ST25TV02K datasheet(51/90 Pages) STMICROELECTRONICS

51 / 90 page

Figure 24. Write Configuration frame exchange between VCD and ST25TV02K/512

SOF

Write

Configuration

request

VCD

EOF

ST25TV02K/512

SOF

Write

Configuration

response

EOF

ST25TV02K/512

Write Configuration

sequence when error

SOF

Write

Configuration

response

EOF

6.4.20

Write Password

On receiving the Write Password command, the ST25TV02K/512 use the data contained in the request to write

the password and reports whether the operation was successful in the response. It is possible to modify a

Password value only after issuing a valid Present password command (of the same password number). When

the Option_flag is set, wait for EOF to respond. Refer to Section 5.2 Data protection for details on password

Management.

During the RF write cycle time, Wt, there must be no modulation at all (neither 100% nor 10%), otherwise the

ST25TV02K/512 may not correctly program the data into the memory.

The Wt time is equal to t1nom + N × 302 µs (N is an integer). After a successful write, the new value of the

selected password is automatically activated. It is not required to present the new password value until the

ST25TV02K/512 power-down.

There is no anti-tearing mechanism during Write_Password command. Command must be applied with stable RF

field. Otherwise the write operation may not complete properly, and could imply a loss/corruption of password

content with no recovery capability.

It is recommended to use Write_Password command in Addressed or Selected modes, in order to improve the

system robustness. This allows to ensure that Password change is only applied to the concerned tag/UID.

Table 90. Write Password request format

Request SOF Request_flags

Write

password

IC Mfg code UID (1)

Password

number

Data

CRC16 Request EOF

8 bits

B1h

02h

64 bits 8 bits

32 bits 16 bits

1. The field is optional.

Request parameter:

•

Request flags

•

UID (optional)

•

Password number:

–

00h = PWD_KILL or PWD_UNTRACEABLE

–

01h = PWD_1

–

02h = PWD_2

–

03h = PWD_CFG

–

other = Error

•

Data

ST25TV02K ST25TV512

RF commands

DS12074 - Rev 11

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