#define F_CPU 3686400

#include <avr/interrupt.h>
#include <avr/io.h>
#include <util/delay.h>

int main(void) {

VPORTA_DIR=0b11000000; // LEDs: A6, A7 cave!: siehe auch die ISRs

CPU_CCP = CCP_IOREG_gc;
CLKCTRL.XOSCHFCTRLA = CLKCTRL_ENABLE_bm | CLKCTRL_RUNSTDBY_bm;
CPU_CCP = CCP_IOREG_gc;
CLKCTRL_MCLKCTRLA=CLKCTRL_CLKSEL_EXTCLK_gc;

//RTC
RTC.CTRLA = RTC_RTCEN_bm; // RTC aktivieren
while (RTC.STATUS > 0);   // Warten, bis der RTC bereit ist
while (!(CLKCTRL.MCLKSTATUS & CLKCTRL_OSC32KS_bm));
  
RTC.PITINTCTRL = RTC_PI_bm;
RTC.PITCTRLA = RTC_PERIOD_CYC32768_gc | RTC_PITEN_bm;
RTC.CLKSEL = RTC_CLKSEL_OSC32K_gc;

//TCA
TCA0.SINGLE.PER = 3600-1; //180;
TCA0.SINGLE.CTRLA = TCA_SINGLE_CLKSEL_DIV1024_gc | // 3600Hz source
TCA_SINGLE_ENABLE_bm; // start timer
TCA0.SINGLE.CTRLB = TCA_SINGLE_WGMODE_NORMAL_gc; // set Normal mode
TCA0.SINGLE.INTCTRL = TCA_SINGLE_OVF_bm;

sei();
while (1) {
}
}

ISR(RTC_PIT_vect) {
  VPORTA_IN=0b10000000;
  RTC.PITINTFLAGS = RTC_PI_bm;
}

ISR(TCA0_OVF_vect) {
  VPORTA_IN=0b01000000;
  TCA0.SINGLE.INTFLAGS = TCA_SINGLE_OVF_bm;
}