Re: [CAD_CAM_EDM_DRO] Re: PIC DRO Dreaming

>
> From: stratton@...
>
> > The only issues I can think of right off would be the floating point
> > math, even if nothing more than counting clicks, and multiplying by
> > .00045354, tracking everything to 5 or 6 digits, and rounding it off
> > to provide the current displayed value to .0001 or whatever.
>
> You don't have to do floating point math - simply multiply it by a
> binary fraction large enough to get whatever accuracy you want.
>
> For example, to do 1440 counts/inch and display in thousandths of an
> inch you multiply by 45511 and divide by 65536 or 2^16, which is
> easily accomplished by simply discarding the rightmost two bytes of
> the result. With this approximation, you will be off by 2 parts per
> million, which is far better than the temperature stability of the
> strip, machine, or workpiece. For ten thousandths, use 455111. For
> metric use 115598 and place the decimal point to be consistent with a
> reading in tens of micrometers (10^-5) with an error of 1.9 ppm.

That was why I was a bit iffy on the floating point routines.
I thought there were ways around it, but never had to bother with them.

Thanks.

Marc