Hi Jon,
just for clarification:
I can attach a NC to a signal thats connected to only one component
pin in eeschema. ERC then recognizes that the signal is terminated and
does not throw an error. I can also give that net a label that is then
exported to the netlist (with a leading "/", maybe to signal it's a
single pad net?).
What I did not check until today (with 4.0.7):
I can put that net into a net group. When reading the netlist into
Pcbnew I have to check "keep single pad nets". Then the design rule is
observed during routing. Very fine!
Why would I do something like this?
Lets say I have a transformer in my design that has two mains windings
with a common middle pin. That pin is not used in my design but still
carries mains voltage. I would give that pin a net with a name and
then in pcbnew in the design rules I can put that net (easily, due to
its name) in a net group with a high distance from other nets.
On a sidenote:
I work for a company where we do this all the time (in Zuken) to be
able to handle (very) complex designs where high voltages and low
voltage control circuits are on the same board.
Checking this today in Pcbnew also showed me, that net groups can only
have one distance. I wonder if no one until now had the requirement
where nets in different voltage domains need to be kept away from
another but can have a close distance within the net group. Can
Pcbnew/Kicad do this? Or is this too exotic of an requirement? I know
that this can get _very_ complex when you have up to over 100 net
groups due to isolation requirements…
Regards,
André
Zitat von Jon Evans <[email protected]>:
For your PS, do you mean NCs attached to the end of wires rather than the
end of pins? I don't think that's how it's designed to work today (NC
symbols are only for pins) We could add that though.
On Tue, Jun 5, 2018 at 12:50 PM, André S. <[email protected]>
wrote:
One reason one wants (labeled) NC nets can be isolation of nets via net
classes to ensure proper distances between not connected pins and other
signals.
Regards,
André
PS: This reminds me that eeschema correctly recognizes NC symbols as
termination for nets (via ERC) but still shows a “not terminated" marking
on that NC terminated net ending. Is there a bug filed for this somewhere?
On June 5, 2018 2:38:24 AM UTC, Jon Evans <[email protected]> wrote:
Hi all,
In the current netlisting algorithm, pins with no-connects sometimes
appear in the netlist, with auto-generated names like Net-(U1-Pad1).
This seems to not always happen, but I haven't investigated why yet,
since I'm approaching netlisting from a different direction with my new
connectivity algorithm. In my algorithm, a pin with a no-connect attached
will never generate an entry in the netlist.
Is there some reason we should be including these pins on the netlist?
It seems like if they are marked as no-connects and don't actually connect
to anything, we shouldn't be forwarding them to the layout.
-Jon
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