TDA935x Philips, TDA935x Datasheet - Page 49

• Manufacturer Part Number: TDA935x
• Description: TV Signal Processor-Teletext Decoder with Embedded u-Controller
• Manufacturer: Philips

Philips Semiconductors
Screen and Global Controls
A number of attributes are available that affect the whole
display region, and cannot be applied selectively to
regions of the display.
TV
The number of TV scan lines per field used for each
display row can be defined, the value is independent of the
character size being used. The number of lines can be
either 10/13/16 per display row. The number of TV scan
lines per row is defined TXT21.DISP_LINES<1:0>.
A value of 9 lines per row can be achieved if the display is
forced into 525 line display mode by
TXT17.DISP_FORCE<1:0>, or if the device is in 10 line
mode and the automatic detection circuitry within display
finds 525 line display syncs.
C
There are four different character matrices available, these
are 12x10, 12x13, and 12x16. The selection is made using
TXT21.CHAR_SIZE<1:0> and is independent of the
number of display lines per row.
If the character matrix is less than the number of TV scan
lines per row then the matrix is padded with blank lines. If
the character matrix is greater than the number of TV scan
lines then the character is truncated.
2001 Jan 18
HARACTER
TV signal processor-Teletext decoder with
embedded -Controller
SCAN LINES PER
M
ATRIX
ROW
(H
X
V)
49
D
CC: When attributes superimpose or when boxing (see
Table 18, Serial Mode 0/1, bit 6) is set, the resulting display
depends on the setting of the following screen control
mode bits in REG0:Display Control.
Table 19 Display Modes
TXT: The display mode is controlled by the bits in the TXT5
and TXT6. There are 3 control functions - Text on,
Background on and Picture on. Separate sets of bits are
used inside and outside Teletext boxes so that different
display modes can be invoked. TXT6 is used if the
newsflash (C5) or subtitle (C6) bits in row 25 of the basic
page memory are set otherwise TXT5 is used. This allows
the software to set up the type of display required on
newsflash and subtitle pages (e.g. text inside boxes, TV
picture outside) this will be invoked without any further
software intervention when such a page is acquired.
Table 20 TXT Display Control Bits
ISPLAY
Display Mode
Video
Full Text
Mixed Screen
Colour
Mixed Video
Picture On
0
0
0
1
1
1
M
TDA935X/6X/8X PS/N2 series
ODES
Text On
0
1
1
0
1
1
MOD
1 0
0 0
0 1
1 0
1 1
Background
On
x
0
1
x
0
1
Description
Video mode disables all display
activities and sets the RGB to true
black and VDS to video.
Full Text mode displays screen
colour at all locations not covered by
character foreground or background
colour. The box attribute has no
effect.
Mixed Screen mode displays screen
colour at all locations not covered by
character foreground, within boxed
areas or, background colour.
Mixed Video mode displays video at
all locations not covered by
character foreground, within boxed
areas or, background colour.
Tentative Device Specification
Text mode, black screen
Text mode, background always black
Text mode
Video mode
Mixed text and TV mode
Text mode, TV picture outside text area
Effect