void set_clk()
{
	sbi(AVR32_PM.oscctrl0, 0);	//Taktquelle externer Quarz > 8MHz
	sbi(AVR32_PM.oscctrl0, 1);
	sbi(AVR32_PM.oscctrl0, 2);
	
	sbi(AVR32_PM.oscctrl0, 9);	//Startup-Time Quarz 16384 Zyklen des RC-Oszillators 0 (115,2 kHz --> 142ms)
	sbi(AVR32_PM.oscctrl0, 10);
	
	sbi(AVR32_PM.mcctrl, 2); // Osc0 enable
	while(bit_is_clear(AVR32_PM.poscsr, 7))	//Warten bis Oszillator 0 stabil ist
	{
		
	}
	sbi(AVR32_PM.mcctrl, 0); // Osc0 = Source für Main Clock
}