saa569x NXP Semiconductors, saa569x Datasheet - Page 82

• Manufacturer Part Number: saa569x
• Description: Enhanced Tv Microcontrollers With On-screen Display Osd
• Manufacturer: NXP Semiconductors

Philips Semiconductors
23.5.19
The device can act on the TV’s display circuit to reduce
contrast of the video by driving the COR output LOW.
Contrast reduction improves the readability of characters
in mixed mode.
TXT: Bits COR IN in SFRs TXT5 and TXT6 control when
the COR output of the device is activated. These bits allow,
for example, the display to be set-up so that the areas
inside Teletext boxes are contrast reduced when a subtitle
is displayed, leaving the rest of the screen displayed as in
normal conditions.
CC: Here, the contrast reduction is controlled by the
contrast reduction attribute (see Table 35). This attribute is
valid from the time set until the end of a row of a display
window, or otherwise modified if set with Serial Mode 0.
If set with Serial Mode 1, it is set from the next character
onwards.
23.6
This section describes the character and attribute coding
for each mode.
23.6.1
Character coding is split into character oriented attributes
(parallel, see Table 34) and character group coding
(serial, see Table 35). The serial attributes take effect
either at the position of the attribute (set at), or at the
following location (set after) and remain effective until
either modified by a new serial attribute or until the end of
a row of a display window. A serial attribute is represented
as a space (the space character itself however is not used
for this purpose). The attributes that are still active,
e.g. overline and underline, are visible during the display
of the space.
The default setting at the start of a row is:
2002 May 06
1
Flash off
Overline off
Underline off
Italics off
Display mode = superimpose
Fringing off
Background colour duration = 0
End of row = 0.
Enhanced TV microcontrollers with
On-Screen Display (OSD)
size
Character and attribute coding
CONTRAST REDUCTION
CC
MODE
82
The coding is done in 15-bit words. The codes are stored
sequentially in the Display memory. A maximum of
768 character positions can be defined for a single display.
23.6.2
Character coding is in a serial format, with only one
attribute being changed at any single location. The serial
attributes take effect either at the position of the attribute
(set at), or at the following location (set after). The attribute
remains effective until either modified by new serial
attributes or until the end of a row of a display window.
The default settings at the start of a row are:
The attributes have individual codes which are defined in
the basic character table (see Fig.39).
23.6.3
Table 34 Parallel character coding
12 to 13 character set selection; see Section 23.12.2
8 to 10
Foreground colour white (CLUT address 7)
Background colour black (CLUT address 8)
Horizontal size
Alphanumeric on
Contiguous Mosaic Graphics
Release Mosaics
Flash off
Box off
Conceal off
Twist off.
0 to 7
BITS
11
14
TXT
P
ARALLEL CHARACTER CODING
8-bit character code
three bits for eight foreground colours
mode bit: 0 = parallel code
special graphics; see Section 23.5.17
MODE
1, vertical size
SAA567x; SAA569x
DESCRIPTION
Objective specification
1 (normal size)