MAX66020
ISO/IEC 14443 Type B-Compliant
1Kb Memory Fob
14 ______________________________________________________________________________________
Write AFI
This command writes the AFI byte and reports the suc-
cess of the operation in the response. The AFI byte can
alternatively be defined by writing to the proper loca-
tion in memory block 10h using the Write Single Block
command. If this command is processed without any
error, the response information field consists of an indi-
cator byte with the code 00h.
Lock AFI
This command permanently locks (write protects) the
AFI byte and reports the success of the operation in the
response. Before using the Lock AFI command, the AFI
byte should be written to the device using the Write AFI
command. The AFI byte can alternatively be locked by
writing the AFI-Lock byte in memory block 11h to AAh,
using the Write Single Block command. To lock the AFI,
issue a request with the command code 28h in the
request information field. If this command is processed
without any error, the response information field con-
sists of an indicator byte with the code 00h.
Get UID
This command allows the master to retrieve the
device’s unique identification number, UID. In the
response, the least significant UID byte is transmitted
first. To read the UID, issue a request with the com-
mand code 30h in the request information field.
ISO/IEC 14443-3 Type B Initialization
and Anticollision Protocol
Before an ISO/IEC 14443-compliant RF device gives
access to its memory, a communication path between
the master and the RF device must be established.
Initially, the master has no information whether there
are any RF devices in the field of its antenna. To find
out whether there are one or more RF devices compli-
ant to a known standard in the field, the master uses a
standard-specific initialization and anticollision proto-
col. The ISO/IEC 14443 Type B protocol defines six
states: POWER-OFF, IDLE, WAITING FOR SLOT-
MARKER, READY, HALT, and ACTIVE. Figure 17
shows these states and the conditions under which a
slave transitions between states. For most cases, let-
ters surrounded by small circles reference the condi-
tion under which a transition occurs. The conditions
are explained in the legend to Figure 17. Table 5
explains terms that are used in the anticollision proto-
col and in the network function command description.
