Re: gEDA-user: SMT assembly and gerbv lilbro.mosquito.net.nz

[Stuart Brorson <sdb@xxxxxxxxxx>]

>>> Could gerbv be modified to generate lists of pads after finding where silk outline intersects
>>> or encloses soldermask openings?

I've been watching this discussion with some interest.  I do think it
would be quite difficult to implement this feature, since RS-274X is a
very dumb format.

>  Anyone
>> wanting to hack some gerbv is always welcome on the gerbv-devel mailing
>> list.

Link to subscribe:

http://sourceforge.net/mail/?group_id=33921

> Does standard RS274X allow attribs on pads?  Could you put pad numbers and groups,
> and still be RS274X?

No.  RS-274X is a dumb plotting format.  It basically has commands to
draw individual lines, set the linewidth, and draw a very small number
of primitive shapes.  It does not have the concept of pin, pad, 
component, characters, groups, or much of anything else.

Gerbv used to just draw the screen by (more or less) mindlessly
following the Gerber file's commands line by line, and drawing lines
and other items as commanded by the file [1].   Starting with the 2.1
versions (unreleased, not even complete in CVS), gerbv will first
construct a big data structure corresponding to the Gerber file, and
then it will render the drawing based upon what's in the data
structure.

Therefore, as Stefan said, it is in principle easier to implement some
recognition of components based upon the newer stuff, but I gotta say
that even with the new stuff, gerbv is only 10% further down the road
to autorecognizing components than before.

> I am still thinking of Lil Brother's request as a valid one -- they have customers that pay money
> for action, and they want action based on the current state of the art of pcb making, so
> RS274X with no knowledge of pin numbers is what you have to go on.

Another CAD format, ODB++, is a newer, smarter format for PCB CAD.
Although I haven't read the spec in detail, I believe it has the
necessary knowledge to support Lil Bro's request.  We've discussed
supporting it in both PCB and in gerbv in the past. However, it's only
been talk so far.  Can your buddies over at Lil Brother accept ODB++?

Stuart

[1]  Yes, an oversimplification, but true to the level of detail
we need here.


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