Ok. That makes total sense about you having limited timing options.
I only pointed out the 56Hz in case it wasn't intentional. :).
It does seem like the page offsets to the blit instruction have
changed though. For a rectangle operation I used to use drawpage<<19
as the offset to that page, but it now seems like that's somehow not
correct since all of my blits seem to be happening earlier in memory
than I would expect. Any tidbits of info that'd help me fix this? I
figure Peter probably has documentation or just flat out knowledge of
the layout since he requested it, but I thought I'd ask here first.
James
--- In "Jesse Off" <> wrote:
>
> --- In "gamehoser" <james.singer1@> wrote:
> >
> > Alright, I just fired this up to give it a shot. It sync'd up just
> > fine on my monitor, but I did notice that the monitor is reporting
> > 56Hz for the refresh rate. If it's supposed to be hitting 60 for your
> > 10.4" display, then that could be your issue with it only getting 790
> > pixels. If the pixel clock was not at the right rate, I could see
> > this happening.
>
> Its supposed to be hitting 56Hz. I don't have a lot of options for
> easily attainable pixel clock rates with the PLL circuitry I have on
> the FPGA. I ran 640x480 at a 25Mhz pixel clock and am currently
> running 800x600 at 37.5Mhz. The SVGA timing spec calls for 38.1Mhz--
> but a delta of 600Khz is well within the margins of most CRT sync
> circuitry. A low 56Hz vert refresh may cause eye fatigue on old CRT
> monitors, but should be a non-issue for LCD's and also conserves SDRAM
> bandwidth and power though admittedly rendering 800x600 at 60Hz only
> takes 54 of the ~130 megabytes/sec of SDRAM to FPGA bandwidth I have.
>
> The vertical off-center on the original was more an artifact of my
> horizontal timing state machine than of the refresh rate. Its a bit of
> a black art to get a timing that syncs up centered with most monitors
> and LCDs without actually talking to the monitor. I'm a bit surprised
> that the first didn't sync up well on LCDs as it sync'ed perfectly on
> my 10 yr old test CRT and was very close to the original SVGA 56Hz
> timing. All I changed in the 2nd bitstream was the ratio between the
> horizontal front/back porch and shortened the length of the horizontal
> sync pulse.
>
> //Jesse Off
>
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