Thanks for the info about the input voltage sensitivity of the Beaglebone, good chance this is the real issue, especially as there was a good chance for "ground bounce" between different parts of the system from my mistake in powering one of the PIR sensors off the "wrong" UPS. Time will tell. If it happens again now that I've corrected that mistake, I'll look into powering the BB with a better supply, and/or look into adding the backup battery option.
Due to the location, shielding the BB in a metal box is way too invasive to try. Since the RPi2 has had no issues either time I consider the evidence that shielding would help to be shaky at best. I got it booted again by unplugging the BB wal-wart 5V supply and plugging it back in. As a last resort I can add a watchdog and relay to interrupt the BB power and re-apply it after ~30 seconds. -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/023e9e06-2c70-4980-a197-ed9435c7a90c%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
