CRX14_10 Datasheet, PDF (29/47 Pages) STMicroelectronics – ISO14443 type-B contactless coupler chip with anti-collision, CRC management and anti-clone function

CRX14
CRX14 ISO14443 type-B radio frequency data transfer
6.7
Answer start of frame
The PICC SOF must be compliant with the ISO14443 type-B, and is shown in Figure 24
● Ten or eleven Elementary Time Units (ETU) each containing a logical ‘0’,
● Two ETUs containing a logical ‘1’.
Figure 24. Answer start of frame
b0 b1 b2 b3 b4 b5 b6 b7 b8 b9 b10 b11 b12
ETU 0
0
0
0
0
0
0
0
0
0
1
1
1
ai09254
6.8
Answer end of frame
The PICC EOF must be compliant with the ISO14443 type-B, and is shown in Figure 25:
● Ten or eleven Elementary Time Units (ETU) each containing a logical ‘0’,
● Two ETUs containing a logical ‘1’
Figure 25. Answer end of frame
b0 b1 b2 b3 b4 b5 b6 b7 b8 b9 b10 b11 b12
ETU 0
0
0
0
0
0
0
0
0
0
1
1
1
ai09254
6.9
Transmission frame
The Request Frame transmission must be followed by a minimum delay, t₀ (see Table ), in
which no ASK or BPSK modulation occurs, before the Answer Frame can be transmitted. t₀
is the minimum time required by the CRX14 to switch from transmission mode to reception
mode, and should be inserted after each frame. After t₀, the 13.56MHz carrier frequency is
modulated by the PICC at 847kHz for a minimum time of t₁ (see Table ) to allow the CRX14
to synchronize. After t₁, the first phase transition generated by the PICC represents the start
bit (‘0’) of the Answer SOF (or the start bit ‘0’ of the first data character in non SOF/EOF
mode).
Doc ID 8880 Rev 4
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