At 08:49 AM 5/10/01 -0700, Brad Velander wrote:
>Hidden Pins: hidden pins are a special case in Protel. They are seemingly
>assumed to be similar to power pins and they will netlist together with
>other hidden pins which bear the same pin name (i.e. NC, N/C, Open, etc. are
>the most common examples). Therefore there is basically an unwritten rule
>with Protel that states "Use hidden pins at your own risk...".
I can say more. Don't use hidden pins period unless you know exactly what
you are doing and you *need* them. Further, if a hidden pin has no name, it
will netlist together with other hidden pins which have no name. That is a
bug, in my book, and it should be fixed, but it's easy to see how it
happened. The programmers assumed that hidden pins would be power pins or
*maybe* something like a clock pin, so they treated no-name pins just the
same as they treated power pins, or visible pins, for that matter. The null
string is a unique name, and therefore all pins with that name are connected.
>There was an earlier suggestion that you may have this problem to blame for
>your unwanted nets, doesn't really make sense because how would you have
>placed an ERC on a hidden pin. Whoever posted it wasn't following the
>details of your issue that close.
I think Mr. Velander missed the point. The No-ERC directives were a red
herring. It could happen that one has a symbol with both visible and hidden
pins; in that case, the hidden pins would make a connection even if the
visible pins were open, and no warning would be generated. While this is
*probably* not the problem, it should be checked in order to rule it out.
[...]
>Your problem with unwanted nets: this is a shot in the dark but minimally
>possible, I have seen others do it before. By any chance do you have a wire
>which is not intended to connect to these pins but passes the pin at 90
>degrees on the same grid coordinate.
This is a good suggestion, it should also be checked. We have to remember
that we are dealing with a newcomer to the program, and there are lots of
assumptions -- even reasonable assumptions -- that can be made that will
lead one down the rosy road to ruin and bad net lists.
If the hot spot of a pin touches any wire or any other pin's hot spot, it
will connect to it. I think this cannot be suppressed merely by having no
connection dot. Connection dots are *almost* irrelevant. The one exception
is if you want to cross two wires and join them at the intersection. It's
bad drawing practice, but lots of people do it.
[EMAIL PROTECTED]
Abdulrahman Lomax
P.O. Box 690
El Verano, CA 95433
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