RESET:
 cli

 ldi	Temp, 0b11100000	;setup external Oscillator: 12..16Mhz, 16k clock cycles start up, 32kHzOscLowPower
 sts	OSC_XOSCCTRL, Temp

 ldi	Temp, OSC_XOSCEN_bm	;enable external oscillator or clock
 sts	OSC_CTRL, Temp

 ldi	Temp, 0b11000011	;external Oscillator or clock as PLL input, Factor 3 (36,864 MHz)
 sts	OSC_PLLCTRL, Temp

 ;ldi	Temp, $D8		;disable I/O Register protection for 4 cycles
 ;out	CPU_CCP, Temp
 ;ldi	Temp, 0b00000001	;PrescalerC divide/2, CPU-Clock 32Mhz, PER2 64Mhz
 ;sts	CLK_PSCTRL, Temp

 
WaitOSC:
 lds	Temp, OSC_STATUS
 sbrs	Temp, 3			;wait for Oscillator to be stable
 rjmp	WaitOSC
 
 lds	Temp, OSC_CTRL
 ori	Temp, OSC_PLLEN_bm	;enable PLL
 sts	OSC_CTRL, Temp

WaitPLL:
 lds	Temp, OSC_STATUS
 sbrs	Temp, 4			;wait for PLL to be stable
 rjmp	WaitPLL

 
 ldi	Temp, $D8		;disable I/O Register protection for 4 cycles
 out	CPU_CCP, Temp
 ldi	Temp, CLK_SCLKSEL_PLL_gc
 sts	CLK_CTRL, Temp

 clr	Null