Rainbow Electronics MAX66020 User Manual

Page 9

ISO/IEC 14443 Block

Transmission Protocol

Before the master can send a data packet to access the
memory, the MAX66020 must be in the ACTIVE state.
The protocol to put the MAX66020 into the ACTIVE state
is explained in the

Network Function Commands

sec-

tion. While in the ACTIVE state, the communication
between the master and the MAX66020 follows the
block transmission protocol as specified in Section 7 of
ISO/IEC 14443-4. Such a block (Figure 11) consists of
three parts: the prologue field, the information field, and
the epilogue field. The prologue can contain up to 3
bytes, called the protocol control byte (PCB), card iden-
tifier (CID), and the node address (NAD). Epilogue is
another name for the 16-bit CRC that precedes the EOF.
The information field is the general location for data.

Block Types

The standard defines three types of blocks: I-block,
R-block, and S-block. Figures 12, 13, and 14 show the
applicable PCB bit assignments.

The I-block is the main tool to access the memory. For
I-blocks, bit 2 must be 1 and bit 6, bit 7, and bit 8 must
be 0. Bit 5, marked as CH, is used to indicate chaining,
a function that is not used or supported by the
MAX66020. Therefore, bit 5 must always be 0. Bit 4,
marked as CID, is used by the master to indicate
whether the prologue field contains a CID byte. The
MAX66020 processes blocks with and without CID as
defined in the standard. The master must include the
CID byte if bit 4 is 1. Bit 3, marked as NAD, is used to
indicate whether the prologue field contains an NAD
byte, a feature not supported by the MAX66020.
Therefore, bit 3 must always be 0. Bit 1, marked as #, is

MAX66020

ISO/IEC 14443 Type B-Compliant

1Kb Memory Fob

_______________________________________________________________________________________

TRANSMISSION OF A SINGLE BIT

SHOWN AS EIGHT CYCLES OF THE 847kHz SUBCARRIER

DATA*

*DEPENDING ON THE INITIAL PHASE, THE DATA POLARITY MAY BE INVERSE.

Figure 10. Uplink: Load Modulation of the RF Field by the BPSK Modulated Subcarrier

PROLOGUE FIELD

INFORMATION FIELD

EPILOGUE FIELD

PCB

CID NAD

(DATA)

CRC

(LSB)

CRC

(MSB)

1 BYTE

0 OR MORE BYTES

1 BYTE

Figure 11. ISO/IEC 14443-4 Type B Block Format

BIT 8

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

MSb

LSb

CID

NAD

Figure 12. Bit Assignments for I-Block PCB