FS450, FS451
PRELIMINARY PRODUCT DESCRIPTION
JUNE, 2000, VERSION 1.2
6
COPYRIGHT
©
© 1999, 2000 FOCUS ENHANCEMENTS, INC.
PRELIMINARY INFORM ATION
2.2 Serial Control Port
FS450 setup is programmed by registers that are accessible via the I
2C‡ compatible serial port (SIO).
Status and Revision ID can also be read from the registers.
‡Note: I2C is a registered trademark of Philips Corporation. The FS450 SIO bus is similar but not identical
to Philips I
2C bus.
2.3 Sync Control
The FS450 operates in a slave mode, pseudo-master mode or full master mode. In pseudo-master mode,
the GCC graphic controller derives the VGA pixel clock, horizontal sync, and vertical sync from
VGA_CLKOUT supplied by the FS450. The syncs are used inside the FS450 to capture the computer video
and are regenerated to supply to external devices such as genlocked video from a DVD player or tuner. In
full master mode, the FS450 supplies to the GCC horizontal and vertical sync in addition to the VGA pixel
clock.
2.4 Input and Output Frame Formats
The FS450 does not contain a frame memory. Therefore, the FS450 output frame rate must be
synchronous to the input frame rate. To accomplish this, the active video portion in the output stream must
overlay the corresponding active video time in the input stream. Several registers on the FS450 control this
timing as illustrated in the following figures:
VGA_HSYNC
IHO
B
VGA_VSYNC
A
IHO + IHW
IVO
Blank
Blank
Blank
Blank
Blank
C
Blank
Black
Black
Black
Blank
D
Blank
Black
Active Video
Black
Blank
IVO + IVW
Blank
Black
Black
Black
Blank
Blank
Blank
Blank
Blank
Blank
Figure 3: GCC Frame Format
IHO = OHO / Hscale
IVO = OVO / Vscale
IHW = OHW / Hscale
IVW = OVW / Vscale
The output frame timing is determined by the CCIR601 and 656 specifications. Input parameters IHO, IVO,
and IHW must be set correctly so that when the image is scaled to the 656 output frame, the timing
requirements are met. Parameters A, B, C, and D are determined by the amount of underscan the user
wants on the target television screen.
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