saa6712e NXP Semiconductors, saa6712e Datasheet - Page 50

• Manufacturer Part Number: saa6712e
• Description: Xga Rgb To Tft Graphics Engine
• Manufacturer: NXP Semiconductors

Philips Semiconductors
8.10
8.10.1
The implemented OSD is a character based window
system. It consists of a character matrix memory where all
character definitions are stored, and an OSD window
memory defining the OSD window’s contents. The OSD
window will be inserted into the video data stream if
osd_active is set to logic 1. Writing to these memories can
be done during data processing.
8.10.2
The OSD window contains the character, colour and
appearance information to be displayed. Such a definition
exists for each character position. A character can use one
of 8 different foreground and background colours. Some of
these colours can be defined as transparent colours where
the original picture information will be displayed instead,
as alpha blended colours where a 1 : 1 or 1 : 2 alpha
blending will be done between picture and OSD, or as
normal colours. Transparency or alpha blending effects
will be enabled or disabled for the single characters.
The size and outline of the visible OSD window can be
programmed as long as the internal memory meets the
needs. This memory is able to store information of
1152 characters information.
The programming registers osd_v_size and osd_h_size
define the OSD window size in characters. The window
position inside the output frame must be defined with
osd_v_offset and osd_h_offset (see Fig.15).
1999 Aug 25
XGA RGB to TFT graphics engine
On screen display
OSD
OSD
GENERALS
WINDOW
50
The OSD can be programmed to use a 24
matrix, or a 12
Kanji and the second for standard characters.
The selection of the font size is done by char_size.
A logic 1 selects 24
12
128 different characters can be defined. Alternatively up to
42 characters of the larger 24
Table 12 gives some possible OSD settings.
handbook, halfpage
16 font. If the small 12
OUTPUT FRAME
osd_h_offset
Fig.15 OSD window positioning.
16 matrix. The first one should be used for
osd_v_offset
OSD
24 font, and a logic 0 the smaller
osd_h_size
16 font is used, up to
24 font can be used.
Preliminary specification
SAA6712E
MHB260
24 character
osd_v_size