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Pads libraries: Are there any up-to-date free symbol libraries available?

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ted

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Hi guys,

I have tried using one free symbol creation service for PADS: http://libedit.free.fr

Well, I visited the site, and have mixed feelings after using it. It works, kind of, but is quite limited and not awful much more productive than the native tools of PADS.

Also, it is quite large effort with a lot of opportunities for mistakes to create a bunch of new components for a new design - even with some tools and checks available.

My current hobby project is to construct an electrometer with both digital and analog outputs. I'm using (mostly analog) chips from National, Linear Technology and Maxim, plus a bunch of crazy electromechanical parts and piles of discretes.

To create all of the op-amps and other ICs takes time, and, worse, I am very afraid of mistakes which could render the PCB faulty or even useless. That would be very costly both money-wise and in waste of time.

One can naturally go and buy a library for maybe a couple of hundred dollars or more. For an enterprise, no big deal, but for hobby use, a lot of money. (It is a happy state to have access to a licensed installation to do the work. But to convince even good friends to buy and pay for stuff, which they themselves don't see the need for, requires more than my talents of persuasion!)

Once upon a time there were free, and quite large, ready-made libraries available for download. However, PADS library format has changed a few times since 2006 or whatever year I saw those. Therefore my question is: Are there free up-to-date (PADS9.4.1-compatible) libraries around somewhere? Or could somebody maybe help in any other way in this matter?

- Ted
 

sky_123

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I've decided that there will never be any ready-made library that will have more than 10-20% of the components that I need for
any project.
In the end, I came up with a personal solution that works for me, for EAGLE. A similar concept may work for PADS, but I don't know.
Basically, the solution is to write a simple program to auto-generate the component pads. I can specify SIL, SOP, TQFP-style, and the
dimensions, and it will create a script file that I can import into EAGLE, containing the pads and silkscreen outline. It is simple,
very crude stuff, but saves a lot of time.
If PADs has some scripting method, I'd suggest it is worth spending a day or two creating some simple software to do this.
For example my simple program is just about 50 lines long, command-line driven, no fancy GUI, and generates a .scr output.
I have another program to do the same for toroids for me.
I put my personally created parts in a separate library, since I tend to reuse components a lot, so that makes them easier to find too.
For schematic symbols, unfortunately that tends to be a manual process since you probably want it customized, but it doesn't take
long per component.
example.jpg
example2.jpg
 

ted

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Thanks!

My experience regarding libraries varies a lot. For PCB decals there are usually footprints - or they can be created easily using semiautomatic tools such as PADS has. It seems that the scripts you have for Eagle do about the same thing. One can also find useful IPC-based symbols,where different manufacturing aspects are well considered.

My worry and trouble is more regarding schematics symbols. Even if the work is pretty simple and quite fast, there is always a danger of mistakes, when transcribing details from the data sheet. It is enough to have wrong pin number in one symbol to create a lot of mess! And therefore I would appreciate ready-made and checked library symbols, or at least machine-readable lists of device pin-out in a format, which even uses the same pin numbering convention than the PCB decals. (For especially connectors and other electromechanical parts that is another potential source of ugly errors).
 

sky_123

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I'm surprised manufacturers have not come up to a joint standard to publish a standards based symbol and footprint for all their components. Then, each CAD vendor could have their own import routine to read in the details into their own formats. I suppose it is not in the interest of CAD firms to make it easy for people to move from one CAD package to another.

I'm not really knowledgeable on this, so I don't know much more on this, but I hope one or two component manufacturers can adopt some open standard, so that others follow suit. I suppose it would need some people to write a standard. In the Internet world it is done with RFCs, rather than having to wait for some IEEE standard. It could be a very simple standard, using snippets of (say) HPGL to define the component outline, and an XML portion for the pin numbers and pin definitions, so that it could be expanded in the future to also have (say) pin direction information, etc.

Actually, one way in which we (the public) could "encourage" manufacturers to adopt this would be for people to start creating component symbols/outlines ourselves in some standard format, and having our own conversion tools to EAGLE, PADS, etc. Also, to speed it up, for people to figure out what the proprietary format for each CAD vendor looks like, and export out the existing symbols into the standard format and publish them.

Personally I'd be happy to collaborate on such an open standard if I could get support from others, i.e. people working for a few influential companies, to work on a standard together - it needs buy-in from people in a few companies, to make it a truly open, non-biased standard. It wouldn't need to be super-complex standard, if it was made extensible using XML for future enhancements.

Maybe some standard already exists, but I've not seen it (I'm not a PCB design engineer though).
 

ted

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I am myself sort of "Universal Engineer" - active in all kinds of product-development functions, especially Electronics-related ones. And my experience of CAD systems is limited to a few.

What I have seen is that the library elements tend to be vector- and shape based and have relatively similar basic parts: Outline is presented by key coordinates such as corners and simple shape primitives (line, arc...). The pin-out has a list containing at least pin number, pin name, pin symbol (such as simple piece of line, or with inverter "ball" etc.), pin orientation, pin coordinates in relation to the symbol's origin, and then signal attributes (input, output, bidirectional, source, load, undefined, and so on). Also there are some typographic and other presentation definitions such as text sizes and possibly font types.

Thus it should be nearly a piece of cake to describe most components in a generic language containing those kinds of basic primitives and elements, allowing a pretty neat and painless conversion to the format used by a particular CAD system. However, "selling" and promoting such a project to component manufacturers seems to me to be a huge effort - at least compared with the practical language definition and coding of a few converters.

Also, starting the development and promotional activities now would not bring much of anything to the market for years. So, if there is enough eagerness in somebody to run the show, I could offer my voluntary efforts to help finding the practical solutions. But I am not able to run a show of that size. I have to keep my engineering work bringing some sustenance, and want to execute my little hobby- and research projects with a shoestring budget, and without unnecessary mistakes or re-inventing every wheel....
 

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