ade3000 STMicroelectronics, ade3000 Datasheet - Page 68

• Manufacturer Part Number: ade3000
• Description: Lcd Display Engines With Integrated Dvi, Adc And Yuv Ports
• Manufacturer: STMicroelectronics

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effects. An alpha value of 255 makes the OSD opaque, while a value of 0 makes the OSD invisible,
with a linear ramp of transparency between these two endpoints. Separate registers control alpha
for foreground and background pixels.
A fade-in/fade-out feature ramps the alpha values every six frames, starting from their current value
and going up or down the sequence: 0, 16, 32, 64, 128, 192, 224, 240, 255.
Row 15 also contains definitions for the four display windows. These windows define regions on the
screen to which borders and shadows can be applied. (They are not analogous to windows in a GUI
display, in that they do not represent four independent data displays. There is only one character
map. The windows essentially define an area around which a border can be drawn or to which
attributes can be assigned.) Windows also determine which of the two color tables will be used for
the characters inside. Windows have a fixed precedence: window 0 has the highest precedence
and window 3 the lowest. When windows overlap, the precedence determines which borders will be
displayed and which color tables will be used in the overlapping area.
Monochrome and color fonts are affected differently by attribute bytes. Monochrome characters are
affected by shadows and borders, and have their color specified by the foreground/background
attributes. Color characters interpret the attribute byte differently than monochrome characters,
using it to define blinking and 90-degree rotations rather than blinking, foreground color, and
background color.
Color Tables
There are two color tables, each containing sixteen entries by three bytes each, giving a 24-bit RGB
value for each entry. Entry 0 is used for the shadow color for monochrome characters and borders.
Color-table selection is made on a window-by-window basis.
When writing the color table, the “row” value in the first header byte is interpreted as the color table
index, while the “column” value in the second header byte encoded to select the color table (0 or 1)
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00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
wa = window attributes
ga = global attributes
wa
Figure 9: Character Attribute Map
Character Attributes
ga
wa
ga
wa
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