This project will measure the turbidity in the water and display on an LCD screen how pure the water is. Also, a green, yellow or red RGB LED will light up and a buzzer will sound. It is useful because it can detect if the water from the tap at home is safe to drink or it can detect how pure the water in a lake is.

Voi conecta la Arduino turbidimetrul si ii voi lua valorile care vor fi procesate si transformate intr-un procentaj de la 0 la 100. Pe baza acestui procentaj se va aprinde led-ul RGB, buzzerul si va arata acest procentaj pe LCD.

List of components:

- Arduino UNO R3
The Arduino IDE (Integrated Development Environment), a software tool made to make it simple to write, upload, and debug code for the board, can be used to program the Arduino UNO, which can be used to control a variety of electronic devices, including sensors, motors, lights, and other components.

- LCD 1602
A 16×2 LCD display module (LCD 1602) is a device that can be used to display alphanumeric characters, symbols, and even simple graphics. It has a display size of 16 columns and 2 rows.

- Passive Buzzer
A passive buzzer is a type of electronic component that is used to generate sound in electronic circuits. It is called passive because it does not have an integrated oscillator circuit and requires an external signal to produce a sound. The buzzer consists of a piezoelectric element that vibrates when an electric signal is applied to it, creating a sound wave.

- Turbidity Module (+Turbidity Sensor)
A turbidity module is a sensor used to measure the level of turbidity, or cloudiness, in a liquid. It works by shining a light through the liquid and measuring the amount of light that is scattered by particles in the liquid. The more particles there are, the more the light will scatter, and the higher the turbidity measurement will be.

-RGB LED
Three distinct LED chips—one each for red, green, and blue—are housed inside an RGB LED. A variety of colors can be created by independently altering the brightness of each of these hues.

Other components:
- USB Cable
- 10k and 330 ohm resistors
- Potentiometer
- Wires
- Button

I made this project in Arduino IDE.
Extra libraries: LiquidCrystal.
Sources 3-rd party: I also used Tinkercad to develop the project and to test various software/hardware segments.

Several variables are also used. A debugging mode that is normally commented out is also included. The debugging mode will transform the values of the turbidity module to values that steadily increase. This should normally only be used for developing or testing the project.

I start off the software by defining all the variables, including the library and setting up the components. In the loop section of the code i have the Buzzer playing a melody for the first loop and showing a short welcome on the LCD. At the very start of the loop we can also see the Arduino reading the turbidity module's values and transforming them to values from 0 to 100. Afterwards, we test the turbidity. If the turbidity is 20 or lower, the RGB led turns red and the buzzer sings 3 lower tones. If the turbidity is 50 or lower, the RGB led turns yellow and the buzzer sings another 3 tones. If the turbidity is higher than 50, the RGB led turns green and the buzzer sings 3 other corresponding tones. During this, the LCD also shows the procentage of turbidity and a short message saying wheter it's dirty, cloudy or clean. The loop will reset every 3 seconds. I have set a variable to stop repeating the same buzzing if the value is in the same category as the last loop as it can get annoying fast.

  void loop() {
  int sensorValue = analogRead(A0);
  int turbidity = map(sensorValue, 0,640, 100, 0);
  if(turbidity < 0) turbidity = 0;
  //for debugging only:
  //if(i == 0) turbidity = 30;
  //if(i != 0) {turbidity = debug_int*10; debug_int++;}
  //if(i != 0 && debug_int>=10){turbidity = 0; debug_int=0;}
  //end of debugging section

  if(i==0){
  
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Stan Alex's");
  tone(13, 261, 200); //Middle C
  setColor(luminozitate_led, luminozitate_led, luminozitate_led);
  delay(200);
  tone(13, 277, 200); //C#
  delay(200);
  tone(13, 294, 200); //D
  delay(200);
  tone(13, 311, 200); //D#
  delay(200);
  setColor(luminozitate_led, luminozitate_led, 0);
  tone(13, 370, 200); //F#
  delay(400);
  setColor(0, luminozitate_led, luminozitate_led);
  tone(13, 370, 200); //F#
  delay(400);

  lcd.clear();
  lcd.setCursor(0, 1);
  lcd.print("Turbidity Meter");
  setColor(0, luminozitate_led, 0);
  tone(13, 349, 200); //F
  delay(200);
  tone(13, 311, 200); //D#
  delay(200);
  tone(13, 294, 200); //D
  delay(200);
  setColor(0, 0, luminozitate_led);
  tone(13, 370, 200); //F#
  delay(400);
  setColor(luminozitate_led, 0, 0);
  tone(13, 370, 200); //F#
  delay(400);
  setColor(0, 0, 0);
  i=1;
  }
  delay(3000);

  if(turbidity < 21){
    setColor(luminozitate_led, 0, 0);
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("It's dirty");
    lcd.setCursor(0, 1);
    lcd.print("Procent: "); lcd.print(turbidity);lcd.print(" %");

    //red
   	if(buzz==1 && stop_repetition != 40){
      tone(13, 330, 200); //E
      delay(200);
      tone(13, 294, 200); //D
      delay(200);
      tone(13, 261, 200); //Middle C
      delay(200);
      stop_repetition = 40;
      }

    } else if(turbidity < 51){
    setColor(luminozitate_led, luminozitate_led, 0);
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("It's cloudy");
    lcd.setCursor(0, 1);
    lcd.print("Procent: "); lcd.print(turbidity);lcd.print(" %");

    //yellow:
	  if(buzz==1 && stop_repetition != 20){
      setColor(luminozitate_led, luminozitate_led, 0);
      tone(13, 349, 200); //F
      delay(200);
      tone(13, 311, 200); //D#
      delay(250);
      tone(13, 311, 200); //D#
      delay(150);

      stop_repetition = 20;
      }
    setColor(luminozitate_led, luminozitate_led, 0);
    } else{
    setColor(0, luminozitate_led, 0);
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("It's clean");
    lcd.setCursor(0, 1);
    lcd.print("Procent: "); lcd.print(turbidity);lcd.print(" %");
    setColor(0, luminozitate_led, 0);
    //green:
  	if(buzz==1 && stop_repetition != 30){
      setColor(0, luminozitate_led, 0);
      tone(13, 392, 200); //G
      delay(200);
      tone(13, 370, 200); //F#
      delay(200);
	    tone(13, 392, 200); //G
      delay(200);

      stop_repetition = 30;
      }
      setColor(0, luminozitate_led, 0);
    }
    
}

We will now talk about the functions used:
I used a function to set the color of the RGB led to whatever is received through 3 parameters, the Red Value, the Green Value and the Blue Value. This function then sets the intensity of each pin accordingly.

void setColor(int redValue, int greenValue, int blueValue) {
  analogWrite(led_Rosu, 255-redValue);
  analogWrite(led_Verde, 255-greenValue);
  analogWrite(led_Albastru, 255-blueValue);
}

I used another function to interrupt the normal ongoing processes of the loop and set a variable used to activate/deactivate the buzzer when the button is pressed.

void ISR_button(){
  if(buzz == 1){
  	buzz =0;
  }
  else{buzz = 1;}
}

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