SR176_07 Datasheet, PDF (9/35 Pages) STMicroelectronics – 13.56 MHz, 176-bit short range contactless user EEPROM with 64-bit Unique ID

SR176
3.4
Request end of frame
The EOF, as shown in Figure 6, consists of:
● one falling edge
● followed by 10 ETUs set to logic 0
● followed by one single rising edge
Figure 4. SR176 request frame character format
b0 b1 b2 b3 b4 b5 b6 b7 b8 b9
Start
1 ETU _"0"
LSb
Information Byte
MSb ^Stop
"1"
Data transfer
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Table 2.
Bit
Bit description
Description
b₀
b₁ to b₈
b₉
Start bit used to synchronize the transmission
Information Byte (command, address or data or
CRC)
Stop bit used to indicate the end of a character
Figure 5. Request start of frame
Value
b₀ = 0
Information Byte sent, least
significant bit first
b₉ = 1
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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Figure 6. Request End Of Frame
b0 b1 b2 b3 b4 b5 b6 b7 b8 b9
ETU 0
0
0
0
0
0
0
0
0
0
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3.5
Output data transfer from the SR176 to the Reader (answer
frame)
The SR176 uses load modulation to return data to the reader. This modulation is achieved
by modifying the SR176 current flow in its antenna. With appropriate detector circuitry, the
reader is able to decode the information from the SR176. The data is transmitted using a
BPSK coding of a 847.5 kHz subcarrier frequency, f_S, as specified in ISO 14443-2 Type B,
and as shown in Figure 7.
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