I can't seem to find any reference as to the range of the OSCTUNE register. That is, if I vary the value from 01111 to 10000, approximately how far does the frequency shift?

My goal is to find the frequency error of a chip, calculate the correct OSCTUNE value in one step and write the new value.

I realize that it won't be perfect. Close is good enough. I can try it myself tomorrow, but does anyone know the answer?