Rainbow-electronics MAX66040 Manual do Utilizador descarregar pdf (Página 6)

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 function commands, the command code,

parameters, and response are embedded between

SOF and CRC. With memory function commands, com-

mand code, and parameters are placed into the infor-

mation 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 in the case of ISO/IEC 14443

is 13.56MHz. The subsequent paragraphs are a con-

cise 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 8). 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.

MAX66040

ISO/IEC 14443 Type B-Compliant

Secure Memory

8 _______________________________________________________________________________________

ABRIDGED DATA SHEET

START

BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7 BIT 9

STOP/IDLE

BIT 8

Figure 6. ISO/IEC 14443 SOF/EOF Character Format

SOF ONE OR MORE DATA CHARACTERS

CRC (LSB) CRC (MSB) EOF

TIME

Figure 7. ISO/IEC 14443 Frame Format

CARRIER AMPLITUDE

11 1100

MODULATION INDEX M = = 0.08 TO 0.14

A - B

A + B

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

1 2 3 4 5 6 7 8 9 10 11 ... 24 25

ABRIDGED DATA SHEET 1

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