Could this problem be a result of leaving the Reset pin (44) of U2 (TPS65217C) unconnected in the BBB design? Would resetting U2 cause a recovery?
On Thursday, May 1, 2014 8:43:57 PM UTC-4, James Littlefield wrote: > > Brown-out conditions are handled quite robustly by many devices including > many micro-controllers and at least some of the PMICs that I've used in > other systems.... but apparently not the one used on the BBB. > > The particular behavior about which I posted is not related to "graceful > shutdown" but rather to coming back up when power returns. The TPS65217 > part will apparently never re-enable its outputs after a brownout ...no > matter how long the valid input voltage persists. > > There are a number of mitigation approaches which all require additional > external circuitry but don't need additional backup power sources. > > Cheers, > Jim > > > > > > > > > On Wed, Apr 30, 2014 at 7:47 AM, Ulf Samuelsson <apric...@gmail.com > <javascript:>> wrote: > >> 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 <jms.lit...@gmail.com >> <javascript:>>: >> >> 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, <jay.l...@gmail.com <javascript:>> >> 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 >>> beagleboard...@googlegroups.com <javascript:>. >>> 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 >> beagleboard...@googlegroups.com <javascript:>. >> 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 >> beagleboard...@googlegroups.com <javascript:>. >> 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. 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