> The autorouter is old technology, we need to remember. It was not written
> to handle arcs, nor does it handle the full rule set, far from it, and it
> also gets a little crazy with off-grid pads. One of the recent service
> packs added a warning to design rules that are not respected by the
router.
>
> The autorouter is a relatively good router within its limitations,
> especially considering the price; we understand from Protel staff comments
> at recent PCB Design Conferences that the coming router upgrade will be
far
> more rule-compliant as well as better and more powerful in other ways.
My thoughts on the autorouter. Interesting that Abdul thinks the autorouter
is old technology. The router is based on neural net technology from the
Neurorouter company that Protel acquired several years ago. Neural nets are
AI, and AI is the future, right? ;-)
The autorouter is astoundingly fast. It definitely does not always obey the
rules, however. I suppose this comes with the AI territory. After all, one
of the characteristics of AI is to selectively ignore rules which prevent
achievement of the goals, if the goals cannot be achieved by strict
compliance with the rules (see Asimov's three rules of robotics). I wish
the autorouter was smarter about when it is really necessary to disobey the
rules, and which rules carry the least adverse consequences of violation.
Still, I look forward to the autorouter improvements.
Best regards,
Ivan Baggett
Bagotronix Inc.
website: www.bagotronix.com
----- Original Message -----
From: "Abd ul-Rahman Lomax" <[EMAIL PROTECTED]>
To: "Protel EDA Forum" <[EMAIL PROTECTED]>
Sent: Thursday, September 13, 2001 5:05 PM
Subject: Re: [PEDA] Autorouting Problems
> At 07:47 PM 9/11/01 -0700, G. Allbee wrote:
> >In this revision of the board I added a slot in the middle of the board.
I
> >remembered an email from this group some time ago that said something
like
> >put a through hole on each end of the slot and then draw lines on the
> >perimeter of the slot. So this is what I did, however I used lines on
> >multilayer figuring they would also work as keepouts and prevent routing
in
> >the slot.
> >
> >I discovered that the multilayer lines were preventing the autorouter
from
> >routing and when changed to a mechanical layer the router would work like
> >normal.. Hmmm - a bug?
>
> Thanks to Mr. Albee for reporting the source of tthe problem to us, with
> its solution.
>
> Technically, this is not a bug; rather it is a situation where a program
> has been fed data which was not anticipated by the programmers. It is,
> indeed, a shortcoming, because a truly complete program would detect and
> report such data conditions. But we do not expect Protel to be "truly
> complete" because it would take unlimited programming resources, and we
> cannot afford to pay for that!
>
> We *can* hope that the documentation will continue to become more complete
> and more accessible, and we may also hope that future releases will be
able
> to detect this condition; but there will always be such traps; with
> continued work they will become rarer. As to the documentation, we should
> not depend completely on Protel for this: we have better resources, we
only
> lack coherent organization, so maintenance and depth of the FAQ depends on
> an occasional volunteer. (More accurately, we *are* organized, but the
> organization is developing slowly.)
>
> The multilayer was not intended for anything other than pads which exist
on
> all copper layers; it could be argued that Protel should not permit any
> other primitives on that layer. The purpose of this layer is to create
> copper on all copper layers. Mr. Allbee perhaps expected that this would
> serve as a keepout, which, indeed, it should (i.e., it should function
> identically to a set of copper primitives matching it in location and size
> on every copper layer).
>
> Mechanical layers have no effect on routing; they are pure drawing layers
> at present. The lines in the old suggestion that Mr. Albee remembered were
> lines which would appear on a documentation layer; they should have been
on
> the fabrication drawing, which is, most simply, the drill drawing layer,
or
> it is a mech layer assigned to the purpose of a fab drawing.
>
> I used free track in the past for layer-specific keepouts, but this is no
> longer necessary, since Protel now has a keepout checkbox for lines, arcs,
> and fills. These are respected by the autorouter, I think; someone will
> correct me if I am wrong. Such keepouts do not photoplot. For a multilayer
> keepout, use the keepout layer!
>
> The autorouter is old technology, we need to remember. It was not written
> to handle arcs, nor does it handle the full rule set, far from it, and it
> also gets a little crazy with off-grid pads. One of the recent service
> packs added a warning to design rules that are not respected by the
router.
>
> The autorouter is a relatively good router within its limitations,
> especially considering the price; we understand from Protel staff comments
> at recent PCB Design Conferences that the coming router upgrade will be
far
> more rule-compliant as well as better and more powerful in other ways.
>
>
> [EMAIL PROTECTED]
> Abdulrahman Lomax
> Easthampton, Massachusetts USA
>
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