Better precision on flow metter

Community Help With My Project
1

Hi i use this code, and this code working, but i have flow in range 1 - 2 L/min, and in this range i need better precision for flowrate, now flowrate metter show me only 1; 1,2 ; 1,4 ; 1,6 ; 1,8 ; 2 L/min this only 0,2l/min precission, but i need precission 0,05 L/min. Any idea for this code.

Code

/*
Liquid flow rate sensor -DIYhacking.com Arvind Sanjeev

Measure the liquid/water flow rate using this code. 
Connect Vcc and Gnd of sensor to arduino, and the 
signal line to arduino digital pin 2.
 
 */
#define CAYENNE_PRINT Serial
#include <CayenneMQTTESP8266.h>
#define VIRTUAL_PIN0 V0
#define VIRTUAL_PIN3 V1
#define VIRTUAL_PIN3 V2
// Your network name and password.
char ssid[] = "";
char wifiPassword[] = "";

char username[] = "";
char password[] = "";
char clientID[] = "";

byte statusLed    = 13;

byte sensorInterrupt = 0;  // 0 = digital pin 2
byte sensorPin       = 0;

// The hall-effect flow sensor outputs approximately 4.5 pulses per second per
// litre/minute of flow.
float calibrationFactor = 5;

volatile byte pulseCount;  

float flowRate;
unsigned int flowMilliLitres;
unsigned long totalMilliLitres;
unsigned long totalLitres;
unsigned long oldTime;

void setup()
{
  
  // Initialize a serial connection for reporting values to the host
  Serial.begin(9600);
  Cayenne.begin(username, password, clientID, ssid, wifiPassword);
   
  // Set up the status LED line as an output
  pinMode(statusLed, OUTPUT);
  digitalWrite(statusLed, HIGH);  // We have an active-low LED attached
  
  pinMode(sensorPin, INPUT);
  digitalWrite(sensorPin, HIGH);

  pulseCount        = 0;
  flowRate          = 0.0;
  flowMilliLitres   = 0;
  totalMilliLitres  = 0;
  totalLitres       = 0;
  oldTime           = 0;

  // The Hall-effect sensor is connected to pin 2 which uses interrupt 0.
  // Configured to trigger on a FALLING state change (transition from HIGH
  // state to LOW state)
  attachInterrupt(sensorInterrupt, pulseCounter, FALLING);
}

/**
 * Main program loop
 */
void loop() 
{
  Cayenne.loop();
   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(sensorInterrupt);
        
    // 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, then multiply by 1000 to
    // convert to millilitres.
    flowMilliLitres = (flowRate / 60) * 1000;
    
    // Add the millilitres passed in this second to the cumulative total
    totalMilliLitres += flowMilliLitres;
    totalLitres = totalMilliLitres / 1000;
      
    unsigned int frac;
    
    // Print the flow rate for this second in litres / minute
    Serial.print("Flow rate: ");
    Serial.print(int(flowRate));  // Print the integer part of the variable
    Serial.print(".");             // Print the decimal point
    // Determine the fractional part. The 10 multiplier gives us 1 decimal place.
    frac = (flowRate - int(flowRate)) * 10;
    Serial.print(frac, DEC) ;      // Print the fractional part of the variable
    Serial.print("L/min");
    // Print the number of litres flowed in this second
    Serial.print("  Current Liquid Flowing: ");             // Output separator
    Serial.print(flowMilliLitres);
    Serial.print("mL/Sec");

    // Print the cumulative total of litres flowed since starting
    Serial.print("  Output Liquid Quantity: ");             // Output separator
    Serial.print(totalLitres);
    Serial.println("L"); 

    // Reset the pulse counter so we can start incrementing again
    pulseCount = 0;
    
    // Enable the interrupt again now that we've finished sending output
    attachInterrupt(sensorInterrupt, pulseCounter, FALLING);
  }
}

/*
Insterrupt Service Routine
 */
void pulseCounter()
{
  // Increment the pulse counter
  pulseCount++;
}

CAYENNE_OUT(V0)                                  //Flow rate:
{
  Cayenne.virtualWrite(V0, flowRate);
}

CAYENNE_OUT(V1)                                  //Current Liquid Flowing:
{
  Cayenne.virtualWrite(V1, flowMilliLitres);
}

CAYENNE_OUT(V2)                                  //Output Liquid Quantity:
{
  Cayenne.virtualWrite(V2, totalLitres);
}