Re: gEDA-user: Footprints with mounting holes

[Andy Fierman <andyfierman@xxxxxxxxxxxxxxx>]

I think I put that badly.

The nc symbols are purely for visual purposes. They don't of
themselves stop nets or pins being connected together. However, if
they are placed directly on any pin that is to be left unconnected
then it is made clear that there is no net connected to those pins.

Playing with PCB just now it seems that if pins are left just with
dangling nets (a pin with a single connection to a net that goes
nowhere else), as long as the nets have unique names then even if the
pins on the symbol have the same pinlabel and pinnumber attributes and
the pin numbers on the footprint are the same, they do not show up as
being connected together in PCB. After going through the steps of
gsch2pcb, the rats nest shows no connection between unconnected pins.

Not sure if that makes it any clearer though.

:)

         Andy.

http://signality.co.uk



2009/6/15 Stefan Salewski <mail@xxxxxxxxxxxx>:
> On Mon, 2009-06-15 at 10:27 +0100, Andy Fierman wrote:
>> Add the pins to the symbol, name them as already suggested and then in
>> schematic add one of the not connected symbols
>> (nc-bottom/left/right/top-1.sym in the "Misc unsorted symbols"
>> library) to each pin.
>>
>> That should ensure that all the pins in the symbol and the footprint
>> then match but the nc symbols stop them all being connected together.
>>
>> Of course, you may want them all connected to ground or some other
>> rail but if the pins are there, you can connect them as you like.
>>
>>          Andy.
>>
>
> This info about the nc symbols is new for me -- I was thinking that they
> are only for visual purposes. Are they magic?
>
> I think pins or pads of a footprint with the same name are always
> electrically connected in PCB. Pins or Pads for which there is no
> identical pinname in a gschem schematic symbols remain unconnected to
> other copper. (Additional there are the unplated holes, which have no
> copper and can not connect to something.)
>
> If the nc symbols really have any magic -- is there a description about
> this in the wiki?
>
> Best regards
>
> Stefan Salewski
>
>
>
>
>
>
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