ST92185B STMicroelectronics, ST92185B Datasheet - Page 92

• Manufacturer Part Number: ST92185B
• Description: 16k/24k/32k Rom Hcmos Mcu With On-screen-display
• Manufacturer: STMicroelectronics

ST92185B - ON SCREEN DISPLAY (OSD)
ON SCREEN DISPLAY (Cont’d)
7.4.3.2 Color Processing
The color of any pixel on screen is the result of a
priority processing among several layers which
are (going from the lowest priority to the highest
one):
Color processing is also the result of register con-
trol bits (for global color attributes) and color ori-
ented attribute bits (from serial or parallel at-
tributes), refer to the
7.4.3.3 Pixel Clock Control
The pixel clock is generated outside of the display
macrocell by the on-chip Pixel Frequency multipli-
er which provides great frequency flexibility con-
trolled by software (refer to the RCCU chapter).
For example, reconfiguring the application from a
4/3 screen format to a 16/9 format is just a matter
of increasing the pixel frequency (i.e. reprogram-
ming the pixel frequency multiplier to its new val-
ue).
The output signal of the pixel frequency multiplier
is rephased by the Skew Corrector to be perfectly
in phase with the horizontal sync signal which
drives the display.
7.4.3.4 Display Character
Each character is made up of a 10 x 10 dots ma-
trix. All character matrix contents are fully user de-
finable and are stored in the pixel ROM (except the
G1 mosaic set which is hardware defined).
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Full Screen Color where nothing is processed
Default Background Color (it assumes pixel is
off)
Serial
background color serial attributes activated)
Parallel Background Color (pixel off, but
background color parallel attribute activated)
Default Foreground Color (pixel on, but no
foreground attribute activated)
Serial
foreground serial attribute activated)
Parallel Foreground Color (pixel on and
foreground parallel attribute activated)
Background
Foreground
Figure 0.1.4.3
Color
Color
(pixel
(pixel
off,
on
and
but
A set of colors defines the final color of the current
pixel.
In general, the character matrix content is dis-
played as it is, the pixel processing adding the
shape and the color information received from the
current attributes. Only three kinds of attributes al-
ter the displayed pixel. They are the following:
7.4.3.5 Rounding
Rounding can be enabled for the whole display us-
ing the GRE global attribute bit (See
this effect one half-dot is added in order to smooth
the diagonal lines. This processing is built into the
hardware. The half-dot is painted as foreground.
This half-dot is field-sensitive for minimum vertical
size
An extra ‘smooth rounding’ capability is also built-
in (see
added even if dots make an ‘L’. This capability is
activated using a parallel attribute (See
7.4.3.6 Underline
In this effect the last TV line of the character is dis-
played as foreground
7.4.3.7 Fringe
The fringe is a half-dot black border surrounding
completely the character foreground. This half-dot
is field sensitive for minimum vertical size
4).
7.4.3.8 Translucency
Certain video processors are able to mix the RGB
and video signals. This function of the chroma pro-
cessor is then driven by the TSLU output pin of the
ST9 device. See
7.4.3.9 Half-Tone
If the HT signal is activated, for example, while a
text box is displayed and a transparant back-
ground selected for all the display (MM bit =1 in
the FSCCR register), the HT signal performs a
contrast reduction to the background inside the
box. See
(Figure
Figure
Figure
4).
5). In smooth rounding, a pixel is
8.
Figure
(Figure
7.
4).
Figure
Table
(Figure
1) In
4)