I guess I should scratch the idea about fan sockets as the power source: they are rated typically at 0.2A each, so fan headers should be expected 1A max (3A in some vendors/models), well under the 5A that the RPi5 wants.
Jim On Sat, Sep 28, 2024 at 11:52 AM Jim Klimov <[email protected]> wrote: > Follow-up: > > * Powering the Raspberry Pi5 from an USB-C port wired on the motherboard > was much more promising, it survived over 8 hours building NUT in a loop > (in a tmpfs). And in the morning I found it turned off (red light on the > Pi). > > * Per > https://stackoverflow.com/questions/4702216/controlling-a-usb-power-supply-on-off-with-linux > it seems not possible to programmatically truly power-cycle USB port/hub, > as 5V pins are "always on"; and per > https://stackoverflow.com/a/16316401/4715872 - at least not on MoBo ports > (some hubs may have invested into being fully up to spec and control power > fully). The referenced uhubctl <https://github.com/mvp/uhubctl> on my PC > said "No compatible devices detected!" so I guess that's it. > > * Whatever I could find with (suggestions welcome) `grep -r . `find > /sys/devices/pci0000\:00 -name '*usb*port*'` /sys/bus/usb/devices/` did > not expose any differences beside timestamps with the RPi5 plugged and off, > unplugged, and plugged back in again (with auto-boot). I hoped for some > power draw statistics to at least learn which port it lives on, to try > managing that somehow. > > * Overall, housing the Pi inside a cooled and somewhat dust-protected PC > case seems a neat idea, but for powering the Pi, it seems I would need to > use a real wall-power adapter (as noted many times on the net, ideally > Raspberry's own one as others tend to vary in actual voltage provided under > load). > > * But before that, I'm thinking if I could tap into the ATX power supply > though (using "HDD" or "FDD" plugs) or fan sockets (could be individually > manageable? gotta exempt one from OS/HW temperature-based mgmt then). > > Did anyone trod these side paths yet, any learnings? :D > > Jim > > > > > > > > On Fri, Sep 27, 2024 at 4:43 PM Jim Klimov <[email protected]> > wrote: > >> 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 < >> [email protected]> wrote: >> >>> Kelly Byrd <[email protected]> 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. >>> >>> >>> _______________________________________________ >>> Nut-upsuser mailing list >>> [email protected] >>> https://alioth-lists.debian.net/cgi-bin/mailman/listinfo/nut-upsuser >>> >>
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