proper response?

Excellent response! Quite the proper action(s) as well.

We dropped off the support/upgrade bandwagon when it became obvious that Mentor would wreck PADS. When they started offering courses to longtime users on how to use the new version of Logic, we were outta there.

PowerPCB V5.0 (July 2002) seems like a perfect PC layout program, so all they can do is break it.

John

I did! I wanted him to find all possible mistakes, which he can only do if he assumes I can make all possible mistakes. Which I can!

John

John Larkin hath wroth:

Well, that's a good start, but not sufficient. During the late

One person can do a tolerable design review, but it's much better to have a "team" of people look at a design. It's the same as with any team effort. The participants competative pressure push each other along until the results are much better than if they had worked individually.

It's also a good idea to get manufacturing involved early in the design review. They may not know anything about electronic design, but they sure know that you can't hang components over the edge of a board, or use top heavy parts that require hand insertion, or want to deal with awkwardly milled boards, or a thousand other things that only ocurr in passing to the average design engineer.

Formality is also a major impediment. Far better results were obtained with engineers over pizza and beer than in the corporate boardroom with the managers pretending to be helpful. If the results look promising, you might want to go somewhere with your new found accomplis, and discuss some of his logic and reasoning.

The most difficult part is to recognize the difference between implimentation selection and a bad approach. Neigher is totally wrong, but both involve alternatives which may not necessarily be any better. For example, I might decide to use some some sole source vendors magic bullet chip, instead of a more expensive, but more commonly available discrete solution. To the design engineer, the integrated solution offers substantial benifits in consistency and production variations. To purchasing and production, the sole source may soon become a major problem if the vendor decides to obsolete the product or delay chip production because it's insufficiently popular. So, which is the best implimentation? Well, it depends on what the designer and reviewers consider important. No, it's not a coin toss.

Yeah, a lot of users on the Forum say that. Did you install the Service Pack(s) for that version or just use as is?

Did you hear that they charge you something like 60% (IIRC) of the Maintenance price for the time you were off to get back on? Plus the regular Maintenance fee.

Robert H.

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

Yep. That was the luck I meant. Paired up (at least in the same cube) with a guy where you could bat ideas back and forth like that.

Robert H.

One issue I've seen with PADS is in schematic entry. What you see is not necessarily what you get - a trace can appear to be connected, without sharing the correct net. You have to query every single one to be sure.

Schematic 'errors', of course, go through the other processes like grease through a pig.

Another issue I have is with drill and pad detail. Firstly, no attempt is made to produce representative scale drill work in the art - so you'd best check the DD of the gerbers, if you don't want surprises. This issue with scale actually applies to the traces and patterns themselves - so I count on printed gerbers to tell me what the board vendor will see. Producing different pad art on varying layers, or thermal relief differing from the default is both error-prone and frequently impossible, given the choices offered in the GUI.

It sure ain't art, not by a long shot.

RL

I've never seen that happen. PADS-Logic, unlike some other schematic programs, simply doesn't allow dangling line segments on a schematic. You can't draw a line that near-misses another net, and if you delete any segment of a connection, the entire thing vanishes.

I did notice this problem on older versions of Orcad, near-miss connections, but that was a long time ago.

The only hazard we see is the strangely-named "signal pins" which are, in fact, invisible power and ground pins. If a part is created with a hidden pin named "+3.3V" but you really want to power it from "+3.5V", from a separate regulator maybe, you've got to check that carefully.

Again, we don't see a problem here. Traces and pads are shown on the screen drawn to scale, on all the proper layers, as are drills. We don't look at gerbers, we don't prototype, we go directly to multilayer pcb's, and most of our stuff is sellable at rev "A", the first etch. I can't remember a time when PADS itself caused a problem, or even crashed.

John

One of the many circuits I came up with, with Tom betting I couldn't do it, was the "Thompson" Current Mirror in....

Another was...

a co-design with Tom.

...Jim Thompson

Weird how that sickness spreads around the globe. Over here these guys and girls can be a real menace because they think they own the road.

Like the one where you think you know how to properly use a vapor phase degreaser machine.

Or a broken computer... Bad memory can do weird things to a PCB design and you won't notice it until the board is on your bench.

I didn't buy it and I don't use it. I hire people to manufacture things, so I can spend my time designing. Thirty million dollars worth of clean boards later, I'm not complaining.

But OK, tell us the proper way to use a "vapor degreaser" to clean flux off of production PC boards.

John

That's why you should use ECC memory in a CAD workstation.

I lIke it! best of all, I can make them with my favourite dual transistor, the BC847BPN.....

Cheers Terry

I never, ever have hidden pins. spent too much time faffing around with this sort of problem.

I worked on one design in the US, done in PADS, that had some serious problems. The layout guy was a contractor (and a fairly crap one). We fixed some problems, and got him to spin a new rev. When I was debugging it, I found an inner-layer trace shorted to chassis. turns out he'd dragged the trace, right thru a (thru-plated) mounting hole. At which point alarm bells started ringing. So I asked about the DRC, and got an odd response - basically dissembling, about how it was "too hard". Turned out the schematic had been drawn up, then the PCB laid out

I made him fix it. turned out to be a serious PITA, as (at that stage) PADS couldnt automagically re-assign net names. So Ralph had to do it manually - it took about 2 days, and in the process we found several other glaring mistakes. Needless to say, I was gobsmacked, having never before (or since) seen such a misuse of CAD tools.

mind you, a young techie did a layout for a tester me, his first PCB. He DRC'd it, said all was fine and we built it. During debug, he had some problems, so I helped him figure out what was wrong - and found several tracks were missing:

"did you DRC it?"

"yep"

"show me"

He DRC'd it all right; Protel comes with with a "DRC completed" box, with a big OK button. And created a DRC file with 5,000 violations, but didnt automatically open it. He clicked "OK".....

so it was entirely my fault!

(later versions of protel (AKA no-go-tel) noiw open the DRC file....)

Cheers Terry

I have encountered them riding eight abreast, across both lanes of a rural two lane highway. Lots of blind curves, and a 55 MPH speed limit. Its a wonder most of them weren't killed.

The boards I see are combined linear, digital and power, with through-hole and SMD. Although I seldom see trouble with elementary digital gate packages (once the VCC and VSS are defined and manually assigned), the LSI and multipinned mixed signal devices do allow overlapping drawn signal butt-ends that are not actually joined.

As well, dots showing a connection may be mislocated back into the net, or lost underneath another, so that connections that do exist are not explicit in the rendered schematic - the reverse of my beef.

The problem with scale occurs where it matters the most - at 1:1 or

At 1:1 and 2:1, rendered art displays resemble actual gerbers like cartoons represent life study. Gerbers more acurately reflect the errors produced as the vendor reproduces the art using real line widths - including all artifacts that the PADS program and netlist are unaware of, and may not bother to dislplay in the selective GUI.

Maybe you've seen these? Drawn circles or squares or other geometric shaps, solid or filled, coming out of nowhere, without a netlist association? In real life they short out traces and void clearances just as effectively as an erronious intentional foil pattern. They need not cause an obvious malfunction, right away - so the proof isn't even in the pudding.

RL

I wouldn't be surprised if he can't. The "Critical Mass" groups (very pro-cycling ---

I probably don't agree with Jim's views on bicycling that much, but I do think he's entirely within his rights to call them a bunch of pansies if he feels like it, and if that offends them, well, hey, I guess they need slightly thicker skin. :-) Just wait -- soon someone will claim what he's written is "hate speech!"