Well, as I understand it, resetting the PMIC resets the PMIC. That would in some cases cause the destruction of the processor. But, feel free to give it a shot.
Gerald On Sat, Aug 9, 2014 at 11:42 AM, <[email protected]> wrote: > 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 <[email protected]> >> 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 <[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 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. > -- 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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