Datasheet
ADV7194
–48–
REV. A
APPENDIX 3
COPY GENERATION MANAGEMENT SYSTEM (CGMS)
The ADV7194 supports Copy Generation Management System
(CGMS) conforming to the standard. CGMS data is transmit-
ted 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
put out on ODD and EVEN fields. CGMS data can only be
transmitted when the ADV7194 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 96. These bits are put out 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 auto-
matically on the ADV7194 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 calcu-
lation 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 then
all 20 bits (C0–C19) are output directly from the CGMS regis-
ters (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 1 0
B1 Aspect Ratio 16:9 4:3
B2 Display Format Letterbox Normal
B3 Undefined
WORD 0
B4, B5, B6 Identification Information About Video and
Other Signals (e.g., Audio)
WORD 1
B7, B8, B9, Identification Signal Incidental to Word 0
B10
WORD 2
B11, B12, Identification Signal and Information
B13, B14 Incidental to Word 0
CRC SEQUENCE
49.1s 0.5s
11.2s
2.235s 20ns
REF
C0 C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12
C13 C14 C15 C16
C17 C18 C19
100 IRE
70 IRE
0 IRE
–40 IRE
Figure 96. CGMS Waveform Diagram