Volume Calculation Header File

#ifndef VOLCALC_H
#define VOLCALC_H

#include <Arduino.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include "OTA.h"

// Global Variables from main.cpp file
extern Adafruit_SSD1306 display;

float flowRate = 0.0;
unsigned int flowMilliLitres = 0;
unsigned long totalMilliLitres = 0;
unsigned long oldTime = 0;
float calibrationFactor = 45.028;         // You can change according to your datasheet
volatile byte pulseCount = 0;         // pulse count
int sensorInterrupt = 4;              // GPIO pin 4 same as sensor pin
unsigned long currentTime = millis(); // Store the current time

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

void displayCount()
{
  // Display flow rate, total volume, and pulse count on OLED display
  display.clearDisplay();
  display.setTextSize(1);    // Normal 1:1 pixel scale
  display.setTextWrap(true); // Enable text wrapping
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(1, 10);
  display.print("Rate: ");
  display.print(flowMilliLitres, DEC); // Display with 2 decimal places
  display.println(" mL/sec");
  display.setCursor(1, 23);
  display.print("Total Vol:");
  // Print only a portion of the total volume, adjust as needed
  display.print(totalMilliLitres, DEC); // Display with 2 decimal places
  display.println(" mL");
  display.display(); // Display the content on OLED
}

void volCalc()
{
  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;

    unsigned int frac;

    // 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);

    // Call displayCount() to update the OLED display
    displayCount();

    // Print the flow rate for this second in litres / minute
    Serial.print("Flow rate: ");
    Serial.print(flowMilliLitres, 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(totalMilliLitres,DEC);
    Serial.println("mL");
    Serial.print("\t");
  }
}

#endif