From: John Syne <[email protected]> Date: Tuesday, June 24, 2014 at 1:41 PM To: "[email protected]" <[email protected]> Cc: Robert Nelson <[email protected]>, Gerald Coley <[email protected]> Subject: Re: [beagleboard] Power down a battery backed up BeagleBone Black
> > From: Colin Bester <[email protected]> > Reply-To: "[email protected]" <[email protected]> > Date: Tuesday, June 24, 2014 at 8:14 AM > To: "[email protected]" <[email protected]> > Subject: Re: [beagleboard] Power down a battery backed up BeagleBone Black > >> >> Several observations. >> >> When pressing power button or executing halt instruction, processor does >> shutdown but the voltage rails SYS_5V and VLD02 don't (I didn't check >> VLDO01). VLDO2 does drop to less than 2V but appears to still be enough to >> trigger U4 TL5209's enable pin thus switching SYS_5V to VDD_3V3B. This to me >> doesn't look right, this level (VLD02) should either be asserted or negated >> and not in between levels. > Yep, you are right, the SYS_5V remains on after a sudo halt or pressing the PB > for more than 8 seconds. Since the 3V3B is derived and enabled from the > SYS_5V, it also remains powered. Looks like we need to also turn off the > AC_EN and USB_EN bits in the PPATH register on the TPS65217C PMC. I¹ve copied > both Robert and Gerald to see if this is something they want to fix. Thinking about this some more, this isn¹t going to work. Not sure how to fix the problem you have. Regards, John > > Regards, > John >> >> Powering up with just battery and no 5V (not pressing any buttons) shows >> SYS-5V active high (5V) and VLD02 at expected 0V. >> >> Looks to me like there is a power switching problem although fixing this >> still won't fix the issue I am having as I want to totally switch off LCD4 >> which is using SYS_5V for backlight. I am not sure from the tech notes if >> it's possible or not to switch off SYS_5V voltage (Pins 7.8 SYS1/SYS2 on >> TPS65217C). >> >> If one can't then my question to LCD module supplier/manufacturer is how did >> they intend us to shut device down with a battery connected. >> >> ~C >> >> On Monday, June 23, 2014 6:52:03 PM UTC-5, john3909 wrote: >>> >>> Power Button is also on P9 Pin 9. BTW, sudo halt powers off all power rails >>> and is functionally equivalent to holding the power button for 10 seconds. >>> If your LCD backlight is still on, then it is powered from the 5V rail >>> because all other power rails are off. >>> >>> Regards, >>> John >>>> >> >> -- >> 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.
