STV3550 Datasheet, PDF (39/144 Pages) STMicroelectronics – LCD and Matrix Display TV Processor

Graphics Functional Description
STV3550
● A color palette which defines the colors in the SDRAM. Up to 256 colors can be used by the
bitmap. If required, one of these colors can be “transparent” allowing the background to show
through. These colors are loaded in the OSD CLUT.
● A bitmap composed of 2 blocks of 32-bit words.
CAUTION: When 2 regions are displayed one after the other, there must be at least one TV scan
line between them with nothing displayed. This enables the OSD to reload the 256 colors in the
CLUT.
OSD specifications are stored as linked lists, as shown in Figure 28 and Figure 29. The order that the
specifications are stored in SDRAM is the order that the regions are displayed on the screen. This
self-chained mode is managed by software by programming the address of the next OSD region to
be displayed in the Next OSD Specification pointer (OSDp[31:0]). The Stop Linked List (SLL) bit
indicates the last specification in the list.
Figure 28: OSD Specification
First Specification Address register
SDRAM
Header 1
Palettep[31:0]
Free Space
OSDp[31:0]
Topp[31:0]
Bottomp[31:0]
SLL
=0
=1
The OSD will stop at
the end of Region 2.
Palette 1
Free Space
Top Field Block 1
Free Space
Bottom Field Block 1
Free Space
Header 2
Free Space
Palette 2
Free Space
Top Field Block 2
Free Space
Bottom Field Block 2
Free Space
Header 3
Memory
space
between
Header,
Palette, Top
and Bottom
Field blocks
Linked Lists
An OSD specification can be placed anywhere within the entire 64-Mbit SDRAM. Each OSD region
displayed on the screen is the object of an OSD specification. The position of the first OSD region
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