Identiv uTrust 3720F, Reference Manual

Page: 26 / 87

Document Version 1.00 Last revised on Page 26 of 87
2020-04-10
Reference Manual for uTrust 3720F and uTrust 3721F Readers
5.3.3.2. ATR for ISO/IEC 14443-4 user tokens
The credential exposes its ATS or application information which is mapped to an ATR. The table
describes how this mapping is done.
Byte# Value Designation Description
0 0x3B Initial header
1 0x8n T0 n indicates the number of historical bytes in following ATR
2 0x80 TD1 upper nibble 8 indicates no TA2, TB2, TC2
lower nibble 0 means T=0
3 0x01 TD2 upper nibble 0 indicates no TA3, TB3, TC3
lower nibble 1 means T=1
4...3+n Historical
bytes or
application
information
Type A: the historical bytes from the ATS (up to 15 bytes) Type
B (8 bytes):
●
Byte 0 through 3: application data from ATQB,
●
Byte 4 through 6: protocol info byte from ATQB,
●
Byte 7: highest nibble is the MBLI (maximum buffer
length index) from ATTRIB, lowest nibble is 0x0
4+n TCK XOR of all previous bytes
Example of the ATR built for an ISO14443-4 credential:
Type A Type B