AL250 International Power Sources, Inc., AL250 Datasheet - Page 10

• Manufacturer Part Number: AL250
• Description: Video Scan Doubler
• Manufacturer: International Power Sources, Inc.

The H-sync Start and End (registers 22h and 23h) define the output horizontal sync period relative to
the input H-sync leading edge.
The Horizontal Blank Start and End (registers 2Bh and 2Ch) define the output H-sync blanking
period.
The Horizontal Capture Start and End (registers 20h and 21h) define the active pixels in each line
relative to the input video H-sync. These registers can also be used for adjusting the position of the
output picture.
The Horizontal Total High and Low (registers 24h and 29h) define the total number of pixels per line.
The AL250/251 can detect the H-total automatically when the input data is of the typical resolution
mentioned in the Default Resolution section.
The V-sync Start and End (registers 27h and 28h) define the output V-sync period relative to the input
V-sync start.
The Vertical Blank Start and End (registers 2Dh and 2Eh) define the output V-sync blanking period.
The Vertical Capture Start and End (registers 25h and 26h) define the active lines.
The total number of lines per frame (Vertical Total) is detected by the AL250/251 automatically.
To take advantage of the auto detection of the AL250/251, set the bit 3 of the Control register #08h
(Softtime) as 0. If a user-defined input format is used, then disable the hardware default by setting
this bit as 1, and write all of the parameters to the corresponding registers to define the format. The
sample code the AL250EVB provides disables the hardware settings.
The following typical parameters (as well as hardware default values) are for reference:
Mode
H(Horizontal) total
V(Vertical) total
HDE Start
HDE End
H-sync Start
H-sync End
VDE Start
VDE End
V-sync Start
V-sync End
Square NTSC
780
525
120
736
776
500
56
48
4
8
Square PAL
944
625
160
896
604
72
60
0
4
8
CCIR NTSC
858
525
752
792
856
500
72
48
4
8
July 28, 1999
CCIR PAL
864
625
760
808
604
80
16
60
4
8
AL250
10