kicad-developers team mailing list archive

["�vind Aabling" <Oyvind.Aabling@xxxxxxxx>]

On Sat, 7 Aug 2010, Alex G wrote:

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> On 08/06/2010 10:04 PM, Vesa Solonen wrote:
> > On Fri, 6 Aug 2010, Alex G wrote:
> >
> > > I've been struck by Kicad's lack of all but the most basic footprints.
> > > As such, I have started drawing some footprints, and would like to get
> > > them into the official Kicad release ASAP.
> >
> > I might put some prerelease directory for unchecked libraries, but I
> > fear no symbol-footprint associations will get there. Maybe I'll spend
> > my sunday pondering the library structure. Any ideas from everybody are
> > appreciated. In short form, please.
> >
> > > Here's a short list of the footprints I'm currently working on
> > >
> > > TDFN-EP 6, 8, 10, and 14 pin
> > > This is a 3x3mm package, and I also have a basic 3D model for it
> > > More info on this package at:
> > > http://pdfserv.maxim-ic.com/package_dwgs/21-0137.PDF
> >
> > This is definitely something to be added to the generating script for:
> > http://www.uni-c.dtu.dk/~univind/kicad/oaa_smd_qfn.brd

Yes, I'll add them to the DFN+QFN library.

The datasheet doesn't include recommended footprints,
but they'll be similar to the DFNs I've already defined.

> > > Sharp S202S02 - Solid-State relay
> > > I have a beta 3D-model and footprint for this.
> > > More at:
> > > http://www.parallax.com/Portals/0/Downloads/docs/prod/compshop/400-00053Datasheet.pdf
> > >
> > >
> > > Molex Micro-fit connectors
> > > Nothing yet here, but am plannig to get footprints and 3D models for the
> > > entire line (SMD and throughhole; single-row and double-row).
> > > (Luckily, Molex provides 3D models for these).
> > > http://www.molex.com/molex/common/staticLoader.jsp?fileName=/cmc_upload/0/000/0-8/368/w-b-matrix/wtb-matrix.html&pageTitle=Introduction&chanName=family&channel=products&key=microfit_30
> >
> > With these I'm happy with hand drawn stuff, but for the connectors I'd
> > suggest working with Oyvind. Just in case a scripted way can be
> > developed easily enough. I've used those SSRs with just very rudimentary
> > fooprint, so I thank you in advance :)
> I've forwarded the discussion to Oyvind. Took some time as Gmail
> IMAP/SMTP was down for several hours. I'll see what he has to say, and
> get back as soon as I hear from him.

Defining the footprint and silkscreen for a new part is pretty simple,
and usually doesn't require more than a few lines of (very simple) code.
There are a few exceptions that requires a little math, e.g. the TO-3 house.

Writing the code that defines the package 3D shape (incl. the pins)
can take some time, though, depending on the desired level of details.

Packages with holes or other concave (but flat :-) polygon surfaces
are a bit of a pain, as VRML can only deal with convex polygons :-(

Well, you _can_ specify a "convex false" flag in a VRML
IndexedFaceSet, but KiCad ignores it, and in whitedune,
it doesn't work either (the surface is rendered wrong).

I've taken a quick look at these parts, and if we don't need to go
over the top and create every little nook and cranny, they're doable.

I'll add them to the todo list.

> > > As you may tell by now, I am the definition of noob.
> > > I draw the footprints with Inventor, export them as IGES, import the
> > > IGES in FreeCAD, export it as .obj, and finally import that into Wings
> > > 3D.
> > > I'm not very good with applying colors, so help from someone with more
> > > experience is greatly appreciated.
> > >
> > > I've been hearing some fuss about a scripted approach to generating
> > > footprints. Does anyone have examples on that?
> >
> > Please take a look at http://www.uni-c.dtu.dk/~univind/kicad/

I'll join the kicad-newlib team as soon as I get a "round tuit",
as this webserver will go away in a few months time,
so I'll soon need a new home for my kicad lib work.

I could setup another webserver, but I guess, it's better to
create a lp repository for it instead (just have to get yet
another round tuit, and read those bzr tutorials first ...).

> > > Then, how do I get the files to the right place? Can I just attach them
> > > to the emails, or should I rather upload them to a public place and only
> > > send the link?
> >
> > Kicad-newlib on Launchpad for bigger work, but ocassional stuff is fine
> > on the list or even directly to me. Ping on the list first is a good
> > practice.
> >
> > > There's also a question on 3D-modles for packages that don't have
> > > protruding pins, such as TDFN. Should I draw the pins on the model, or
> > > will a rectangular box do? This is more a matter of aestethics. I'm not
> > > lazy, just trying to avoid extra work if it has no meaning.

I've drawn the DFN and QFN packages as a box, with each pin as
another box, moved 0.2mm away from the body, to make them visible.

Drawing all "pins" (whatever shape they are) gives
a good visual check of the pin-to-pad relationship.

When looking at the part in a VRML browser (I use whitedune),
the pads of course aren't there, but looking at it in
pcbnew or (even better), in cvpcb, is a good way to check
that the pads and pins are where they're supposed to be.

> > Again I'd like to point you to Oydvind's work.
> >
> > > I've been hearing discussions about a format change for library files. I
> > > think that getting the footprints in properly with the current format,
> > > and then converting them if/when that happens is the best choice. Having
> > > to import several libraries in each project is time consuming, and it
> > > would be nice to have them in the default install.
> >
> > I'm leaning towards incomplete newlib as a branch in release library.
> > Just a bunch of symbols with coherent style, footprints and 3D without
> > association data. When file format features get ready, we'll start
> > actual component specific data gathering for pin/part swap etc. When the
> > branch is strong enough we may chop the old trunk away. Any objections
> > to that?
> If that means that the footprints will be in the official release, no
> objection. We can always add the associations later.
>
> Alex

Øyvind.