It is said in this answer here that

Some of them have a controller chip that will permanently lock them to read only if they detect a write error, as a preservation measure.

Is it possible for a flash controller to permanently lock a SD card into readonly such that it cannot even be formatted?

  • 1
    \$\begingroup\$ Welcome to EE.SE. The short answer is yes, many SD cards and many MPU's with internal flash can be write protected, even block protection for crucial boot-up programs or boot loaders. "Yes" is not a complete answer as the datasheet for a given device gives you the details about write protection. As a hobby you would not do that, because you cannot reverse it once set. \$\endgroup\$
    – user105652
    Commented Nov 20, 2018 at 7:09
  • \$\begingroup\$ @Sparky256 For SD Card's you can actually put and take off write protection by accessing registers through commands, the protection only doesn't allow writing and erasing of data block. \$\endgroup\$
    – MaNyYaCk
    Commented Nov 20, 2018 at 7:32

1 Answer 1


Yes! For SD Cards writing 1 to CSD Register's Bit 12 and 13 can enable write protection, permanent or temporary.

Regarding the Q&A you have referenced over here. I am not sure or I can confirm but while working with SD Card's I read on some material that when SD card starts to detect that it's life cycle is getting over,It puts itself into Read Only mode so you dont put up your valuables over there and can read all the stuff that you have stored on it.

I have just READ, I haven't confirmed it because I don't remember the source neither have I tested it practically. So take it with a pinch of salt.


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