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Rockbox mail archiveSubject: Re: 5.5G iPod shutdown confusing the boot code?Re: 5.5G iPod shutdown confusing the boot code?
From: Dave Woyciesjes <woyciesjes_at_sbcglobal.net>
Date: Wed, 04 Mar 2009 14:56:50 -0500 Boris Gjenero wrote: > Dave Woyciesjes wrote: >> Well, my iPod wouldn't start up this morning. I've been using it >> in iPod/iTunes mode for the past week+, without issue. This morning, >> had to give it the 2finger to get it going. When it finally started >> up, there was a quick flash before the Apple logo, but I couldn't >> catch of it was a low battery symbol. When it came all the way up, I >> did notice the battery was only at 50% charge. Which is very odd, >> since I didn't use it off charger for any length of time yesterday. It >> should've been at least 90%. >> Looking at the Last Played timestamp in iTunes shows what I >> expected. Nothing was played between 5:38 pm yesterday & 8:04 am today... >> Seems like it didn't properly go to sleep last night. > > Thanks a lot for this report! I was always sceptical about this > happening with the Apple firmware and you just proved that it does. > > When you turn "off" the iPod in the original firmware, it goes to sleep > which means memory contents are retained and code which has been loaded > from disk retains control. After sleeping for a while, the iPod > transitions to deep sleep or hibernation mode. Memory is saved to the > hibe part of the firmware partition and the iPod actually turns off. > When you turn on the iPod, the first part is just like when you turn it > on to run Rockbox. The code in flash runs, and it needs to read from > disk to see that it needs to restore from hibe data instead of loading > osos. Since this problem happens before the disk has a chance to spin > up, whether you're resuming from hibernation or starting Rockbox is > irrelevant. > > According to several online sources, iPods go into deep sleep after 14 > hours of inactivity, and yours has been off for 14 over hours. > > The only easy solution I can think of is patching the code in flash to > remove or alter low battery checks. They're done via the BVMC register > and ADC of the PCF chip. Of course you have to watch out for flash > checksum checks; I'm not sure if there are any. > > I wonder if this only happens with older batteries. Internal resistance > rises as batteries age. There might be a significant inrush current > right after the iPod is turned on, and if battery internal resistance is > high, that would lower voltage. > > I don't think this can happen because of the iPod not going to sleep > properly. That could actually drain the battery, but I don't see how it > could mess up the PCF ADC or BVMC register. > The patching you're referring to sounds to me like something Apple should do... AS for age, mine is 2 maybe 3 years old. Like I mentioned, I think mine didn't go to sleep properly last night. The charge meter showed only about 50% charge this morning when I finally go it going. It should've shown around 90 - 95% since I puased the music, and took it off the charger at 55:40 pm last night, and didn't touch it until this morning. -- --- Dave Woyciesjes --- ICQ# 905818 --- AIM - woyciesjes --- CompTIA A+ Certified IT Tech - http://certification.comptia.org/ --- HDI Certified Support Center Analyst - http://www.ThinkHDI.com/ "From there to here, From here to there, Funny things are everywhere." --- Dr. SeussReceived on 2009-03-04 Page template was last modified "Tue Sep 7 00:00:02 2021" The Rockbox Crew -- Privacy Policy |