nick stedman wrote:
>
> Hi,
> I'm working on a project to display low res video (64 x 48 pixels) on a
> custom built LED screen.My bigger concern is
> acquiring the video. How might this be done? Originally I tried using the
> USART but 56 kbps was too slow. I've been thinking about using USB


Use a PC running DOS and driving the parallel
port. You can get a fairly easy 500kbyte/sec
which is more than enough.

You have only 3072 pixels, and for this app 6 bits
per pixel (64 greyscale) will give a good image.
3072 x 6 = 18432 bits/frame, you can get an easy
20+ frames per second with no data compression etc.

The advantage of using the parallel port is that you
have an 8bit out port, and another 5 bit output port,
which is enough lines to drive your latches direct
and save a lot of PIC processing. Check into TI's
parallel DACs, you can get 8bit DACs with multiple
DACs per package and simple latched parallel input.
:o)
-Roman

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