CRX14_10 Datasheet, PDF (26/47 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
6
CRX14 ISO14443 type-B radio frequency data
transfer
CRX14
6.1
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 sinusoidal 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
contactless PICC from a short distance. The energy received 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 19. The data transfer rate is 106 kbit/s.
Figure 19. 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
6.2
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 20.
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 26.
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).
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Doc ID 8880 Rev 4