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Mail Archives: geda-user/2015/02/07/10:23:38

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Subject: Re: [geda-user] Re: Ground Plane Behavior?
From: Peter Clifton <pcjc2 AT cam DOT ac DOT uk>
To: geda-user AT delorie DOT com
Date: Sat, 07 Feb 2015 15:22:24 +0000
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On Sat, 2015-01-31 at 09:40 -0500, Jason White wrote:

> > I know PCB is quite old and there are a lot of issues. I just wanted to know
> > if this behaviour: "Outboxed planes don't flood again if re-connected" is
> > documented as bug?
> >
> > I am also willing to invest some time in bug hunting and maybe provide
> > patches ...
> 
> 
> Well, that is an interesting idea.
> 
> To clarify, the behavior you are proposing is:
> 1. An existing copper pour gets "boxed out" so that their is a "hole"
> where the plane no longer extends due to traces on the PCB.
> 2. Placing a via in the "hole" and electrically connecting it to the
> "boxed out" copper pour would result in the hole being refilled with
> copper.
>
> That might be convenient, but I think it could be a bit of a "trap" so
> to speak. If you have large currents flowing from the re-flooded
> "hole" in the copper pour, you may not realize that their is an
> electrically poor connection (a single via) to the actual plane.
> 
> If this behavior was added, I would think that this behavior should be
> explicitly called up with a tool or menu item in PCB as opposed to
> being an automatic behavior.
> 
> 
> Does anyone else have any input on Bernhard's idea?


I wrote code for this a long long time ago... it is mostly functional,
but might be worth resurrecting. No promises I'll get to it soon, but
for anyone really curious, branches in my repo.or.cz repository with
"pours" in the name relate to this feature.

The basic code just allows you to keep all polygon pieces (like the
"full polygon" flag, but with actual electrical connectivity checking
for the pieces).

There was an extension that was less "production ready", but implements
exactly as you suggest above.. hides any piece of the polygon not
explicitly connected to something with a via, or other connection. I
called this "island removal".

Peter


-- 
Peter Clifton <peter DOT clifton AT clifton-electronics DOT co DOT uk>

Clifton Electronics

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