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Strange DRC errors

On dynamic copper I have recently changed the drc to 12mils for shape-pad & shape-via... So, away it goes and updates the shapes only to reply with numerous errors stating the gap is only 11.999? I change the rule to 11.999 & it comes back with errors saying its only 11.998??

Why???? The drawing parameters accuracy is set to 3 decimal places....?

*confussed*

Originally posted in cdnusers.org by cartouche

archive over 19 years ago

Seems to be some sort of computation problem. I work around it by setting an oversize value of 0.1 in my Global Dynamic Shape Parameters->Clearances section.

Originally posted in cdnusers.org by Randy R.
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archive over 19 years ago

This is what's known as a "roundoff" error - in 15.2, 15.5 and 15.5.1 these sort of errors are common, less so in 15.5.1 as the code is improved here. The roundoff errors should mainly be fixed in 15.7, which is due in the next month or 2.

The workaround, as Randy R mentioned, is to add a oversize value to the shape - it's better to add the oversize value to individual shapes ratrher than as a Global Dynamic Shape Parameter. The oversize can also be added to individual elements - vias, pins etc.

One last word here - it's a good idea to work with the latest HotFix of the tools - this has improved code for dynamic shapes which should result in less errors.

Andy

Originally posted in cdnusers.org by andrewjw
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