Finding shorts in OrCAD Capture

Run a ERC, it should circle the error with a green circle. Or do a search for Vcc3. I've had no problems copying and renaming Power dohickies.

Cheers

Thanks!

If Martin's idea doesn't bear fruit -- do you have any IC's with implied power? I detest logic symbols that don't show the VCC pins -- how do you hook them up to a different power net, or decouple them, or _know they're there_, or keep them from shorting out Vcc3?

Yes, they're everywhere. It's a complex product, a schematic I've inherited, with multiple madness everywhere. I looked back at my source (input) file, and find it has the same problem, yet the manufactured product obviously does not.

So, maybe I didn't do it after all, and I have to look beyond what I've done and dredge through the rest of the whole thing for this problem.

I tried Martin's idea. I set Capture to report all instances of 'power connected to power', hoping for '+3.3 connected to +5v,' but that gives me a list of all power pins that are connected to ... any kind of power or ground! That's a starting point, but it's a longgg list.

I'm thinking I'll narrow things down by making a copy of the file, then deleting pages one by one until the short clears, then home on in it from there.

Exactly.

-- Best, James Arthur

Can Orcad output a complete ASCII netlist? We do that from PADS, and it is very handy for things like this.

John

Yes, and it's well worth doing, IMHO. I use the wirelist.dll formatter.

PS. The padspcb.dll formatter will create a .asc netlist.

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Thanks, I was just doing that. Yes, I output an ASCII netlist, and the motherloving file I got as input has +5V shorted to +3.3V.

That netlist doesn't help me much more than proving that there is in fact a short--it doesn't tell me where.

I tried deleting pages one-by-one to clear the short, but having isolated the short to page 3, when I come back with all pages and delete page 3, the short's still there.

Conclusion? Multiple shorts. This came from a group that was laid off--it could be a going away present.

Sheesh.

--James

Look for $G_... nodes. That should help you sort out how the short(s) occurred. ...Jim Thompson

Lots of layout people leave the schematic wrong and force the PCB to be right. That gets interesting for the next rev. The Brat doesn't allow that at our place any more.

John

et

ned

lied

Thanks, I was just doing that. Yes, I output an ASCII netlist, and the motherloving file I got as input has +5V shorted to +3.3V.

That netlist doesn't help me much more than proving that there is in fact a short--it doesn't tell me where.

I tried deleting pages one-by-one to clear the short, but having isolated the short to page 3, when I come back with all pages and delete page 3, the short's still there.

Conclusion? Multiple shorts. This came from a group that was laid off--it could be a going away present.

Sheesh.

--James

Does Capture support listing "aliases" like PSpice Schematics? If so, look for a .als file. ...Jim Thompson

In Pads, all I do is click on file/export and go from there, all GUI. Pads has dialog boxes that allow me to select what items I want to include in the ascii files; I can include everything if I want, even the part decals. Pads will import the ascii files, too, so once in a while we fix things by going ascii out/edit/in.

I wrote some PowerBasic programs to munch the ascii files from Logic (the schematic prog) and PCB. We can compare netlists in any combination, see if parts types are right (like 0805 on sch but 1206 on board), and compare the stock numbers+values on a sch or board with the separate BOM. Those are enormously useful, and fairly easy to do from the ascii files. Someone suggested doing them in perl, but for some reason I can't get perl to run on my PC. And besides, a simple .exe program is, well, simple.

John

$G_... nodes? I don't understand. As those in the netlist?

Meanwhile, I've narrowed the shorts to 2 pages, so that's some progress...

Thanks, James

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That's a quality Brat!

-- Cheers, James

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That's a quality Brat!

-- Cheers, James

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You can say that again!

John

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Hey, I plead innocent--I only hit send once. But yes, that's a quality Brat. Good work!.

--James

Yeah, it's all GUI in orcad too, but they have selection dialog with drop-down box for the lesser-used "Other" formatters. The common ones are Allegro, EDIF, INF, Layout, PSpice, SPICE, Verilog & VHDL.

The only option in the PADS output is a switch that has something to do with BGAs.

Perl has the advantage that a lot of people know how to use it, and since the interpreter is free, every workstation can have it installed, which means that everyone can have the tools to make changes.

Obviously PowerBasic is a serious tool since there are examples of obfuscated code around the net:

$IF 0 Obfuscation Contest Entry Email to: snipped-for-privacy@ptd.net Author: Michael Mattias, Sturtevant WI USA ( snipped-for-privacy@compuserve.com) Date: 5.02.98 Requires: PowerBASIC/DOS version 3.2 or 3.5 Rated: PG-13 (D) $ENDIF $LIB ALL OFF DEFINT A-Z DIM V AS BYTE PTR READ N: REDIM Z(N-1) AS DWORD: DIM ABSOLUTE B(N*4-1) AS BYTE AT VARSEG (Z(0)) COLOR 7,1:CLS:V=pbvScrnBuff+1800 FOR I=0 TO N-1: READ Z(I):FOR J=0 TO 3:@V=B(I*4+J): INCR V:DELAY .05:INCR V:NEXT, END DATA 9,1936943435,544820512,544437057,1293971017,662266721 DATA 1917198451,544501359,1684957527,538998639

REM ** END OF PROGRAM ***=