> Is there any way to around it or is it the configuration problem ?
> So is it really worth in using the AutoRouter ? has anybody successfully
> made a PCB in Traxmaker or Eagle with the Autorouter ?
>
> Any solutions to make realistic PCB's out of Computers ?

A couple of years ago I went through the exercise of trying every
autorouter I could lay my hands on. For each one we had existing
boards from single sided through to 8 layer/SMT both sides that had
been done manually. The 8 layer board had taken me 4 weeks to get
full connectivity and then another couple to tidy it up, check and so
on.

All of the ones we tried (which covered the spectrum from cheap to
expensive) fell into 1 of 2 categories.
1) Specctra
2) The rest

Neuroroute (as it was being marketed then) produced good results on
some boards but failed on others. There was no means to tell it
anything about the board, so if it didn't work, that was it.

There were two things that makes Specctra stand out, IMHO.
The routing algorithm is sensible. On the first pass it tries to
achieve 100% connectivity with no regard for design rule conflicts.
On subsequent passes it changes that rule so that the conflicts have
more influence on where the tracks are placed. From a users point of
view this means that it tells you almost straight away, if it thinks
it will succeed.

More importantly, it allows the board designer to tell the router
things about the board that influence the routing. Each of those
items that David VanHorn mentioned can be specified and given a
weighting. eg. The track from pinA.1 to pinB.1 must go by the
shortest path and/or on top of the board and so on. You can specify
rules like this for pin to pin, nets, components, groups of
components, areas of the board, etc.
There are also crosstalk based rules, equal length rules,
driver-load-termination rules and so on.
It's not a cheap tool but it does allow the designer to do the
thinking and the software to do the work. That is where the others
all fall down.

You can get useful work out of cheap autorouters but I wouldn't pay
extra to get one. I found the most productive way to use those is to
lay out your components the way you want them and then spread them
out to 4-8 times the size of the board. Give the board to the
autorouter with plenty of space and let it join up the pins. Then
start moving tracks and components back to where you want them. As
you do this, you can make changes to the tracks and still keep your
connectivity.

(I have no association with CCT but having done it manually for
years, I appreciate its worth)

Steve.
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Steve Baldwin                Electronic Product Design
TLA Microsystems Ltd         Microcontroller Specialists
PO Box 15-680, New Lynn      http://www.tla.co.nz
Auckland, New Zealand        ph  +64 9 820-2221
email: steveb@tla.co.nz      fax +64 9 820-1929
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