Re: gEDA-user: Parts DB API

[Paul Tan <pt75234@xxxxxxx>]

Hi,

In some commercial VLSI EDA tools, the native symbol attributes
(which comes from symbol library) are really just a place holder
for viewing (location to update attributes from the external DB 
library).
Not all attributes are used by the schematic, in reality, most 
attributes
are used by other backend tools, such as simulation, path-analysis,
layout, LVS, etc.

The native symbol does have a "base" attribute value which
indicate its base cell (parts or component) family, and an index(key)
attribute whose value is instance specifically assigned to select the
set of attributes, and its corresponding parameterized schematics
from its cell family attribute DB.  This will make sure you wont
select the wrong parts nor the wrong set of atributes values
from the DB.

In fact, this scheme is normally called the "parameterized cell"
design, which makes billion transistor VLSI design possible.



-----Original Message-----
From: Levente <leventelist@xxxxxxxxx>
To: geda-user@xxxxxxxx
Sent: Wed, 19 Dec 2007 12:33 am
Subject: Re: gEDA-user: Parts DB API



Steve Meier <smeier@xxxxxxxxxxxxxxxxxxx> wrote:
> On Tue, 2007-12-18 at 23:22 +0000, Levente wrote:
>> peter@xxxxxxxxxxxxx wrote:
>>
>> Hi Peter,
>>
>>
>
>>
>> The symbol files should be as light as possible, and we should make 
them
>> heavy by adding information coming from the database.
>>
>
>
> So can we make a list of what should come from the light symbol and 
what
> should be injected by the database?

Symbol file should only contain graphical objects, and a pin 
identifiers,
which has nothing to do with pinnumbers. Maybe a refdes prefix could 
included
in the symbol file, like "refdes=R?".

Footprint, value, description, documentation, model attributes, and pin
assignment information must come from the datebase. Moreover, gsch2pcb 
could
be taught to use information coming from the database, such as 
technology. For
example the same component can have different footprints for reflow, 
wave
soldering, etc. So maybe we should make some rules in footprint name 
format.
Such as, for example SOT23_R.fp meaning SOT23 package for reflow 
technology.

I have been using successfully the pinseq attribute as pin identifier, 
and
made a small algorithm to add pinnumbers according to pin assignment
information coming from the database.


--
Levente
http://web.interware.hu/lekovacs



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