Lab set Program-6

Develop a program to classify dry and wet waste with the Moisture sensor (DHT22).

Important Note:

• In real life, a Soil Moisture Sensor is used to detect wet/dry conditions.

• Tinkercad does not provide a Soil Moisture sensor or DHT22 directly.

• But we can simulate moisture detection using a Potentiometer as a replacement (to act like varying soil/moisture resistance).

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Objective

To develop an Arduino program that classifies dry and wet waste using a moisture sensor (simulated with a potentiometer in Tinkercad) and displays the result through LEDs.

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Learning Outcomes

After completing this experiment, students will be able to:

1. Understand how a moisture sensor works (wet waste = high moisture, dry waste = low moisture).

2. Simulate unavailable sensors in Tinkercad using alternatives (here, potentiometer).

3. Write Arduino programs to classify sensor data.

4. Apply IoT-based waste classification for smart cities.

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Components (from Tinkercad Palette)

• Arduino UNO board

• Potentiometer (simulated moisture sensor, connected to A0)

• 2 LEDs (Red = Dry waste, Green = Wet waste)

• 220Ω resistors × 2

• Breadboard

• Jumper wires

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Circuit Wiring

1. Potentiometer (Moisture Sensor substitute)

   • One outer leg → 5V

   • Other outer leg → GND

   • Middle pin → A0

2. LEDs

• Green LED (Wet Waste) → Pin 9 (with 220Ω resistor to GND)

• Red LED (Dry Waste) → Pin 10 (with 220Ω resistor to GND)

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Arduino Sketch

int moisturePin = A0;     // Potentiometer as moisture sensor
int greenLED = 9;         // Wet waste indicator
int redLED = 10;          // Dry waste indicator
int moistureValue = 0;

void setup() {
  pinMode(greenLED, OUTPUT);
  pinMode(redLED, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  moistureValue = analogRead(moisturePin);  
  Serial.print("Moisture Value: ");
  Serial.println(moistureValue);

  if (moistureValue > 600) {          // High moisture = wet waste
    digitalWrite(greenLED, HIGH);
    digitalWrite(redLED, LOW);
  } else {                            // Low moisture = dry waste
    digitalWrite(greenLED, LOW);
    digitalWrite(redLED, HIGH);
  }

  delay(500);
}

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How It Works

1. The potentiometer simulates a moisture sensor:

   • Turning it one way increases analog value → simulating wet waste.

   • Turning the other way decreases value → simulating dry waste.

2. Arduino reads analog values (0–1023).

3. Threshold (600) decides classification:

   • Above 600 = Wet Waste → Green LED ON.

   • Below 600 = Dry Waste → Red LED ON.

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Common Mistakes & Quick Fixes

• Forgetting to connect potentiometer middle pin to A0 → always 0 reading.

• Not using a resistor with LEDs → LED may burn out.

• Using very small threshold → unstable switching.

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Viva / Check-Your-Understanding

1. What is the principle of a soil/moisture sensor?

2. Why do we use a potentiometer in Tinkercad instead of a moisture sensor?

3. How does Arduino distinguish between wet and dry waste?

4. What real-world applications can use this system?

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Extensions (Mini-Tasks)

• Add a buzzer to beep when wet waste is detected.

• Use Serial Plotter to visualize moisture changes.

• Classify three levels: Dry, Moist, and Wet using multiple thresholds.

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Lab Record (Suggested Headings)

1. Title

2. Objective

3. Components Used

4. Circuit Diagram (Tinkercad screenshot)

5. Arduino Program

6. Output

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Tinkercad Link

https://www.tinkercad.com/things/dIh5cIvwTpB-labset-prog-6