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Date: Sat, 26 Oct 2013 14:05:59 -0700
From: Girvin Herr <girvin DOT herr AT sbcglobal DOT net>
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To: geda-user AT delorie DOT com
CC: James Jackson <james DOT a DOT f DOT jackson DOT 2 AT googlemail DOT com>
Subject: Re: [geda-user] Power to ICs with numslots > 1
References: <CANhYM9G+eK=9V8L59PyU8nCOO22GVVF1bRb3TRC9kbACazfg8w AT mail DOT gmail DOT com> <201310261908 DOT r9QJ8Vv8025803 AT envy DOT delorie DOT com> <526C1AF1 DOT 8000107 AT sbcglobal DOT net> <CANhYM9GCyOjemHcYBv75kt2D6973F_4Uymx1UusjPCQ9JokoAg AT mail DOT gmail DOT com>
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James,
I have not done any PCB layouts yet with gschem/pcb.  All of my work so 
far has been with gschem documenting existing designs for posterity to 
get out of the volatile paper domain and into the digital age.  I have 
learned the hard way not to change existing symbols, which would mess up 
my existing schematics big time. "Where did all those red triangles come 
from?!"  However, I plan to switch over to this method, using new 
versions of my existing symbols.  That way, the work I have done so far 
will still be okay, but new work will be clearer using this method of 
separate device and power symbols.

Before I retired from Lockheed Martin, I remember they used this system 
of representing power and ground with separate symbols, usually all on 
one schematic sheet.  The decoupling capacitors were represented right 
alongside the particular symbol, which made the design unambiguous.  As 
I said, I am not sure these schematics had the intelligence to extract a 
netlist, but they may have.  Even so, it was much better for 
documentation and troubleshooting.  It gets even better when the design 
has both analog and digital power and grounds.  There is no question 
about what rail goes where.

Good luck.
Girvin



On 10/26/2013 12:53 PM, James Jackson wrote:
> DJ,
>
> Thanks - I had a suspicion this was the way to go, but good to get 
> confirmation. Girvin: I've implemented this method in my schematic, 
> but haven't seen what the netlister / PCB layout software makes of it 
> yet. It certainly unclutters the schematic though.
>
> Yours,
> James.
>
>
> On Sun, Oct 27, 2013 at 12:11 AM, Girvin Herr 
> <girvin DOT herr AT sbcglobal DOT net <mailto:girvin DOT herr AT sbcglobal DOT net>> wrote:
>
>     DJ,
>     I have seen this done on production schematics.  However, I am not
>     sure they were "intelligent", just documentation.
>     Does this separate symbol method replace the net=GND:n and
>     net=+5V:n etc. symbol attributes or are they still needed in the
>     symbol?
>     The two methods sound redundant.  Using the symbol attributes
>     "hardwires" the net name, but the separate power and ground
>     symbols allow netnames other than what otherwise would be
>     specified in the symbol.  I like that versatility.
>
>     Girvin Herr
>
>
>
>
>     On 10/26/2013 12:08 PM, DJ Delorie wrote:
>
>         Typically, you'd have a separate symbol that had *only* the
>         two power
>         pins, and the same refdes.  The netlister will merge those
>         pins with
>         the slotted pins when the schematic is exported.
>
>
>


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    James,<br>
    I have not done any PCB layouts yet with gschem/pcb.&nbsp; All of my work
    so far has been with gschem documenting existing designs for
    posterity to get out of the volatile paper domain and into the
    digital age.&nbsp; I have learned the hard way not to change existing
    symbols, which would mess up my existing schematics big time.&nbsp;
    "Where did all those red triangles come from?!"&nbsp; However, I plan to
    switch over to this method, using new versions of my existing
    symbols.&nbsp; That way, the work I have done so far will still be okay,
    but new work will be clearer using this method of separate device
    and power symbols.<br>
    <br>
    Before I retired from Lockheed Martin, I remember they used this
    system of representing power and ground with separate symbols,
    usually all on one schematic sheet.&nbsp; The decoupling capacitors were
    represented right alongside the particular symbol, which made the
    design unambiguous.&nbsp; As I said, I am not sure these schematics had
    the intelligence to extract a netlist, but they may have.&nbsp; Even so,
    it was much better for documentation and troubleshooting.&nbsp; It gets
    even better when the design has both analog and digital power and
    grounds.&nbsp; There is no question about what rail goes where.<br>
    <br>
    Good luck.<br>
    Girvin<br>
    <br>
    <br>
    <br>
    <div class="moz-cite-prefix">On 10/26/2013 12:53 PM, James Jackson
      wrote:<br>
    </div>
    <blockquote
cite="mid:CANhYM9GCyOjemHcYBv75kt2D6973F_4Uymx1UusjPCQ9JokoAg AT mail DOT gmail DOT com"
      type="cite">
      <div dir="ltr">DJ,
        <div><br>
        </div>
        <div>Thanks - I had a suspicion this was the way to go, but good
          to get confirmation. Girvin: I've implemented this method in
          my schematic, but haven't seen what the netlister / PCB layout
          software makes of it yet. It certainly unclutters the
          schematic though.</div>
        <div><br>
        </div>
        <div>Yours,</div>
        <div>James.</div>
      </div>
      <div class="gmail_extra"><br>
        <br>
        <div class="gmail_quote">On Sun, Oct 27, 2013 at 12:11 AM,
          Girvin Herr <span dir="ltr">&lt;<a moz-do-not-send="true"
              href="mailto:girvin DOT herr AT sbcglobal DOT net" target="_blank">girvin DOT herr AT sbcglobal DOT net</a>&gt;</span>
          wrote:<br>
          <blockquote class="gmail_quote" style="margin:0 0 0
            .8ex;border-left:1px #ccc solid;padding-left:1ex">DJ,<br>
            I have seen this done on production schematics. &nbsp;However, I
            am not sure they were "intelligent", just documentation.<br>
            Does this separate symbol method replace the net=GND:n and
            net=+5V:n etc. symbol attributes or are they still needed in
            the symbol?<br>
            The two methods sound redundant. &nbsp;Using the symbol
            attributes "hardwires" the net name, but the separate power
            and ground symbols allow netnames other than what otherwise
            would be specified in the symbol. &nbsp;I like that versatility.<span
              class="HOEnZb"><font color="#888888"><br>
                <br>
                Girvin Herr</font></span>
            <div class="HOEnZb">
              <div class="h5"><br>
                <br>
                <br>
                <br>
                On 10/26/2013 12:08 PM, DJ Delorie wrote:<br>
                <blockquote class="gmail_quote" style="margin:0 0 0
                  .8ex;border-left:1px #ccc solid;padding-left:1ex">
                  Typically, you'd have a separate symbol that had
                  *only* the two power<br>
                  pins, and the same refdes. &nbsp;The netlister will merge
                  those pins with<br>
                  the slotted pins when the schematic is exported.<br>
                  <br>
                </blockquote>
                <br>
              </div>
            </div>
          </blockquote>
        </div>
        <br>
      </div>
    </blockquote>
    <br>
  </body>
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