MAX66040 Maxim, MAX66040 Datasheet - Page 6

• Manufacturer Part Number: MAX66040
• Description: The MAX66040 combines 1024 bits of user EEPROM with secure hash algorithm (SHA-1) challenge-and-response authentication (ISO/IEC 10118-3 SHA-1), a 64-bit unique identifier (UID), one 64-bit secret, and a 13
• Manufacturer: Maxim

ISO/IEC 14443 Type B-Compliant
Secure Memory
Figure 6. ISO/IEC 14443 SOF/EOF Character Format
Figure 7. ISO/IEC 14443 Frame Format
Figure 8. Downlink: 8% to 14% Amplitude Modulation
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.
8
_______________________________________________________________________________________
SOF
A
CARRIER AMPLITUDE
B
1
0
ONE OR MORE DATA CHARACTERS
1
ABRIDGED DATA SHEET
START
BIT 1
0
BIT 2
MODULATION INDEX
BIT 3
1
BIT 4
CRC (LSB)
BIT 5
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.
M =
1
BIT 6
A + B
A - B
= 0.08 TO 0.14
BIT 7
0
BIT 8
BIT 9
CRC (MSB)
1
STOP/IDLE
EOF
t
TIME