VDP3108B datasheet(19/72 Pages) MICRONAS

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PRELIMINARY DATA SHEET

VDP 31xxB

Micronas

2.8.12. Picture Frame Generator

When the picture does not fill the total screen (height or

width too small) it is surrounded with black areas. These

areas (and more) can be colored with the picture frame

generator. This is done by switching over the RGB signal

from the matrix to the signal from the OSD color look-up

table.

The width of each area (left, right, upper, lower) can be

adjusted separately. The generator starts on the right,

respectively lower side of the screen and stops on the

left, respectively upper side of the screen. This means,

it runs during horizontal, respectively vertical flyback.

The color of the complete border can be stored in the

programmable OSD color look-up table in a separate

address. The format is 3

4 bit RGB. The contrast can

be adjusted separately.

The picture frame generator includes a priority master

circuit. Its priority is programmable and the border is

generated only if the priority is higher than the priority at

the PRIO bus. Therefore the border can be underlay or

overlay depending on the picture source.

2.8.13. Priority Codec

The priority decoder has three input lines for up to eight

priorities. The highest priority is all three lines at low lev-

el. A 5-bit information is attached to each priority (see

table 3–1 ‘Priority Bus’). These bits are programmable

via the I2C-bus and have the following meanings:

– one of two contrast, brightness and matrix values for

main and side picture

– RGB from video signal or color look-up table

– disable/enable black level expander

– disable/enable peaking transient suppression when

signal is switched

– disable/enable analog fast blank input 1

– disable/enable analog fast blank input 2

2.8.14. Scan Velocity Modulation

The RGB input signal of the SVM is converted to Y in a

simple matrix. Then the Y signal is differentiated by a fil-

ter of the transfer function 1–Z–N, where N is program-

mable from 1 to 6. With a coring, some noise can be sup-

pressed. This is followed by a gain adjustment and an

adjustable limiter. The analog output signal is generated

by an 8-bit D/A converter.

The signal delay can be adjusted by

±3.5 clocks in half-

clock steps. For the gain and filter adjustment there are

two parameter sets. The switching between these two

sets is done with the same RGB switch signal that is

used for switching between video-RGB and OSD-RGB

for the RGB outputs. (See Fig. 2–19).

2.8.15. Display Phase Shifter

A phase shifter is used to partially compensate the

phase differences between the video source and the fly-

back signal. By using the described clock system, this

phase shifter works with an accuracy of approximately

1 ns. It has a range of 1 clock period which is equivalent

±24.7 ns at 20.25 MHz. The large amount of phase

shift (full clock periods) is realized in the front-end circuit.

Fig. 2–19: SVM block diagram

Matrix and

Shaping

Modulation

Notch

Differen-

tiator

1–Z–Nx

Coring

adjustment

Gain

adjustment

Limiter

Delay

adjustment

D/A

Converter

Coring

Gain1

Gain2

Limit

Delay

RGB Switch

Output

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