TL;DR: What does it take for e.g. the Power LED on the ATX board to sense a signal?
Long version: I’m trying to connect a Raspberry Pi 5 to the ATX board. I’ve soldered a header onto the Rpi5 (remember it’s different than previous Pi’s) for the power button and that works nicely, but sensing power on the Rpi5 is complicated because, as my Google-fu is telling me, the GPIO’s aren’t on the SoC directly but are external and so stay powered even when the Pi proper is off.
I’ve added
dtoverlay=gpio-poweroff,gpiopin=26 to /boot/firmware/config.txt
which does make the pin go high, to 3v3, when the machine is active, and low (~0V) when the machine is powered off. I measured that with a voltmeter, not with any load connected.
However, the PiKVM doesn’t see the system as powered; shows me the screen nicely, but the power LED indicator is black.
Does the power LED connection require load, some sort of current through? Or does it want more than 3v3, like maybe 5V? Or is this the sort of thing where I should be sacrificing rubber chickens to the RPi gods?
A couple of our electronically savvy team members suggested you could use the 3v3 with the power LED with the other leg to a GND pin, but the Pi5 is a fun beast that also keeps the 3v3 active unless you change some EEPROM settings and the config.txt.
I don’t have a Pi5 on hand to test, but trying some of these settings might help, depending on what HATs might conflict.