Re: gEDA-user: Mirrored headers: how do I define the footprints ?

[Magnus Danielson <cfmd@xxxxxxxxxxxx>]

From: DJ Delorie <dj@xxxxxxxxxxx>
Subject: Re: gEDA-user: Mirrored headers: how do I define the footprints ?
Date: Mon, 20 Dec 2004 13:57:01 -0500
Message-ID: <200412201857.iBKIv14j006685@xxxxxxxxxxxxxxxx>

DJ,

> > Does the user define the footprint when it is used in the schematic
> > to make it more versatile ?
> 
> Yes, because there are many different types of 50-pin headers.  In
> general, there are a few relationships you (the user) needs to specify
> for a given schematic symbol: Its physical packaging and its value are
> the two common ones, part numbers are often specified too.  For
> example, the "resistor" symbol could mean a 1/4w axial or an SMD, it
> could mean 100k or 47 ohms, it could be a standard 1% or a 47-X3J
> alpha-hardened mil spec part.  These are all things that you, the
> designer, need to choose when you add a part to your schematic.
> 
> What GAF is missing is a giant global database mapping vendor part
> numbers to the corresponding symbol sets, footprints, and values.
> Imagine the possibilities - you add a resistor symbol, and a "find it"
> dialog lets you navigate the thousands of resistor types, eventually
> narrowing it down parametrically to the one you want.  Default
> preferences for starting search (803 SMD, SOICs, mil spec, vendor,
> etc), full footprint support, etc.

Actually, when you start out you only know you need a resistor there. Only
later you want to bother with the details of which value, which precission,
which effect tolerance, which package etc. These later things may be decided at
different times and may also be changed many time over. The original decission
to place a resistor between two nets is however stable. If you know directly
what you want, then toss that directly into the system.

However, even hinting parametric search or complexer structures has not been
taken well before.

Cheers,
Magnus