SRI4K Datasheet, PDF (13/45 Pages) STMicroelectronics – 13.56 MHz short-range contactless memory chip with 4096-bit EEPROM and anticollision functions

SRI4K
3.4
Data transfer
CRC
The 16-bit CRC used by the SRI4K is generated in compliance with the ISO14443 Type B
recommendation. For further information, please see Appendix A. The initial register
contents are all 1s: FFFFh.
The two-byte CRC is present in every request and in every answer frame, before the EOF.
The CRC is calculated on all the bytes between SOF (not included) and the CRC field.
Upon reception of a request from a reader, the SRI4K verifies that the CRC value is valid. If
it is invalid, the SRI4K discards the frame and does not answer the reader.
Upon reception of an answer from the SRI4K, the reader should verify the validity of the
CRC. In case of error, the actions to be taken are the reader designer’s responsibility.
The CRC is transmitted with the least significant byte first and each byte is transmitted with
the least significant bit first.
Figure 11. CRC transmission rules
LSbit
LSByte
MSbit LSbit
MSByte
MSbit
CRC 16 (8 bits)
CRC 16 (8 bits)
ai07667
13/45