MITSUBISHI MICROCOMPUTERS

M35052-XXXSP/FP

SCREEN CHARACTER and PATTERN DISPLAY CONTROLLERS

16

Supplemental explanation about display control register

(1) How to effect synchronous separation from composite video signals

Synchronous separation is effected as follows depending on the width of L-level of the vertical synchronous period.

1. Less than 8.4 ˚s ······ Not to be determined to be a vertical synchronous signal.

2. Equal to or higher than 8.4 ˚s but less than 15.6 ˚s ······ When two clocks continue, if take place, it is “L” period is determined to be a

vertical synchronization signal.

3. Equal to or higher than 15.6 ˚s ······ It is “L” period is determined to be a vertical synchronous signal with no condition.

The determination is made at the timing indicated by V in Fig.3 either in case 2 or in case 3.

Fig. 4 The method of synchronous separation from composite video signal.

Fig. 5 Field definition

VA horizontal scanning line number corresponds to slice lines DVP4 through

stands for either an equalizing pulse or sequence of synchronizing

pulse to be used as a trigger of a receiving set. H stands for a hori-

zontal scanning period.

(2) Field definition

8.4

µs

15.6

µs

Vertical synchronous signal

Composite video signal

V

8.4

µs

Equalizing pulse

Sequence of synchronizing pulse

First field

Pulses during a vertical

retrace line erasure period

Second field

1/2H

1H

123

456

7

8

9

10

1/2H1H

8–12H

1'2'3'4'5'6'7'8'9'10'

11

V