[Openchrome-users] PAL modes and vx800

[Anders Gunnarsson]

On Thursday 05 February 2009 11:37:42 Tim Williams wrote:
> On Wed, 4 Feb 2009, Anders Gunnarsson wrote:
> > As I understand you need support for a slow rate on the dot clock, around
> > 14MHz. Both open chrome and the via drivers give me "Clock range:  20.00
> > to 230.00 MHz". Does that mean I'm smoked?
>
> As an experiment I built a convertor circuit (using the
> design on http://www.nexusuk.org/projects/vga2scart) a year or two
> ago. Cost very little and it works beautifully, I built it small enough
> to fit inside a standard plastic scart plug. However my experiments
> proved that you need a dot clock of ~14Mhz to get it to work. Haven't
> tried it with an OpenChrome driver, it worked with the Nvidia card on my
> regular desktop, but failed with the intel chip on my laptop and the
> permedia 2 on my server, neither could manage the necessary dot clock
> rate.
>
> to fit inside a standard plastic scart plug. However my experiments
> I suspect the 20-230MHz range of the driver is caused by a hardware
> limitation, rather than an issue with the software. Your best bet is
> probably something like
> http://www.maplin.co.uk/Module.aspx?ModuleNo=35258, which essentially does
> the same thing that the tv out hardware on many graphics adapters does, ie
> it converts the signal down to something the TV can cope with so that the
> graphics card doesn't need too.
>
> Tim W

Hi Tim,

Thanks for your answer!

I have a cable just like that one so that would be my first option to use. I 
could use a converter, but in that case I would like it to be a little bit 
better. I would like it to follow the refresh rate of the input, 50 or 60Hz 
and to have scart output or component.

One id?a would be to double the dot clock and the horizontal resolution with a 
1440x576 at 50i mode. I have found some positive feedback on that so i tried to 
get i working. But get a "vertical timing out of range" for that mode.

Where can I find supported timings, dot clocks, etc for the vx800?

/Anders