Abusing the BA6592F as a general purpose encoder

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Guilty
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Re: Abusing the BA6592F as a general purpose encoder

Post by Guilty » Mon Aug 07, 2017 6:20 pm

lidnariq wrote:No need to 'scope it, we have jwdonal's redrawn schematics. /BURST from PPU2 is tied to both /PCP and /BFP.

/BURST should be low during the colorburst, which is a time that—in the absense of Macrovision—should be 0 IRE on average. So a delayed copy of /HSYNC that's only true during some subset of the "breezeway", colorburst, and "back porch" would be the signal you'd want.
Isn't all of that time just a little shorter than the sync pulse? I'll have to mess around with this once I get some kind of variable delay working.

I just thought to mention that when my near-black colors are not coming up on screen they are still visible on the scope. It looks like my blanking up to black is not the IRE value we were talking about before. In fact it looks like my black video sits at the blanking level. This seems like a key factor in the problem. Maybe there's a different way for me to stage inputs.

lidnariq
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Re: Abusing the BA6592F as a general purpose encoder

Post by lidnariq » Mon Aug 07, 2017 6:56 pm

To the best of my memory, they're both ≈4.7µs?
Guilty wrote: In fact it looks like my black video sits at the blanking level. This seems like a key factor in the problem. Maybe there's a different way for me to stage inputs.
Not to the severity you're talking about...

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Guilty
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Re: Abusing the BA6592F as a general purpose encoder

Post by Guilty » Mon Aug 07, 2017 7:04 pm

Then I'm off to dick with timing delays then! Thanks again lid. Good talk, see you again in another month or so.

EDIT: Oof, I really hope this delay thing pans out because if the PCP clamp doesn't fix my contrast problem then solving it through gamma correction is surprisingly expensive. At least through the only way I've found so far.

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