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

Luke Kenneth Casson Leighton lkcl at lkcl.net
Fri Dec 22 14:51:24 GMT 2017

crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68

On Fri, Dec 22, 2017 at 8:54 AM, Luke Kenneth Casson Leighton
<lkcl at lkcl.net> wrote:
> http://hands.com/~lkcl/eoma/a20/275_hdmi/
> ok so this is four pictures, i did flood-fill, i'm going to update
> them incrementally, for example layer 1 in between the 2 points where
> the flood-fill keepout is too narrow to let it in (the maximum
> "curve" is something like 11 mil diameter) i've expanded that to let
> it in.  also layer5 the horizontal track doesn't reach all the way
> over.  the layer2 one i don't exactly know what to do, there's no VIA
> nearby (and i can't fit one either).
> this is a pain!  i might see if i can set a clearance to GND on
> individual tracks / connections as opposed to NETs.

 ok that worked.  just uploading a video here:


 turns out that there's a feature i'd not used before, called
"conditional rules".  you can specify that *if* GND meets HDMI Group,
clearance rules shall be different.  ordinarily you have to forcibly
set the *entire* GND plane to specific clearances (to ALL objects), or
the *entire* HDMI group to specific clearances (to ALL objects)...
this "conditional" rule does the trick.

 richard i go over it in the video but i believe the layer... 5
keepout needs to also be extended under the layer 6 (blue, bottom)
tracks leading to the VIAs that jump up to the DC3 connector pads.
also i believe that i should be adding some tracks (pink) which,
particularly if there is to be a hole in layer 5 underneath, should be
around a 5 mil clearance, to match the fact that it's swapping
vertical distance for horizontal distance, what do you think?

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