Possible to convert eMMC Socket to a micro SD Card socket?

[Isabella91]

I have seen many posts where the eMMC can be read via a SD card reader, however can the opposite be achieved?

Read/Write a Micro SD Card from an eMMC Socket.

I have a Motherboard with a Kingston BGA153 ball socket, using HS400 bus mode, which is 8bit, as Micro SD is usually 1bit or 4bit mode, I accept that a loss of speed in read/write will occur, but I would sill like to convert.

Theoretically speaking, Im thinking if I hard solder DAT0-3 from eMMC to SD Card Reader, this should force 4-bit mode, or only DAT0 to force 1-bit mode.

Not to remove the underlying socket, but run some of the traces to a micro sd socket.








I have a good solder & hot air station.

What do you think?

[stj]

maybe,
but check the datasheet for the emmc - it has to be 3.3v
you cand link am sdcard if it's 1.8v

[Isabella91]

stj

emmc datasheet:

Operating voltage range:
o VCCQ = 1.8 V/3.3 V
o VCC = 3.3 V

source: https://www.mouser.co.uk/datasheet/2..._1-3236210.pdf

However, does the host(motherboard OS) expect/request 8-bit mode? as we would only be soldering DAT0-3, leaving DAT-4-7 unsoldered, due to sd card being 1 or 4 bit mode.

Or are all host read/write requests are the same? IE the eMMC controller decides the bus modes etc?

[CapLeaker]

Look at my Dreamlink T1 thread. There may be some useful stuff in there, I read and wrote to the eMMC using only DAT0. Less lanes slower read and write, However if that resistor on these DAT lanes fucks up by going higher in resistance, the data transfer does not work. You can see all the crap I did to these poor little boxes in that thread mentioned above.
If it would be me, I'd start with one data line, then add the others.

[stj]

i dont know how the controller decides bus width,
you should check the VCCQ voltage on the motherboard - see if it's 1.8v or 3.3v

[Isabella91]

CapLeaker
Did you only write in DAT0 due to the constraints of the RT809H being DAT0?
Also, Where you replaced your eMMC with another eMMC, im attempting to replace and eMMC with a Micro SD Card - What do you think about this? Could work or never?

[CapLeaker]

Isabella91 I used the RT809h hard wired to the EMMC on board using only the D0 line, Once I took off the EMMC and using an BGA adapter with the RT809h I got much better speeds, since it is using multiple data lines and not only one (D0).

Replacing an EMMC with an SD card or even an SSD? Why not. The only problem with this is someone has to do the hard work on figuring things out and having the right knowledge and equipment to do it. Plus the will on not giving up that easily. Remember use same speeds or as close as you get it and start with at least the same size of a replacement. Most of the time if you swap an 8 for a 16GB card should work, but going from 8 to 64GB chances are not so good.

[sam_sam_sam]

I going to ask a question about this because I have real understanding of this topic but one question comes to mind what would the advantages of doing this

“ eMMC Socket to a micro SD Card socket ”

Is it faster or does it have more memory capacity or faster access time

I read the post and it got my attention maybe for the wrong reasons but that is the reason for asking questions

[lotas]

If this is a TV board that requires eMMC, then this idea will not work here, especially where the ID (CID, CSD, Device Revision (MMC v5.0, v5.01, v5.1)) and processor are linked.

[Isabella91]

sam_sam_sam
Its likely the eMMC has faster access times, I want to convert to be able to remove the media card easily to put in another device, I cannot do so with a eMMC.
As you have experience with this, Do you think its possible?

lotas
Its not a TV, but thanks for this info, its useful to know for the future.
Is there no way of changing the ID serial, revision etc?

CapLeaker
Noted, and yes the tracing maybe the most time consuming part.

[CapLeaker]

worst part is the need of an electronic microscope and real steady hands. Soldering these little wires isn't much fun. There are some real fast SD cards. I have a few SD cards that are over twice the speed than the eMMC in that Dreamlink. What is this device you are trying to convert and what is / was the eMMC that was on it?

[sam_sam_sam]

Its likely the eMMC has faster access times,
I want to convert to be able to remove the media card easily to put in another device, I cannot do so with a eMMC.
As you have experience with this, Do you think its possible?

It was suppose to be that I do not have any experience or knowledge about this topic but that is the reason I was asking the questions that I did
You did answer my question thanks

[dschnur]

There is this:

https://320volt.com/en/32-gb-emmc-be...rt-baglantisi/