Is it possible to Unlock an RFID TAG ?

[GPaiv.1]

I use the standard function " STUHFL_T_RET_CODE Gen2_Lock(STUHFL_T_Gen2_Lock *lockData) " to Lock a Tag, But now I wanted to unlock the same Tag and following the standards information in Gen2 protocol Like the pictures below, I try using the same function but with a different "mask" but don't obtain a successful.

Is It possible to Unlock a Tag? Can you send a Mask to Unlock all Fields in one Tag?

Mask to Lock: FFFFFh.

Mask to Unlock: FFC0h.

https://www.gs1.org/sites/default/files/docs/epc/Gen2_Protocol_Standard.pdf

 

[Bart Herse · Accepted solution]

Dear GPaiv.1,

looking at the lock mask you was using it seems that all memory banks have been permalocked.

As defined in the corresponding standards:

Permalock or permalocked:

A memory location whose lock status is unchangeable (i.e. the memory location is permanently locked or permanently unlocked).

Therefore unlocking is not possible anymore.

Note that your unlock mask is missing a nibble.

Note as well that in our lock function the mask information stretches over 3 bytes - maskAction[0:2]

The 20 bit mask payload is stored as shown below

maskAction[0]: Bit 19 - Bit 12

maskAction[1]: Bit 11 - Bit 4

maskAction[2]: Bit 3 - Bit 0

For maskAction[2] the lower nibble is not used: maskAction[2] & 0xf0

I hope this information is helpful.

Cheers,

B

[GPaiv.1]

Dear Bart,

Thanks so much, for your answer.

You help a lot, I could saw now, where are my mistake.

I'm written the wrong mask.