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Date: Tue, 13 Oct 2015 09:01:27 +0200
From: "Nicklas Karlsson (nicklas DOT karlsson17 AT gmail DOT com) [via geda-user AT delorie DOT com]" <geda-user AT delorie DOT com>
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Subject: Re: [geda-user] A lesson from gnet-makefile
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> > I also agree about poor usefulness of auto placement. The firts
> > problem is the decoupling capacitors. Maybe it would work better
> > with autoplacement in several steps:
> >   1. Disperse components.
> >   2. Place decoupling capacitors.
> >   3. As a first approximation place tightly coupled components as
> >   groups which of curse may be very hard to define.
> >   4. Autoplace this group of components there the tightly coupled
> >   components may have to be fine tuned.
> 
> Autoplace is one of those things that's easy to experiment with using a plug-in.
> 
> It's also something that's very hard to "get right" algorithm-wise.
> 
> Heck, even a plugin that auto-selects bypass caps would be a
> considerable challenge, but very useful.
> 
> I did one project where bypass caps had their own refdes (CB instead
> of just C) and were numbered according to the pins they went with, but
> that project only had one big IC on it anyway...

I guess a bypass capcitor could be defined as this: it is connected to power and ground lines, there is one for each power input of components. Special naming or attributes I guess would add to much clutter to be worth it except for special cases.

I think it would be a good idea to make find and place bypass capacitors be the first step in auto placement. Then this have been done there must be a mechanism to work with them as a group.

As soon as I get enough time I will try to take a look at this and the bug list of course. If I succeed I guess this could be added as a first step before current algorithm.