24.11.7 Clock Selection

Name: CLKSEL
Offset: 0x07
Reset: 0x00
Property: -

Bit 76543210 
       CLKSEL[1:0] 
Access R/WR/W 
Reset 00 

Bits 1:0 – CLKSEL[1:0] Clock Select

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.

ValueNameDescription
0x0INT32K32.768 kHz from OSCULP32K
0x1INT1K1.024 kHz from OSCULP32K
0x2TOSC32K32.768 kHz from XOSC32K or external clock from TOSC1
0x3EXTCLKExternal clock from EXTCLK pin