ATtiny1624/1626/1627

CLKSEL

Clock Selection

  0x07 8 - 0x00    

Clock Selection

Bit  7 6 5 4 3 2 1 0  
              CLKSEL[1:0]  
Access              R/W R/W  
Reset              0 0  

Bits 1:0 – CLKSEL[1:0]: Clock Select

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 (SEL) bit and Run Standby (RUNSTDBY) bit in the XOSC32K Control A of the Clock Controller (CLKCTRL.XOSC32KCTRLA) register must be configured accordingly.
Value Name Description
0x00 INT32K Internal 32.768 kHz oscillator
0x01 INT1K Internal 1.024 kHz oscillator
0x02 TOSC32K 32.768 kHz crystal oscillator
0x03 EXTCLK External clock from EXTCLK pin