Re: gEDA-user: More robust support of multi-part symbols.

[Joerg <joergsch@xxxxxxxxxxxxxxxxxxxxx>]

Kai-Martin Knaak wrote:
> I like to use separate power symbols for ICs. However, I constantly hit 
> the usability issues associated with this approach. Support for multi-
> part symbols is quite fragile. 
> For example, gnetlist just checks the footprint attribute  of the first 
> symbol it encounters. That is, the footprint actually used depends on the 
> relative position of the various parts in the *.sch file. There is no 
> check for completeness, no warning if a power symbol is missing. This is 
> clearly an invitation for nasty surprises. 
> 
> My time schedule is a bit relaxed in the weeks to come. So I thought, I 
> might engage in contributing to the geda project by tweaking this aspect 
> a little. ...


Great idea!


>        ... I figure, that it may not be too difficult for a low time 
> hacker like me. This is a list of sub goals for this little project:
>   
> 1) gnetlist should look for a footprint in every instance of a refdes
> 
> 2) add a known attribute "parts" that lists all symbols of a component
>   (should the entries in the list be separated by space, or something
>    more sophisticated?)
> 
> 3) gnetlist should complain if the lists of attributes are inconsistent.
> 
> 4) gnetlist should complain if there are different footprints present
> 
> 5) gnetlist should complain if a component is not complete (part missing).
> 

Yes. This avoids forgetting to place U4D and then its input is floating 
or the feedback trace missing.


> 6) gschem should read the parts list and insert all parts at once.
> 
> 7) auto number of gschem should keep multi-part symbols with the same 
> refdes.
> 
> Next step would be to treat slotted components like multi-part symbols.
> 


7) and your sentence after that is the main reason why I do not use gEDA 
and currently do not recomend it to clients. (Ales: Don't explode now ...)

While you are at it, another feature would be really useful: Be able to 
select that auto-renumbering leaves U1A, U1B, U1C and U1D in exactly 
this order. It can re-assign it to U12A, U12B and so on but not mix with 
other refdeses and not switch B and C and so on. Such a lock-in isn't 
needed for all designs but anyone who has done very drift-critical 
analog designs knows what I am talking about.

Another nice feature would be if gschem would allow parts with inherent 
supplies on the A-slot, meaning it'll always be there when you place it 
but not on the B, C and so on parts. This is how Kicad does it. Many 
engineers prefer that versus a "floater" power symbol that you scoot 
over the part.


> Any comments?
> 

No, just that you had a good idea there. This could really give gEDA a 
boost and more acceptance.

-- 
Regards, Joerg

http://www.analogconsultants.com/



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