As a general comment, whenever people are talking about edge detection, there's an implied timing specification of the sharpness and/or quality of that edge---there's an implied slope and setup/hold times, and your actual V(t) may be such that it is not seen as a valid, recognized positive edge.
Specifically, the voltage rise could be too fast or too slow, or the voltage dip is too shallow, or there are ringing/bouncing artefacts that lock out the edge detector. On Fri, Apr 4, 2014 at 5:17 AM, <ad...@mxm-upgrade.com> wrote: > Just to confirm this. > > From the TPS datasheet: > > OFF In OFF mode the PMIC is completely shut down with the exception of a few > circuits to monitor the AC, > USB, and push-button input. All power rails are turned off and the registers > are reset to their default > values. The I2C communication interface is turned off. This is the > lowest-power mode of operation. To exit > OFF mode one of the following wake-up events has to occur: > * The push button input is pulled low. > * The USB supply is connected (positive edge). > * The AC adapter is connected (positive edge). > To enter OFF state, set the OFF bit in the STATUS register to '1' and then > pull the PWR_EN > pin low. Please note that in normal operation OFF state can only be entered > from ACTIVE > state. Whenever a fault occurs during operation such as thermal shutdown, > power-good fail, > under voltage lockout, or PWR_EN pin timeout, all power rails are shut-down > and the device > goes to OFF state. The device will remain in OFF state until the fault has > been removed and > a new power-up event has occurred. > > When the brownout occurs, the unit goes in the "off" state and happily stays > there. Apperently, the voltages subject to brownout recovering does not > define as a "positive edge". > > If anyone has a pretty solution for this, I'd be interested. Obviously, I > can implement some kind of a watchdog that cuts the 5V altogether at some > point but is there a SW or other 'easy' solution? > > > On Tuesday, December 17, 2013 1:35:13 PM UTC+1, James Littlefield wrote: >> >> As I said in the original post, the bench supply is capable of more than >> 3A...far more than the BBB takes. I've duplicated the problem on 2 >> difference bench supplies and with multiple BBBs (ie the problem is not >> specific to one particular BBB board). >> >> J- >> >> >> On Friday, December 13, 2013 10:49:07 AM UTC-5, Kees k wrote: >>> >>> Hey, did you try another power supply? Probably the PS has problem >>> supplying the current and drops voltage? Or there is a current limitation. >>> >>> I tried to reproduce by only connecting P9.5, P9.6 and P9.1 (GND) , but >>> could not. >>> >>> On Tuesday, November 19, 2013 2:00:55 AM UTC+1, 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 the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to beagleboard+unsubscr...@googlegroups.com. > 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 beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
