ADV7321 datasheet(46/88 Pages) AD

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ADV7320/ADV7321

Rev. 0 | Page 46 of 88

VERTICAL BLANKING INTERVAL

The ADV7320/ADV7321 accepts input data that contains VBI

data (such as CGMS, WSS, VITS) in SD and HD modes.

For the SMPTE 293M (525p) standard, VBI data can be

inserted on Lines 13 to 42 of each frame, or on Lines 6 to 43 for

the ITU-R BT.1358 (625p) standard.

This data can be present on Lines 10 to 20 for SD NTSC and on

Lines 7 to 22 for PAL.

If VBI is disabled [Address 0x11, Bit 4 for HD; Address 0x43,

Bit 4 for SD], VBI data is not present at the output and the

entire VBI is blanked. These control bits are valid in all master

and slave modes.

In Slave Mode 0, if VBI is enabled, the blanking bit in the

EAV/SAV code is overwritten. It is possible to use VBI in this

timing mode as well.

In Slave Mode 1 or 2, the BLANK control bit must be enabled

[Address 0x4A, Bit 3] to allow VBI data to pass through the

ADV7320/ADV7321. Otherwise, the ADV7320/ADV7321

automatically blanks the VBI to standard.

If CGMS is enabled and VBI is disabled, the CGMS data will

nevertheless be available at the output.

See Appendix 1—Copy Generation Management System.

SUBCARRIER FREQUENCY REGISTERS

[Subaddresses 0x4C to 0x4F]

Four 8-bit registers are used to set up the subcarrier frequency.

The value of these registers is calculated using the equation

line

video

one

cycles

clk

MHz

Number

line

video

one

periods

subcarrier

Number

Frequency

Subcarrier

where the sum is rounded to the nearest integer.

For example, in NTSC mode

569408543

1716

227

⎟

⎠

⎞

⎜

⎝

⎛

Value

Subcarrier

where:

Subcarrier Register Value

= 0x21F07C1F

SD FSC Register 0: 0x1F

SD FSC Register 1: 0x7C

SD FSC Register 2: 0xF0

SD FSC Register 3: 0x21

See the MPU Port Description section for more details on

accessing the subcarrier frequency registers.

Programming the FSC

The subcarrier register value is divided into 4 FSC registers as

shown above. To load the value into the encoder, users must

write to the FSC registers in sequence, starting with FSC0. The

value is not loaded until the FSC4 write is complete.

Note that the ADV7320/ADV7321 power-up value for FSC0 is

0x1E. For precise NTSC FSC, write 0x1F to this register.

ADV7321 Datasheet(PDF) 46 Page - Analog Devices

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