![](http://datasheet.mmic.net.cn/310000/ADV7312_datasheet_16243972/ADV7312_38.png)
REV. 0
–38–
ADV7312
Vertical Blanking Interval
The ADV7312 accept input data that contains VBI data
[CGMS, WSS, VITS, and so on] in SD and HD modes.
For SMPTE 293M [525p] standards, 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.
For SD NTSC this data can be present on Lines 10 to 20, and
in PAL on Lines 7 to 22.
If VBI is disabled [Address 11h, Bit 4 for HD; Address 43h,
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, and it is possible to use VBI in
this timing mode as well.
In Slave Mode 1 or 2, the
BLANK
control bit must be set to
enabled [Address 4Ah, Bit 3] to allow VBI data to pass through
the ADV7312. Otherwise, the ADV7312 automatically blanks
the VBI to standard.
If CGMS is enabled and VBI is disabled, the CGMS data will
nevertheless be available at the output.
Subcarrier Frequency Registers
[Subaddress 4Ch–4Fh]
Four 8-bit registers are used to set up the subcarrier frequency.
The value of these registers is calculated using the equation
Subcarrier Frequency Register
Number of subcarrier frequencyvaluesinonevideoline
Numberof 27 MHz clkcyclesinonevideoline
=
2
23
*
*
Rounded to the nearest integer
For example, in NTSC mode,
Subcarrier FrequencyValue
=
×
=
227.5
1716
2
569408542
23
Subcarrier Register Value = 21F07C1Eh
SD F
SC
Register 0: 1Eh
SD F
SC
Register 1: 7Ch
SD F
SC
Register 2: F0h
SD F
SC
Register 3: 21h
Refer to the MPU Port Description section for more details on
how to access the subcarrier frequency registers.
Square Pixel Timing
[Register 42h, Bit 4]
In square pixel mode, the following timing diagrams apply.
Y
C
r
Y
F
F
0
0
0
0
X
Y
8
0
1
0
8
0
1
0
F
F
0
0
F
F
A
B
A
B
A
B
8
0
1
0
8
0
1
0
F
F
0
0
0
0
X
Y
C
b
YC
r
C
b
Y
C
b
Y
C
r
EAV CODE
SAV CODE
ANCILLARY DATA
(HANC)
272 CLOCK
4 CLOCK
4 CLOCK
1280 CLOCK
4 CLOCK
4 CLOCK
344 CLOCK
1536 CLOCK
END OF ACTIVE
VIDEO LINE
START OF ACTIVE
VIDEO LINE
ANALOG
VIDEO
INPUT PIXELS
NTSC/PAL M SYSTEM
(525 LINES/60Hz)
PAL SYSTEM
(625 LINES/50Hz)
Y
Figure 33. EAV/SAV Embedded Timing
FIELD
PIXEL
DATA
PAL = 44 CLOCK CYCLES
NTSC = 44 CLOCK CYCLES
PAL = 136 CLOCK CYCLES
NTSC = 208 CLOCK CYCLES
Cb
Y
Cr
Y
HSYNC
BLANK
Figure 34. Active Pixel Timing