VDP3108 Просмотр технического описания (PDF) - Micronas

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VDP3108

Single-Chip Video Processor

Micronas 

VDP 3108

ADVANCE INFORMATION

2.3. Digital Video Interfaces

The digital video interface allows insertion of digital data

in YCrCb format on the internal YCrCb data bus. The ort-

hogonal data structure of this bus is the ideal interface

point to external data sources and sinks. On top of this,

a host of formats are supported, e.g. support of level-2

teletext or the priority pixel bus concept.

Figure 2–13 shows all available digital interfaces:

YCrCb 16 bit 4:2:2

RBG 5 bit 4:4:4

PRIO 3 bit, source selection

The YCrCb bus is used for video insertion. The RGB in-

terface is used for insertion of a Teletext or OSD picture.

The priority bus allows to mix up to 8 sources on the

YCrCb / RGB bus.

VDP

PIP

ÈÈÈÈVidÈÈeoÈÈÈÈÈÈÈÈÈÈcDeissÉÉÉÉÉÉÉÉÉÉÈÈÈspolaryÉÉÉÈÈÈPrÉÉÉÈÈÈo-

CCU/

OSD

TPU

Fig. 2–13: VDP video interfaces

2.3.1. Picture Bus Interface

The picture bus format between all DIGIT3000 ICs is

YCrCb with 20.25 Msamples/s. Only active video is

transferred, synchronized by the system main sync sig-

nal (MSY) which indicates the start of valid data for each

scan line. The number of active samples per line is 1068

for all standards (525 and 625).

Via the MSY line, serial data is transferred which con-

tains information about the main picture such as current

line number, odd/even field etc.). It is generated by the

deflection circuitry and represents the orthogonal time-

base for the entire system.

Feature ICs (e.g. PIP) will be synchronized to the main

YCrCb bus. Digital insertion (boxing) is controlled by a

priority system.

2.3.2. Digital RGB Interface

Digital RGB from text or on-screen-display is connected

via the Picture bus. The RGB signal is 5 bits wide. The

RGB signals are not subject to any post-filtering. The

RGB signal provides 3–bit RGB (one bit per color), the

4th bit allows to display half contrast colors. Bit 5 enables

a programmable color–look–up table with 16 entries and

4 bit resolution per color. This allows the support of a

World System Teletext level-2 color display. Display con-

trast for RGB data can be adjusted separately by three

contrast multipliers.

2.3.3. Priority Codec

Up to eight digital YCrCb or RGB sources (main decoder,

PIP, OSD, Text, etc.) may be selected in real-time by

means of a 3-bit priority bus. Thus a pixelwise bus arbi-

tration and source switching is possible. It is essential

that all YCrCb-sources are synchronous and orthogonal.

In general each source (= master) has its own YCrCb bus

request. This bus request may either be software or

hardware-controlled, i.e. a fast blank signal. Data colli-

sion is avoided by a bus arbiter that provides the individ-

ual bus acknowledge in accordance to a user defined

priority.

Each master sends a bus request with his individual

priority ID onto the PRIO-bus and immediately reads

back the bus status. Only in case of positive arbitration

(send-PRIO-ID = read-PRIO-ID) the bus acknowledge

becomes active and the data is sent.

This treatment has many features that have impact on

the appearance of a TV picture:

real-time bus arbitration (PIP, OSD, ...)

priorities are software configurable

different coefficients for different sources

12

MICRONAS INTERMETALL

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