From: Colin Bester <bester.co...@gmail.com> Reply-To: "beagleboard@googlegroups.com" <beagleboard@googlegroups.com> Date: Tuesday, June 24, 2014 at 8:14 AM To: "beagleboard@googlegroups.com" <beagleboard@googlegroups.com> 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. 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 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.
