Thread: Kindle Touch bricked without USB
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Old 01-14-2012, 03:30 AM   #42
geekmaster
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Join Date: Nov 2011
Location: Multiverse 6627A
Device: K1 to PW3
Quote:
Originally Posted by eureka View Post
Wonderful! Thanks!

Yes, mode is wired in chip but it can initiated either by hardware (with setting of "boot mode" pins), or by software (with calling into USB downloader code from running program). I was unsure, which method is used in KT, but now it seems that Home button is connected to "boot mode" pin(s) and USB downloader mode is initiated by hardware even before U-Boot loading.
If correct, it would be safe to customize U-Boot or replace it with a different boot loader. That would require using SPI (or possibly i2c) to write to the serial memory chip containing the boot loader. Any errors and you could recover with USB downloader boot mode. At least you could replace the missing or disabled functions in the touch U-Boot.
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