Re: gEDA-user: blue sky ideas - written down finally

[Bill Gatliff <bgat@xxxxxxxxxxxxxxx>]

Steven Michalske wrote:
>>
>>> [(A,B),Y]=[1,2,3], [4,5,6], [9,10,8], [12,13,11]
>>>
>>> I think that this simplified down to the required parts.
>>>       
>> I suppose some of the syntax can be defined as "optional" and implied,
>> if we can guarantee that it's deterministic.
>>
>> I can imagine cases where pins can be swapped on some of the gates,
>> but not all, for example an FPGA where some pins are input only, or an
>> MCU where some UARTs are less configurable than others.  Let's define
>> the swappability as a property of the chip, not the symbol, so parens
>> on the left are migrated to the corresponding pins on the right - then
>> if you have parens only on the right, you have the ability to define
>> swappability on a per-gate basis.  I.e. your example is changed to
>> this internally:
>>
>>  [A,B,Y]=[(1,2),3], [(4,5),6], [(9,10),8], [(12,13),11]
>>     

Some software I have worked with (not EDA) uses a "compatible="-type
syntax for such things.  It can get kind of verbose when you have a
really generic symbol that's compatible with pretty much everything, but
that's what computers are for: slogging through all the grunt work.  :)

In this specific situation, you can't think just about swapping two
pins, you have to be much more generic.  In a microcontroller, for
example, you might have whole banks of functionality that can move
between groups of pins numbering to a dozen or so.  If the syntax won't
accommodate that, it's an opportunity lost.

> A package is a footprint and a mapping,  how will you cope with parts
> with the same footprint and different pinouts?  These parts exist, but
> I don't have a particular example on the top of my head
>   

That's similar to the "transistor problem", if not exactly it.

The "pin numbers" on a symbol cannot be mapped directly to footprint pin
numbers, except through a table of some kind.  So the pin numbers on
symbols cannot be actual pin numbers at all, as I mentioned in my post
on this topic a month or two ago.


b.g.

-- 
Bill Gatliff
bgat@xxxxxxxxxxxxxxx



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