Volume Calculation Function

// Interrupt service routine to count pulses
void IRAM_ATTR pulseCounter()
{
  pulseCount++;
}

void pulseCounterCalculation()
{
  if ((millis() - oldTime) > 1000) // Only process counters once per second
  {
    // Disable the interrupt while calculating flow rate and sending the value to the host
    detachInterrupt(flowSensor);

    // Because this loop may not complete in exactly 1 second intervals we calculate the number of
    // milliseconds that have passed since the last execution and use that to scale the output.
    // We also apply the calibrationFactor to scale the output based on the number of
    // pulses per second per units of measure (litres/minute in this case) coming from the sensor.
    flowRate = ((1000.0 / (millis() - oldTime)) * pulseCount) / calibrationFactor;

    // Note the time this processing pass was executed. Note that because we've
    // disabled interrupts the millis() function won't actually be incrementing right
    // at this point, but it will still return the value it was set to just before
    // interrupts went away.
    oldTime = millis();

    // Divide the flow rate in litres/minute by 60 to determine how many litres have
    // passed through the sensor in this 1 second interval,
    flowLitres = (flowRate / 60.0);

    // Add the millilitres passed in this second to the cumulative total
    totalLitres += flowLitres;

    //Print the flow rate for this second in litres / minute
    Serial.print("Flow rate: ");
    Serial.print(flowLitres, DEC); // Print the integer part of the variable
    Serial.print("mL/Second");
    Serial.print("\t");

    // Print the cumulative total of litres flowed since starting
    Serial.print("Output Liquid Quantity: ");
    Serial.print(totalLitres, DEC);
    Serial.println("mL");
    Serial.print("\t");

    // Update Blynk
    // Blynk.virtualWrite(V1, pulseCount);
    // Blynk.virtualWrite(V2, totalLitres);

    // Reset the pulse counter so we can start incrementing again
    pulseCount = 0;

    // Enable the interrupt again now that we've finished sending output
    attachInterrupt(flowSensor, pulseCounter, FALLING);
  }
}