Atmel Evaluation Kit AT91SAM9G25-EK AT91SAM9G25-EK データシート

177

SAM9G25 [DATASHEET]

11032D–ATARM–10-Mar-2014

The same procedure must be followed to switch from a 32768 Hz crystal to the internal 32 kHz RC oscillator. 



Switch the master clock to a source different from slow clock (PLL or Main Oscillator). 



Enable the internal 32 kHz RC oscillator for low power by setting the bit RCEN to 1



Wait internal 32 kHz RC Startup Time for clock stabilization (software loop).



Switch from 32768 Hz oscillator to internal RC by setting the bit OSCSEL to 0.



Wait 5 slow clock cycles for internal resynchronization.



Disable the 32768 Hz oscillator by setting the bit OSC32EN to 0.



Switch the master clock back to the slow clock domain