Re: gEDA-user: Soft and Hard symbols

[Stefan Salewski <mail@xxxxxxxxxxxx>]

On Mon, 2011-01-03 at 16:04 -0800, Edward Hennessy wrote:
> On Jan 3, 2011, at 8:20 AM, Stefan Salewski wrote:
> 
> > I guess all this was discussed on the list multiple times in the past,
> > so this is more a note to myself...
> > 
> > I think it may be useful to have two types of symbols, soft and hard.
> > Hard symbols have an footprint attribute and maybe additional hard
> > properties. Soft symbols are simple an OpAmp or a resistor -- only type,
> > no parameters defined. For schematic entry the use can select "Add soft
> > symbol" or add hard symbol (if he exactly knows what he wants). If a
> > schematic contains soft symbols, then there is an additional step
> > necessary before PCB layout can start: Selecting footprints and slots --
> > this step may be supported by databases. (The user may have the optional
> > choice to generate hard symbols from soft ones by specifying footprints
> > and other hard facts in an early input stage.)
> 
> Besides allowing attributes to contain a value representing unknown or
> be empty, I don't see why the application needs to know the difference
> between a hard and soft symbol.
> 
> If the schematic editor allows empty attributes and allows the user
> to edit these attributes, wouldn't it be capable of the functionality
> requested above?
> 

At least the slotdef attribute is an example where we currently have to
make a decision in an very early design stage. If I know that I may need
some OpAmps or logic gates for my design, I may want to do not care
about single, dual or quad packages when drawing the schematic. But
currently we have to pick one of these types -- later we may have to
replace it.

For many tasks heavy/hard symbols may be fine -- when we know in advance
what we need. 

But I really would like to have the ability to do a top down design:
OpAmp -> VoltageFeedback -> FetInput -> Dual -> SOT8

Similar like selection at Digikey -- and now I remember postings of DJ,
I really should read his

http://www.delorie.com/pcb/component-dbs.html

and try to understand it.




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