So you generate a Brown-Out condition, which means that you operate the part outside the spec. Dont expect to get any electronic to work after you enter Brown-Out... Once Brown-Out occurs, you typically have to recover by totally removing power until you are below certain thresholds which are chip dependent. This can take a number of seconds.
To protect agaist Brown-Out you need a backup battery (or a SuperCap) and electronics which shuts down the Beaglebone gracefully and keps the Beaglebone off power until nomal power is restored. Best Regards Ulf Samuelsson 28 apr 2014 kl. 16:39 skrev James Littlefield <[email protected]>: > Hi Jay, > > I think this was covered in my original post.... > > "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" > > The command line is not involved. > > I was using a lab supply and just switching it off for about 500ms then back > on. I have also been able to cause the problem using an adjustable output > supply by lowering the input voltage to around 2V then going back up to 5V. > > Regards, > Jim > > > > > On Fri, Apr 25, 2014 at 7:58 PM, <[email protected]> wrote: > 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 a topic in the Google > Groups "BeagleBoard" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/beagleboard/p0CwsGzNYNw/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > For more options, visit https://groups.google.com/d/optout. > > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to a topic in the Google > Groups "BeagleBoard" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/beagleboard/p0CwsGzNYNw/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > For more options, visit https://groups.google.com/d/optout. -- 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.
