Sorry for the delay in replying. I’ve only seen the problem start when using my custom cape, which has the following voltage supply:
linear regulator: LT1529-5, capable of supplying 3A of output current. After noticing the failure to power up, I’ve removed the cape and attempted to power it using a 5V AC to DC adapter capable of supplying 2A. This also doesn’t work after entering this state. I will try another supply but I doubt it will make any difference. I’ve only seen this on issue on revision 000B beagle bone blacks. I have several A6’s and A6A’s that are not exhibiting this behavior, although I also swapped regulators (originally using LM1086, 5V, 1.5A) upon switching to the 000Bs so this is a bad comparison. I will swap the regulators and let them run for a while to see if this is a likely source of my problem. This problem sounds similar to that described in the following post ( https://groups.google.com/d/msg/beagleboard/p0CwsGzNYNw/6Ig85JJJviEJ ). However, James noticed the problem occurred when cycling the power, suggesting that it was caused by a brownout. I’m not removing power at all but can still enter a similar state. My only thought now is that maybe when the regulator is entering a low quiescent state that it is somehow triggering a brownout…? It isn’t occurring consistently so it’s difficult to catch this behavior on an oscilloscope but I will try to capture it. Any other suggestions of things to look into would be greatly appreciated. Thanks jay On Monday, April 28, 2014 5:21:44 AM UTC-7, Gerald wrote: > > Any chance you can give some more information, like the revision of the > board and details on the power supply? > > Gerald > > > > On Fri, Apr 25, 2014 at 6:22 PM, <[email protected] <javascript:>> wrote: > >> Hi, >> >> A couple of my BBBs have begun to not respond or intermittently not >> respond to the 5V supply, i.e. VDD_5V, but still are able to be powered >> through the USB. When in this state the board does not appear to respond at >> all to 5V power, no power or status LEDs. When I first noticed the problem >> I found that they would eventually return to normal operation if all power >> was removed for an undetermined period of time. >> >> >> These devices are setup as remote systems that power up periodically via >> an external RTC, which momentarily pulls PWR_BUT to ground in order to turn >> the device on. They are powered through VDD_5V via a custom cape, as such, >> the error I’m seeing effectively breaks the function of my device. >> >> >> I don’t know what’s causing this error, but assume that it’s something >> related to the PMIC. I believe I’ve only seen this issue on RevB BBB’s but >> the PMIC is the same for both the RevB and RevA boards that I have. I’ve >> also seen various levels of current draw from VDD_5V when in this state, >> ~18.5mA in one case and ~0.39mA another time. I was wondering if the PMIC >> might be in some lockout mode, I know there is an “Under Voltage Lockout” >> mode. However, I haven’t figured out a good way to test this. >> >> >> Any suggestions to help debug this issue would be greatly appreciated. >> >> >> Thanks >> >> jay >> >> -- >> 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] <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. 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.
