Hariharan Subramanian

int flowPin = 5;    //Digital input pin on the Arduino

double flowRate;    //Variable to hoold the calculated flow rate

 

//This variable is incremented when interrupt runs.

//This needs to be set as volatile ensure to ensure it updates correctly during the interrupt process.

 

volatile int count; void setup() {  

      // Setup code here, to run once:  

      pinMode(flowPin, INPUT);           //Sets the pin as an input  

 

      //Configures interrupt 0 which is pin number 2 on the Arduino Uno, which runs the function 'calculateNumberOfPulsees()'  

      attachInterrupt(0, calculateNumberOfPulsees, RISING);      

      Serial.begin(9600);  //Start Serial

}

 

void loop() {  

      // Main code here, runs repeatedly:    

 

      count = 0;      // Reset the counter before running the interrupt      

 

      interrupts();     //Enables interrupts on the Arduino.

                               //This will start checking the interrupt and run the calculateFlowRate() every time when the signal Rises                                                   //When the interrupt is active for 1 second, the  

 

      delay (1000);     

      noInterrupts();   //Disables the interrupt check on the Arduino. This will stop incrementing the counter  

 

     //LPM calculation: as per sepcifications, Frequency = 7.5 x liters per minute. So, Liters per minute = Frequency / 7.5    

 

     flowRate = (count / 7.5);          

 

     //Print the number of interrupts in the last second  

     Serial.print("Number of interrup is: ");           

     Serial.print(count);           

     Serial.print(" & The flow rate is : ");  

     Serial.print(flowRate);         //Print the variable flowRate to Serial  

     Serial.println(" lpm");          //Print the variable flowRate to Serial

 

}

 

void calculateNumberOfPulsees() {  

     

     count++; //count gets incremented every time this function is called

 

}