SRTAG2K-D datasheet(22/51 Pages) STMICROELECTRONICS

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RF command sets

SRTAG2K-D

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DocID025446 Rev 3

5.4

S-Block format

The S-Block is used to exchange control information between a reader and a contactless

tag.

There are two requests using the S-Block format:

•

S(DES): the deselect command

•

S(WTX): the Waiting Frame eXtension command or response.

A Waiting Time eXtension request occurs, in RF or I2C, when the operating time

needed by M24SRxx is greater than 9.6 ms.

The WTX field indicates the increase time factor to be used in this command execution

(FDTtemp = WTX * 9.6 ms).

Table 15. R-Block detailed format

b7-b6

0b10

R-Block

RFU

0: NAK

1: ACK

0: DID field is not present

1: DID field is present

Must be set to 0

RFU

Block number

Table 16. S-Block format

NFC frame

SoD

EoD

PCB

DID

Payload

CRC

Length

1 byte

1 to 255 bytes

2 bytes

0xC2: for S(DES) when the DID field is not present

0xCA: for S(DES) when the DID field is present

0xF2: for S(WTX) when the DID field is not present

0xFA: for S(WTX) when the DID field is present

DID field (optional)

WTX field (1)

2 CRC bytes

1. This field is present when b5-b4 bits are set to 0b11 (S-Block is a WTX). see Table 17: S-Block detailed format.

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