// internal 32MHz RC oscillator
void clock_init(void){
  //CCP=CCP_IOREG_gc; // unlock writing to CLK.PSCTRL (option)
  //CLK.PSCTRL = CLK_PSADIV_2_gc; // Set up prescalers (option)
  // after reset all prescalers are /1
  OSC.CTRL |=OSC_RC32MEN_bm; // enable internal 32MHZ oscillator
  while (!(OSC.STATUS & OSC_RC32MRDY_bm)){};	// wait until 32MHz is on
  CCP=CCP_IOREG_gc; // unlock writing to CLK_CTRL
  CLK.CTRL = CLK_SCLKSEL_RC32M_gc; // select 32MHz as system clock
  //OSC.CTRL &=~(OSC_RC2MEN_bm); // disable unused 2MHz oscillator (option)	
}