Re: gEDA-user: Embedded Power Pins

[sdb@xxxxxxxxxx (Stuart Brorson)]

> 
> Em Sex 03 Mar 2006 21:32, John Luciani escreveu:
> > The gschem logic symbols seem to have embedded Vcc and GND connections
> > (at least the ones that I was looking at). Since I am working on a
> > board that has 3.3V and 5V logic this is a problem.
> >
> > I created a script that takes a logic symbol with embedded Vcc and GND
> > nets and creates (1) a new symbol with the power nets removed and (2)
> > a new symbol with two power pins. My plan is to place power symbols
> > (and decoupling caps) for each IC in a separate section of my
> > schematic.
> >
> > Since many symbols contain the same pinout for power pins the power
> > pin symbol is a symlink to a generic symbol. The new symbol without
> > power pins have a _np suffix. The symbol containing the power pins has
> > a _pwr suffix.
> >
> I allways used that way. I redrawed all my symbols to fit that standard. 
> Unfortunatelly, there are a lot of people that dislikes that way.
> IMHO all the pins used in a component must be showed on the schematic, no 
> matter what the pin is. I have a lot of boxes with power pins, and its a good 
> way to place decoupling caps.
> When you mix analogic components with digital, its common to have, for 
> example, two 5V, one for the digitals and another for the analogic. If you 
> use the embedded pins, they will all use only one power supply. And when 
> routing the board, its better to know exactly where all the connections go 
> taking a look at the schematic.

FWIW, I wrote a blurb about this question for the wiki a couple of
weeks ago.  Here it is: 

http://geda.seul.org/dokuwiki/doku.php?id=geda:faq-gschem#what_should_i_do_about_power_pins_on_my_symbolsmake_them_visible_explicit_or_invisible_implicit

Stuart