#include <stdint.h>
#include <util/delay.h>

 volatile uint16_t Capt1, Capt2, timeStamp1, timeStamp2;//VARIABLES TO HOLD TIMESTAMPS
 volatile uint8_t Flag; //CAPTURE FLAG
 float deltatime;
 volatile uint16_t rpm;
 volatile uint8_t start=1; //Startindikator
 
 #define icpPin 8 // PB0 ICP D8 Interrupt input
 /*--------------------------------------------------------------------------------------------------
 INTIALIZING TIMER
 ---------------------------------------------------------------------------------------------------*/
 void InitTimer1(void)
 {
 TCNT1=0; //SETTING INTIAL TIMER VALUE
 TCCR1B|=(1<<ICES1); //SETTING FIRST CAPTURE ON RISING EDGE ,(TCCR1B = TCCR1B | (1<<ICES1)
 TIMSK1|=(1<<ICIE1)|(1<<TOIE1); //ENABLING INPUT CAPTURE AND OVERFLOW INTERRUPTS
 }
 /*--------------------------------------------------------------------------------------------------
 STARTING TIMER
 ---------------------------------------------------------------------------------------------------*/
 void StartTimer1(void)
 {
 TCCR1B|=(1<<CS12); //STARTING TIMER WITH PRESCALER 256
 }
 /*--------------------------------------------------------------------------------------------------
 CAPTURE ISR
 ---------------------------------------------------------------------------------------------------*/
 ISR(TIMER1_CAPT_vect)
 {
   if (Flag==0)
    {
       Capt1=ICR1; //SAVING CAPTURED TIMESTAMP
       //TCCR1B&=~(1<<ICES1); //CHANGE CAPTURE ON FALLING EDGE
    }
   
   if (Flag==28)
    {
       Capt2=ICR1; //SAVING CAPTURED TIMESTAMP
       //TCCR1B|=(1<<ICES1); //CHANGING CAPTURE ON RISING EDGE
    }
   
   Flag++; //INCREMENTING FLAG
 }

 /*--------------------------------------------------------------------------------------------------
 INIT FUNCTION
 ---------------------------------------------------------------------------------------------------*/
void Init (void)
{
  pinMode(icpPin,INPUT);
  digitalWrite(icpPin,HIGH); //pull up
  Serial.begin(115200);
  Serial.print("Bereit");
}
 /*--------------------------------------------------------------------------------------------------
 MAIN FUNCTION
 ---------------------------------------------------------------------------------------------------*/
int main (void)  {

 volatile uint8_t FINALTIME; //VARIABLE TO HOLD THE FINAL TIME

 InitTimer1(); //CALLING FUNCTION INITTIMER1 TO INITIALIZE TIMER 1
 StartTimer1(); //CALLING FUNCTION STARTTIMER1 TO START TIMER 1
 Init();
 
 sei(); //ENABLING GLOBAL INTERRUPTS
 
 while(1) {
   
     timeStamp1 = 0;
     timeStamp2 = 0; 
     
     if (Flag==29)
     {
         timeStamp1 = Capt1;
         timeStamp2 = Capt2;         
       
         deltatime = (Capt2-Capt1)*0.016; // Prescaler 256
         rpm = 60000 / ((timeStamp2-timeStamp1)*0.016); // Prescaler 256
         Serial.print("\n");
         Serial.print(" RPM: ");
         Serial.print((float)rpm);
        
         _delay_ms (1000);
         Flag=0; //CLEARING FLAGS 
        // interrupts();
         //TIMSK1|=(1<<ICIE1)|(1<<TOIE1); //ENABLING INPUT CAPTURE AND OVERFLOW INTERRUPTS
         //TCNT1 = 0;
      }   
    }
    return 0;
 }