HTMS8x01 datasheet(45/57 Pages) NXP

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HTMS1x01_8x01

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Product data sheet

COMPANY PUBLIC

Rev. 3.3 — 17 October 2014

152933

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:

u16 + u12 + u5+ 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.

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