MB87P2020 Datasheet, PDF (175/356 Pages) Fujitsu Component Limited. – Colour LCD/CRT/TV Controller

Graphic Processing Unit
Table 3-8: Assignment between pixel values in intermediate and physical color space when using duty
ratio modulation for mapping from intermediate RGB222to physical RGB111.
channel R
interm.,
bits [5:4]
phys.,
bit [2]
0 constant off
1 DRM 4 output
2 DRM 5 output
3 constant on
pixel value
channel G
interm.,
bits [3:2]
phys.,
bit [1]
0 constant off
1 DRM 2 output
2 DRM 3 output
3 constant on
channel B
interm.,
bits [1:0]
phys.,
bit [0]
0 constant off
1 DRM 0 output
2 DRM 1 output
3 constant on
3.9 Master Timing Information
The generation of the correct timing is a rather complex issue, due to the great variety of displays supported.
Therefore, a coherent, flexible and easy-to-use approach is extremely important. This is achieved by sepa-
rating the GPU internal timing (for fetching and bit stream generation) from external timing (for sync sig-
nals).
The main timing frame for all display types is completely defined by four or six values. Fig. 3-7 gives a
geometrical interpretation of the four primary values.
ystart
Blanking
Active Display Data
DualScanOffs
Blanking
Active Display Data
Blanking
ystart+DualScanOffs
ystart
ystop
xstart
PX ScanDots
xstop
xstart
PX ScanDots
xstop
ystop+DualScanOffs
ystop
Single Scan
Dual Scan
Figure 3-7: Interpretation of main timing parameters in relation to geometrical parameters of the
physical display.
The general idea is to assign every scan dot (i.e. the bits written during one display clock cycle) a pair of
integer numbers, one for the horizontal and one for vertical timing, thus representing display timing as co-
ordinates within a two-dimensional scan area. X-values smaller than zero represent horizontal blanking be-
fore visible pixels, X-values greater than or equal to PXScanDots horizontal blanking after visible pixels.
Active display area (i.e. visible pixels, either background or layer) is designated by values from 0 to (PX-
ScanDots - 1). The same applies toY-values. Those below zero designate leading vertical blanking, those
greater than or equal to PY trailing vertical blanking, and those between zero and (PY - 1) visible lines.
GPU Control Information
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