CRX14_10 Datasheet, PDF (30/47 Pages) STMicroelectronics – ISO14443 type-B contactless coupler chip with anti-collision, CRC management and anti-clone function

CRX14 ISO14443 type-B radio frequency data transfer
CRX14
Figure 26. Example of a complete transmission frame
Sent by
the CRX14
SOF
12 bits
at 106Kb/s
Cmd
10 bits
Data
10 bits
tDR
CRC
10 bits
Case of Answer Frame with SOF & EOF
Sent by the PICC
CRC
10 bits
EOF
10 bits
fs = 847.5kHz
Sync
SOF
Data CRC CRC EOF
t0
t1
64/fs Min 80/fs Min
tWDG
12 or 13
bits
10 bits
10 bits
10 bits
12 or 13
bits
Case of Answer Frame without SOF & EOF
Output Data Transfer using ASK Modulation
Sync
Data Data Data CRC CRC
t0
t1
64/fs Min 80/fs Min
tWDG
10 bits
10 bits
10 bits
10 bits
10 bits
Input Data Transfer using 847kHz BPSK Modulation
ai09255
6.10
CRC
The 16-bit CRC used by the CRX14 follows the ISO14443 type B recommendation. For
further information, please see Appendix A on page 44.
The two CRC Bytes are present in all Request and Answer Frames, just before the EOF.
The CRC is calculated on all the Bytes between the SOF and the CRC Bytes.
Upon transmission of a Request from the CRX14, the PICC verifies that the CRC value is
valid. If it is invalid, it discards the frame and does not answer the CRX14.
Upon reception of an Answer from the PICC, the CRX14 verifies that the CRC value is valid.
If it is invalid, it stores the value FFh in the Input/Output Frame Register.
The CRC is transmitted Least Significant Byte first. Each Byte is transmitted Least
Significant Bit first.
Figure 27. CRC transmission rules
LSBit
LSByte
MSBit LSBit
MSByte
MSBit
CRC 16 (8 bits)
CRC 16 (8 bits)
ai09256
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Doc ID 8880 Rev 4