Lab set Program-11

Water Level Depth Detection System using Ultrasonic Sensor

---

Objective

To develop a water-level depth detection system using an ultrasonic sensor (HC-SR04) and Arduino, where the sensor measures the distance to the water surface and calculates the water level in a tank.

---

Learning Outcomes

After completing this experiment, students will be able to:

• Interface an ultrasonic sensor with Arduino.

• Measure distance using TRIG–ECHO timing.

• Convert distance readings into water depth level.

• Display measurements on the Serial Monitor.

• Understand practical applications in water tanks, overhead tanks, sumps etc.

---

Components (from Tinkercad Palette)

• Arduino Uno

• Ultrasonic Sensor (HC-SR04)

• Breadboard

• Jumper Wires

• (Optional) LEDs to represent tank levels

---

Circuit Wiring (Exact)

1. Ultrasonic Sensor → Arduino

   • VCC → 5V

   • GND → GND

   • TRIG → Pin 9

   • ECHO → Pin 10

2. No additional components required.

3. Keep the ultrasonic sensor facing a flat object in Tinkercad to simulate water surface.

---

Arduino Sketch

// Lab Program 11: Water Level Depth Detection using Ultrasonic Sensor

#define trigPin 9
#define echoPin 10

long duration;
float distance;      // Distance between sensor and water surface
float tankHeight = 30.0;  // Height of tank in cm (you can change this)
float waterLevel;    // Actual water depth

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  Serial.begin(9600);
}

void loop() {
  // Trigger pulse
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Measure echo time
  duration = pulseIn(echoPin, HIGH);

  // Convert time → distance (cm)
  distance = duration * 0.034 / 2;

  // Calculate water level depth
  waterLevel = tankHeight - distance;
  if (waterLevel < 0) waterLevel = 0;  // Avoid negative values

  // Print details
  Serial.print("Distance to Water Surface: ");
  Serial.print(distance);
  Serial.print(" cm | Water Level: ");
  Serial.print(waterLevel);
  Serial.println(" cm");

  delay(700);
}

---

How It Works (Explain to Students)

• The ultrasonic sensor sends a sound pulse and measures how long it takes to return.

• This time is converted into a distance from the sensor to the water surface.

• If the tank height is known (example: 30 cm):

  Water Level = Tank Height − Distance Measured
  

• If the water surface is close → water level is high.

• If the distance is large → water level is low.

• The output shows both values in the Serial Monitor.

---

Common Mistakes & Quick Fixes

Issue	Cause	Fix
Distance always 0 or very high	TRIG/ECHO swapped	Recheck pin mapping
Output not updating	Simulation not running	Click Start Simulation
Random values	No object in front of sensor	Place a flat object in front
Negative water level	Wrong tankHeight	Adjust tank height value

---

Viva / Check-Your-Understanding

1. What physical principle does an ultrasonic sensor use?

2. Why do we divide the pulse duration by 2?

3. How does tank height affect water level calculation?

4. Can ultrasonic sensors measure through water? Why/why not?

5. Where are ultrasonic-based water level systems used in the real world?

---

Extensions (Mini-Tasks)

• Add 3 LEDs (low, medium, full) based on water level.

• Add a buzzer when the tank is almost empty.

• Display water level on an LCD (16×2).

• Show the water level percentage (0–100%).

---

Lab Record (Suggested Headings)

• Title

• Objective

• Components Used

• Circuit Diagram (Tinkercad Screenshot)

• Arduino Code

• Output / Observations

• Explanation

• Viva Questions

• Extensions

---