SRIX4K_07 Datasheet, PDF (12/50 Pages) STMicroelectronics – 13.56 MHz short-range contactless memory chip with 4096-bit EEPROM, anticollision and anti-clone functions

Data transfer
SRIX4K
3.2.3
Answer end of frame
The EOF shown in Figure 9 is composed of:
– followed by 10 ETUs at logic-0,
– followed by 2 ETUs at logic-1.
Figure 9. Answer end of frame
b0
b1
b2
b3
b4
b5
b6
b7
b8
b9
b10 b11
ETU 0
0
0
0
0
0
0
0
0
0
1
1
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3.3
Transmission frame
Between the Request data transfer and the Answer data transfer, all ASK and BPSK
modulations are suspended for a minimum time of t₀ = 128/ƒ_S. This delay allows the reader
to switch from Transmission to Reception mode. It is repeated after each frame. After t₀, the
13.56 MHz carrier frequency is modulated by the SRIX4K at 847 kHz for a period of
t₁ = 128/ƒ_S to allow the reader to synchronize. After t₁, the first phase transition generated
by the SRIX4K forms the start bit (‘0’) of the Answer SOF. After the falling edge of the
Answer EOF, the reader waits a minimum time, t₂, before sending a new Request Frame to
the SRIX4K.
Figure 10. Example of a complete transmission frame
Sent by the
Reader
Sent by the
SRIX4K
SOF Cmd Data CRC CRC EOF
12 bits
10 bits
at 106kb/s
10 bits
t _DR
10 bits
10 bits
10 bits
Input data transfer using ASK
fs=847.5kHz
Sync SOF _{Data CRC CRC EOF}
t₀
128/fs
t₁
128/fs
12 bits 10 bits 10 bits 10 bits 12 bits
t₂
Output data transfer using BPSK
SOF
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