When I first observed the behavior I was testing a custom cape (sort of an LCD4 clone w/ some mechanical changes). To eliminate the cape as a factor I did the same test without the cape and powering the BBB directly from the header pins. The results were the same either way.
Regards, Jim On Friday, November 22, 2013 11:59:56 PM UTC-5, Gerald wrote: > > Is there anything else plugged in when the power is switched off? > > Gerald > > > On Fri, Nov 22, 2013 at 9:18 PM, James Littlefield > <[email protected]<javascript:> > > wrote: > >> Watching the 5V supply on a scope I see that there is a sort of 5V >> "brownout" during the time that the power is switched off but it does not >> go down much below 2.5V. This appears to leave the PMIC with most of the >> outputs latched OFF. I will add some external stuff to switch the 5V >> all the way off if the BBB hangs. >> >> Jim >> >> >> On Monday, November 18, 2013 8:14:05 PM UTC-5, Gerald wrote: >> >>> Obviously the PMIC is not liking what you are doing. The 3A current is >>> not a factor in this scenario. >>> >>> Check the timing diagrams in the datasheet and make sure you are not >>> violating the power up ramp requirements No lights means there is no power >>> to the rest of the board and the PMIC has basically shutdown either due to >>> a lockup of the sate machine or an over current condition The only way to >>> reset the state machine, is to pull power and start the process over. >>> >>> It could also be seeing excess current if you have anything else plugged >>> into the I/O pins. If you are careful you could try grounding the reset pin >>> on the PMIC and see if it recovers when in this state. I don't recall how >>> many states are affected by the reset line. >>> >>> No, I have never seen or heard of this before. >>> >>> Gerald >>> >>> >>> >>> Gerald >>> >>> >>> On Mon, Nov 18, 2013 at 7:00 PM, James Littlefield <[email protected] >>> > 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<http://www.google.com/url?q=http%3A%2F%2Fbeagleboard.org%2Fdiscuss&sa=D&sntz=1&usg=AFQjCNEpMSpbklk_hXqEMMJhBr1sf-iMfQ> >>>> --- >>>> 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/groups/opt_out. >>>> >>> >>> -- >> For more options, visit >> http://beagleboard.org/discuss<http://www.google.com/url?q=http%3A%2F%2Fbeagleboard.org%2Fdiscuss&sa=D&sntz=1&usg=AFQjCNEpMSpbklk_hXqEMMJhBr1sf-iMfQ> >> --- >> 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/groups/opt_out. >> > > -- 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/groups/opt_out.
