View Single Post
Old 04-12-2012, 07:45 AM   #152
TCCPhreak
Member
TCCPhreak is a glorious beacon of lightTCCPhreak is a glorious beacon of lightTCCPhreak is a glorious beacon of lightTCCPhreak is a glorious beacon of lightTCCPhreak is a glorious beacon of lightTCCPhreak is a glorious beacon of lightTCCPhreak is a glorious beacon of lightTCCPhreak is a glorious beacon of lightTCCPhreak is a glorious beacon of lightTCCPhreak is a glorious beacon of lightTCCPhreak is a glorious beacon of light
 
Posts: 14
Karma: 12366
Join Date: Mar 2012
Device: Kindle 4GNT
Quote:
Originally Posted by geekmaster View Post
This is why it is a bad idea to write to /dev/mmcblk0 with dd, as suggested in some posts I have read. Because a backup copy has zeroes in the write-only areas, a restore with dd would write zeroes onto your important private idme var data.
Hmm.. seems like a lucky coincidence that I took a photo of the device settings in diag-mode when it still worked..

Quote:
Originally Posted by geekmaster View Post
Regarding the serial port,
I finally got one of those USB-cables for mobile phones and patched it into a generic (PL2303) USB-serial@3.3V.

Btw: I guess it can't hurt to have this information here, too: Kindle 4 Nontouch-serial port is P2 (east on the main board), GND is top one (easily identifyable as it's connected to large ground areas), RxD is middle, TxD is bottom (identifyable by the 1.8V level compared to GND)

As those pads are very fragile, I soldered some small wires to them and to a small adapter piece allowing for easier soldering, later.

http://imgur.com/nkU2o,TMQqe,rfV7n

Connecting the PC-RxD to Kindle-TxD already showed me the boot-messages (without the pullup-resistors). If I ever connect the other direction, I'll use the resistor for voltage dividing but right now it seems like there is no need for that.

Quote:
Originally Posted by geekmaster View Post
Did you read the docs supplied with the full MfgTool for the iMX50 from Freescale? Download and read the iMX50 Reference Manual too (or at least the relevant parts). It *is* complicated.
I read the files available in Document.zip and there were some examples and instructions. Still, those that didn't fail right away gave no positive results.
I found surprisingly few information about the downloader mode and the commands in the reference manual.

It's nice to see the serial output - as it shows that internally, the kindle is still working. Still, it further fundaments my guesses of something really being broken on hardware level:
Bootmode Override is fastboot. There is this "Battery Voltage too low. Please plug in a charger" message and although a charger is connected, the voltage goes down in the next messages.
I've watched it decrease from 3360 to 2952. Still, it's up at 33xx or so when I reboot.

Well.. I guess, I'll attach the resistor and interrupt the boot process - just to see what I can do at that point.

Regards,

TCC

Update:
With a 20k resistor I could stop booting and get into uboot. Unfortunately, the Kindle freezes pretty quick there, too. Sometimes it doesn't even countdown the 3 seconds to starting fastboot.

I guess I'll keep it at the charger for the rest of the day. At least I can see some absolute numbers about voltage on serial output.

Still, this experiment showed me that my main kernels really are broken, that no such error appears with fastboot and that this freezing is very independent from what I boot.
Now I only need to find out how to directly interface the e-ink display so I can get rid of the main board and just use the display..

Last edited by TCCPhreak; 04-12-2012 at 08:09 AM.
TCCPhreak is offline   Reply With Quote