AD9380/PCB Analog Devices Inc, AD9380/PCB Datasheet - Page 20

• Manufacturer Part Number: AD9380/PCB
• Description: BOARD EVALUATION FOR AD9380
• Manufacturer: Analog Devices Inc

Specifications of AD9380/PCB

• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

AD9380
VSYNC Filter and Odd/Even Fields
The VSYNC filter is used to eliminate spurious VSYNCs,
maintain a consistent timing relationship between the VSYNC
and HSYNC output signals, and generate the odd/even field
output.
The filter works by examining the placement of VSYNC
with respect to HSYNC and, if necessary, slightly shifting
it in time at the VSOUT output. The goal is to keep the
VSYNC and HSYNC leading edges from switching at the
same time, eliminating confusion as to when the first line
of a frame occurs. Enabling the VSYNC filter is done with
Register 0x21[5]. Use of the VSYNC filter is recommended for
all cases, including interlaced video, and is required when using
the HSYNC per VSYNC counter. Figure 11 and Figure 12
illustrates even/odd field determination in two situations.
HDMI RECEIVER
The HDMI receiver section of the AD9380 allows the reception
of a digital video stream, which is backward compatible with
DVI and able to accommodate not only video of various for-
mats (RGB, YCrCb 4:4:4, 4:2:2), but also up to eight channels of
audio. Infoframes are transmitted carrying information about
the video format, audio clocks, and many other items necessary
for a monitor to use fully the information stream available.
QUADRANT
QUADRANT
O/E FIELD
O/E FIELD
VSOUT
VSOUT
HSIN
HSIN
VSIN
VSIN
2
2
FIELD 1
FIELD 1
SYNC SEPARATOR THRESHOLD
Figure 11. VSYNC Filter—Even
3
3
Figure 12. VSYNC Filter—Odd
4
4
SYNC SEPARATOR THRESHOLD
FIELD 0
FIELD 0
EVEN FIELD
ODD FIELD
1
1
2
2
FIELD 1
FIELD 1
3
3
4
4
FIELD 0
FIELD 0
1
1
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The earlier digital visual interface (DVI) format was restricted
to an RGB 24-bit color space only. Embedded in this data
stream were HSYNCs, VSYNCs, and display enable (DE)
signals, but no audio information. The HDMI specification
allows transmission of all the DVI capabilities, but adds several
YCrCb formats that make the inclusion of a programmable
color space converter (CSC) a very desirable feature. With this,
the scaler following the AD9380 can specify that it always
wishes to receive a particular format—for instance, 4:2:2
YCrCb—regardless of the transmitted mode. If RGB is sent, the
CSC can easily convert that to 4:2:2 YCrCb while relieving the
scaler of this task.
In addition, the HDMI specification supports the transmission
of up to eight channels of S/PDIF or I
information is packetized and transmitted during the video
blanking periods along with specific information about the
clock frequency. Part of this audio information (audio
infoframe) tells the user how many channels of audio are
present, where they should be placed, information regarding the
source (make, model), and other data.
DE GENERATOR
The AD9380 has an onboard generator for DE, for start of
active video (SAV), and for end of active video (EAV), all of
which are necessary for describing the complete data stream for
a BT656-compatible output. In addition to this particular
output, it is possible to generate the DE for cases in which a
scaler is not used. This signal alerts the circuitry following the
AD9380 which video pixels are displayable.
4:4:4 TO 4:2:2 FILTER
The AD9380 contains a filter that allows it to convert a signal
from YCrCb 4:4:4 to YCrCb 4:2:2 while maintaining the
maximum accuracy and fidelity of the original signal.
Input Color Space to Output Color Space
The AD9380 can accept a wide variety of input formats and
either retain that format or convert to another. Input formats
supported are:
•
•
•
Output modes supported are:
•
•
•
4:4:4 YCrCb 8-bit
4:2:2 YCrCb 8-, 10-, and 12-bit
RGB 8-bit
4:4:4 YCrCb 8-bit
4:2:2 YCrCb 8-, 10-, and 12-bit
Dual 4:2:2 YCrCb 8-bits
2
S audio. The audio