The High-Frequency Internal Oscillator (HFINTOSC) is a precision digitally-controlled internal clock source that produces a stable clock up to 64 MHz. The HFINTOSC can be enabled through one of the following methods:
110’ (FOSC = 1 MHz) or ‘000’
               (FOSC = 64 MHz) to set the oscillator upon device Power-up or Reset.The HFINTOSC frequency can be selected by setting the HFFRQ<3:0> bits.