23.3.1.2 Configure RTC

To operate the RTC, follow these steps:

  1. Set the compare value in the Compare register (RTC.CMP), and/or the overflow value in the Top register (RTC.PER).
  2. Enable the desired interrupts by writing to the respective Interrupt Enable bits (CMP, OVF) in the Interrupt Control register (RTC.INTCTRL).
  3. Configure the RTC internal prescaler and enable the RTC by writing the desired value to the PRESCALER bit field and a '1' to the RTC Enable bit (RTCEN) in the Control A register (RTC.CTRLA).
Note: The RTC peripheral is used internally during device start-up. Always check the Busy bits in the RTC.STATUS and RTC.PITSTATUS registers, also on initial configuration.