Smart Water Bottle

#include <NewPing.h>
#include "SSD1306.h"

#define TRIGGER_PIN  26  // Arduino pin tied to trigger pin on the ultrasonic sensor.
#define ECHO_PIN     25  // Arduino pin tied to echo pin on the ultrasonic sensor.
#define MAX_DISTANCE 25 // Maximum distance we want to ping for (in centimeters). Maximum sensor distance is rated at 400-500cm.

float old_amount = 0;
float water_amount_in_ml = 0;

NewPing sonar(TRIGGER_PIN, ECHO_PIN, MAX_DISTANCE); // NewPing setup of pins and maximum distance.

SSD1306 display(0x3c, 4, 15);

void setup() {
  Serial.begin(115200); // Open serial monitor at 115200 baud to see ping results.

  display.init(); // initialise the OLED
  display.setFont(ArialMT_Plain_24);
  display.setTextAlignment(TEXT_ALIGN_CENTER_BOTH);
}

void waterCaclulation() {
  float water_level = 0;
  float read_value = 0;
  for (int i = 0; i < 5; i++) { // Take five reading to calculate an average

    read_value = sonar.ping_cm();
    if (read_value <= 21 && read_value >= 1) { // Indicatiing a valid value
      water_level = water_level + read_value;
    } else {
      return;
    }
    delay(50);
  }

  float average_water_level = 21 - water_level / 5; //find average from five reading, 21 = bottle height
  water_amount_in_ml = float(average_water_level * 37.5); //1 cm water level = 37.5 mL
  Serial.print(water_amount_in_ml);
  Serial.print(" ML Remaining\r\n");
  Serial.println(read_value);

  display.clear();
  display.drawString(63, 20, String(water_amount_in_ml) + " mL");
  display.display();

}

void loop() {
  waterCaclulation();
  delay(1000);
}