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Design007-Jun2018

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JUNE 2018 I DESIGN007 MAGAZINE 33 and you need to be able to propagate changes like that throughout the broader system. So, connectivity management should be a part of pin-swapping as well. Looking into the future, we've solved the basic pin assignments, connectivity manage- ment, and synchronization of pin swaps on the schematic side. What we have not yet done, but it's on our road map, is model the cables. There's a multi-board assembly and there's cable connectivity between them. Maybe a single wire or a multi-point cable or a harness. We don't compete with the MCAD tools which do a fabulous job of modeling cable harness assemblies, and it's not in our plan to try to do what they do; SolidWorks Electrical is fantas- tic. But the goal is to model wire and cable to a level where a PCB designer can actually make sure they are specifying the basics of it, say- ing this goes to here and here and joins these boards together, and it has to sit in this kind of envelope in 3D, and it's got these connections, and these signals travel through it, and we can swap pins again. There's a lot more we could do in this space, in this domain with problem solving, I think. We haven't done anything with power integ- rity or signal integrity, for example. But that is definitely something that has to be considered with multi-board design. Speaking of power integrity, it's very easy to forget that you have one PCB and if you test that one PCB, it will pass EMI requirements in isolation. You make that a part of a multi-board system where there are signals going across connectors and return paths may be forced around the design through power cables in strange ways, if you can't design your connectivity right. Individual modules may well pass for FCC regulations or CE regulations, and then com- pletely fail once you integrate the whole sys- tem together as a multi-board assembly. So, these are the kinds of issues we have to think about. Shaughnessy: One of challenges that designers talk about with multi-board design is virtual prototyping. What's your take on multi-board virtual prototyping? Jordan: That's kind of a buzz phrase in our industry. The first time I read that was in mar- keting about three years ago, and it was always related to simulation. But simulation has been around for a long time. Let's call it virtual pro- totyping today. Maybe it's a little more than that. It's simulating the whole system, and that's really actually very difficult to do. I think on the engineering side, people have been talking about simulation-based design. That's something that MathWorks would talk about with MATLAB and maybe PTC with Mathcad and some of those analysis simulation tools that take a high level programming language. I think there are opportunities for us to integrate that more into the front-end design process. But as a basic starting point, we really do need to consider modeling power integrity. We do have tools for simulation in Altium Designer. We've had that for a long time, so you can do mixed analog and digital simula- tion from our regular PCB design schematic editor. It supports Spice 3F5, PSpice models, and Digital SimCode. You can do mixed-mode analysis for actual functional prototyping. Not many people know too much about those fea- tures or use them regularly, but the engineers know about it. Front-end engineers use it in small ways if they are designing a new circuit they'll simulate. Most of the time they don't bother, because they're using circuit design principles they have been using for a while, and they know it's good. Or they're just follow- ing the data sheet for a chip and hooking it up the way the application note says, and they've prototyped it on the bench and it works.

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