SDA6000 Datasheet, PDF (294/380 Pages) Infineon Technologies AG – Teletext Decoder with Embedded 16-bit Controller

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Layer 2
Layer 1
SDA 6000
Display Generator
Background Color
Video
UEA11173
Figure 10-4 Priority of Layers in Embedded Layer Mode
Depending on the transparency bits of both layers, the following signals are switched to
the RGB, COR and BLANK (normal polarity assumed) outputs of M2. As a result, one of
the two layers or the screen background will be visible on the screen. If layer 2 is not
available for a pixel, signals COR, BLANK and RGB output depends only on layer 1.
The transparency hierarchy is again controlled, for each pixel, by two bits (TR1 … 0)
which are defined in the pixel format. On the RGB output of M2 there is a mix of layer 1
and layer 2 RGB stream with the screen background.
Depending on the transparency bits of one of the layers subsequent signals are switched
to RGB, COR and BLANK (normal polarity assumed).
The output signals of M2 (COR, BLANK, RGB) depend only on transparency bits of layer
1 or on layer 2 and never on both layers because there is no pixel position where both
layers are available in parallel.
10.3.3 Transparency in Screen Background Area
Depending on the height and width definition of layer 1 there is a remaining portion of
visible screen area without any pixel definition of layer 1 or layer 2. For this area the
transparency bits for layer 1 and layer 2 are not available. For this ‘Screen Background
Area’ the colour attributes and transparency attributes are globally defined for the whole
screen. Also refer to instruction SAR described in Chapter 10.7.1.
Users Manual
10 - 9
2000-06-15