SR176 datasheet(9/35 Pages) STMICROELECTRONICS

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SR176

Data transfer

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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

Figure 5.

Request start of frame

Figure 6.

Request End Of Frame

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, fS, as specified in ISO 14443-2 Type B,

and as shown in Figure 7.

Table 2.

Bit description

Bit

Description

Value

Start bit used to synchronize the transmission

b0 = 0

b1 to b8

Information Byte (command, address or data or

CRC)

Information Byte sent, least

significant bit first

Stop bit used to indicate the end of a character

b9 = 1

ai07664

1 ETU

Start

"0"

Stop

"1"

MSb

LSb

Information Byte

ai07665

ETU

b10

b11

0000000000

ai07666

ETU

0000000000

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