ST25TV02K datasheet(15/90 Pages) STMICROELECTRONICS

15 / 90 page

5.2.3

User memory protection

On factory delivery, areas are not protected.

Each area can be individually protected in read and/or write access.

Area 0 is always readable.

Furthermore, Area 0 can be independently write locked.

Each memory area can also have individual Read/Write access conditions.

For each area 1 and 2, an AiSS register is used to:

•

Select the protection against read and write operations for this area

(See Table 8. A1SS, and Table 9. A2SS for details about available read and write protections).

When updating AiSS registers, the new protection value is effective immediately after the register write

completion.

•

Block 0 is an exception to this protection mechanism:

–

Block 0 can be individually write locked by issuing a Lock Single Block command. Once locked, it

cannot be unlock.

–

User needs no password to lock block 0.

–

Locking block 0 is possible even if the configuration is locked (LOCK_CFG=1).

–

Unlocking Area 1 (through A1SS register) does not unlock block 0 if it has been locked though Lock

Block command.

–

Once locked, the user cannot unlock block 0.

•

Other blocks can be individually locked.

Retrieve the security status of a user memory block or byte

User can read a block security status by issuing following commands:

•

Get Multiple Blocks Security Status command

•

(Fast) Read Single Block with option flag set to 1

•

(Fast) Read Multiple Blocks with option flag set to 1

•

(Fast) Inventory Read

ST25TV02K/512 responds with a Block security status containing a Lock_bit flag as specified in ISO 15693

standard. This lock_bit flag is set to 1 if block is locked against write.

Lock_bit flag value may vary if corresponding user security session is open or closed.

5.2.4

System memory protection

By default, the system memory is write protected, except the kill password and the EAS settings.

Th system memory consists of all the registers defined in Table 4. System configuration memory map accessible

through write_cfg and read_cfg commands. Some registers are read-only and can never be written.

To enable write access to system configuration registers, which have write capability, user must open the

configuration security session (by presenting a valid password 3) and system configuration must not be locked

(LOCK_CFG=00h).

By default, user can read all system configuration registers, except all passwords, LOCK_DSFID and LOCK_AFI.

Configuration lock:

•

Write access to system configuration registers can be locked by writing 01h in the LOCK_CFG register.

•

User cannot unlock system configuration if LOCK_CFG=01h, even after opening configuration security

session (Lock is definitive).

•

When system configuration is locked (LOCK_CFG=01h), it is still possible to change passwords (0 to 3).

Device identification registers:

•

AFI and DFSID registers can be independently locked by user, issuing respectively a Lock AFI and a Lock

DSFID command. Lock is definitive: once locked, AFI and DSFID registers cannot be unlocked.

•

Other device identification registers (MEM_SIZE, BLK_SIZE, IC_REF, UID) are read only registers.

ST25TV02K ST25TV512

Data protection

DS12074 - Rev 11

page 15/90

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