Pcell symbol with curved shapes using dbCreateArc failing

Glen,

The issue is that arcs are (I believe) limited to a maximum of 180 degrees, and this would result in a longer arc than 180 degrees. The error message (which comes from OpenAccess) doesn't make this terribly clear; I've requested that the documentation is improved to make the 180 degree limit clear and also to mention what might trigger this error message.

Andrew

Andrew,

Thanks for the reply.  I discovered that the ellipse bbox and the arc bbox can only overlap on 1 or 2 edges.  My call was overlapping on 3.  This is consistent with your comment about a maximum 180 degree.  I'd say that is more like just under 180 degree as 180 would require 3 edge overlap.  Once I pulled back the arc bbox to only overlap 2 sides, it worked.  

Thanks for your response.

-Glen

Hi Glen,

Actually, you can have a 3 edge overlap if it ends up being a narrow region of one end of the ellipse box (I tried this). For example - the white box is the ellipse box, the yellow is the arc box:

There are a few other failure modes that can result in the error message (for example, a zero-area rectangle for the arc box), but the main one appears to be due to the angle constraint.

Regards,

Andrew

Andrew,

Interesting.  I re-entered my original command, which failed.  I then reduced the x(UR) of the arc bbox until it worked.  

Original: dbCreateArc(cv lineLayer list(0.08125:0.1375 0.13125:0.1875) list(0.08125:0.1375 0.1125:0.1875))

Worked: dbCreateArc(cv lineLayer list(0.08125:0.1375 0.13125:0.1875) list(0.08125:0.1375 0.1093:0.1875))

It seems the 0.1125 is just over half of the x of the ellipse bbox.  Half would be (0.08125:0 + 0.13125) / 2 = 0.10625, within the working range of the arc bbox.

Thanks for the insight.

Regards,

Glen