Mail Archives: geda-user/2014/07/09/02:09:47
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On 07/08/2014 11:17 AM, Peter Clifton wrote:
> Please don't use zero width pads...
OK :)
>
> The file format makes no guarantee how they behave, and it seems like
> the special case free situation should view them as an under width DRC
> error.
Yes, its a total belly-flop onto "maybe it happens to work."
>
> Adding support for defining additional mask within a footprint should
> not be insurmountable, just needs in the first instance, someone to
> define the extension to the file format.
Extending the file format is the easy part. I can come up with lots of
ideas for syntax. And I could have a patch for the flex .l-file in
minutes and recognize the the constructs in the bison code quite quickly
as well. It's getting past that point is where we smack into a wall --
it's not clear to me that the internal data structures are ready to
accept copper-clearance and mask-clearance features that are not
associated with a pad or a pin.
A friend across town has been using KiCad for a while, and since we are
interested in building the same sorts of things we try to share what we
can in terms of tools and designs. Right now, we are hot on the "grand,
unified, footprint generator script" problem. We would like to come up
with a single front-end that can create footprints for both pcb and
KiCad so that we could share footprints more easily. So... I've been
looking at the KiCad footprint file format and their new one can handle
a lot of things that are somewhat vexing in pcb -- although I'm not too
hot on the S-expression idea overall. Anyway, KiCad seems to leave some
things out that my friend and I have been talking about -- like keep-outs.
So the point of the above paragraph is, yes, I can suggest some
extensions, and now would be a good time to capture that since I am
trying to wrap my head around the issues right now. What I can do:
1. write up some straw-man spec extensions
2. update the "footprint creation for.." document with what ever settles
out of that.
What I can not do:
Investigate the feasibility of implementing the extensions. I simply
don't know the code well enough.
-dave
>
> Peter
>
>
> ---
> Peter Clifton <Peter DOT Clifton AT clifton-electronics DOT co DOT uk >
>
> (Sent from my phone)
>
> -------- Original message --------
> From: DJ Delorie
> Date:07/07/2014 19:00 (GMT+00:00)
> To: geda-user AT delorie DOT com
> Subject: Re: [geda-user] pour clearing around pads
>
>
> > I'm not sure where to look for how a zero-thickness pad might cause
> > phantom shorts or how it interacts with route blocking. Clues welcome.
>
> The code considers a pad to be a line segment between two points, and
> may do a "do these segments intersect" test independent of the "check
> the width" test. djopt, I think, does this - intersection of segments
> is a different test than the "happen to touch due to width" test.
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<div class=3D"moz-cite-prefix">On 07/08/2014 11:17 AM, Peter Clifton
wrote:<br>
</div>
<blockquote
cite=3D"mid:tdei7xok2jel0ik0d6j1r048 DOT 1404843436262 AT email DOT android DOT co=
m"
type=3D"cite">
<meta http-equiv=3D"Content-Type" content=3D"text/html; charset=3DU=
TF-8">
<div>Please don't use zero width pads...</div>
</blockquote>
OK :)<br>
<blockquote
cite=3D"mid:tdei7xok2jel0ik0d6j1r048 DOT 1404843436262 AT email DOT android DOT co=
m"
type=3D"cite">
<div><br>
</div>
<div>The file format makes no guarantee how they behave, and it
seems like the special case free situation should view them as
an under width DRC error.</div>
</blockquote>
Yes, its a total belly-flop onto "maybe it happens to work."<br>
<blockquote
cite=3D"mid:tdei7xok2jel0ik0d6j1r048 DOT 1404843436262 AT email DOT android DOT co=
m"
type=3D"cite">
<div><br>
</div>
<div>Adding support for defining additional mask within a
footprint should not be insurmountable, just needs in the first
instance, someone to define the extension to the file format.</di=
v>
</blockquote>
Extending the file format is the easy part.=C2=A0 I can come up with =
lots
of ideas for syntax. And I could have a patch for the flex .l-file
in minutes and recognize the the constructs in the bison code quite
quickly as well.=C2=A0 It's getting past that point is where we smack
into a wall -- it's not clear to me that the internal data
structures are ready to accept copper-clearance and mask-clearance
features that are not associated with a pad or a pin. <br>
<br>
A friend across town has been using KiCad for a while, and since we
are interested in building the same sorts of things we try to share
what we can in terms of tools and designs.=C2=A0 Right now, we are ho=
t on
the "grand, unified, footprint generator script" problem.=C2=A0=C2=A0=
We would
like to come up with a single front-end that can create footprints
for both pcb and KiCad so that we could share footprints more
easily.=C2=A0 So... I've been looking at the KiCad footprint file for=
mat
and their new one can handle a lot of things that are somewhat
vexing in pcb -- although I'm not too hot on the S-expression idea
overall.=C2=A0 Anyway, KiCad seems to leave some things out that my
friend and I have been talking about -- like keep-outs.=C2=A0 <br>
<br>
So the point of the above paragraph is, yes, I can suggest some
extensions, and now would be a good time to capture that since I am
trying to wrap my head around the issues right now.=C2=A0 What I can =
do:<br>
<br>
1. write up some straw-man spec extensions<br>
2. update the "footprint creation for.." document with what ever
settles out of that.<br>
<br>
What I can not do:<br>
<br>
Investigate the feasibility of implementing the extensions.=C2=A0 I
simply don't know the code well enough.<br>
<br>
-dave<br>
<br>
<blockquote
cite=3D"mid:tdei7xok2jel0ik0d6j1r048 DOT 1404843436262 AT email DOT android DOT co=
m"
type=3D"cite">
<div><br>
</div>
<div>Peter</div>
<div><br>
</div>
<div><br>
</div>
<div>---</div>
<div>Peter Clifton <a class=3D"moz-txt-link-rfc2396E" href=3D"mailt=
o:Peter DOT Clifton AT clifton-electronics DOT co DOT uk"><Peter DOT Clifton AT clifton-elec=
tronics.co.uk
></a></div>
<div><br>
</div>
(Sent from my phone)<br>
<br>
-------- Original message --------<br>
From: DJ Delorie <dj AT delorie DOT com> <br>
Date:07/07/2014 19:00 (GMT+00:00) <br>
To: <a class=3D"moz-txt-link-abbreviated" href=3D"mailto:geda-use=
r AT delorie DOT com">geda-user AT delorie DOT com</a> <br>
Subject: Re: [geda-user] pour clearing around pads <br>
<br>
<br>
> I'm not sure where to look for how a zero-thickness pad
might cause <br>
> phantom shorts or how it interacts with route blocking.=C2=A0
Clues welcome.<br>
<br>
The code considers a pad to be a line segment between two
points, and<br>
may do a "do these segments intersect" test independent of the
"check<br>
the width" test.=C2=A0 djopt, I think, does this - intersection o=
f
segments<br>
is a different test than the "happen to touch due to width"
test.<br>
</dj AT delorie DOT com></blockquote>
<br>
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