Re: gEDA-user: Database on symbols, footprints and other (was "Re: gattrib")

[John Doty <jpd@xxxxxxxxx>]

On May 3, 2010, at 10:16 AM, Britton Kerin wrote:

>   On Mon, May 3, 2010 at 7:04 AM, John Doty <[1]jpd@xxxxxxxxx> wrote:
> 
>   On May 2, 2010, at 11:41 PM, Britton Kerin wrote:
>> I use a probably almost identical project symbol approach.  If this
>   is
>>  high-productivity way I'd hate to see the alternative.
>   Essentially,
>>  everybody gets to continually reinvent the same heavy symbols.  Its
>   got
>>  to be possible to do better than this.
> 
>     Reinvent the same symbols? Nah. There are trillions of possibilities
>     for heavy symbols. It's unlikely two independently developed
>     projects would have much in common here. Even my own projects tend
>     not to have much overlap: different customers, different
>     requirements, even different project phases.
> 
>   How much really changes for a chip resistor or SOIC uc?

In one recent project, we started out thinking we'd use 0402 resistors to save space. Found we had more space than expected, so changed to 0603. Also, package changes are common between prototype and production.

>  These things
>   should take ZERO effort to get something pretty in gschem that will
>   work with pcb.

Maybe you use pcb, but I don't (although there's this new project where it might fit). There are lots of ways to use gEDA.

>  If people care about the exact mask settings and such
>   they can tweak.

Tweaking is much more common than you think.

> 
>     I don't know about you, but customizing pre-existing symbols takes
>     me very little time compared to the rest of the design process.
>     Creating new ones from scratch takes more time, but between the gEDA
>     library and [2]gedasymbols.org, there's often a starting point for
>     anything truly common.
> 
>   If you have a reference design that you're trying to modify or extend
>   getting a working set of symbols takes most
>   of the time.  And reference designs are the open source way.

You can distribute symbol files with a reference design. No problem. Still, I'd expect to have to tweak them.

Indeed, design reuse is a strength of the project symbol approach. Change packages, even parts selection (have symbols fast_npn.sym, etc, choose part to fit requirements later) by changing project symbols. Leave the schematics alone. Like changing include files in software.

> 
>     If people were reinventing the same heavy symbols, there'd be a high
>     probability of finding a suitable heavy symbol on
>     [3]gedasymbols.org. In practice, I find those symbols almost always
>     need customization. But of course this shouldn't be surprising.
> 
>   Interestingly, I've looked at [4]gedasymbols.org briefly before and
>   failed to find most of its content, since its hiding
>   under the names of the contributors and in the search field.  I
>   concluded it had ended up as a footprint library.

Footprints for pcb are apparently more of a problem than symbols for gschem, so they've tended to take over.

>   I'd suggest the following (heck I'll do it if someone wants to give me
>   access):
>     * Put the whole ball of symbols tarball under a Download section.
>     * Or at least put the cvs checkout incantation somewhere on the
>   page.  I'm assuming you can check it all out
>       without an account?  Oh in fact poking around more I find this
>   information under "ask for a CVS account" link.

Yes, and as far as I'm concerned that's the easy way to use it. New files show up frequently.

John Doty              Noqsi Aerospace, Ltd.
http://www.noqsi.com/
jpd@xxxxxxxxx




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