![](http://datasheet.mmic.net.cn/310000/ADV7302A_datasheet_16243964/ADV7302A_52.png)
REV. A
–52–
ADV7302A/ADV7303A
Appendix A
COPY GENERATION MANAGEMENT SYSTEM
HD CGMS DATA Registers 2–0
[Subaddress 12h]
HD CGMS is available in 525 p Mode only, conforming to
“CGMS-A EIA-J CPR1204-1, Transfer Method of Video ID
information using vertical blanking interval (525 p System),
March 1998” and IEC61880, 1998, video systems (525/60)—
video and accompanied data using the vertical blanking
interval—analog interface.
When HD CGMS is enabled, CGMS data is inserted on Line 41.
The HD CGMS Data Registers are to be found at Addresses
21h, 22h, and 23h.
C0
C1
C2
C3
C4
C5
C6
C7
C8
C9 C10 C11 C12 C13 C14 C15 C16 C17 C18 C19
CRC SEQUENCE
21.2 s 0.22 s
22T
REF
5.8 s 0.15 s
6T
0mV
–300mV
70% 10%
BIT 1
T = 1/(f
33) = 963ns
f
= HORIZONTAL SCAN FREQUENCY
T 30ns
+700mV
BIT 20
Figure 80. CGMS Waveform
SD CGMS Data Registers 2–0
[Subaddresses 59h, 5Ah, and 5Bh]
The ADV7302A/ADV7303A supports Copy Generation Man-
agement 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 ADV7302A/ADV7303A is config-
ured 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 reference pulse of the same amplitude and
duration as a CGMS bit, see Figure 81.
If SD CGMS CRC [Address 59h, Bit 4] is set to a Logic “1,”
the last six bits, C19–C14, that comprise the 6-bit CRC check
sequence are calculated automatically on the ADV7302A/
ADV7303A 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
x
6
1
+
+
with a preset value of 111111. If SD CGMS CRC [Address
59h, Bit 4] is set to a Logic “0,” then all 20 bits (C0–C19) are
output directly from the CGMS registers (no CRC calculated;
must be calculated by the user).
Table XXIV. Function of CGMS Bits
Word
Bit
Function
0
B1
Aspect Ratio
0 = 4:3
1 = 16:9
0 = Normal
1 = Letterbox
B2
Display Format
B3
B4–B6
Undefined
Identification Information about Video
and Other Signals (i.e., Audio)
1
B7–B10
Identification Signal. Incidental to Word 0.
2
B11–B14
Identification Signal and Information.
Incidental to Word 0.
C0
C1
C2
C3
C4
C5
C6
C7
C8
C9 C10 C11 C12 C13 C14 C15 C16 C17 C18 C19
CRC SEQUENCE
49.1 s 0.5 s
REF
11.2 s
0 IRE
–40 IRE
+70 IRE
+100 IRE
2.235 s 20ns
Figure 81. CGMS Waveform