Re: gEDA-user: Symbol creation

[sdb@cloud9.net (Stuart Brorson)]

Hi Henrik --
> 
> For the current project i'm drawing I need a few new symbols (PGA2310 from
> TI and few devices from Allegro). How do I draw a symbol that needs three
> different power connections and three different ground connections using
> net-attributes? Now I have drawn pins for the power and ground stuff.

This is my opinion only.  

If your parts are analog parts, or have analog and digital sections
(e.g. an A/D), my opinion is that the pwr/gnd connections should be
brought out on pins explicitly.   For power nets this is good practice
because then you can explicitly attach the power decoupling/bypass
networks to the pin.  For GND, this is good practice because you often
want to attach analog GND pins to an analog GND plane, whereas digital
GND pins often go to a separate digital GND plane.   

If your parts are digital parts, but require independent decoupling
networks (like some communications chips, or some high-speed digital
parts), the same considerations apply.  THerefore, bringing the
pwr/GND connections out to pins is a good idea. 

If you have a low-speed, generic digital part with, say, three pins
which all attach to the same pwr/GND net, then you can probably just
attach the pwr/GND nets to the same net using an attribute.  I don't
know how to do this, however, since I generally always attach pwr/GND
nets to pins due to the nature of my projects . . . . 

Stuart