Lucent Technologies MN102H75K User Manual

198

Through register settings, you can independently control shuttering for text, text 

background, graphics, and color background. You can also output blanks to the 
shuttered area.

You cannot shutter the cursor layer.

Table 7-13 shows the register settings required for these effects. There are three 

types of shuttering —shuttering of text, text background, and graphics, shuttering 
of the color background, and shutter blanking. The sections below describe how 

to control each of these.

■

Do not allow the horizontal shut-

tering boundaries to overlap any 

italicized portion of a closed-
caption display. This distorts the 

italicized characters.

Text
Set the text shutter control bit, CCSHT, of the shutter control register, SHTC 

(x’007F28’) to 1.

Set the text background shutter control bit, BCSHT, of SHTC to 1.

Set the text background shutter control bit, GSHT, of SHTC to 1.

Figure 7-33 shows three setup examples of text-layer shuttering.

Text shuttering

CCSHT

0: Shutter text-layer characters

1: Don’t shutter text-layer characters

Text background 

shuttering

BCSHT

0: Shutter text-layer background

1: Don’t shutter text-layer background

Graphics shuttering

GSHT

0: Shutter graphics layer

1: Don’t shutter graphics layer

Color background 

shuttering

COLBSHT

0: Shutter color background

1: Don’t shutter color background

Shutter blanking

SHTBLK

0: Don’t output blanks to the shuttered area

1: Output blanks to the shuttered area