On 3/4/08, Michael Meeuwisse <[EMAIL PROTECTED]> wrote: > I continued digging a little, the vid_control module has vid_clock as > an input, module video_wrapper uses this module and also has > vid_clock as an input. Right now, the s3_top_level maps vid0_clock or > vid1_clock to these inputs, but these signals are somewhat odd; > > BUFG Vid0_BUFG ( > .I(vid0_clock_ext), > .O(vid0_clock) > ); > > vid0_clock_ext is once again, an input: > > // Tempory hack to make everything pass synthesis > input mem_clock_ext, > input vid0_clock_ext, > input vid1_clock_ext, > > Am I deducting correctly that this comment is an elegant "TODO", and > the clocks aren't dynamic yet?
Exactly. Howard's the one who knows what to do here, but he's a strapped resource, and there's tons the rest of us can do in the mean time. > > > On 4 Mar 2008, at 02:24, Timothy Normand Miller wrote: > > > The simplest way is to have a high frequency into a divider. But > > that's kinda limited. Another thing you can do is take the DCM > > output, run that through a divider, and then use the output of that as > > feedback. > > > The problem is that the frequencies needed don't really have a common > divider, unless you start running several GHz. Say, for example, we > want some basic ones; > > 640x480 @ 60Hz = 25.175 MHz (say 25, works just as fine) > 800x600 @ 60Hz = 40 MHz > 1024x768 @ 60Hz = 65 MHz > > I guess we could do something like, run at 130 MHz. Then we get > 640x480 - divide by 5.2 (count to 5, every fifth time count to 6?) > 800x600 - divide by 3.25 (count to 3, every fourth time count to 4?) > 1024x768 - divide by 2 That's interesting, but it wouldn't leave you with a 50/50 duty cycle. This could be a problem for the DVI transmitters, which are DDR. > > Correcting the clock like that all the time is bound to give odd > display results. So I don't know how to do it, but a divider sounds > imho impossible. I'm going to get in touch with Howard and find out how he got it to work. > > > > I think. I'm really not sure how Howard did it. > > > > On 3/3/08, Michael Meeuwisse <[EMAIL PROTECTED]> wrote: > >> Quick question. > >> > > > Cheers, > > Michael > www.projectvga.org > > -- Timothy Normand Miller http://www.cse.ohio-state.edu/~millerti Open Graphics Project _______________________________________________ Open-graphics mailing list [email protected] http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
