Rainbow Electronics MAX66040 - Manual (Page 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
1
0
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
A
B
CARRIER AMPLITUDE
t
1 1 1 1 0 0
MODULATION INDEX M = = 0.08 TO 0.14
A - B
A + B
Figure 8. Downlink: 8% to 14% Amplitude Modulation