On 4/19/07, Nicholas S-A <[EMAIL PROTECTED]> wrote:
> A number of you are very keen on having a "graphics card" with some
> kind of CPU or DSP on it.
not to be nagging or anything, but isn't that just what oga is? We might
be using a small micro, but it is still integral to the DMA transfer,
VGA, etc.
or are you referring to a prebuilt ones like I suggested?
The microcontroller we're designing is very tiny and is an
insignificant part of the over-all design.
The alternative suggestion is that we use a powerful general-purpose
CPU or DSP as the primary processing element of the graphics chip
design.
I have almost no experience designing high speed multilayer boards,
but I want some. Is there some good source of information on laying them
out that I can look at? Up until this point I have only tried google
searches,
which invariably turn up empty, or datasheets, which invariably only
describe
via routing, noise considerations, etc of the chip in question. I
just want a doc
that has general guidelines.
I suggest joining the gEDA-user mailing list. Before doing that, do
as much reading as you can about gEDA.
> While Howard, Andy, and I can't do this work (any time soon), we can
> guide others through the process. Time to get grease on your hands,
> folks.
>
> Oh, and don't shoot yourselves in the foot by trying to pack in too
> many features. Figure out what is the minimum to make it work and
> design that. If you can get that to work, then make another version
> with more stuff.
Well, some basic questions to ask ourselves:
1) What will it do? I personally think that a reasonable aim is decoding
video, hopefully even 720p/i or possibly 1080p/i, in real time (30+
fps),
while also providing a simple framebuffer and possibly audio. If
video is
the way to go, what formats?
Is that what you really want? A video decoder? Not a graphics card?
2) What should we use? I have no idea on this one. I like the idea of
an FPGA,
since I at least understand a little verilog and it makes for a
compact board
due to almost complete integration. Any sort of DSP should also work.
How much RAM? Do we need RAM?
If you want a graphics card, I think what you'll need is some
combination of a processing element (some processor) and a small FPGA
to send the video data. Most likely, you'll want a DSP with a bus on
it for memory, not a built-in memory controller, because we'd most
likely want to do the memory through the FPGA so that we have enough
bandwidth for video.
3) What sort of interface? PCI? PCIe? USB? Ethernet? There are a
myriad of
possibilities, and they all have advantages and disadvantages.
That's a design decision that y'all are going to have to make.
4) What sort of output? DVI, s-video, S/P-DIF, etc.
5) What is the purpose? Is it designed as a media center, linux video
"savior", or what?
6) Should the functionality be split into e.g. audio processing,
colorspace transform, ...
or integrated into one behemoth?
Minimize, minimize, minimize.
--
Timothy Normand Miller
http://www.cse.ohio-state.edu/~millerti
Open Graphics Project
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