[Coco] RGB to XGA

[Bruce Borer]

Hi Allen,
    Converting composite to digital is more work than the PICO can do.
There are devices that can do that but would be more expensive then to
decode the RGB that the CoCo3 already produces.  I did a crude A/D for the
2 bits of each RGB is read and saved to a video buffer in the PICO.  That
video buffer is sent out with XGA timing.  Each pixel is sent with the
width of two XGA pixels.  The hard work was sending each RGB line twice to
the XGA stream.
   I am in the process of putting my schematic files and my PICO code on
github but not completed yet.

Bruce P. Borer

On Tue, Dec 23, 2025 at 6:37 PM Allen Huffman via Coco <coco at maltedmedia.com>
wrote:

> > On Dec 23, 2025, at 4:45 PM, Bruce Borer via Coco <coco at maltedmedia.com>
> wrote:
> >
> >   I just completed my first Raspberry Pi PICO project.
> > It takes the RGB  from the CoCo 3 and converts it to
> > XGA.  There were two pictures shows the difference
> > between CoCo 3's RGB and CMP at Width 80 but they
> > make the post too big. (I am new to posting here)
> > There is more work to do and I will post more as I improve
> > the conversion.
> >   Currently the CoCo 3 RGB is 256 pixels wide with 192 lines
> > when the Width is 32.  This expands to 400 pixels when width
> > is 80.  Therefore I converted 400 pixels by 192 lines for all
> > CoCo widths.  XGA is 800 x 600. To use as much of the screen
> > I doubled the width of CoCo pixels and repeated each line twice.
> >   When I learn to post a video with my daughter's help I will let
> > the group know where to view it.
> >
> > Bruce P. Borer
> >
> > PS - If there is any interest of what I have done, post a reply.
>
> I am aware of some video converter that uses the Pico to do something like
> this — I think I bought one and have it somewhere (though maybe not all the
> components).
>
> Do you try to handle composite mode with CMP type colors, even going to
> the XGA monitor?
>
>                 — A
>
>
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