Re: gEDA-user: Spice netlister

[John Doty <jpd@xxxxxxxxxxxxx>]

On Jan 21, 2008, at 3:51 PM, a r wrote:

> On Jan 21, 2008 8:47 PM, John Doty <jpd@xxxxxxxxxxxxx> wrote:
>>
>> It seems like netlists, not schematics, are the basis here. I don't
>> see why that is at all a problem for gEDA as currently structured.
>> Either a separate tool or a gnetlist back end could do this. I don't
>> see why you think a spice-subcircuit-LL component could get in the
>> way here.
>
> I don't want to put backend specific components on the schematic. If
> the "spice-subcircuit-LL" is _the_ way of making hierarchical
> schematics, and "spice-subcircuit-IO" is _the_ way of connecting them,
> then I have no objections against using them. But for now they look
> strongly tied to the spice-sdb backend only.

Yes. That's the way it works. Each specialized netlister has its  
specialized needs. I'd rather use source= hierarchy too, but it  
doesn't work well for my flow, while Stuart's approach does. Results  
have priority over minor convenience.

>
>> I don't know what open source tools exist here. It would be
>> interesting to investigate incorporating them into a gEDA flow.
>
> The flow is very rigid. You still _have to_ use the "blessed" flow, at
> least for sign-off. Sure, you can use some cheaper tools meantime but
> to really make a difference these tools would have to be 100%
> compatible with rule sets provided by the fab and work reasonably
> well. Very similar thing happens with simulators. For sign-off you
> _must_ use the simulator (often in a specific version) your fab
> requires (together with their models). Otherwise, in the best case,
> you are left without support.

Osaka U. has educational licenses to tools that I can't afford (VLSI  
is a sideline). So we often run the same sims on different simulators  
(hurray for spicepp!). Ngspice is actually pretty good: not as touchy  
about minimum conductance settings as the big $$ simulator.

>
> Good place for gEDA to start spreading in this industry is to
> concentrate on design entry tools (schematics editor, netlisters),

Works great, and I have the silicon to prove it.

> logic simulators and data viewers (simulation results etc). This is
> because these tools are relatively simple, non-critical, easy to adopt
> and its commercial counterparts can be expensive. Analog simulation is
> a next step - this is more difficult because of higher compatibility
> requirements but still it would be possible to compete with commercial
> simulators by price.

Ngspice is actually pretty good: not as touchy about minimum  
conductance settings as the big $$ simulator, and otherwise getting  
equivalent results.

John Doty              Noqsi Aerospace, Ltd.
http://www.noqsi.com/
jpd@xxxxxxxxx




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