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Subject: 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. Seuss
Received on 2009-03-04

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