[Nut-upsuser] Weekend Puzzle: computer posing as an UPS

[Jim Klimov]

FWIW, a few lessons learned:

* Different USB-A sized ports (even if marked USB-3.2) did not prove a
stable source, with Pi5 occasionally turning off or rebooting. Sort of
behaved well for days, but as soon as I added load like package installs or
NUT builds, it did not survive 5 minutes...

* Might be the MoBo turning off or cycling the port due to "overload"?..

* Tried the `usb_resetter` script (referenced in NUT contribs) and host
`dmesg` did show re-detection of keyboard etc., but a turned-off Pi did not
boot up. Did not check much further, but did harbor hopes that a funny NUT
driver could "shutdown/reboot" the USB port acting as an UPS for Pi...

* The Pi power socket is dumb-USB so the host does not "see" any IDs about
it.

* Currently trying with a USB-C port on the MoBo, and a USB-C to USB-C
cable rated for 60W -- and so far it survived a few loops of NUT fightwarn
builds. Complains of undervoltage fairly frequently (every 30-60s), but now
did not crash yet.

Jim


On Mon, Sep 16, 2024, 13:57 Greg Troxel via Nut-upsuser <
nut-upsuser at alioth-lists.debian.net> wrote:

> Kelly Byrd <kbyrd at memcpy.com> writes:
>
> > With USB-C ports and cables, there are a ton of profiles, I don't know
> what
> > the new Pi's support, but likely something like 3A @ 5V, 9V, or 12V over
> > USB-C
>
> Up to the RPI4, I was pretty sure there wasn't PD, just 5V and it drew
> what it drew, and you hoped that the supply was big enough.
>
> It seems the RPI5 will use PD if given a capable supply.  Looks like 5V
> 5A, and it won't negotitate higher voltages.   There's an official
> supply that does PD
>
>
> https://www.newark.com/raspberry-pi/sc1153/power-supply-usb-c-5-1v-5a-white/dp/82AK3955
>
> and the output spec is
>
>   5A at 5.1V, 3A at 9V, 2.25A at 12V, 1.8A at 15V
>
>   looks like a TUV seal
>
>
>
> I find Jim's way of using this interesting, but my approach is totally
> different.  First, when I'm using a Pi, it's because I want a low power
> computer that I can leave on all the time, or can place in a different
> physical location I don't particularly want to do things on a Pi instead
> of a desktop.  And then I want it to be reliable.
>
> That leads me to plug a power supply into a UPS, or to use POE (from a
> POE switch which is plugged into a UPS).  For RPI3, I found a POE
> ejector that splits the POE ethernet cable into ethernet only and a
> micro USB.
>
>
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