SAA5500PS Philips Semiconductors, SAA5500PS Datasheet - Page 61

• Manufacturer Part Number: SAA5500PS
• Description: Standard TV Microcontrollers with On-Screen Display(OSD)
• Manufacturer: Philips Semiconductors

Philips Semiconductors
19.8.1
This area is covered by the screen colour. The screen
colour display area starts with a fixed offset of 8 s from
the leading edge of the horizontal sync pulse in the
horizontal direction. A vertical offset is not necessary.
Table 18 Screen colour display area
19.8.2
The text area can be defined to start with an offset in both
the horizontal and vertical direction.
Table 19 Text display area
The horizontal offset is set in the MMR Text Area Start.
The offset is done in full width characters using TAS<5:0>
and quarter characters using HOP<1:0> for fine setting.
The values 00H to 08H for TAS<5:0> will result in a
corrupted display.
The width of the text area is defined in the MMR Text Area
End by setting the end character value TAE<5:0>. This
number determines where the background colour of the
text area will end if set to extend to the end of the row. It will
also terminate the character fetch process thus eliminating
the necessity of a row end attribute. This entails however
writing to all positions.
The vertical offset is set in the MMR Text Position Vertical
Register. The offset value VOL<5:0> is done in number of
TV scan lines.
1999 Oct 27
Horizontal
Vertical
Horizontal
Vertical
VECTOR
VECTOR
Standard TV microcontrollers with
On-Screen Display (OSD)
S
T
EXT DISPLAY AREA
CREEN COLOUR DISPLAY AREA
Start at 8 s after leading edge of
horizontal sync for 56 s.
Line 9, field 1 (321, field 2) to leading
edge of vertical sync (line numbering
using 625 standard).
Up to 40 full sized characters per row.
Start position setting from 8 to 64
characters from the leading edge of
horizontal sync. Fine adjustment in
quarter characters.
256 lines (nominal 41 to 297). Start
position setting from leading edge of
vertical sync, legal values are 4 to 64
lines. (line numbering using
625 standard).
DESCRIPTION
DESCRIPTION
61
Note that the Text Position Vertical Register should not be
set to 00H as the Display Busy interrupt is not generated
in these circumstances.
19.9
A set can consist of alphanumeric characters as required
by WST Teletext or customer definable OSD characters.
Two character sets can be displayed at once. These are
the basic G0 set or the alternate G2 set (Twist Set).
The basic set is selected using TXT18.BS<1:0>.
The alternate/twist character set is defined by
TXT19.TS<1:0>. Since the alternate character set is an
option it can be enabled or disabled using TXT19.TEN,
and the language code that is defined for the alternate set
is defined by TXT19.TC<2:0>.
19.10 Display synchronization
The horizontal and vertical synchronizing signals from the
TV deflection are used as inputs. Both signals can be
inverted before being delivered to the Phase Selector
section.
SFRs bits TXT1.HPOLARITY and TXT1.VPOLARITY
control the polarity.
A line locked 12 MHz clock is derived from the 12 MHz free
running oscillator by the Phase Selector. This line locked
clock is used to clock the whole of the Display block.
The horizontal and vertical sync signals are synchronized
with the 12 MHz clock before being used in the Display
section.
19.11 Video/data switch (fast blanking) polarity
The polarity of the Video/data (fast blanking) signal can be
inverted. The polarity is set with the VDSPOL bit in the
MMR RGB Brightness.
Table 20 Fast blanking signal polarity
VDSPOL
0
0
1
1
Character set
VDS
1
0
0
1
Preliminary specification
Video display
Video display
CONDITION
RGB display
RGB display
SAA55xx