Re: Cheap Schematic Capture
- From: "Brad Velander" <bveland@xxxxxxxxxxxx>
- Date: Fri, 15 Feb 2008 03:07:07 GMT
Joel,
Your points are valid but I think it is far exceeding the OP
needs/knowledge. Would you really think that he is going to do even a
quarter of all that? And the PCB designer can swap gates manually and then
ink ammend the schematics if the OP does the schematics.
But addressing some of your actual comments, yes OrCAD was very popular
as a front-end for PADs. That is because back in it's day the PADs Logic was
a horrible clunky program. As a matter of fact it still is today but now
Mentor charges $1500 for it when PADs couldn't give it away free back in the
90s. Actually they did give it away free, but typically nobody would use it.
The part swapping is most dependant on the schematic packages ability to
read it back in. OrCAD could read back the PADs Was/Is file.
--
Sincerely,
Brad Velander.
"Joel Koltner" <zapwireDASHgroups@xxxxxxxxx> wrote in message
news:vP_sj.6114$ea6.4683@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Hi Brad,
"Brad Velander" <bveland@xxxxxxxxxxxx> wrote in message
news:fnPsj.43674$FA.8801@xxxxxxxxxxxx
I wouldn't concur with your statement of needing the same program. For
many years I used OrCAD schematic with PADs...
OrCAD/PADS seems to be a popular combination, at least on the west coast
here.
Let me add to your informative post: While it certainly is viable to use a
different schematic capture and PCB package, what you normally lose
includes:
-- The ability to "trivially" (quickly) swap equivalent gates within a
package or equivalent pins within a gate. Most PCB/schematic capture
packages can do this with "is/was" files *and the PCB guy having knowledge
of what the allowable swaps are* (this information is in the schematic
library files but not a PCB netlist), but this makes it somewhat klunkier
(slower) to get done.
-- The ability to apply various layout rules based on net class. E.g.,
your have your clock net class, your differential pair net class, your
power net class, etc. and the PCB package automatically sets the right
defaults (clocks might need to be routed point to point rather than in a
home-run topology, power nets are far, diff. traces have matched lengths,
etc.) This can sometimes be overcome with 3rd-party software -- for
OrCAD/PADS Prescience (http://www.precience.com/pages/PCBNavigator.asp)
seems to be the well-known, get-out-your-checkbook-and-weep solution. For
small designs going around and defining a bunch of net classes usually
isn't that big of a deal since the PCB guy can just go around and do the
same thing in his tool... for big designs schematic capture and PCB layout
are potentially far enough removed that you'd really prefer to have the
schematic "drive" the layout with such rules.
---Joel
.
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