Simple DIY project using HC-SR04 Ultrasonic Sensor

You can create a circuit to measure the water level of a water tank using this HC-SR04 Ultrasonic Sensor. You only have to add few lines in to the code that I used to display measured distance from this sensor. Revised code is given below.

int echoPin = 2;  //Define Echo pin

int trigPin = 3;     // Define Trig pin

long  inches, duration, cm;   //Define variables

int height=300; //define depth of tank in cm

int firstLED = 4; // define LEDs pin

int secondLED = 5;

int thirdLED = 6;

int fourthLED = 7;

void setup() {

Serial.begin (9600);

pinMode(trigPin, OUTPUT);  //Define output pin

pinMode(firstLED, OUTPUT);

pinMode(secondLED, OUTPUT);

pinMode(thirdLED, OUTPUT);

pinMode(fourthLED, OUTPUT);

pinMode(echoPin, INPUT);  //Define input pin

}

void loop()

{

//Give a short low pulse  to trigPin for ensure a clean high pulse

digitalWrite(trigPin, LOW);

delayMicroseconds(5);

//give high pulse to trigPin 10 microseconds

digitalWrite(trigPin, HIGH);

delayMicroseconds(10);

digitalWrite(trigPin, LOW);

// Read the signal from the sensor

duration = pulseIn(echoPin, HIGH);

// convert time into a distance

// The speed of sound is 29.1 microseconds per centimeter.

cm = (duration/2) / 29.1;

//Print distance

Serial.print(cm);

Serial.print("cm");

Serial.println();

if (cm >= (3*height/4)) {

    digitalWrite(firstLED, HIGH);

    digitalWrite(secondLED, LOW);

    digitalWrite(thirdLED, LOW);

    digitalWrite(fourthLED, LOW);

  } 

else if(cm >= (height/2)){

    digitalWrite(firstLED, HIGH);

    digitalWrite(secondLED, HIGH);

    digitalWrite(thirdLED, LOW);

    digitalWrite(fourthLED, LOW);

  }

else if(cm >= (height/4)){

    digitalWrite(firstLED, HIGH);

    digitalWrite(secondLED, HIGH);

    digitalWrite(thirdLED, HIGH);

    digitalWrite(fourthLED, LOW);

  }

else if(cm <= 10){

    digitalWrite(firstLED, HIGH);

    digitalWrite(secondLED, HIGH);

    digitalWrite(thirdLED, HIGH);

    digitalWrite(fourthLED, HIGH);

  }

}

I have used four LEDs to illustrate the water level of the tank. Each LEDs short lead (negative) is connected to the same wire and that wire is connected to a ground pin of Arduino board. Each LEDs are going to illuminate according to the water level of the tank. First LED is connected to the 4^th Digital pin. Second LED is connected to the 5^th Digital pin. Third LED is connected to the 6^th Digital pin. And fourth LED is connected to the 7^th Digital pin. The sensor panel should be placed inside the water tank and above 5 cm from the maximum water level. Transducers’ face should be aimed to water surface. LED panel and Arduino board can be kept at any place.

If the water level is

1.       Below the quarter of height of the tank– illuminates first LED.

2.       Half of height of the tank – illuminates first and second LEDs.

3.       Below the three quarter of height of the tank – illuminates first, second and third LEDs.

4.       Maximum height of the tank – illuminates every LEDs.

Illustration of LED illumination is given below according to the water level as described above.

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