17.2.2.2 Clocking

The RTC has two clock inputs:

• RTCCLK: This is used to clock the RTC.
• PCLK: This is used for the CPU interface.

The configuration bits in the mode registers should not be changed while the RTC is operational. The Alarm and Compare registers can be written by disabling the alarm (bit 2), as explained in the 17.4.3 Control Register.