4.16.4.1 Processor Clock Ratio

The Processor Clock frequency can be controlled more precisely using PMC_CPU_RATIO.RATIO.

fCPU=(RATIO+1)16×fFCLK

By default, RATIO = 15, and the Processor Clock frequency equals the Free-Running Clock frequency. Modifying the RATIO field modifies the frequency of the Processor Clock with a frequency step of fFCLK/16.