Re: gEDA-user: pick and place ?plugin?footprints.c? for

["Steven Michalske" <smichalske@xxxxxxxxx>]

If we really want this we might look into fully supporting arbitrary
rotations as a first step.  the current method is a elegant
hack\b\b\b\b workaround.

adding a rotation field to the data structures would be what is required for
DRC checking ( i believe that it still assumes 90 degree rotations )
pick and place exports

other stuff.....???

Hardkrash

On Mon, Feb 25, 2008 at 5:22 PM, Dan McMahill <dan@xxxxxxxxxxxx> wrote:
> Dave N6NZ wrote:
>
>  > OK, I'll take a look at doing some testing.  I can think of three
>  > footprints where I have the same pin number.  One is a SPST momentary
>  > switch with four legs, and the other two have big heat sink pads with
>  > the same pin numbers as ground.
>
>  I think the multiple pin thing will just weigh in more and shift the
>  computed centroid towards the multiple pins.
>
>
>  >> I'm not sure how to make the algorithm properly deal with angles other
>  >> than multiples of 90 degrees.  That is a pretty major assumption.
>  >
>  > What are the barriers to other angles?
>
>  Think about a SOIC package for example.  It is fairly easy to decide
>  what quadrant pin #1 is and once you know that, you're done if you only
>  allow 90 degree steps.  Now suppose you allow 45 degree steps.  Pin 1
>  for a SO6 will be in a different 45 degree slice than pin 1 of a SO16 of
>  the same orientation.  If you want to support arbitrary rotations, you
>  now have to take more steps to estimate what the axis of the part is.
>  There could be some metrics like "look for rows of pins that fall on a
>  line" but that will clearly fail for something that has its pads/pins
>  distributed around a circle.
>
>  I'm not saying it can't be done, I'm just saying it gets more
>  complicated and you probably need a lot of heuristics to deside what
>  constitutes zero degrees for the part.
>
>  This is the advantage of storing the center and rotation of each
>  footprint in the library.  You can deal with arbitrary footprints with
>  arbitrary rotations.  The downside is you now have an opportunity for
>  human error on every single footprint.
>
>  Still, the suggestion about letting a footprint optionally include this
>  information to deal with "problem" parts might be an option.
>
>  -Dan
>
>
>
>
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