Magnus,
I am trying to understand your idea of schematic capture workflow.
1) Select the symbolic device for example an And Gate or an op amp
2) Determine the requirements for that element (speed, logic voltage level, etc)
3) find the set of devices that could fullfill the element requirements (different devices or the same "second source" devices that could fulfill the requirements
3) Pick the phyisical devices and organize the elements into these devices
4) Pick the packages for the devices (This is the first moment we actually have pins)
Comments?
Thanks,
Steve Meier
Magnus Danielson wrote:
From: "Timmerman, LJH" <[EMAIL PROTECTED]>
Subject: RE: gEDA: Component Packages and PCB Land Pattern - naming Conven tions
Date: Thu, 4 Nov 2004 08:49:39 +0100 Message-ID: <[EMAIL PROTECTED]>
Hi Steve,
IMHO the gschem symbol mechanism lacks a few features.
A couple of them are listed in your mail below, and some are even more fundamental as I see them.
For instance:
[Fundamental] A lot of [CMOS, TTL] components are available in SMD and in
through-hole packages --> their pin nummbering is not allways identical.
It's not practical to have two or more sets of symbols. This should be
solved at the attribute level (pins) if possible, for their graphical
representation is identical.
The actual problem is that too much is tied to "symbol". It doesn't scale well into the modern world.
[Fundamental] The visible name of the package should be implemented as an
attribute, that is [7400, 74S00, 74LS00, ...].
You need to indicate Speedgrade, Temperature-range, Package for most things. There is a number of specialized things like Pb-free, avionics/space approval etc. etc.
Once you actually have that, you need to get the ACTUAL ordering number, which differs from different vendors. Also, alternative stuffing both in family and from different vendors comes into play.
The actual ordering number is even more complex, since it will depend on which delivery form you buy a whole bunch of these... tape, tablett or whatever.
Depending on how large design one is making, the work-flow becomes quite different. For a larger design, choosing all the details at a singular moment in time becomes hard, and recycling that process becomes more and more expensive the larger design there is.
Moving away from that kind of hard-select and rather select function, device, speedgrade/package/component and finaly delivery form is a better way to do it.
Choosing a "symbol" is only representing the first step. Pin-numbers come further down the line.
But then, I've been down this road before with no succsess. I've been stating this many times here. I can't see a chance of gEDA being used as a tool in my company ever as a result, since it will not match our most basic needs. I am sure many will enjoy it for other projects thought, but if you want to aim for prime-time you need to address the issues we are facing.
Cheers, Magnus
