STV3550 datasheet(49/144 Pages) STMICROELECTRONICS

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Graphics Functional Description

STV3550

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4.1.5.1 Pixel Mixing Mode

In Pixel Mixing mode, the only mixing factor applied is the Alpha mixing factor parameter (Alpha[7:0])

programmed in the CLUT.

4.1.5.2 Global Mixing Mode

In Global Mixing mode, the mixing factor applied is the Mix-Weight parameter (MiW[7:0])

programmed in the header. These bits define the mixing factor (transparent level) for each OSD

region used for blending the OSD and video signals. This mixing value is applied to the entire OSD

region and the Alpha mixing factor in the CLUT is ignored.

4.1.5.3 Proportional Mixing Mode

In Proportional Mixing mode, the mixing factor is the result of the multiplication or division of the

Alpha mixing factor (Alpha[7:0]) programmed in the CLUT by the Mix-Gain parameter (MiGa[8:0])

programmed in the header. The Mix-Gain bits define the offset applied to the mixing factor (the

transparent level) for each pixel of one OSD region. In this mode, if the MSB bit (MiGa[8]) is set, the

operation is multiplication. If reset, the operation is division.

Note:

Due to the GAMMA specification, the Alpha[7:0] range is from 0 to 128 in decimal (00h is

transparent, 80h is full OSD). All values greater than 80h (from 81h to FFh) are clamped to 80h.

4.1.5.4 No Mixing Mode

In No Mixing mode, the mixing factor is the full OSD. The Alpha mixing factor (Alpha[7:0])

programmed in the CLUT is ignored.

4.2

2D Graphics Accelerator

A 2D Graphics Accelerator can be used to speed-up the re-location and display of graphic images.

This function will automatically generate the desired link list required to move an image block from

one position to another in order to accelerate data transfers in memory.

This module reads a block from one area of the memory, processes this block (a process could be

a simple copy), and writes the result in an other area. Memory addresses can be byte-aligned.

The copying is managed by a DMA engine which alleviates the CPU load.

To perform a 2D block move (with or without processing), the module must be initialized with the

source and destination start addresses, the width and the height of the block and the source and

destination skip value. (The skip value is equal to the number of columns of the region minus the

width.) SKIP_SOURCE and SKIP_DEST data can be specified and their values can be different.

Proportional Mixing mode

No Mixing mode

MiGa[8]

MiGa[7:0]

Description

XXh

Alpha[7:0] is divided by MiGa[7:0]/128

XXh

Alpha[7:0] is multiplied by MiGa[7:0]

Table 13: Mixing Modes

MiMo[1:0]

Description

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