HFINTOSC Frequency Tuning

The HFINTOSC frequency can be fine-tuned via the HFINTOSC Tuning (OSCTUNE) register. The OSCTUNE register is used by Active Clock Tuning hardware or user software to provide small adjustments to the HFINTOSC nominal frequency.

The OSCTUNE register contains the HFINTOSC Frequency Tuning (TUN) bits. The TUN bits default to a 6-bit, two’s compliment value of 0x00, which indicates that the oscillator is operating at the selected frequency. When a value between 0x01 and 0x1F is written to the TUN bits, the HFINTOSC frequency is increased. When a value between 0x3F and 0x20 is written to the TUN bits, the HFINTOSC frequency is decreased.

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

Important: OSCTUNE tuning does not affect the LFINTOSC frequency.