ADV7172 datasheet(44/59 Pages) AD

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ADV7172/ADV7173

–44–

REV. A

The ADV7172/ADV7173 supports Copy Generation Management System (CGMS) conforming to the standard. CGMS data is

transmitted on Line 20 of the odd fields and Line 283 of even fields. Bits C/W05 and C/W06 control whether or not CGMS data

is output on ODD and EVEN fields. CGMS data can only be transmitted when the ADV7172/ADV7173 is configured in NTSC

mode. The CGMS data is 20 bits long, the function of each of these bits is as shown below. The CGMS data is preceded by a refer-

ence pulse of the same amplitude and duration as a CGMS bit (see Figure 70). These bits are output from the configuration registers

in the following order: C/W00 = C16, C/W01 = C17, C/W02 = C18, C/W03 = C19, C/W10 = C8, C/W11 = C9, C/W12 = C10,

C/W13 = C11, C/W14 = C12, C/W15 = C13, C/W16 = C14, C/W17 = C15, C/W20 = C0, C/W21 = C1, C/W22 = C2, C/W23 = C3,

C/W24 = C4, C/W25 = C5, C/W26 = C6, C/W27 = C7. If the Bit C/W04 is set to a Logic “1,” the last six bits, C19–C14, which

comprise the 6-bit CRC check sequence, are calculated automatically on the ADV7172/ADV7173 based on the lower 14 bits

(C0–C13) of the data in the data registers and output with the remaining 14 bits to form the complete 20 bits of the CGMS data.

The calculation of the CRC sequence is based on the polynomial X

6 + X + 1 with a preset value of 111111. If C/W04 is set to a

Logic “0,” all 20 bits (C0–C19) are directly output from the CGMS registers (no CRC calculated, must be calculated by the user).

Function of CGMS Bits

Word 0 – 6 Bits

Word 1 – 4 Bits

Word 2 – 6 Bits

CRC

– 6 Bits

CRC Polynomial = X

6 + X + 1 (Preset to 111111)

Word 0

Aspect Ratio

16:9

4:3

Display Format

Letterbox

Normal

Undefined

Word 0

B4, B5, B6

Identification information about video and other signals (e.g., audio)

Word 1

B7, B8, B9, B10

Identification signal incidental to Word 0

Word 2

B11, B12, B13, B14 Identification signal and information incidental to Word 0

CRC SEQUENCE

49.1 s

0.5 s

11.2 s

2.235 s

20ns

REF

C9 C10 C11 C12 C13 C14 C15 C16 C17 C18 C19

100 IRE

70 IRE

0 IRE

–40 IRE

Figure 70. CGMS Waveform Diagram

APPENDIX 3

COPY GENERATION MANAGEMENT SYSTEM (CGMS)

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