Read eMMC chip using SD card reader

[vbogoev]

Hello,

I found several sources where guys successfully read eMMC chip using a SD card reader. I was interested to try it, just to practice micro soldering, but for some reason I am unable to read the chip. The chip is known working one (desoldered from an old working device) model Samsung KLM8G1WE4A-A001. The card reader is Transcend USB 3.0. So basically I've connected everything as it is described in the schematic, but the sd card reader didn't even start to blink. I am not sure what I am missing, so I'll appreciate some help...

[harp]

Re: Read eMMC chip using SD card reader

So, have you check power voltage on sd and mmc?
From pictures, I can not trace anything...
When you working on such delicate things, sometimes is best to disconect and clean everything, and start all again from null rather then to troubleshooting. Be careful about orientation and view point on schematics, and maintain fully concentrate and piece while doing that. Use a ribbon cable from ide drive or so if is handy to minimise mess.

[stj]

Re: Read eMMC chip using SD card reader

first, as your soldering to a socket, did you deal with the switch that tells the interface you have a card plugged in?

second, how are you reading it? you probably need to do a block-dump, if you expect windows to show you a bunch of files your probably going to be dissapointed.

[vbogoev]

Re: Read eMMC chip using SD card reader

So, have you check power voltage on sd and mmc?
From pictures, I can not trace anything...
When you working on such delicate things, sometimes is best to disconect and clean everything, and start all again from null rather then to troubleshooting. Be careful about orientation and view point on schematics, and maintain fully concentrate and piece while doing that. Use a ribbon cable from ide drive or so if is handy to minimise mess.

Thanks for the advices. I started 3 times from the beginning, but at the end I am pretty sure everything is connected as described. I am not sure if RSTN should be pulled up in order to enable the chip, but from the datasheet it seems like this is how it is supposed to work.

first, as your soldering to a socket, did you deal with the switch that tells the interface you have a card plugged in?

second, how are you reading it? you probably need to do a block-dump, if you expect windows to show you a bunch of files your probably going to be dissapointed.

Indeed, at first I didn't know for the card detect switch, but then I plugged another card in the socket, wrapped with capton tape on the pins and now card detect pin on the chip is ON.

However, there's no voltage passed to the chip, between 4 and 6 pins there are 0 volts. If I test with normal SD Card there are 3.3V.

What I am expecting to see is first to have 3.3V on the power rails and then the reader flash to indicate something's going on. After that I'll think about the data extract, but yeah, I expected to see a bunch of files, like I was inserted normal sd card.

So I am missing something, but not sure what...

[stj]

Re: Read eMMC chip using SD card reader

well i'v never seen an 8bit emmc, sdcards are only 4bit i think.

that doesnt explain why the 3.3v isnt coming on - you would expect that just with the detect switch even if there was no card/chip

[vbogoev]

Re: Read eMMC chip using SD card reader

OK, found the problem. It was me of course...

The schematic show the chip pinout when it's upside up, I interpreted it as upside down as the pinout is symmetric.

Anyway, I successfully read the IC but it was not possible to open the userdata volume using Linux Reder program. Not sure it the content is encrypted. However, I successfully opened the system volume.

[stj]

Re: Read eMMC chip using SD card reader

if you dumped it as a big block of data, you may be able to identify the filesystem and mount it