ST25DV64K datasheet(154/220 Pages) STMICROELECTRONICS

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RF operations

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RF Reading of the last byte of mailbox message automatically clears b1 of MB_CTRL_Dyn

“HOST_PUT_MSG” and allows RF to put a new message.

The data rate of the response is multiplied by 2 compated to Read Message.

The subcarrier_flag should be set to 0, otherwise the ST25DVxxx answers with an error

code. The Option_flag is not supported, and the Inventory_flag must be set to 0.

Request parameters:

•

Request flag

•

UID (Optional)

•

Pointer (start at 00h)

•

Number of bytes is one less than the requested data

Response parameters:

•

(number of bytes + 1) data bytes

Response parameter:

•

Error code as Error_flag is set:

–

02h: command not recognized

–

03h: command option not supported

–

0Fh: error with no information given

7.6.35

Write Password

On receiving the Write Password command, the ST25DVxxx uses 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 5.6: Data Protection for details on password

Management. The Inventory_flag must be set to 0.

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

10%), otherwise the ST25DVxxx 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 ST25DVxxx power-down.

Caution:

If ST25DVxxx is powered through VCC, removing VCC or setting LPD high during Write

Password command can abort the command. As a consequence, before writing a new

password, RF user should check if VCC is ON, by reading EH_CTRL_Dyn register bit 3

(VCC_ON), and eventually ask host to maintain or to shut down VCC, and not to change

Figure 63. Fast Read Message frame exchange between VCD and ST25DVxxx

VCD

SOF

Fast Read

Message request

EOF

ST25DVxxx

<-t1-> SOF

Fast Read Message

response

EOF

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