We are looking at the idea that maybe the PMIC gets confused when there is a power dip on power up, basically a power supply that can't handle the surge when the board powers up. The idea is the PMIC starts shutting down and then tries to power up again when the dip goes away. I have yet to capture this myself, but there is one person he says he sees this on his board.
If you have power than can brown out for a short period of time, this could be your issue based on this idea we are looking out. You might try adding a battery to the battery lead or maybe a super cap that can at least stop the shutdown from starting when it thinks the 5V is going away.. Gerald On Thu, Sep 25, 2014 at 10:49 AM, <[email protected]> wrote: > Thanks for your fast reply. > > I've seen it on two of our boards - out of about 15. Only one of them had > a cape (the RTC cape). Any idea if that one causes the issue? > > I admit that the boards are installed over in Africa where clean AC power > sources are not common. We are putting a UPS on the system to clean up > spikes and avoid brown outs. > > One question... > > Does powering down a unit via unplugging a supply from the AC (the wall) > also constitute a "violent" interruption in power, or is it just unplugging > the power connectors from the board? > > > > On Wednesday, September 24, 2014 1:33:52 PM UTC-7, Gerald wrote: >> >> It is still an issue. We have seen it on .003% of the boards shipped. The >> issue can also be related to improper design of capes that violate the >> power up sequence. It may be a while before that shows up as a failure. >> >> Gerald >> >> >> On Wed, Sep 24, 2014 at 3:05 PM, <[email protected]> wrote: >> >>> Hello, >>> >>> I saw the following on the Beagle Bone wiki page... >>> >>> "Improper Power Down....All Revisions >>> >>> ... Based on the latest information we have gathered, this appears to be >>> an instance where the PMIC does not power down the processor in the right >>> order due to the violent removal of the power cables, either USB or DC. So, >>> we are recommending that the power button be used to power off the board or >>> by issuing the Halt command. After that you can remove the power cable. If >>> everyone follows this process, we should see a decrease in these issues, >>> but it will take a while for the results, either good or bad, to show up. >>> This will also help prevent the contamination of the eMMC and the SD cards >>> by allowing the kernel to shutdown properly before power is removed." >>> >>> >>> I also saw in one post that Gerald noted this was thought to be an >>> issue, but now has been dismissed. >>> >>> >>> Can you confirm that this is still an issue or not. >>> >>> >>> The reason that I ask is that we are having Beagle Bone Black failures >>> in the field where they go dead and we are trying to nail down why. >>> >>> >>> If this is still an issue would unplugging a power supply from the wall >>> be considered "violent" removal of the power? >>> >>> >>> Thanks, >>> >>> >>> Jeremy >>> >>> -- >>> 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. > 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. 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.
