AN3955 datasheet(19/68 Pages) STMICROELECTRONICS

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AN3955

CR95HF low level layer

Doc ID 022017 Rev 1

19/68

Table 11 describes the SendRecv command in ISO/IEC 14443-3 Type B case.

Table 11.

SendRecv command in ISO/IEC 14443-3 Type B case

For more information, refer to CR95HF datasheet.Table 12 describes the CR95HF success

response value for ISO/IEC 14443-3 Type A.

Parameter name

Byte

Bit

Value

Comments

Example

Command Code

7:0

0x04

REQB command:

0x040305000

Length

7:0

0xXX

Length of entire

data

Data

2:X

7:0

0xXX

Data

Table 12.

CR95HF success response value for ISO/IEC 14443-3 Type A

Parameter

name

Byte

Bit

Value

Comments

Example

Result

Code

7:0 0x04

Success code

0X80054400280000

where:

: success

: Number of bytes

4400

: ATQA

: CRC error(1) &

Number of significant

bits: 8

00 00

: No collision

detected

CRC error bit is set but there is no CRC on ATQA response. So this bit is not significant.

Length

7:0 0xXX

Number of bytes of Data

+ control bytes

Data

2:X 7:0 0xXX

Contactless tag response

Control

bytes

X+1

1: CR95HF has

detected a collision

0: No collision detected

Collision between two

contactless tag

responses

RFU

1: CRC error

0: No CRC error

CRC error on contactless

response

1: Parity error

0: No Parity error

Parity error on

contactless response

3:0

Number of significant bits

in the first byte(2)

Since the ISO/IEC 14443-3 Type A is a bit-oriented protocol, CR95HF can receive a non integer amount of

bytes.

X+2 7:0 0xXX

Index of the first byte

where the collision is

detected(3)

To calculate the point of collision between two contactless tag responses, the user application must refer to

the control bytes. The byte where the collision is detected is indicated by Control Byte X+2 (Index of first

byte), and the specific bit in the byte where the collision is detected is indicated by Control Byte X+3 (Index

of first bit). Both indices start from 0 and the bit index can be 8, meaning that the collision affected parity.

This information is only valid if the Collision Dectected bit (Bit 7 of control Byte X+1) is set.

X+3 7:4 0b000

RFU

3:0 0bXXXX

Index of the first bit where

the collision is detected

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