Mail Archives: geda-user/2013/10/26/17:02:41
This is a multi-part message in MIME format.
--------------020600070905070805070900
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
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.
>
>
>
--------------020600070905070805070900
Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
<html>
<head>
<meta content="text/html; charset=ISO-8859-1"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
James,<br>
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.<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. 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.<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"><<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>></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. 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. 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.<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. 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>
</html>
--------------020600070905070805070900--
- Raw text -