#include "PinChangeInterrupt.h"

#define INTERRUPT_PIN 5;
int flowPin = 5;
 

double flowRate;
volatile int count;
void setup()
{
Serial.begin(9600);

pinMode(flowPin, INPUT_PULLUP);
 
//attachPinChangeInterrupt(digitalPinToPinChangeInterrupt(flowPin) ,Flow, CHANGE);
}

void loop()
{
count = 0;
attachPinChangeInterrupt(digitalPinToPinChangeInterrupt(flowPin) ,Flow, CHANGE); 
delay (1000);
detachPinChangeInterrupt(digitalPinToPinChangeInterrupt(flowPin)); 
flowRate = count *60;
flowRate = flowRate / 1000;

Serial.println (flowRate);
}

void Flow()
{
count++;
}