Re: Keyboard and Video interfacing


"David L. Jones" <altzone@xxxxxxxxx> wrote in message
news:1142820676.845039.264370@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Abstract Dissonance wrote:
I was thinking about trying to do a project that involves a PC
keyboard(and
maybe mouse) and possibly a PC video monitor.

Can someone point me in the right direction to get started? I'd like
basicaly to "sense" or "transform" information between the data paths of
the
pc and these devices... the keyboard one is sorta like a data logger type
of
thing but actually is something else.

I'm sure the PS/2 port for the keyboard/mouse is very easy to handle but
what I'm woried about is for USB keyboards... not sure if the protocol is
standardized... if so then it should be pretty easy to interface using a
PIC
that supports USB?

The USB keyboard will be a pain, stick with the PS/2, that's real easy
to decode with any micro. Lots of sample code around etc.


I have a pic that does USB so it can't be much more difficult that the PS/2.

What kinda signals come out from the graphics card to the video monitor?
I
assume there are both analog and digital outputs since I've seen newer
graphics cards with D/V out. Would it be relatively easy to "sample" the
video output of a graphics card and transform it then sent it along its
way
to the monitor?

Basically, forget it, it will be too diffcult. You are talking very
high speed sample rate ADC's, lots of memory, not to mention resolution
and syncing problems in the hundreds of MHz range. It takes a massive
custom ASIC device to do this.
It was very diffcult when I did it back in 1994 with 640x480 LCD
panels, and is now an order of magnitude harder. No one does it without
a special purpose design VLSI chipset these days.


heh

1994 and 2006 is a huge difference. Surely they now have chips that
interface between a pc graphics signal and a crt or LCD...

the AVG2510 from NS does just this except it does not allow custom graphics
operation... What I need to do is be able to draw basic primitives and do
bitmap testing which I could implement myself if I had access at the pixel
level.

On the other hand, if you simply want to drive a VGA screen direct (at
low resolution) from a micro or FPGA, that is pretty easy, and there
are several around who have done this and sell a module like this one:
http://www.dontronics.com/micro-vga.html
There are others too.

Dave :)



Well, I need something like that but also need to "get at" the underlying
graphics that is sent out from the pc graphics card. Basicaly recreating a
simple graphics card that sits inbetween the monitor and pc graphics card.

First things first I guess... need to work on the keyboard and get that done
then I can worry about the video part. One thing I'm wondering though is
what type of signal is output from the pc graphics card. Is it composite for
analog and serial/parallel for digital(what else would there be for digital)
where the bits represent pixel colors(like RGB format)?

Thanks,
Jon


.

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