I just foolishly posted pretty much the same question... I'm seeing very similar behavior, I also noticed that it can still be powered from the USB when in this state but not VDD_5V.
Can you please elaborate on the brownouts that you're seeing. You said they're occurring when "the power is switched off", is this in software, i.e. "shutdown -h now"? I haven't been able to see this on my scope but I also can't reliably recreate the situation in which it occurs. I know the PMICs are the same on RevA and RevB, but I believe I've only seen this on RevB boards. Thanks! jay On Monday, November 18, 2013 5:00:55 PM UTC-8, James Littlefield wrote: > > New to BBB but experienced with embedded systems. > > I'm working on a project using the BBB. Supplying +5V (up to 3A) > directly to the pins on P9 from a quality bench supply. I've found that > briefly switching the +5V supply OFF and then back on can pretty reliably > leave the BBB in an odd state characterized by... > a) No LEDs on > b) Very little current drawn from supply (10mA or less) > c) +5 present on P9.5 and P9.6 > d) 0.687V on P9.7 and P9.8 ( should be SYS_5V ). > e) P9.9 = 3.57V > f) P9.10 = 0V > > I've found that once the system is in this mode no amount of > pressing/holding the momentary BBB pushbuttons will get the system working > again. Removing input power, waiting 10 sec or so, then restoring power > will get things working again. > > Has anyone else seen this? It seems sort of like an issue with > the TPS65217C chip but I've not found any reported errata on that part. > > Thanks > Jim > > > -- 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]. For more options, visit https://groups.google.com/d/optout.
