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]> 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 > --- > 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 --- 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.
