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Re: gEDA-user: GND and Vcc pin on IC 74245

No disagreement Marvin... GAF is very flexible and very powerfull my ideas would only be a small improvement. They tend to come into play only if the board has multiple families of devices each which require different Vcc values.

For example, the interface to a board might be TTL (0v/5v) while the internal board might have lvpecl (2.0v/3.0v) and lvttl (0v/3.3v) for the various families of digital logic the Vcc is different (5v or 3.3v) with little need for filtering other then bipass capacitors. Here if the symbols had hidden nets for Vcc could be over ridden by an attribute might make the schematics some what clearer (or not what power should be on that pin?).

These arn't simple issues. And to quote an old friend who said "I think we should put a great deal of thought into what we are going to have for breakfast". Well there is no need to rush without dumping a lot of ideas on the table. Plus, I have already demonstrated )to myslef and partners) very complex boards can be built with these tools.

Steve Meier

Marvin Dickens wrote:

On Thursday 08 September 2005 09:47 pm, Stephen Meier wrote:


GAF does allow symbols to have pins for the power connections or to have
the power connections as hidden nets.

The problem often is is what voltage is Vcc or Vdd.

Why not make the symbols have a +5v or a +3.3v power net?

What about devices that Vcc could be any value .. say less then 12
Volts? For these we need a way to assign the values. We could have
multiple symbols. We could use expossed pins there are a number of
solutions available in gaf. I would prefer to have only 2 sets of
symbols one which uses hidden nets that can be over ridden by an
attribute and one set with expossed pins.

(point for discussion --- should this be on the developer list?)



The device characteristics that you described are the reasons why I like it the way it is. With the current implimentation, you can have it any way that you want it. I don't see how you can improve a feature that lets you have something any way you want it.


Regards


Marvin