31.4 Slow Clock

The Slow Clock Controller embeds a Slow clock generator that is supplied with the VDDBU power supply. As soon as VDDBU is supplied, both the 32.768 kHz crystal oscillator and the embedded 64 kHz (typical) RC oscillator are powered, but only the RC oscillator is enabled.

The Slow clock is generated either by the 32.768 kHz crystal oscillator or by the embedded 64 kHz (typical) RC oscillator divided by two.

The selection of the Slow clock source is made via the OSCSEL bit in the Slow Clock Controller Configuration register (SCKC_CR).

SCKC_CR.OSCSEL and PMC_SR.OSCSELS report which oscillator is selected as the Slow clock source. PMC_SR.OSCSELS informs when the switch sequence initiated by a new value written in SCKC_CR.OSCSEL is done.