12.1.2 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)
Internal oscillator selection is performed one of two ways:
- Program the RSTOSC Configuration bits to select one of the INTOSC sources which will be used upon a device Reset.
- Write the New Oscillator Source Request (NOSC) bits to select an internal oscillator during run time.
In INTOSC mode, the OSC1/CLKIN and OSC2/CLKOUT pins are available for use as
a general purpose I/Os, provided that no external oscillator is connected. The function
of the OSC2/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.