Rainbow Electronics MAX66120 - Manual (Page 6)

MAX66120
ISO 15693-Compliant 1Kb Memory Fob
6 _______________________________________________________________________________________
ISO 15693 Communication
Concept
The communication between the master and the
MAX66120 (slave) is based on the exchange of data
packets. The master initiates every transaction; only
one side (master or slaves) transmits information at any
time. Each data packet begins with a start-of-frame
(SOF) pattern and ends with an end-of-frame (EOF)
pattern. A data packet with at least 3 bytes between
SOF and EOF is called a frame (Figure 5). The last 2
bytes of an ISO 15693 frame are an inverted 16-bit
CRC of the preceding data 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 15693 Part 3, Annex C.
For transmission, the frame information is modulated on
a carrier frequency, which is 13.56MHz for ISO 15693.
The subsequent paragraphs are a concise description
of the required modulation and coding. For full details
including graphics of the data coding schemes and
SOF/EOF timing, refer to ISO 15693-2, Sections 7.2,
7.3, and 8.
CODE DESCRIPTION
00000000b
(00h)
Unlocked (factory default)
10101010b
(AAh)
Locked (irreversible)
All other codes Unlocked
Table 3. Protection Code Assignments for U-Lock, AFI-Lock, DSFID-Lock, S-Lock
SOF 1 OR MORE DATA BYTES CRC (LSB) CRC (MSB) EOF
TIME
Figure 5. ISO 15693 Frame Format
Figure 6. Downlink Modulation (e.g., Approximately 100% Amplitude Modulation)
CARRIER
AMPLITUDE
100%
t