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Mail Archives: geda-user/2015/03/18/15:47:23

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Wed, 18 Mar 2015 12:47:08 -0700 (PDT)
Date: Wed, 18 Mar 2015 15:47:08 -0400
Message-ID: <CA+uY=MQH047XpAqz2L91dcOV6fBVSFPBsgrFxhF-X=zpq1a4Lg@mail.gmail.com>
Subject: [geda-user] Here's how to do auto-routing with ground and power planes
From: Russell Nelson <russnelson AT gmail DOT com>
To: geda-user AT delorie DOT com
Reply-To: geda-user AT delorie DOT com

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HA!! I have figured out how to do no-fuss auto-routing with ground planes
that works well. Here is what you do:

   - Group bottom, ground, and bottom layer together.
   - Group top, power, and power layer together.
   - Lay out your circuit, yadda yadda.
   - Run ground traces on the ground layer and power traces on the power
   layer:
   - Do these steps for both top/power and bottom/ground:
   - Turn off all layers but the top layer.
      - Use Ctrl-F on any power connection.
      - Use Select/Select all found.
      - Use Connects/Auto-route selected rats.
      - Auto-optimize and miter.
   - Turn on the top and bottom layers.
   - Route everything else using Connects/Auto-route all rats.
   - Auto-optimize and miter.
   - The Message Log will report that your layout is complete.
   - Select the top and draw a rectangle.
   - Select the bottom and draw a rectangle.
   - This fills-in the ground plane, but you're not done, because you still
   have the traces.
   - Do these steps for both ground and power:
      - Use Ctrl-F on any ground connection (best where the power comes in).
      - While you're there, select the Via tool and drop a via on that
      connection.
      - Use Select/Select all found
      - Use Select/Rip up selected auto-routed tracks.
   - Use Connects/Optimize rats nest again.
   - Use Connects/Auto-route all rats.
   - The Message Log will report that your layout is complete.

There's a bunch of steps, but it will work a champ every time, because
first routing power and ground ensures that when you flood it with power
and ground planes, you'll have full connectivity. The only drawback is that
you can get unnecessarily long traces and jumps to the other plane
involving extra vias. On a 27 part board, I only spotted two jumps and one
derp trace.

All of this is necessary because the auto-router doesn't know that the
ground plane will magically disappear when you lay a trace across it.

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<div dir=3D"ltr"><span style=3D"font-size:12.8000001907349px">HA!! I have f=
igured out how to do no-fuss auto-routing with ground planes that works wel=
l. Here is what you do:</span><div style=3D"font-size:12.8000001907349px"><=
ul><li style=3D"margin-left:15px">Group bottom, ground, and bottom layer to=
gether.</li><li style=3D"margin-left:15px">Group top, power, and power laye=
r together.</li><li style=3D"margin-left:15px">Lay out your circuit, yadda =
yadda.</li><li style=3D"margin-left:15px">Run ground traces on the ground l=
ayer and power traces on the power layer:</li><li style=3D"margin-left:15px=
">Do these steps for both top/power and bottom/ground:<br></li><ul><li styl=
e=3D"margin-left:15px">Turn off all layers but the top layer.</li><li style=
=3D"margin-left:15px">Use Ctrl-F on any power connection.</li><li style=3D"=
margin-left:15px">Use Select/Select all found.</li><li style=3D"margin-left=
:15px">Use Connects/Auto-route selected rats.</li><li style=3D"margin-left:=
15px">Auto-optimize and miter.</li></ul><li style=3D"margin-left:15px"><spa=
n style=3D"font-size:12.8000001907349px">Turn on the top and bottom layers.=
</span><br></li><li style=3D"margin-left:15px">Route everything else using =
Connects/Auto-route all rats.</li><li style=3D"margin-left:15px">Auto-optim=
ize and miter.</li><li style=3D"margin-left:15px">The Message Log will repo=
rt that your layout is complete.</li><li style=3D"margin-left:15px">Select =
the top and draw a rectangle.</li><li style=3D"margin-left:15px">Select the=
 bottom and draw a rectangle.</li><li style=3D"margin-left:15px">This fills=
-in the ground plane, but you&#39;re not done, because you still have the t=
races.</li><li style=3D"margin-left:15px">Do these steps for both ground an=
d power:</li><ul><li style=3D"margin-left:15px">Use Ctrl-F on any ground co=
nnection (best where the power comes in).</li><li style=3D"margin-left:15px=
">While you&#39;re there, select the Via tool and drop a via on that connec=
tion.</li><li style=3D"margin-left:15px">Use Select/Select all found</li><l=
i style=3D"margin-left:15px">Use Select/Rip up selected auto-routed tracks.=
</li></ul><li style=3D"margin-left:15px">Use Connects/Optimize rats nest ag=
ain.</li><li style=3D"margin-left:15px">Use Connects/Auto-route all rats.<b=
r></li><li style=3D"margin-left:15px">The Message Log will report that your=
 layout is complete.</li></ul><div>There&#39;s a bunch of steps, but it wil=
l work a champ every time, because first routing power and ground ensures t=
hat when you flood it with power and ground planes, you&#39;ll have full co=
nnectivity. The only drawback is that you can get unnecessarily long traces=
 and jumps to the other plane involving extra vias. On a 27 part board, I o=
nly spotted two jumps and one derp trace.<br><br>All of this is necessary b=
ecause the auto-router doesn&#39;t know that the ground plane will magicall=
y disappear when you lay a trace across it.</div></div></div>

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