ADV7191 datasheet(39/69 Pages) AD

39 / 69 page

ADV7190/ADV7191

–39–

REV. 0

HUE ADJUST CONTROL REGISTER (HCR)

(Address (SR5–SR0) = 20H)

he hue control register is an 8-bit-wide register used to adjust

the hue on the composite and chroma outputs. Figure 74 shows

the operation under control of this register.

HCR7 – HCR0

HUE ADJUST VALUE

HCR7

HCR6

HCR5

HCR4

HCR3

HCR2

HCR1

HCR0

Figure 74. Hue Adjust Control Register

HCR Bit Description

Hue Adjust Value (HCR0–HCR7)

These eight bits represent the value required to vary the hue of

the video data, i.e., the variance in phase of the subcarrier during

active video with respect to the phase of the subcarrier during the

colorburst. The ADV7190/ADV7191 provides a range of

±22.5°

increments of 0.17578125

°. For normal operation (zero adjust-

ment) this register is set to 80Hex. FFHex and 00Hex represent

the upper and lower limit (respectively) of adjustment attainable.

Hue Adjust [

°] = 0.17578125° × (HCRd – 128); for positive Hue

Adjust Value

Example:

To adjust the hue by 4

° write 97

h to the Hue Adjust Control

(4/0.17578125) + 128 = 151d* = 97h

To adjust the hue by (–4

°) write 69h to the Hue Adjust Control

(–4/0.17578125) + 128 = 10dd* = 69h

*Rounded to the nearest integer.

BRIGHTNESS CONTROL REGISTERS (BCR)

(Address (SR5–SR0) = 21H)

The brightness register is an 8-bit-wide register which allows

brightness control. Figure 75 shows the operation under control

of this register.

BCR BIT DESCRIPTION

Brightness Value (BCR0–BCR6)

Seven bits of this 8-bit-wide register are used to control the

brightness level. The brightness is controlled by adding a pro-

grammable setup level onto the scaled Y data. This brightness

level can be a positive or negative value.

The programmable brightness level in NTSC without pedestal

and PAL are max 15 IRE and min –7.5 IRE, in NTSC with

pedestal max 22.5 IRE and min 0 IRE.

Table IV. Brightness Control Register Value

etup

Setup

Brightness

Level in

Setup

Control

NTSC with

NTSC No

Level in

Pedestal

PAL

Value

22.5 IRE

15 IRE

1Eh

15 IRE

7.5 IRE

0Fh

7.5 IRE

0 IRE

00h

0 IRE

–7.5 IRE

71h

NOTE

Values in the range from 3Fh to 44h might result in an invalid output signal.

EXAMPLE

1. Standard: NTSC with Pedestal. To add +20 IRE brightness level, write 28h into the Brightness Control Register:

[Brightness Control Register Value]h = [IRE Value

2.015631]h = [20

× 2.015631]h = [40.31262]h = 28h

2. Standard: PAL. To add –7 IRE brightness level write 72h into the Brightness Control Register:

[|IRE Value|

× 2.015631] = [7 × 2.015631] = [14.109417] = 0001110b

[0001110] into two’s complement = 1110010b = 72h

BCR6 – BCR0

BRIGHTNESS VALUE

BCR7

ZERO MUST BE

WRITTEN TO

THIS BIT

BCR7

BCR6

BCR5

BCR4

BCR3

BCR2

BCR1

BCR0

100 IRE

0 IRE

+7.5 IRE

–7.5 IRE

NTSC WITHOUT PEDESTAL

NO SETUP VALUE

ADDED

POSITIVE SETUP

VALUE ADDED

WRITE TO BRIGHTNESS

CONTROL REGISTER: 12h

NEGATIVE SETUP

VALUE ADDED

WRITE TO BRIGHTNESS

CONTROL REGISTER: 6Eh

Figure 75. Brightness Control Register

ADV7191 Datasheet(PDF) 39 Page - Analog Devices

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