5.3 Clock Switching

The system clock source can be switched between external and internal clock sources via software using the New Oscillator Source (NOSC) bits. The following clock sources can be selected using the following:
  • External oscillator
  • Internal Oscillator Block (INTOSC)
    Important: The Clock Switch Enable bit in Configuration Word 1 can be used to enable or disable the clock switching capability. When cleared, the NOSC and NDIV bits cannot be changed by user software. When set, writing to NOSC and NDIV is allowed and switches the clock frequency.