CR14 STMicroelectronics, CR14 Datasheet - Page 30

• Manufacturer Part Number: CR14
• Description: Low Cost Iso14443 Type-b Contactless Coupler Chip With Anti-collision And Crc Management
• Manufacturer: STMicroelectronics

6 CR14 ISO14443 type-B Radio Frequency data transfer
6.9
Figure 26. Example of a Complete Transmission Frame
6.10
30/46
the CR14
Sent by
Case of Answer Frame with SOF & EOF
Case of Answer Frame without SOF & EOF
Transmission Frame
The Request Frame transmission must be followed by a minimum delay, t
which no ASK or BPSK modulation occurs, before the Answer Frame can be transmitted. t
the minimum time required by the CR14 to switch from transmission mode to reception mode,
and should be inserted after each frame. After t
by the PICC at 847kHz for a minimum time of t
synchronize. After t
(‘0’) of the Answer SOF (or the start bit ‘0’ of the first data character in non SOF/EOF mode).
CRC
The 16-bit CRC used by the CR14 follows the ISO14443 type B recommendation. For further
information, please see
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 CR14, the PICC verifies that the CRC value is valid. If
it is invalid, it discards the frame and does not answer the CR14.
Upon reception of an Answer from the PICC, the CR14 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
at 106Kb/s
Sent by the PICC
SOF
12 bits
Output Data Transfer using ASK Modulation
10 bits
Cmd
10 bits
Data
t DR
1
, the first phase transition generated by the PICC represents the start bit
10 bits
Appendix A on page
CRC
LSBit
10 bits
CRC 16 (8 bits)
CRC
LSByte
10 bits
EOF
MSBit LSBit
64/f s Min
64/f s Min
44.
t 0
t 0
1
0
, the 13.56MHz carrier frequency is modulated
(see
t WDG
t WDG
f s = 847.5kHz
80/f s Min
80/f s Min
Sync
Sync
CRC 16 (8 bits)
Table
t 1
t 1
Input Data Transfer using 847kHz BPSK Modulation
MSByte
12 or 13
10 bits
SOF
Data
13) to allow the CR14 to
bits
10 bits
Data
MSBit
10 bits
Data
ai09256
10 bits
Data
10 bits
CRC
0
(see
10 bits
CRC
10 bits
CRC
Table
10 bits
CRC
12 or 13
EOF
bits
13), in
ai12052
CR14
0
is