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I've received a reference schematic from a company whose chips I'm interested in using. After studying it for a while and copying the schematic into the CAD program I'm most familiar with, I have some questions about what some of the markings on the schematic indicate: Whatever program they're using does things differently from the ones I've used so far; netlabels and such seem as if they're being used slightly differently than I'm used to. I'm not sure my copy is a faithful copy, because of these differences.

What give-aways can you find in a schematic to figure out which program it was drawn in? Obviously, some programs add their names in the bottom-corner description box, but this one didn't. How can I deduce which program it is, so I can better figure out the mysterious parts of this reference design?

baudot
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  • Note: I imagine someone will say, "Well, post a picture of the schematic and we'll tell you". First off, it was released to me under NDA, so I can't. But regardless, I'm interested in the answer in the abstract, not just in this one specific case. – baudot Nov 29 '18 at 01:37
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    If the schematic is under NDA, at least post the symbols then? But in the generic sense I recognize CAD programs by seeing them beforehand in other contexts, not sure if there is any other way of recognizing interfaces and symbols without that. Alternatively, look up popular ones and/or ones that are known to be used in that industry/country/etc – Wesley Lee Nov 29 '18 at 01:49
  • This is an XY problem. A schematic is a means to communicate. The strange symbols or markings means either you are unfamiliar with some standard practices and need to educate yourself, or they are using unknown annotations and need to knock it off. Either way, you have a social problem more than a technical one. – whatsisname Nov 29 '18 at 04:56

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The colors, style of library parts and such like are a fairly good tip-off, but usually they can be changed. So it depends on how much the designer stayed with the defaults or change them to comply with a company style or with personal whims.

If you look at a reasonably large number of schematics that are created with various different known programs you will soon be able pick up on the differences and similarities.

You can also try google image search for things like directives that you may not recognize, but I am not very optimistic about that working.

Spehro Pefhany
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You can also check the actual data file with an editor (eg vi/vim, etc.). A lot of files have gone to an XML style, and sometimes you can find the program/version number at the front. Even if binary it may have the info you seek.

FWIW Beyond Compare has a nice hex editor/viewer that lets you scroll through even if the file is binary. There are plenty of others, depending on your OS.

For example even old P-CAD PCB files are binary, but have a text header embedded within detailing the program, version, etc.

user201365
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  • It sounds like the asker has the schematic in some printed (paper, pdf, tiff, etc) form, as they're able to view it without knowing what program was used to make it. – Hearth Nov 29 '18 at 02:28
  • @Felthry Ah I see what he's getting at now. That does make it a bit trickier :-). There are some differences in the bus labeling styles, as well as the drawing sheet borders that might prove useful. A timeline of when the design was done may also be of use, as the original program may have mutated or gone extinct. – user201365 Nov 29 '18 at 03:18