Testing with the ultrasonic sensor

​

The idea was that the ultrasonic sensor could be put on top of the glass and measure the distance to the water, emitting different sounds if the distance is big (empty glass) or short (full glass).

 

I searched online for the ultrasonic sensor code and tested it with glasses of water. The ultrasoni sensor has two pins which are the echopin (input) and the trigpin (output). As I tested, they work connected to both digital and analog pins of the Arduino. Once it worked and it could detect the distance to the water by reading the changing values in the serial monitor, I proceeded to add the buzzer to the code. Since my initial plan was to create a wearable, I used the lilyPad buzzer, in which the negative must be connected to the ground and the positive to a resistor and then to a pin in the Arduino. It worked well but the sound emiting was not very easy to control just by changing the values of the distance. So I had the idea of adding also a button, which the user can press to read the distance to the water once the sensor is placed above the glass. I changed the beeping speed in such way that if the distance is less than 10 it would beep faster meaning that the glass is full, and if the distance is bigger than 10 the beeping pace would be slower, meaning that the glass is empty. The code was finalized as the following:

​

const int trigPin = 13;
const int echoPin = 11;
const int buzzer = 2;
const int button = 9;

long duration;
int distance;
void setup() {
pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output
pinMode(echoPin, INPUT); // Sets the echoPin as an Input
pinMode(buzzer, OUTPUT); // Set buzzer - pin as an output
Serial.begin(9600); // Starts the serial communication
pinMode (button,INPUT);
}
void loop() {
  int botao;
  botao = digitalRead(button);//Put the reading value of the switch on botao
Serial.println(botao); //Shows the logic state of the input on Serial Monitor 
                
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
duration = pulseIn(echoPin, HIGH);
// Calculating the distance
distance= duration*0.034/2;
// Prints the distance on the Serial Monitor
Serial.print("Distance: ");
Serial.println(distance);

if (botao == 1) // Pressed button, logic State HIGH (5V)
      {
      digitalWrite(buzzer,1); //Switch pressed, buzzer on 
     if (distance > 10){
     tone(buzzer, 1000);
     //analogWrite (buzzer, 1000);
     delay (500);
     noTone(buzzer);
     delay (1000);
   } 
   if (distance < 10){
     tone(buzzer, 1000);
     //analogWrite (buzzer, 1000);
     delay (200);
     noTone(buzzer);
     delay (100);
   } 

  }else
      { 
      digitalWrite(buzzer,0); //If the switch isn’t pressed, buzzer off. 
      } 
}

​