17.2.2.2.1 Clock Source to RTCCLK

The MSS clock controller supplies three clock sources to RTCCLK:

• Crystal oscillator 32.767 KHz
• 1 MHz oscillator
• 50 MHz oscillator

The prescaler should be programmed to derive a 1 Hz signal. Therefore, for the 32.767 KHz clock, the prescaler should be programmed to 32768 (actual value is N−1, that is, 32767). Microchip recommends that the lowest clock frequency source available is used because this reduces the power consumption; the MSS SYSREG provides the clock selection logic.