Re: gEDA-user: How to deal with single/dual parts?

[Bill Gatliff <bgat@xxxxxxxxxxxxxxx>]

John Doty wrote:
> Let's not say "change the workflow". There are many workflows. Pin  
> numbers and packages are already irrelevant to some.
>   

Well, let's say "change MY workflow".  :)

> Have a tool that translates schematics without pin numbers to  
> schematics with them.
>   

Actually, I kind of like the idea of something like a netlist file that
sits alongside the sch file.  Maybe a script can meld them together for
current versions of gschem, but maybe future versions would not require
that.

> Well, I wouldn't want to have a backwards data flow that mucks with  
> my source schematics. But having the tool output .sch format means  
> you can print the version with pin numbers for documentation. I  
> wouldn't edit such schematics. But you could if that's what you want.
>   

Right.  Like I said above, having a netlist-type file ("pinlist"?) as an
artifact of the workflow would be better.

> You can't select an opamp without knowing its requirements, and it's  
> hard to know those without the schematic.
>   

True.  So when it comes time to select the actual component and
footprint, you'll pick one based on what the schematic and other
requirements say you need.  That component-footprint selection then
would then stipulate a certain pin assignment or choice of assignments
if it was a multi-opamp part.

>   
>>   I don't really care that I chose a chip
>> with four NAND gates rather than four single-chip ones, the logical
>> signal flow is the same in both cases.  But that change often requires
>> that I physically change from one symbol to another in gschem, even  
>> when
>> the visual representations are identical.
>>
>> Of course, you have to deal with making sure that the four-gate  
>> chip has
>> a decoupling capacitor vs. four caps for the four-chip solution, and a
>> convenient way to note that is on some power-related pages attached to
>> your schematic diagram.
>>     
>
> A specialized tool to autogenerate such pages would be useful, too.  
> But such functionality does not belong in gschem itself.
>   

Agreed.

In a way, a schematic diagram is also an incomplete "requirements"
document, in that once you start selecting components, you might create
additional requirements for new decoupling capacitors and nets to
connect power pins together.  But at a minimum, the layout has to
deliver at least the required functionality described in the schematic
diagram.

Ooh, that sounded like a layer of abstraction with some additional
indirection thrown in for good measure.  Maybe I need to re-caffeinate.  :)


b.g.

-- 
Bill Gatliff
bgat@xxxxxxxxxxxxxxx



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