ST25DV64K datasheet(24/200 Pages) STMICROELECTRONICS

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Table 21. MB_LEN_Dyn

Bit

Name

Function

Factory Value

b7-b0

MB_LEN

Size in byte, minus 1 byte, of message contained in FTM

mailbox (automatically set by ST25DVxxx)

Note:

Refer to Table 12. Dynamic registers memory map for the MB_LEN_Dyn register.

5.1.2

Fast transfer mode usage

ST25DV acts as mailbox between RF (reader, smartphone, ...) and an I2C host (microcontroller...). Each interface

can send a message containing up to 256 bytes of data to the other interface through that mailbox.

To send data from RF reader to I2C host, fast transfer mode must be enabled, the mailbox must be free, VCC

power must be present, and the RF user must first writes the message containing data in the mailbox.

I2C host is then informed (by interruption on GPO output or polling on MB_CTRL_Dyn register) that a message

from RF is present in the mailbox.

Once the complete message has been read by I2C, mailbox is considered free again and is available for receiving

a new message (data is not cleared).

The RF user is informed that the message has been read by the I2C host by polling on MB_CTRL_Dyn register.

Figure 9. RF to I2C fast transfer mode operation

I2C host

ST25DV

Fast Transfer Mode mailbox

(256 Bytes)

Dynamic registers

MB_LEN_Dyn

MB_CRTL_Dyn

Static registers

MB_MODE

MB_WDG

ISO/IEC

15693 reader

I2C

GPO/RF_PUT_MSG

RF message

1Mb/s

26.5kb/s

To send data from the I2C host to the RF reader, fast transfer mode must be enabled, the mailbox must be free,

VCC power must be present, and the I2C host must first write the message containing data in the mailbox.

The RF user must poll on MB_CTRL_Dyn register to check for the presence of a message from I2C in the

mailbox.

Once the complete message has been read by RF user, mailbox is considered free again and is available for

receiving a new message (data is not cleared).

The I2C host is informed that message has been read by RF user through a GPO interruption or by polling on the

MB_CTRL_Dyn register.

ST25DV04K ST25DV16K ST25DV64K

Fast transfer mode (FTM)

DS10925 - Rev 9

page 24/200

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