Writing these bits select the source for the RTC clock (CLK_RTC).
When configuring the RTC to use either XOSC32K
or the external clock on TOSC1, XOSC32K needs to be enabled and the Source
Select bit (SEL) and Run Standby bit (RUNSTDBY) in the XOSC32K Control A
register of the Clock Controller (CLKCTRL.XOSC32KCTRLA) must be configured
accordingly.
| Value | Name | Description |
|---|
| 0x0 | INT32K | 32.768
kHz from OSCULP32K |
| 0x1 | INT1K | 1.024
kHz from OSCULP32K |
| 0x2 | TOSC32K | 32.768 kHz from XOSC32K or external
clock from TOSC1 |
| 0x3 | EXTCLK | External clock from EXTCLK pin |
