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iPod video - Disk mode fails, sector size problem. PLEASE help!

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torne:

--- Quote from: eltonart on April 13, 2010, 12:10:13 AM ---I didn't try running it flat but I did try disconnecting the battery.

--- End quote ---
That should've worked, yes. This is rather disconcerting :)


--- Quote ---I dont really understand the bootloader but my guess is that the rockbox bootloader is the same as the apple bootloader with a small change pointing to the rockbox build. Is that right or is it something different?
--- End quote ---
It's something different. The iPod boots in several stages. It starts off executing from flash ROM, which contains the Apple flash bootloader. This flash is *never* modified by Rockbox in any way, so the Apple flash bootloader always runs, completely unmodified. The flash bootloader looks in the hidden firmware partition on the hard drive to find an image called "OSOS", which normally contains the Apple firmware image. It loads this image into ram and then executes it.

The Rockbox bootloader is a completely separate program, unrelated to the Apple flash bootloader. When you install the bootloader, the OSOS image on the firmware partition is modified so that instead of just containing the Apple firmware, it has the Rockbox bootloader appended to the end of the image as well. We also modify the header of the OSOS image to instruct the bootloader to execute our bootloader first. The Apple flash bootloader loads this modified OSOS image into ram, and then runs our bootloader, which goes and looks for the .rockbox folder on your player's normal data partition and loads rockbox.ipod from there.

So, the point here is that the Apple flash bootloader is never modified in any way, and it's responsible for detecting the button-presses at boot and booting the emergency disk mode (which is also in flash) - at the point this is supposed to happen, not one byte of code by Rockbox has been loaded...

eltonart:
Soap:
I missed that one was bits and one was bytes (doh!), thanks for clarifying. The confusion I was talking about was in relation to which board you have or were ordering since they have the same part number. For future reference these are the RAM chips I have seen on 5.5G logic boards but there may be more:

K4M56163PG - Samsung 32MB (30GB logic board)
HYE18L256 - Qimonda 32MB (30GB logic board)
HYE18L512 - Qimonda 64MB (60/80GB logic board)

Torne:
Thanks for your patience and the detailed explanation, that clears it up perfectly. Now I understand why I should be able to still access disk-mode. That prompted me to do some more troubleshooting and I finally worked out the problem! I assumed that the logic board was OK and so I tried connecting an old clickwheel. I was then able to access disk mode. I restored the Ipod and then tried the faulty clickwheel again to confirm. This time it worked even less and I could not even restart the ipod. The connector and ribbon cable is fine so I can only assume it's the controller chip. Strange that the clickwheel itself affected the surface mount buttons on the logic board.

I ordered a new clickwheel and will also try to order a logic board with 64MB RAM. With my old ipod (30GB with 32MB RAM) I had intermittant problems so I think the 64MB RAM is important for a pure FLAC player. Torne, I look forward to testing your build for large drives and will post my results on your thread. Good on you for addressing this issue.

Thanks again for your patience in helping out this noob. Elton. ;D

soap:
No other Rockbox target has 64MB of RAM, 32 should be plenty for FLAC playback - not that 64 hurts, it just isn't a huge benefit.

torne:
You shouldn't have any problems with a 32MB logic board, other than a very slightly shorter battery life. FLAC playback works fine on targets with only a couple of meg of ram. The only difference between the 32 and 64MB logic boards under Rockbox is the battery life, and the difference there is not even very big. Something else must've been causing whatever problems you were having (you don't say what they are...)

eltonart:
OK thanks for the advice, I'll keep that in mind before shelling out unnecessary cash on my "dream" flac player (see below). I didnt want to raise too many problems on the same forum post - the problem I had was that the ipod intermittently restarted during FLAC playback. It didnt happen very often but it was annoying.

My dream FLAC player MKII (work in progress):
- 5.5G ipod logic board with 64MB RAM
- Thin form factor, 5mm 80GB hard-drive
- Classic ipod shell (mod to fit)
- 650mAH thin lithium polymer battery
- Rockbox (of course)
- Grado SR80 headphones

Future upgrade to 128GB CF card (maybe 2011?)
Why? Because I can...

Since I'm buying a new click-wheel, should I buy a classic clickwheel? Is it same connector and does it work on 5.5 logic board? Anyone tried it?

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