16.6.2.1 Initialization

After a Power-on Reset (POR), the PM is enabled and the Reset Cause register indicates the POR source (RCAUSE.POR). The default clock source of the GCLK_MAIN clock is started and calibrated before the CPU starts running. The GCLK_MAIN clock is selected as the main clock without any division on the prescaler. The device is in the Active mode.

By default, only the necessary clocks are enabled (see Table 16-1).