LRI512 datasheet(5/54 Pages) STMICROELECTRONICS

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LRI512

DATA RATE AND DATA CODING

The data coding implemented in the LRI512 uses

pulse position modulation. Both data coding

modes that are described in the ISO15693 are

supported by the LRI512. The selection is made

by the VCD and indicated to the LRI512 within the

Start of Frame (SOF).

Data Coding Mode: 1 Out of 256

The value of one single byte is represented by the

position of one pause. The position of the pause

on 1 of 256 successive time periods of 18.88 µs

(256/fC), determines the value of the byte. In this

case the transmission of one byte takes 4.833 ms

and the resulting data rate is 1.65 kbit/s (fC/8192).

Figure 5 illustrates this pulse position modulation

technique. In this figure, data E1h (225d) is sent by

the VCD to the LRI512.

The pause shall occur during the second half of

the position of the time period that determines the

value, as shown in Figure 6.

A pause during the first period transmit the data

value 00h. A pause during the last period transmits

the data value FFh (255d).

Figure 5. 1 Out of 256 Coding Mode

Figure 6. Detail of One Time Period

AI06656

0 1

. . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

. . . . . . . . .

. . . . . . . . . . . . . . . . . . . . .

4.833 ms

18.88 µs

9.44 µs

Pulse

Modulated

Carrier

AI06657

18.88 µs

9.44 µs

Pulse

Modulated

Carrier

Time Period

one of 256

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