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Date: Tue, 13 Oct 2015 11:18:16 -0400
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Subject: Re: [geda-user] A lesson from gnet-makefile
From: "Evan Foss (evanfoss AT gmail DOT com) [via geda-user AT delorie DOT com]" <geda-user AT delorie DOT com>
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On Tue, Oct 13, 2015 at 2:32 AM, DJ Delorie <dj AT delorie DOT com> wrote:
>
>> 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.

There should be an initial autoplace to just drop stuff on the page
and then a re-placement when the autorouter considers trace
lengths/impedances. This is not just a factor for bypass capacitors.

> 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...



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