The device has the following clock source options, selectable by Clock Main Select
Bits in Clock Main Settings Register (CLKMSR.CLKMS). All synchronous clock signals are
derived from the main clock. The three alternative sources for the main clock are as
follows:
- Calibrated Internal 8MHz
Oscillator
- External Clock
- Internal 128kHz Oscillator.
Refer to description of Clock Main Select Bits in Clock Main Settings
Register (CLKMSR.CLKMS) for how to select and change the active clock
source.