1.3 Parallel Digital Video Data Outputs
to as much as four frames when switching between PAL
and NTSC standards. If this delay is intolerable, the user
can manually set the standard through the HOSTIF write
table. To set the standard manually, the STD_SEL bit must
be set HIGH and the S bit and STD[3:0] bits set
accordingly. The default standard upon resetting the device
is NTSC 4:2:2 component (13.5MHz Y sampling).
PIN
LOGIC OPR
HOST BIT
DOUT[9:0]
LSB_TOP
The S bit, used for single link data standards only, is
encoded in the TRSID word and indicates if the data is in
RGB or YCRCB format as per SMPTE RP174. In automatic
standard detection mode, the S bit can be read from the
HOSTIF read table. In manual mode, the S bit must be set
in the HOSTIF write table.
The output of the device is 10-bit digital video data and is
present on the DOUT[9:0] output pins. The latency through
the device is 8 clock cycles and is illustrated in Figure 3.
The default position of the LSB is DOUT0. Asserting the
LSB_TOP pin HIGH on the GS9021 reverses the order of
the output bits, placing the LSB at DOUT9 and simplifying
board layout in some applications. Figure 11 shows a
simple application circuit illustrating the connections to the
GS9032.
2. FLYWHEEL BLOCK
2.1 FVH Flywheel
1.4 Automatic Standard Detection
PIN
LOGIC OPR
HOST BIT
FLYWDIS
FLYWDIS
OR
PIN
LOGIC OPR
HOST BIT
STD_SEL
STD[3:0]
S
SWITCHFLYW
The flywheel’s primary function is to provide accurate field,
vertical, and horizontal output signals in the presence of
noisy or error prone input data. Flywheel synchronization is
based on the TRS words in the incoming data stream. The
FVH flywheel synchronizes to the incoming data stream in
less than two fields once the incoming standard has been
detected. Once synchronized, the TRS words in the
incoming data stream and those generated by the flywheel
are constantly compared to ensure that the flywheel
remains synchronized.
The device automatically detects the incoming video
standard. The detected standard is encoded on the
STD[3:0] bits of the HOSTIF read table as shown in Tables 1
and 4.
TABLE 1
STANDARD NAME
NTSC 4:2:2 Component with 13.5MHz Y sampling
NTSC Composite
STD[3:0]
0000
Noise insensitivity is accomplished by re-synchronizing the
flywheel to the data stream only if it is not aligned for long
periods of time. For component signals, four mismatches
between the EAV signal in the incoming and flywheel
generated signals over a window of eight lines will trigger
the flywheel to begin re-synchronization.
0001
NTSC 4:2:2 16x9 Widescreen with 18MHz Y
sampling
0010
For composite signals, re-synchronization is triggered by
mismatches in the TRS encoded line numbers or field bits
for seven consecutive lines.
NTSC 4:4:4:4 Single Link with 13.5MHz Y sampling
PAL 4:2:2 Component with 13.5MHz Y sampling
PAL Composite
0011
0100
0101
0110
0111
The flywheel can be disabled by asserting the FLYWDIS
control signal HIGH. Disabling the flywheel will remove the
effective noise immunity. In this mode, FVH values will be
decoded directly from the incoming data stream rather than
being decoded from the flywheel. Note that when the
flywheel is disabled, TRS_BLANK and TRS_ INSERT will not
function correctly if enabled. Therefore, if the flywheel is
disabled, then so should TRS_BLANK and TRS_INSERT.
FLYWDIS is available as an input pin and as a bit in the
HOSTIF write table.
PAL 4:2:2 16x9 Widescreen with 18MHz Y sampling
PAL 4:4:4:4 Single Link with 13.5MHz Y sampling
Noise immunity is included to ensure that momentary signal
corruption does not affect the automatic standards
detection function. This built in noise immunity results in
delayed detection time during power up and when
switching between standards. Delays range from as little as
eight lines when switching between component standards
7
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GENNUM [ GENNUM CORPORATION ]
