Re: gEDA-user: Strange behaviour of gsch2pcb/gnetlist

[John Doty <jpd@xxxxxxxxx>]

On Sep 20, 2008, at 8:18 AM, michalwd1979 wrote:

> Hello,
> I'm working on quite big design (about 650 elements) and I just  
> experienced strange results in pcb file generated by gsch2pcb/ 
> gnetlist. The schematic uses big main sheet and one small second  
> level sheet added to main by symbol with source attribute. In my  
> project file I have then
>
> schematics digital_1.sch digital_psu_1.sch
> output-name digital_board
>
> And I call gsch2pcb with this command: gsch2pcb -v --use-files project
>
> First strange thing is that generation of pcb file takes about 2  
> minutes on 3Ghz Xeon CPU. Is this normal for big projects?

If you have a big main sheet, yes. This causes gnetlist to spend a  
long time tracking down connections (the algorithm appears to be O 
(n^2)). One of the drawbacks of the big main sheet approach.

> Second is that in pcb file some of the elements from second level  
> sheet are included twice. For example I have R400 in  
> digital_psu_1.sch and in pcb file I get
> R400 and S11/R400 (S11 is the reference of the sheet symbol on main  
> sheet). These 2 elements have the same footprint/value. DRC of the  
> project goes without errors.
> Funny thing that only some of the elements are added twice most  
> (more then 90%) are placed correctly.

You shouldn't give the name of the subsheet directly to the  
netlister: it finds the subsheet through the source= attribute. By  
giving the name explicitly, you told gnetlist to include the  
subcircuit at top level, and by using a symbol with a source=  
attribute you told gnetlist to include it as a subcircuit also. So,  
you got it twice. If you look at the netlist, you'll see that the  
version with refdeses without the S11 is "floating", while the  
version with the S11 has the connections you specified on your symbol.

>
> Do You have any ideas about this? Is this a strange bug or maybe  
> I'm doing something wrong?
>
> Best Regards,
> Michael Widlok
>
>
>
>
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John Doty              Noqsi Aerospace, Ltd.
http://www.noqsi.com/
jpd@xxxxxxxxx




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