Re: gEDA-user: Can't route

["Harold D. Skank" <skank54@xxxxxxxxx>]

Mr. Jackson,

I VERY MUCH appreciate your response and comments.  In answer to your
question, "yes, I will use a 24-layer PCB if it's fully necessary."
This issue arises because the principal chip in the circuit has
something like 1700 pins and uses 3 to 4 different voltages on something
like a 45 mil pin spacing.  Without blind/buried vias the high number of
layers become necessary to provide the necessary routing space to get
connections away from the pins.  I will reduce the number of layers to
the minimum necessary to achieve a full route.

As a matter of record, the greatest number of layers I have had to use
in the past was 13.  However, the router I was using was more
sophisticated (and VERY much more expensive).
So, 24 layers are a bit intimidating.

    Harold Skank

On Fri, 2007-07-13 at 19:55 -0700, Ben Jackson wrote:
> On Fri, Jul 13, 2007 at 07:40:12PM -0500, Harold D. Skank wrote:
> > 
> > I'm on a critical job, pretty large, sufficient that I had to recompile
> > for 24 route layers.  Following the re-compile, I seem to be OK for
> > everything until I attempt to start a route, at which point I get the
> > "stale ratsnest" message.
> 
> Are you really going to use the results of a 24 layer PCB autoroute?  Just
> curious.
> 
> Anyway, I modified PCB to highlight the rat that causes the problem.  It
> seems that it's confused by ratlines that go from a pad to the corner of
> the nearest compatible polygon.
> 
> I went into the netlist window and disabled GND and P* (appear to be your
> power nets) for rats, remade the netlist and then ran an autoroute.  It's
> burning up CPU routing the signals now.
> 
> If you are willing to do the power nets by hand, that might be a solution
> for you.  Otherwise maybe the description above will tip off another
> developer as to how to fix the problem.
> 



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