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Introduction
The
AL251A-EVB-A0 is an engineering evaluation
board that is used to demonstrate the
performance of the AL128 VGA-to-TV scan
converter chip and AL251 TV-to-VGA scan
converter chip. The board contains two
3Mbits of field memory (AL422B) for AL128,
and one video decoder (AL242) for AL251.
An attached 80C51 microcontroller is used
to control the AL242 and AL251 via 2-wire
Serial Bus.
The evaluation board accepts VGA analog
signals or analog video signals. AL128
converts the analog VGA signal into NTSC/PAL
S-video and composite video (CVBS), or
analog RGB for SCART application. Additional
bypass VGA output could be added via the
video buffer. This implementation can
display at both the monitor and TV simultaneously.
Through AL251 and AL242, it accepts NTSC/PAL
S-video or composite video (CVBS) and
converts into VGA analog signal output
or 16-bit digital RGB/YUV output.
Various switches and buttons are designed
in the evaluation board for ease of demonstrating
and testing the functions.
The board uses an external DC power adaptor
(+12V/1A).
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Key
Features
AL128
Features
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Converts non-interlaced VGA into interlaced
TV format (NTSC/PAL)
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Composite video and S-Video outputs
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Analog RGB output for SCART interface
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Highly integrated design with built-in
NTSC/PAL encoder, ADC, DAC and SRAM
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High clarity 5-line anti-flicker filter
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8 levels of sharpness control
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Supports up to full 1024x768 VGA resolution
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Automatically supports scan rate from
50 Hz up to 100 Hz
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Linear vertical and horizontal overscan/underscan
control
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Zoom and freeze controls
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Four-touch-button interface with OSD
(on TV) to control all key functions
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Picture panning control
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Brightness control
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Built-in color bar
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Simultaneously displays on PC and TV
monitors
AL251
Features
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Converts interlaced TV signal (NTSC/PAL)
into non-interlaced RGB format for
CRT monitorsor LCD panels
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Highly integrated design with built-in
DAC,SRAM, OSD and LUT
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Built-in on-screen-display with programmable
bitmap
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Auto NTSC/PAL detection
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Analog/digital non-interlaced RGB (VGA)
signal output (Scan Doubled or Deinterlaced)
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Internal RGB video lookup table (LUT)
to provide gamma correction and
special effects
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Overlay support for title making and
complex on-screen display
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16-bit digital RGB/YUV output
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