Internal Oscillator Frequency Adjustment

The internal oscillator is factory-calibrated. This internal oscillator can be adjusted in software by writing to the OSCTUNE register.

The default value of the OSCTUNE register is 00h. The value is a 6-bit two’s complement number. A value of 1Fh will provide an adjustment to the maximum frequency. A value of 20h will provide an adjustment to the minimum frequency.

When the OSCTUNE register is modified, the oscillator frequency will begin shifting to the new frequency. Code execution continues during this shift. There is no indication that the shift has occurred.

OSCTUNE does not affect the LFINTOSC frequency. Operation of features that depend on the LFINTOSC clock source frequency, such as the Power-up Timer (PWRT), WWDT, Fail-Safe Clock Monitor (FSCM) and peripherals, are not affected by the change in frequency.