What is CID and how to chnge it?

[manan-hanan]

hi to anyone
i have one questions
whate is cid change ?
when we need to change cid ?
and in all cpu we need it ?
tnx all

[Medusa Box]

Hello.

whate is cid change ?

As You may know, eMMC chip has different registers - CID Register, CSD Register, Extended CSD Register. Most of bits in these registers are Read Only, and only some of them can be changed. The Card Identification (CID) register is 128 bits wide. It contains the Device identification information (Manufacturer ID, Product Name, Product Revision, Product Serial Number, Manufacturing Date and some others) used during the Device identification phase (eMMC protocol).

Samsung eMMC chips let to change of CID data. eMMC chips of other vendors don't allow (or method is unknown) to change CID.

when we need to change cid ?

You may need to change CID if You want to change or repair some data in it, for example, if device (eMMC) has damaged Product Name and it should be corrected. Or often when You want to change eMMC chip in device to another similar (Samsung) eMMC, it can be necessary to change CID of new Samsung eMMC to similar, that was in old eMMC.

and in all cpu we need it ?

This doesn't depends on device CPU, this depends on the problem.


This is in a few words in general. More info You can read from official JEDEC eMMC specification:

https://www.jedec.org/standards-docu...ufs-emmc/e-mmc,

http://www.issi.com/WW/pdf/IS21_22ES...G_32G_64GB.pdf,

http://theroot.ninja/disclosures/.