At 01:36 PM 9/18/01 -0400, Richard Sumner wrote:
>I tried that, it finds all unconnected pins (which I have a lot of) and
>did not find a named net with only one connection (just a net name on
>only one unused pin). The single pin net does appear in the netlist
>(generated from the pcb), so it isn't flagged as an unconnected pin.
Which could be a problem, since checking the NC pin list is a very good
place to begin to find possible errors. I was taught this twenty years ago,
even before I used a net list (we'd examine a board with all layers in
superposition; unconnected pads were easy to spot). Later, I used to
routinely deliver the NC pin list with jobs, encouraging the engineer to
look it over.
One solution to the problem is to remove the net assignments (in Schematic)
(net labels) from pins without connections. Thus "single-net" pins will
become no-net pins and will appear on the NC report. Schematics with
single-net pins can be very confusing to read, since one may look elsewhere
on the schematic, trying to find the connection. It is difficult to
distinguish between a deliberately single-net pin and one accidentally
unconnected, perhaps because of a minor variation in name.
Note that there is an "unconnected" parameter in the ERC matrix in
Schematic; it is thus possible to generate errors or warnings from
single-net pins, which will be treated, as I recall, the same as if there
were no net on them. Then the "errors" which are deliberate, whether they
are from NC pins with a net name or without, can be suppressed with No-ERC
directives. This is my standard practice, I recommend it.
This would lead also to another standard practice: place all sections of
multipart components, even if only on an additional "unused section" area
or page. This is useful for a lot of reasons.
I think of many implications and possible reasons why one might want to
keep those single-net pins, and for each one of them I imagine I have a
better way to suggest, but I'll leave it here for now.
But if one insists, I'd recommend generating a net list, massage the net
list into a format that will provide one record per net and one field per
pin name, and load the formatted net list into Excel or the like. If the
field that would hole the second pin name in a net is the third field, then
sort the list on the third field; all records with an empty third field
will represent single-pin nets and there you have your list.
[EMAIL PROTECTED]
Abdulrahman Lomax
Easthampton, Massachusetts USA
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