CRX14_05 Datasheet, PDF (21/40 Pages) STMicroelectronics – Low Cost ISO14443 type-B Contactless Coupler Chip with Anti-Collision, CRC Management and Anti-Clone Function

CRX14
CRX14 ISO14443 TYPE-B RADIO FREQUENCY DATA TRANSFER
Output RF Data Transfer from the CRX14 to the
PICC (Request Frame)
The CRX14 output buffer is controlled by the
13.56MHz clock signal generated by the external
oscillator and by the request frame generator. The
CRX14 can be directly connected to an external
matching circuit to generate a 13.56MHz sinusoi-
dal carrier frequency on its antenna.
The current driven into the antenna coil is directly
generated by the CRX14 RFOUT output driver.
If the antenna is correctly tuned, it emits an H-field
of a large enough magnitude to power a contact-
less PICC from a short distance. The energy re-
ceived on the PICC antenna is converted to a
Power Supply Voltage by a regulator, and turned
into data bits by the ASK demodulator. The
CRX14 amplitude modulates the 13.56MHz wave
by 10% as represented in Figure 20. The data
transfer rate is 106 kbit/s.
Figure 20. Wave Transmitted using ASK Modulation
DATA BIT TRANSMITTED
BY THE CRX14
10% ASK MODULATION
OF THE 13.56MHz WAVE,
GENERATED BY THE RFOUT
DRIVER
10% ASK MODULATION
OF THE 13.56MHz WAVE,
GENERATED ON THE CRX14
ANTENNA
Transfer time for one data bit is 1/106 kHz
AI10912
Transmission Format of Request Frame
Characters
The CRX14 transmits characters of 10 bits, with
the Least Significant Bit (b₀) transmitted first, as
shown in Figure 21.
Several 10-bit characters, preceded by the Start
Of Frame (SOF) and followed by the End Of
Frame (EOF), constitute a Request Frame, as
shown in Figure 27.
A Request Frame includes the SOF, instructions,
addresses, data, CRC and the EOF as defined in
the ISO14443 type-B.
Each bit duration is called an Elementary Time
Unit (ETU). One ETU is equal to 9.44µs (1/
106kHz).
Figure 21. CRX14 Request Frame Character Format
b0 b1 b2 b3 b4 b5 b6 b7 b8 b9
1 Start _LSB
ETU '0'
Information Byte
MSB ^Stop
'1'
ai09250
21/40