SAA5531 Philips Semiconductors, SAA5531 Datasheet - Page 59

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

Philips Semiconductors
19.3
All display features are now described in detail for both
TXT and CC modes.
19.3.1
Flashing causes the foreground colour pixel to be
displayed as the background pixels. The flash frequency is
controlled by software setting and resetting the MMR
Status (see Table 34) at the appropriate interval.
CC: This attribute is valid from the time set (see Table 22)
until the end of the row or until otherwise modified.
TXT: This attribute is set by the control character ‘flash’
(08H) (see Fig.30) and remains valid until the end of the
row or until reset by the control character ‘steady’ (09H).
19.3.2
CC: This attribute is valid from the time set until end of row
or otherwise modified if set with Serial Mode 0. If set with
Serial Mode 1, then it is set from the next character
onwards.
In text mode (within CC mode) the background colour is
displayed regardless of the setting of the box attribute bit.
Boxes take effect only during mixed mode, where boxes
are set in this mode the background colour is displayed.
Character locations where boxes are not set show
video/screen colour (depending on the setting in the MMR
Display Control) in stead of the background colour.
TXT: Two types of boxes exist the teletext box and the
OSD box. The teletext box is activated by the ‘start box’
control character (0BH). Two start box characters are
required to begin a teletext box, with the box starting
between the 2 characters. The box ends at the end of the
line or after a ‘end box’ control character.
TXT mode can also use OSD boxes, they are started using
size implying OSD control characters
(BCH/BDH/BEH/BFH). The box starts after the control
character (set after) and ends either at the end of the row
or at the next size implying OSD character (set at).
The attributes flash, teletext box, conceal, separate
graphics, twist and hold graphics are all reset at the start
of an OSD box, as they are at the start of the row.
2000 Feb 23
Enhanced TV microcontrollers with
On-Screen Display (OSD)
Display feature descriptions
F
B
LASH
OXES
59
OSD boxes are only valid in TV mode which is defined by
TXT5 = 03H and TXT6 = 03H.
19.3.3
The size of the characters can be modified in both the
horizontal and vertical directions.
CC: Two sizes are available in both the horizontal and
vertical directions. The sizes available are normal ( 1),
double ( 2) height/width and any combination of these.
The attribute setting is always valid for the whole row.
Mixing of sizes within a row is not possible.
TXT: Three horizontal sizes are available normal ( 1),
double ( 2) and quadruple ( 4). The control characters
‘normal size’ (0CH/BCH) enables normal size, the ‘double
width’ or double size (0EH/BEH/0FH/BFH) enables double
width characters.
Any two consecutive combination of ‘double width’ or
‘double size’ (0EH/BEH/0FH/BFH) activates quadruple
width characters, provided quadruple width characters are
enabled by TXT4.QUAD WIDTH ENABLE.
Three vertical sizes are available normal(x1), double (x2)
and quadruple (x4). The control characters ‘normal size’
(0CH/BCH) enable normal size, the ‘double height’ or
‘double size’ (0DH/BDH/0FH/BFH) enable double height
characters. Quadruple height character are achieved by
using double height characters and setting the global
attributes TXT7.DOUBLE HEIGHT (expand) and
TXT7.BOTTOM/TOP.
If double height characters are used in teletext mode,
single height characters in the lower row of the double
height character are automatically disabled.
19.3.4
CC: This attribute is valid from the time set until the end of
the row or otherwise modified. The attribute causes the
character foreground pixels to be offset horizontally by
1 pixel per 4 scan lines (interlaced mode). The base is the
bottom left character matrix pixel. The pattern of the
character is indented as shown in Fig.25.
TXT: The Italic attribute is not available.
S
I
TALIC
IZE
Preliminary specification
SAA55xx