At 05:25 PM 3/29/2002 -0600, Jon Elson wrote:
>I don't think there is
>any way to easily add a new symbol to the list, however.

I don't know of any way at all. (Except that one can make power ports 
galore with different power net names, but I don't think that was the 
question; this is not a new *symbol*.)

>   On the other hand,
>I think you could create a "component", put it in a library, and make up
>a menu entry that would select that component with a "Place Part"
>command.  If the name of the pin in the component is GND or a power
>net on your board, and the pin is set as a power pin, it should work just 
>like any of the predefined power ports.

No, I don't think it would. A power port creates a global net with its name 
*and* it connects that net to pins and wires through the hot spot of the 
power port.

A power pin on a component does not create any named net if it is visible; 
it will connect, yes, but two of these used, for example, as power sources 
for an IC would not connect power to that IC. Hidden pins create nets with 
their name, but these nets only connect the pin number of the hidden pin to 
the named net; as a hidden pin, it does not establish connectivity to any 
other pin.

*However,* one could make a symbol with no pins with whatever graphic one 
wanted and use this, in conjunction with a net name, to create a local 
"power" net. The origin of the net name (this is the lower left corner of 
the text) should be at the apparent hot spot of this symbol. But I don't 
think this would be terribly useful, and it could cause confusion, since we 
expect power nets to be global; this object create a local net, i.e., 
global only if all nets are global.

Yes, we should be able to control the graphics for power ports. We should 
also have a tool for making the assigned net of a ground power port 
visible, and ERC should flag any identical symbols which have different 
nets. This condition is a common error source, where the schematic appears 
to have a single ground, for example, but there are, in the net list, 
multiple grounds because the ground ports have been given different names.



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