11.2.2 Internal Clock Sources

The internal oscillator block contains two independent oscillators that can produce two internal system clock sources:
  • High-Frequency Internal Oscillator (HFINTOSC)
  • Low-Frequency Internal Oscillator (LFINTOSC)

An internal oscillator source can be used as the device system clock by programming the RSTOSC Configuration bits to select one of the INTOSC sources.

In INTOSC mode, the CLKIN and CLKOUT pins are available for use as general purpose I/Os, provided that no external oscillator is connected. The function of the CLKOUT pin is determined by the CLKOUTEN Configuration bit. When CLKOUTEN is set (CLKOUTEN = 1), the pin functions as a general purpose I/O. When CLKOUTEN is clear (CLKOUTEN = 0), the system instruction clock (FOSC/4) is available as an output signal on the pin.