Rainbow Electronics MAX66000 User Manual

Page 4

3 bytes between SOF and EOF is called a frame
(Figure 6). The last two data characters of an ISO/IEC
14443 Type B frame are an inverted 16-bit CRC of the
preceding data characters generated according to the
CRC-16-CCITT polynomial. This CRC is transmitted with
the LSB first. For more details on the CRC-16-CCITT,
refer to ISO/IEC 14443-3, Annex B. With network func-
tion commands, the command code, parameters, and
response are embedded between SOF and CRC. With
memory function commands, command code, and
parameters are placed into the information field of
I-blocks (see the

Block Types

section), which in turn

are embedded between SOF and EOF.

For transmission, the frame information is modulated on a
carrier frequency, which is 13.56MHz for ISO/IEC 14443.
The subsequent paragraphs are a concise description
of the required modulation and coding. For full details
including SOF/EOF and subcarrier on/off timing, refer to
ISO/IEC 14443-3, Sections 7.1 and 7.2.

The path from master to slave uses amplitude modula-
tion with a modulation index between 8% and 14%
(Figure 7). In this direction, a START bit and logic 0 bit
correspond to a modulated carrier; STOP bit and logic
1 bit correspond to the unmodulated carrier. EOF ends
with an unmodulated carrier instead of STOP bits.

MAX66000

ISO/IEC 14443 Type B-Compliant
64-Bit UID

_______________________________________________________________________________________

START

1
0

BIT 1

BIT 2

BIT 3

BIT 4

BIT 5

BIT 6

BIT 7

BIT 9

STOP/IDLE

BIT 8

Figure 5. ISO/IEC 14443 SOF/EOF Character Format

SOF

ONE OR MORE DATA CHARACTERS

CRC (LSB)

CRC (MSB)

EOF

TIME

Figure 6. ISO/IEC 14443 Frame Format

CARRIER AMPLITUDE

MODULATION INDEX

M = = 0.08 TO 0.14

A - B

A + B

Figure 7. Downlink: 8% to 14% Amplitude Modulation