[Arm-netbook] HDMI High-Frequency Layout: Recommendations

[mike.valk at gmail.com]

2017-08-17 20:59 GMT+02:00 Richard Wilbur <richard.wilbur at gmail.com>:
> On Aug 14, 2017, at 00:14, Luke Kenneth Casson Leighton <lkcl at lkcl.net> wrote:
>>
>> On Mon, Aug 14, 2017 at 7:43 AM, mike.valk at gmail.com
>> <mike.valk at gmail.com> wrote:
>>> 2017-08-13 14:20 GMT+02:00 Luke Kenneth Casson Leighton <lkcl at lkcl.net>:
>>
>>> I don't have any fancy math like Richard so it might be FUD. Or just
>>> my mild form of OCD. :-)
>>
>> :)
>
> I'm sorry if any of this looks like fancy mathematics.  (As someone whose first degree is in mathematics, I thought this was all very mundane algebra at best.  I didn't get into field theory, Maxwell's equations [partial differential], et cetera.)

It is fancy math. And it is mundane. I didn't have the time refresh my
electrical formulas and/or follow yours. So it simply needs time and
attention.

Formulas don't teach you what's going on. It's
applying/verifying/quantifying your understaning of the subject. Any
one can apply simple formulas. But when you don't understand where
they come from you are just repeating tricks with the risk of doing it
wrong.

Your formulas are however infinitely more valuable then the fixed
recommendations but require more time to understand, verify and use:
http://www.ti.com/lit/an/spraar7g/spraar7g.pdf figure 13

That document has some nice recommendations.

I've been away from electrical calculations for 16 years now. So they
need time to enter my mind again and become applicable.

>
>>> Anyway a picture of the flood-fill will reveal everything.
>>
>> attached.  greyscaled (smaller).  original GND tracks are still
>> visible but they're *combined* with the floodfill.
>
> So I enjoyed looking at the picture but I'm curious what I'm looking at.  Is this one layer?  Which layer?  What does the black mean?  What about the gray?

The normal traces are all in black. The GND fill is gray. If a trace
is GND the fill distance is 0 if not 5 thus connecting the GND traces
to the GND fill

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