kicad-developers team mailing list archive
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Re: A way to convert kicad to new internal units
Sat, 31 Oct 2009 11:37:15 -0000
--- In kicad-devel@xxxxxxxxxxxxxxx, Wayne Stambaugh <stambaughw@...> wrote:
> Dick Hollenbeck wrote:
> > viking632 wrote:
> > Among the 4 solutions which have been discussed, this is my least
> > favorite. If we really look at what your problem is, it is not
> > engineering units, but rather granularity at which these units are
> > expressed in a *.brd file.
> > Engineering units can be converted trivially internal by the software
> > without it affecting the file format (it *already* does this). But the
> > current conversion is hampered by the *granularity* of the values
> > contained in a board file. I think your path to support two file
> > formats (both of which are based on the existing format with some
> > tweaks) is a can of worms.
> I for one would not want to maintain the file parsing code to support
> multiple file formats. I also think multiple library files to support
> the old and new format is not practical. I think the real question is
> do we need better than 0.0001" resolution for PCB layouts and 0.001"
> resolution for drawing schematics? The answer to that question should
> drive the file format.
> > Lorenzo put something on the table, as did some others. Can you at
> > least go back and summarize all these options for us before you get too
> > far into this please. This is an exercise that will be helpful for all
> > of us, but especially for you.
> > If we fix the granularity, would not your problem be solved?
> > Thanks,
> > Dick
Well, the only really annoying problem is the rounding errors when using metric grids (e.g. showing 2.499mm resp. 2.601mm instead of 2.5mm resp. 2.6mm).
If this problem can be solved without changing the 1mil/1dmil units, then yes, I would be happy :-)
Although not "entirely accurate" for metric numbers, you're right, the eeschema 1mil (~25microns) IU and the pcbnew 1dmil (~2.5microns) IU _is_ sufficient for practical use - 25.4um resp. 2.54um misalignment of wires resp. tracks, pads and vias won't be noticed by anyone :-)
I still think it's a bit ugly, and an 100nm IU would tidy things up nicely,but if the real problem (practical use of metric grids) can be solved in an easier manner, then yes, let's stick to the current mil/dmil units.