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> Hardware/assembler Questions, devel of a composite video interface
post Sep 17 2005, 05:46 AM
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I'm looking for a high-res PDA (like the Cxx0, for example) whose screen I can use as a camera output-screen.
Since (according to my research) there are no PDA-cams available that use the full VGA resolution in Live-Preview-Mode,
I'm currently considering building an adapter for Composite-Video sources and writing the appropriate driver or "OS"(made exclusively and specifically for this task, of course).
The hardware part wouldn't be an issue: There are cheap ICs which convert composite to RGB or YCrCb. Specifically, I found the ADV7181B which outputs 16 bits pixinfo(YCrCb) @ 13.5MHz.
Can the CF-interface handle such an input? If, as I expect, it can't, then I'll need another chip as buffer/interface ....
I couldn't find any info which CF-standard the Cxx0s support.
Do they support CF+/2.0 or even CF3.0?
To achieve 25 fps (may be less) at 640x480 pixels, a transfer rate of 15MB/s and thus at least CF+/2.0 (16MB/s) is needed.
PS: Does the videomemory/framebuffer have RGB format? If so, how are the 16bits divided among the 3 colors (which one gets an extra bit)?

The main problem of such a project would be the development of the driver / the OS, primarily because hobby programmers usually don't get access to the docu they'd need for such devices like PDAs.
For example, I'd need know how I can (via assembler) receive the data from the interface and write it to the appropriate video memory location.
However, on a Linux PDA, this shouldn't be too much of a problem, since the OS source code is available. In fact, there are (to my knowledge) three alternatives:
-Freescale BSP from Metroworks (any idea which one I'd need?)
Any recommendations?

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