From: <[email protected]> Reply-To: <[email protected]> Date: Friday, April 4, 2014 at 2:17 AM To: <[email protected]> Subject: [beagleboard] Re: Possible TPS65217C/Beaglebone Black Issue
> 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: > EURO The push button input is pulled low. > EURO The USB supply is connected (positive edge). > EURO The AC adapter is connected (positive edge). > To enter OFF state, set the OFF bit in the STATUS register to OE1ยน 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? Unfortunately no, there is no software solution since the processor has no power. You have to use a power supply monitor/controller with a state machine to deal with this issue. This type of circuit is normally included a small energy reserve (battery or supercaps) so that the OS has time to close open files and prevent file system corruption during power fail issues. Normally, any power supply interruptions initiates an orderly shutdown of the OS. When the processor finally halts, power is removed from the PMIC. When power is available, power is applied to the PMIC and everything powers up normally. There are several corner cases that must be considered, such as power interruption during power up phase or power available during power down phase. A simple state machine takes care of these corner cases. Overall, the circuitry includes several voltage regulators (input buck convertor, output boost convertor), energy balance (supercaps), battery charger (battery), and a state machine (8 bit micro or my preference - GreenPAK). Regards, John > > > 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 [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.
