Re: gEDA-user: Hierarchy Refdes and Component Values

[kai-martin knaak <kmk@xxxxxxxxxxxxxxx>]

Rick Collins wrote:

>> >> In addition, I set the refdes of the subsheet symbol to a
>> >> single digit. That way, the refdeses stand a chance to be
>> >> readable in in silk with a three layered hierarchy.
>> >>
>> > How about emitting only the "basename" of a refdes on silk
>>
>>Then, I'd have no way to locate which schematic subsheet a
>>particular "R1" on the layout would correspond to. Of course,
>>all refdeses might be guaranteed to be different like starting
>>at R100 for one sub sheet and at R200 for the second. In that
>>case, refdes mangling can be switched off whole sale in a local
>>gnetlistrc:
>>   (hierarchy-uref-mangle "disabled")
> 
> Can you be sure this will work with all designs?

Of course not. That's why I said, "In that case ...".


> Your approach would 
> limit each subsheet to 100 of each type of component before name 
> collisions happen.  I can picture two ways of working around this.
> 
> One is to instead append a numeral or other indicator to the 
> beginning of a refdes, i.e. when on subsheet 3 a part might be 
> 3R15.

This is exactly, what I like to do in my hierarchical designs.
(See the top of this post.) 


> Of course this could be confused with a part value, i.e. 
> 15R3.

Not with pcb :-)
Pcb prints either refdeses, or values but not both.


> The other is to have a feature in the schematic package to provide a 
> unique number to each component.  The subsheet instances would be 
> processed in turn resulting in a unique number being assigned to
> each component in the design. 

We sort of have this in gschem already: The autonumber dialog 
contains the option to skip numbers found in "whole hierarchy".
This is not perfect, since it only looks at sub sheets but not 
at "parent sheets".


> If I understand correctly how subsheets 
> work, I can see where you might want to display to the user a given 
> subsheet only once rather than separately each time the sheet is 
> referenced. 

Not sure, if I understand what you are aiming at.
One of my current projects involves a subcircuit that needs
to be repeated 69 times. With subsheets I don't need to have 
69 times the same schematic in the documentation. If I have
to change some aspect of the subcircuit, I don't have to
apply the change 69 times. So for this particular project
the way geda treats subsheets is a real work saver. :-)

 
> Does it make sense to let the schematic package reassign
> ref des in multiple instances of a subsheet?

IMHO, this is the job of gnetlist. On schematic level multiple
instances should be exactly the same. That's why they are
instances rather than copies.

---<)kaimartin(>---
-- 
Kai-Martin Knaak
Öffentlicher PGP-Schlüssel:
http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x6C0B9F53



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