T48C893 datasheet(67/82 Pages) ATMEL

67 / 82 page

T48C893

Rev. A4, 22-Jan-02

67 (82)

10111

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Synchronize

Manchester demodulation mode

Timer 3

mode

T3EX

SR–DATA

13817

T3I

CM31=SCI

011

Bit 0

Figure 77. Manchester demodulation

Combination mode 9: Biphase demodulation

SSI mode 1:

8-bit shift register internal data input (SI) and the internal shift clock (SCI) from the Timer 3

Timer 3 mode 11:

Biphase demodulation with Timer 3

In the Biphase demodulation mode the timer works like in the Manchester demodulation mode. The diffenence is that

the bits are decoded with the toggle flip-flop. This flip-flop samples the edge in the middle of the bitframe and the

compare register 1 match event shifts the toggle flip-flop output into shift register. Before activating the demodulation

the timer and the demodulation stage must be synchronized with the bitstream. The Biphase code timing consists of

parts with the half bitlength and the complete bitlength. The synchronization routine must start the demodulator after

an interval with the complete bitlength.

The counter can be driven by any internal clock source and the output T3O can be used by Timer 2 in this mode.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Synchronize

Biphase demodulation mode

Timer 3

mode

T3EX

Q1=SI

CM31=SCI

SR–DATA

13818

T3I

Reset

Counter 3

10101

Bit 0

Figure 78. Biphase demodulation

T48C893 Datasheet(PDF) 67 Page - ATMEL Corporation

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