ADV7182 View Datasheet(PDF) - Analog Devices

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ADV7182

10-Bit, SDTV Video Decoder with Differential Inputs

Analog Devices 

ADV7182

FREE-RUN OPERATION

Free-run mode provides the user with a stable clock and

predictable data if the input signal cannot be decoded; for

example, if input video is not present.

The ADV7182 automatically enters free-run mode if the input

signal cannot be decoded. The user can prevent this operation

by setting the DEF_VAL_AUTO_EN to 0. When the DEF_VAL_

AUTO_EN bit is 0, the ADV7182 outputs noise if it cannot

decode the input video. It is recommended that the user keep

DEF_VAL_AUTO_EN set to 1.

The user can force free-run mode by setting the DEF_VAL_EN

bit to 1. This can be a useful tool in debugging system level issues.

The user can set which video standard is output in free-run

mode with the VS_COAST_MODE bits.

The user can also specify which data is output in free-run mode

with the FREE_RUN_PAT_SEL bits. The following test patterns

can be set using this function:

• Single color

• Color bars

• Luma ramp

• Boundary box

Single Color Test Pattern

In this mode, the ADV7182 device can be set to output the

default luma and chroma data stored in DEF_Y and DEF_C

(see the Color Controls section).

Color Bars Test Pattern

In this mode, the ADV7182 device outputs the 100% color bars

pattern.

Luma Ramp Test Pattern

In this mode, the ADV7182 device outputs a series of vertical

bars. Each vertical bar is progressively brighter than the vertical

bar to its left.

Boundary Box Test Pattern

In this mode, the ADV7182 device outputs a black screen with

a 1-pixel depth white border (see Figure 14).

Figure 14. Boundary Box Free-Run Test Pattern

Data Sheet

DEF_VAL_AUTO_EN, Default Value Automatic Enable,

Address 0x0C[1]

This bit enables the ADV7182 to enter free-run mode if it

cannot decode the video signal that has been input.

Table 31. DEF_VAL_AUTO_EN Function

DEF_VAL_AUTO_EN Description

0

The ADV7182 outputs noise if it loses

lock with the inputted video signal.

1 (default)

The ADV7182 enters free-run mode if it

loses lock with the inputted video signal.

DEF_VAL_EN, Default Value Enable, Address 0x0C[0]

This bit forces free-run mode.

Table 32. DEF_VAL_EN Function

DEF_VAL_EN

Description

0 (default)

Do not force free-run mode (that is, free-run

mode dependent on DEF_VAL_AUTO_EN)

1

Force free-run mode

FREE_RUN_PAT_SEL[2:0], Free Run Pattern Select,

Address 0x14[2:0]

This function selects what data is output in free-run mode.

Table 33. FREE_FUN_PAT_SEL Function

FREE_RUN_PAT_SEL Description

000 (default)

Single color set by DEF_C and DEF_Y

controls; see Color Controls section

001

100% color bars

010

Luma ramp. Note that in order to display

properly, the DEF_C register should be

set to 0x88. See Color Controls section

101

Boundary box

VS_COAST_MODE[1:0], Address 0xF9[3:2]

If no video source is connected, then this function can set the

video output standard during free-run mode.

If a valid input video source is connected to the ADV7182 and

free-run mode is forced, the VS_COAST_MODE bits are

ignored. The free-run standard will be the same as the valid

inputted video standard.

Table 34. VS_COAST_MODE Function

VS_COAST_MODE Description

00 (default)

The ADV7182 outputs in the same

standard as it did before it entered free-run

mode. If no valid standard was output

before entering free-run mode, the

ADV7182 outputs a 576i 50 Hz signal in

free-run mode.

01

Outputs a 576i 50 Hz signal in free-run mode.

10

Outputs a 480i 60 Hz signal in free-run mode.

11

Reserved.

Rev. A | Page 24 of 96

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