Datasheet

457
SAM4S [DATASHEET]
11100E–ATARM–24-Jul-13
 Switch on the Main RC oscillator by writing 1 in CSS field of PMC_MCKR.
 Change the frequency (MOSCRCF) or oscillator selection (MOSCSEL) in CKGR_MOR.
 Wait for MOSCRCS (if frequency changes) or MOSCSELS (if oscillator selection changes) in
PMC_SR.
 Disable and then enable the PLL (LOCK in PMC_IDR and PMC_IER).
 Wait for LOCK flag in PMC_SR.
 Switch back to PLL by writing the appropriate value to CSS field of PMC_MCKR.