ISO/IEC 14443 Type B-Compliant

1Kb Memory Fob

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21

Param 2 informs the slave about the data rate that shall

be used for communication in the ACTIVE state and the

maximum frame size that the master can receive.

Figure 26 shows the bit assignments for the Param 2

byte. The MAX66020 supports the data rates of

105.9kbps (code 00b), 211.9kbps (code 01b),

423.75kbps (code 10b), and 847.5kbps (code 11b).

The master can choose different data rates for request

and response. Since it does not support chaining, the

MAX66020 ignores the frame size capability and

assumes that the master can receive frames as large

as specified in the ATQB response.

The lower nibble of Param 3 is used to confirm the pro-

tocol type as specified in the lower nibble of the second

byte of the ATQB protocol info. Since ISO/IEC 14443-3

sets the upper nibble of Param 3 to 0000b, the Param 3

value to be used for the MAX66020 in the ATTRIB

request is 01h.

Param 4 assigns the slave the CID number that is used

with the block transmission protocol to address one of

several slaves in the ACTIVE state. Figure 27 shows the

Param 4 bit assignments. Since the MAX66020 sup-

ports the CID field, the master can assign any number

in the range from 0 to 14. According to ISO/IEC 14443-

3, code 15 is reserved.

The ATTRIB request frame contains one optional field,

called higher layer information (HLINF). This field can

be used to include data as in the information field of the

ISO/IEC 14443 Type B block transmission protocol (see

Figure 11). If such data is present and the slave sup-

ports the HLINF field, then the slave processes the

HLINF data and returns the result in its response to the

ATTRIB request. Typically, the ATTRIB request is trans-

mitted without HLINF field. The only HLINF data that the

MAX66020 accepts and processes is the Get UID com-

mand, code 30h.

If the ATTRIB request has a matching PUPI and a valid

CRC, the slave transmits an ATTRIB response frame, as

shown in Figure 28. The upper nibble of the indicator,

also referred to as MBLI, is 0000b, telling that the slave

does not provide any information on its internal input

buffer size; the lower nibble returns the card identifier

value that the master has just assigned to the slave.

The HL response field is optional. There are three

cases to be distinguished:

a) If there was no HLINF field in the ATTRIB request,

then there is no HL response field in the response.

b) If there was a Get UID command code (30h) in the

HLINF field of the ATTRIB request, then the HL

response field is identical to the Get UID response

information field (i.e., 00h followed by the 8-byte UID).

c) If the code in the HLINF field of the ATTRIB request

was different from 30h, then the response frame does

not contain an HL response field.

DESELECT Command

The DESELECT command is used to transition the slave

from the ACTIVE to the HALT state after the master has

completed the communication with the slave. There are

two versions of the deselect request frame, one without

CID and one with CID. Figure 29 shows both versions.

Figure 27 shows the CID format.

Logically, the DESELECT command is a special case of

the S-block of the block transmission protocol, as

defined in part 4 of the ISO/IEC 14443 standard. The

MAX66020 responds to a DESELECT command if the

BIT 8

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

MSB

LSB

XXXX

RESPONSE DATA

RATE (UPLINK)

RECEIVER FRAME SIZE CAPABILITY

RESPONSE DATA

RATE (DOWNLINK)

Figure 26. Bit Assignments for Param 2 Byte

BIT 8

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

MSB

LSB

0

(FIXED)

CARD IDENTIFIER VALUE (CID)

0

00

Figure 27. Bit Assignments for Param 4 Byte

SOF

FRAME WITHOUT CID

CRC

EOF

(2 BYTES)

COMMAND

C2h

SOF

FRAME WITH CID

CRC

EOF

(2 BYTES)

CID

(1 BYTE)

COMMAND

CAh

Figure 29. DESELECT Request and Response Frames

INDICATOR

SOF

CRC

EOF

MBLI, CID

(2 BYTES)

HL RESPONSE

(

≥ 0 BYTES)

Figure 28. ATTRIB Response Frame