On Wed, 20 Jun 2018 21:32:54 +0000, bob prohaska wrote:

> 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

From elinux:

vcgencmd measure_volts 

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

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