Re: gEDA-user: autorouter enhancements: net characteristics

[Bert Timmerman <bert.timmerman@xxxxxxxxx>]

Hi all,

On Mon, 2009-06-22 at 21:46 -0400, Harry Eaton wrote:
> >  Stefan Salewski <mail@xxxxxxxxxxxx> wrote:
> >
> > I wonder if the PCB autorouter should be more closely bound to the
> > gschem schematics. For example, in the schematics we may specify
> > priority of nets (fast signals, power, ...), trace width or clearance
> > for net segments. Maybe by attributes? I have no idea how commercial EDA
> > software handles this.
> 
> This is the point of  "(6) use routing styles in the netlist to have
> per-net routing styles."
> It doesn't provide "priority" (whatever that is), but it allows you to
> specify a routing style for each net which includes trace width,
> clearance, and via parameters. This is a feature that pcb's
> netlist-file format (and auto-router) has supported for many years
> now.
> 
> It makes sense for the gschem netlist generator to support it; I'm
> supposing from your comment that it doesn't already. That is not the
> fault of the autorouter, it came first.
> 

<to be included in wiki>

> One major drawback at the moment is that all of the net is expected to
> have the same characteristics, so if for example you make a "power"
> net style that is 20 mils wide with 15 mil clearance, it won't be able
> to connect to a fine-pitch part because the constraints can't be met
> due to the part characteristics, but it will route what it can. If you
> manually create "breakouts" that the autorouter can connect to without
> violating constraints, it can then make the connections. Be sure that
> any such breakouts have either vertically or horizontally oriented
> lines or a via where you want the connection made because the
> autorouter will not connect to any diagonal copper.
> 

</included in wiki>


More insight :-)

Kind regards,

Bert Timmerman.
> 
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