HTMS1x01_8x01 All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2015. All rights reserved.
Product data sheet
COMPANY PUBLIC
Rev. 3.4 — 21 May 2015
152934 45 of 57
NXP Semiconductors
HTMS1x01; HTMS8x01
HITAG µ transponder IC
15. Transponder Talks First (TTF) mode
This mode of the HITAG µ transponder enables data transmission to a RWD without
sending any command. Every time the transponder IC is activated by the field it starts
executing this mode.
The transponder in TTF mode sends the data stored in the EEPROM independent if the
data is ISO compliant or not.
If the transponder IC is configured in TTF mode a SWITCH command or SOF sent by the
RWD within the defined listening window sets the transponder into RTF mode.
16. Data integrity/calculation of CRC
The following explanations show the features of the HITAG µ protocol to protect read and
write access to transponders from undetected errors. The CRC is an 16-bit CRC
according to ISO 11785.
16.1 Data transmission: RWD to HITAG µ transponder IC
Data stream transmitted by the RWD to the HITAG µ transponder may include an optional
16-bit Cyclic Redundancy Check (CRC-16).
The data stream is first verified for data errors by the HITAG µ transponder IC and then
executed.
The generator polynomial for the CRC-16 is:
u
16
+ u
12
+ u
5
+ 1 = 1021h
The CRC pre set value is: 0000h
16.2 Data transmission: HITAG µ transponder IC to RWD
The HITAG µ transponder calculates the CRC on all received bits of the request. Whether
the HITAG µ transponder IC calculated CRC is appended to the response depends on the
setting of the CRCT flag.
