SAA5531 Philips Semiconductors, SAA5531 Datasheet - Page 70

• Manufacturer Part Number: SAA5531
• Description: Enhanced TV microcontrollers with On-Screen Display OSD
• Manufacturer: Philips Semiconductors

Philips Semiconductors
19.8
The dynamic scroll region is defined by the MMR Scroll
Area, MMR Scroll Range, MMR Top Scroll line and the
MMR Status. The scroll area is enabled when the SCON
bit is set in MMR Status.
The position of the soft scroll area window is defined using
the Soft Scroll Position bits (SSP<3:0>) and the height of
the window is defined using the Soft Scroll Height bits
(SSH<3:0>) both are in MMR Scroll Range. The rows that
are scrolled through the window are defined using the Start
Scroll Row (STS<3:0>) and the Stop Scroll Row
(SPS<3:0>) both are in MMR Scroll Area.
The soft scrolling function is done by modifying the Scroll
Line (SCL<3:0>) in MMR Top Scroll Line and the first scroll
row value SCR<3:0> in the MMR Status.
2000 Feb 23
handbook, full pagewidth
Enhanced TV microcontrollers with
On-Screen Display (OSD)
Soft scroll action
pointer SSP < 3:0 > e.g. 6
soft scroll position
SSH < 3:0 > e.g. 4
soft scroll height
ROW
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Fig.32 Soft scroll area.
70
If the number of rows allocated to the scroll counter is
larger than the defined visible scroll area, this allows parts
of rows at the top and bottom to be displayed during the
scroll function. The registers can be written throughout the
field and the values are updated for display with the next
field sync. Care should be taken that the register pairs are
written to by the software in the same field.
Only a region that contains only single height rows or only
double height rows can be scrolled.
TXT: The display is organised as a fixed size of 25 rows
(0 to 24) of 40 columns (0 to 39). This is the standard size
for teletext transmissions. The control data in row 25 is not
displayed but is used to configure the display page
correctly.
usable for
OSD display
should not be used
for OSD display
should not be used
for OSD display
usable for
OSD display
MBK967
SPS < 3:0 > e.g. 11
STS < 3:0 > e.g. 3
start scroll row
start scroll row
soft scrolling area
Preliminary specification
SAA55xx