Re: GPLd PCB Library ( was Re: gEDA-user: Free GNU/Linux hardware design tools)

[John Dalton <jdalton@swiftdsl.com.au>]

On Thu, 15 May 2003 01:03:09 Stephen Meier wrote:
> ... This limitation in 
> PCB can be over come by creating a package with the offset in rotation 
> that you desire. So I would request that you add this into your auto 
> package generator.

By its nature, VRML allows arbitrary rotations of complete reference frames,
so it's already there.

> Yet another issue is specific to flex circuits. Flex circuits are 
> literaly glued together. The copper pads are glued to the flex material 
> and can easily be pulled off. Flex circuits overcome this by making 
> masks that cover parts of the pads or pads that go partly under the 
> masks. Flex ciruits can also use wierd shaped pads, such as pads with 
> tabs that go under the mask layer to achieve that hold down.

In the first version, I'm only going to handle the rules in the standard.
Perhaps this is a 'wishlist' item for a later version?  Such additions
should not be difficult.


*****************************************************
On Thu, 15 May 2003 06:39:24 John Griessen wrote:
> How about the factor of heat dissipative surface area desired for some
> devices?

It would be neat to include thermal characteristics in the
land pattern calculations.   It's too ambitious for the
first version though, so I'll only include any thermal
effects which turn out to be trivial to handle.  Perhaps
a later version could include 'real' thermal calculations?
In the meantime, designers will have to do their own thermal
calculations and add extra metal themselves.

> What language are you coding it in?

C++

> What VRML viewer?

I use freewrl, since it's available for Linux.  In practise,
any compliant VRML viewer will work.

> What form is your 2D output?

VRML allows 2D shapes to be specified, so I'll use VRML
for 2D output, with everything in a single plane (the x-y plane??).
If that doesn't work, I'll look at using SVG.

It should be simple to turn VRML into SVG as the
VRML seems to do it's 2D stuff by essentially including
a subset of SVG (leaving aside syntactic differences).

VRML is actually my second choice of representation.
My first choice is X3D (XML version of VRML).  The only
reason I'm not using X3D is because I couldn't get it
to work with freewrl[1].  My code is written such that it
is trivial to generate X3D instead of VRML.  There
is a reasonable chance the final library will
generate both.


Best wishes
John


[1] freewrl does handle X3D, just that the debian package
didn't seem to support this feature 'out of the box'.