1996 Sep 04 18
Philips Semiconductors Objective specification
High Performance Scaler (HPS) SAA7140A; SAA7140B
The vertical timing is indicated by the positive or negative
edge (programmable by I2C-bus bit REVAW) of the sync
input signal VS. The first valid line may occur not exactly
at the start of the field but with a certain offset, counted in
lines, with qualified pixels. Input signal VS defines, in
relation to HREF, the odd/even field detection
(see
SAA7191B
).
7.1.2 D
ATA FORMATS AND REFERENCE SIGNALS OF THE
EXPANSION PORT
The expansion port (input/output) supports several modes;
simultaneous (parallel) D1 input and D1 output (full
duplex) with auxiliary sync and qualifying signals, or 16-bit
wide YUV input or output (half duplex), selected via
programming with clock, qualify and sync signal.
A discontinuous data stream is supported by accepting or
generating a pixel/byte qualifying signal (PXQ), a
generalization of the CREF definition at the DMSD port
(PXQ = 1 qualified pixel, PXQ = 0 invalid data).
16-bit YUV (half duplex mode = field alternating data I/O):
16-bit YUV data stream (Y = VIDH7 to VIDH0,
UV = VIDL7 to VIDL0). For the 16-bit YUV data input
format, PXQ is inhibited from qualifying adjacent LLC clock
cycles. There must be at least one empty clock cycle
between two valid pixels.
8-bit Cb-Y-Cr-Y; CCIR 656 or D1 (full duplex mode): the
colour difference signals and the luminance signal
(straight binary) are byte-wise multiplexed onto the same
8-bit wide data stream, with sequence and timing in
accordance with CCIR 656 recommendations (according
to D1 for 60 Hz application respectively). The code is in
accordance with CCIR 601 (black = 16, white = 235, no
colour = 128, 100% colour saturation = 16 or 240, etc.
Overshoots and undershoots are permitted and
supported, i.e. processed as they are.
If the CCIR 656 output is selected, the video signal is
clipped to 01H and FEH in order to leave the codes 00H
and FFH for SAV and EAV encoding (SAV and EAV
encoding not yet supported). The clock rate for this format
is twice the pixel clock.
The horizontal sync input HIN is processed in an identical
manner to HREF at the DMSD port. If the CCIR 656 data
input format is selected, the horizontal timing reference is
decoded from the input data stream (SAV, EAV and
SHVS = 1) or taken from the selected H-reference signal
HIN, HREF or HIO (SHVS = 0). The start condition to
enable synchronization to the correct Cb-Y-Cr-Ysequence is provided by the selected horizontal reference
signal. The sequence only increments with qualified bytes.
Instead of a vertical sync signal, as described for the
DMSD port, the expansion port also supports an odd/even
signal applied to the input pin VIN or VIO (controlled by
I
2
C-bus bit FSEL). The frame and the field timing is then
indicated by a positive or negative edge of the V input.
This may occur with a certain offset at the frame and field
start, and is normally counted in lines.
If the CCIR 656 data input format is selected, the vertical
timing reference is decoded from the input data stream by
SAV and EAV (SHVS = 1) or taken from the selected V
reference signal VIN, VS or VIO (SHVS = 0). The vertical
synchronization pin can be programmed to carry either a
vertical sync signal or an odd/even signal.
The horizontal and vertical sync outputs HIO and VIO are
expansion port mode dependent and can be selected via
the I2C-bus (VD1/VD0 and HD1/HD0):
Should the DMSD port be selected as the output source,
HIO will carry a copy of HREF and VIO will carry a copy
of VS.
If the expansion port carries data from the scaler output,
then HIO is a gate signal enveloping the range of active
video along a line and VIO is a positive sync pulse with
a length of 4 lines
If HIN/VIN is selected as the output source, HIO carries
a copy of HIN and VIO carries a copy of VIN (short cut).
If the CCIR 656 data output format is selected, the
horizontal and vertical sync output signals are only
supplied at pins HIO and VIO (SAV and EAV are not
encoded as outputs).
Due to compatibility reasons to the expansion port
definition of the SAA7194/SAA7196 circuits, the
bidirectional pins HIO, VIO and PXQIO can also be
configured as input pins (see Table 3).
The definition of the pin FDIO is I2C-bus selectable.
Configured as an output pin, FDIO carries an odd/even
signal generated in the FLD detection (see Fig.5).
Configured as an input pin, FDIO controls the direction of
the expansion port (compatibility to SAA7194/SAA7196,
(see Table 3 and Chapter 8).