saf7129ah NXP Semiconductors, saf7129ah Datasheet - Page 12
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saf7129ah
Manufacturer Part Number
saf7129ah
Description
Saf7129ah Digital Video Encoder
Manufacturer
NXP Semiconductors
Datasheet
1.SAF7129AH.pdf
(56 pages)
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Philips Semiconductors
7.7
The synchronization of the SAF7129AH is able to operate
in two modes; slave mode and master mode.
In master mode (see Fig.19), the circuit generates all
necessary timings in the video signal itself, and it can
provide timing signals at the RCV1 and RCV2 ports.
In slave mode, it accepts timing information either from the
RCV pins or from the embedded timing data of the
ITU-R BT.656 data stream.
For the SAF7129AH, the only difference between master
and slave mode is that it ignores the timing information at
its inputs in master mode. Thus, if in slave mode, any
timing information is missing, the IC will continue running
free without a visible effect. But there must not be any
additional pulses (with wrong phase) because the circuit
will not ignore them.
In slave mode (see Fig.18), an interface circuit decides,
which signal is expected at the RCV1 port and which
information is taken from its active slope. The polarity can
be chosen. If PRCV1 is logic 0, the rising slope will be
active.
The signal can be:
On the RCV2 port, the IC can provide a horizontal pulse
with programmable start and stop phase; this pulse can be
inhibited in the vertical blanking period to build up, for
example, a composite blanking signal.
The horizontal phase can be set via a separate input
RCV2. In the event of VS pulses at RCV1, this is
mandatory. It is also possible to set the signal path to blank
via this input.
From the ITU-R BT.656 data stream, the SAF7129AH
decodes only the start of the first line in the odd field. All
other information is ignored and may miss. If this kind of
slave mode is active, the RCV pins may be switched to
output mode.
2004 Mar 16
A Vertical Sync (VS) pulse; the active slope sets the
vertical phase
An odd/even signal; the active slope sets the vertical
phase, the internal field flag to odd and optionally sets
the horizontal phase
A Field Sequence (FSEQ) signal; it marks the first field
of the 4 (NTSC), 8 (PAL) respectively 12 (SECAM) field
sequences. In addition to the odd/even signal, it also
sets the PAL phase and optionally defines the subcarrier
phase.
Digital video encoder
Synchronization
12
In slave mode, the horizontal trigger phase can be
programmed to any point in the line, the vertical phase
from line 0 to line 15 counted from the first serration pulse
in half line steps.
Whenever synchronization information cannot be derived
directly from the inputs, the SAF7129AH will calculate it
from the internal horizontal, vertical and PAL phase. This
gives good flexibility with respect to external
synchronization, but the circuit does not suppress illegal
settings. In such an event, the odd/even information may
vanish as it does in the non-interlaced modes.
In master mode, the line lengths are fixed to 1728 clocks
at 50 Hz and 1716 clocks at 60 Hz. To allow
non-interlaced frames, the field lengths can be varied by
does not provide odd/even information and the output
signal does not contain the PAL ‘Bruch sequence’.
At the RCV1 pin the IC can provide:
At the RCV2 pin, there is a horizontal pulse of
programmable phase and duration available. This pulse
can be suppressed in the programmable inactive part of a
field, giving a composite blank signal.
The directions and polarities of the RCV ports can be
chosen independently. Timing references can be found in
Tables 52 and 60.
7.8
The input to LLC1 can either be an external clock source
or the buffered on-chip clock XCLK. The internal crystal
oscillator can be run with either a 3rd-harmonic or a
fundamental crystal frequency.
7.9
The I
supporting 7-bit slave addresses and 400 kbits/s
guaranteed transfer rate. It uses 8-bit subaddressing with
an auto-increment function. All registers are write and
readable, except one read only status byte.
The I
(SA) tied LOW and as 8CH with pin 21 (SA) tied HIGH.
0.5 lines. In the event of non-interlace, the SAF7129AH
A Vertical Sync (VS) signal with 2.5 (50 Hz) or 3 (60 Hz)
lines duration
An odd/even signal which is LOW in odd fields
A Field Sequence (FSEQ) signal which is HIGH in the
first field of the 4, 8 respectively 12 field sequences.
2
2
C-bus interface is a standard slave transceiver,
C-bus slave address is defined as 88H with pin 21
Clock
I
2
C-bus interface
SAF7129AH
Product specification