Renesas PCA7400 Manual de usuario descargar pdf (Pagina 55)

MITSUBISHI MICROCOMPUTERS

M37271MF-XXXSP

M37271EF-XXXSP, M37271EFSP

SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER

and ON-SCREEN DISPLAY CONTROLLER

Notes 1 : 1TC (TC : OSD clock cycle divided by prescaler) gap oc-

curs between the horizontal display start position set by

the horizontal position register and the most left dot of the

1st block. Accordingly, when 2 blocks have different pre-

divide ratios, their horizontal display start position will not

match.

2 : The horizontal start position is based on the OSD clock

source cycle selected for each block. Accordingly, when 2

blocks have different OSD clock source cycles, their hori-

zontal display start position will not match.

Fig. 60. Notes on horizontal display start position

(3) Dot Size

The dot size can be selected by a block unit. The dot size in vertical

direction is determined by dividing HSYNC in the vertical dot size con-

trol circuit. The dot size in horizontal is determined by dividing the

following clock in the horizontal dot size control circuit : the clock

gained by dividing the OSD clock source (data slicer clock, OSC1) in

the pre-divide circuit. The clock cycle divided in the pre-divide circuit

is defined as 1TC.

The dot size of the layer 1 is specified by bits 6 to 3 of the block

control register.

The dot size of the layer 2 is specified by the following bits : bits 3

and 4 of the block control register, bit 6 of the clock source control

ter), refer to Figure 62 (the structure of the clock source control reg-

ister).

The block diagram of dot size control circuit is shown in Figure 61.

Notes 1 : The pre-divide ratio = 3 cannot be used in the CC mode.

2 : The pre-divide ratio of the OSD mode block on the layer 2

must be same as that of the CC mode block on the layer 1

by bit 6 of the clock source control register.

3 : In the bi-scan mode, the dot size in the vertical direction is

2 times as compared with the normal mode. Refer to “(13)

Scan Mode” about the scan mode.

Fig. 61. Block diagram of dot size control circuit

SYNC

Block 1 (Pre-divide ratio 1, clock source data slicer clock)

OSC

✕N

OSC’

✕N

Note 1

Note 2

Block 2 (Pre-divide ratio 2, clock source data slicer clock)

Block 3 (Pre-divide ratio 3, clock source data slicer clock)

Block 4 (Pre-divide ratio 3, clock source OSC1)

Data slicer clock

SYNC

OSC1

Synchronization

Cycle

circuit

Cycle

Pre-divide circuit

Clock cycle

= 1T

Horizontal dot size

control circuit

Vertical dot size

control circuit

OSD control circuit

1 2 ... 50 51 52 53 54 55 56 57 58 59 60 ... 97 98

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