#include <mega8.h>
#include <delay.h>

static float Fx;
unsigned long int N1, N2, N;
unsigned long int M1, M2, M;
unsigned int Perepol_Timer0=0, Perepol_Timer1=0;
unsigned int count_T1, count_T0;

// Timer 0 overflow interrupt service routine
interrupt [TIM0_OVF] void timer0_ovf_isr(void){
Perepol_Timer0++;

}

// Timer 1 overflow interrupt service routine
interrupt [TIM1_OVF] void timer1_ovf_isr(void){
Perepol_Timer1++;
}

// Timer 1 input capture interrupt service routine
interrupt [TIM1_CAPT] void timer1_capt_isr(void){
TIMSK&=0xDF;
count_T0=TCNT0;
count_T1=ICR1;

}


void main(void)
{
PORTB=0x00;
DDRB=0x00;

PORTC=0x00;
DDRC=0x00;


PORTD=0x00;
DDRD=0x00;

// Timer/Counter 0 initialization
TCCR0=0x07;
TCNT0=0x00;

// Timer/Counter 1 initialization
TCCR1A=0x00;
TCCR1B=0x41;
TCNT1H=0x00;
TCNT1L=0x00;
ICR1H=0x00;
ICR1L=0x00;
OCR1AH=0x00;
OCR1AL=0x00;
OCR1BH=0x00;
OCR1BL=0x00;

// Timer/Counter 2 initialization
ASSR=0x00;
TCCR2=0x00;
TCNT2=0x00;
OCR2=0x00;

// External Interrupt(s) initialization
// INT0: Off
// INT1: Off
MCUCR=0x00;

// Timer(s)/Counter(s) Interrupt(s) initialization
TIMSK=0x05;

// Analog Comparator initialization
ACSR=0x80;
SFIOR=0x00;

// Global enable interrupts
#asm("sei")

Perepol_Timer1=0;
N1=0;M1=0;
while (1){
delay_ms(1000);
TIMSK|=0x20;                        
while ((TIMSK&0x20)==0x20){}            
N2=(unsigned long int)(Perepol_Timer1)*65536+count_T1;
M2=(unsigned long int)Perepol_Timer0*256+count_T0;
N=N2-N1;                              
M=M2-M1;
Fx=(float)8000000.0*(float)M/(float)N;
N1=N2;                                
M1=M2;
} }

while ((currenTime-oldTime)<OneSec)    //п.1-условно, можно сделать по-другому
{
}