2

I tried this question on Stackoverflow but it was modded offtopic; they suggested I try over here...

I have a bunch of non-working Android mainboards I need to repair. Many of them have corrupted eMMC which needs to be reprogrammed. I remove the eMMC, connect it to a PC using an SD adapter, and re-image it; this usually works. However sometimes I'll grab an eMMC that came from a "Model 1" board, and after imaging it won't work on a "Model 2". I'm guessing this is due to different code in the boot partition.

I'm only able to "see" the user partition of the eMMC (not talking about the /user partition of the filesystem, but lower down in the eMMC itself) and I need to also be able to replace the boot partitions. I found a document that discusses access to the eMMC partitions, however the files discussed in this document don't seem to exist on my system. It appears I have to issue a special "Switch" command to bring the boot partitions into focus.

Accessing the partitions through a bootloader is not really an option since we're talking about a bare IC in a programming adapter. The system it's plugged into (a PC) is not the system it's going to be booting in (an Android tablet). The problem I'm trying to fix is that the tablet's bootloader is corrupted and thus unavailable.

I've looked at Arduino SD shields, as I've done considerable Arduino programming. But the Arduino shields use SPI to talk to the SD card, and eMMC 4.4x and above (the ones I'm working with) no longer support the SPI interface. I'm considering building a shield that connects to CMD, CLK, and DAT0 and bitbanging my way through. But I'd prefer to use something preexisting if it's out there.

I'm running xubuntu 14.04 and I'm guessing I need to add eMMC support to that in order to send "Switch" and see the low-level eMMC partitions. My skillz skew more towards hardware but I managed to get xubuntu running in a VM with raw access to USB for imaging these parts so I'm not completely useless.

So... how do I get my claws into the eMMC boot partitions? Is xubuntu an appropriate environment? I have Win7 and OSX available as well FWIW. If I can just /see/ the partitions I'm pretty sure I can muddle through from there.

3
  • BTW when I insert the adapter with an eMMC in it, it does show up as /dev/sdb and if the user partition contains a valid filesystem it gets automounted. Problem is, I need to switch to the boot partitions (there are allegedly two of them) on the eMMC. Dec 22, 2015 at 20:57
  • do you find the solution?
    – H.Ghassami
    Mar 2, 2019 at 8:48
  • Nothing yet, sorry. Apr 11, 2019 at 15:43

0

You must log in to answer this question.

Browse other questions tagged .