwired in a lot of
RPi-specific code :(

Martin Gregorie

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Jul 8, 2018, 4:58:40 AM7/8/18

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That wouldn't surprise me at all - just look at the ever-increasing list
of hard-wired user names used by any of the mainstream Linux distros.

That said, I've never used pi on my RPi - one of the first things I did
was to set up another login and configure it to work in much the samw way
as my usual logins on by Fedora systems.

--
Martin | martin at
Gregorie | gregorie dot org