Smart Home Automation System

📘 Individual Debugging Code (Serial Monitor Testing One by One)

🎯 Objective of This Lesson

Students will:

• Test each sensor individually

• Verify correct wiring

• Calibrate thresholds

• Debug hardware issues

• Build confidence before full integration

We will test in this order:

1️⃣ DHT11
2️⃣ Ultrasonic Sensor
3️⃣ MQ3 Gas Sensor
4️⃣ Servo Motor
5️⃣ Relay Modules

🔹 STEP 1 – Test DHT11 (Temperature Sensor)

📌 Debug Code – DHT11

#include "DHT.h"

#define DHTPIN 4
#define DHTTYPE DHT11

DHT dht(DHTPIN, DHTTYPE);

void setup() {
Serial.begin(115200);
dht.begin();
Serial.println("DHT11 Test Started...");
}

void loop() {
float temp = dht.readTemperature();
float hum = dht.readHumidity();

Serial.print("Temperature: ");
Serial.print(temp);
Serial.print(" °C | Humidity: ");
Serial.print(hum);
Serial.println(" %");

delay(2000);
}

✅ Expected Output

Temperature: 28°C
Humidity: 60%

🔧 If Problem Occurs

• Check VCC (3.3V)

• Check DATA pin

• Add pull-up resistor if needed

🔹 STEP 2 – Test Ultrasonic Sensor (Water Level)

📌 Debug Code – Ultrasonic

#define TRIG 5
#define ECHO 18

long duration;
float distance;

void setup() {
Serial.begin(115200);
pinMode(TRIG, OUTPUT);
pinMode(ECHO, INPUT);
Serial.println("Ultrasonic Test Started...");
}

void loop() {

digitalWrite(TRIG, LOW);
delayMicroseconds(2);
digitalWrite(TRIG, HIGH);
delayMicroseconds(10);
digitalWrite(TRIG, LOW);

duration = pulseIn(ECHO, HIGH);
distance = duration * 0.034 / 2;

Serial.print("Distance: ");
Serial.print(distance);
Serial.println(" cm");

delay(1000);
}

✅ Expected Output

Distance: 25 cm

🔧 If Reading is 0 or Very Large

• Check wiring

• Ensure sensor facing object

• Verify 5V supply

🔹 STEP 3 – Test MQ3 Gas Sensor

📌 Debug Code – MQ3

#define MQ3_PIN 34

void setup() {
Serial.begin(115200);
Serial.println("MQ3 Test Started...");
delay(30000); // warm-up
}

void loop() {
int gasValue = analogRead(MQ3_PIN);

Serial.print("Gas Value: ");
Serial.println(gasValue);

delay(1000);
}

✅ Expected Values

Clean air: 300–600
Alcohol vapor: 1500+

🔧 Calibrate Threshold

Observe both values and choose midpoint.

🔹 STEP 4 – Test Servo Motor (Door Lock)

📌 Debug Code – Servo

#include <ESP32Servo.h>

Servo myServo;

void setup() {
Serial.begin(115200);
myServo.attach(13);
Serial.println("Servo Test Started...");
}

void loop() {

Serial.println("Lock Position");
myServo.write(0);
delay(3000);

Serial.println("Unlock Position");
myServo.write(90);
delay(3000);
}

✅ Expected Behavior

Servo rotates between 0° and 90°.

🔧 If Servo Vibrates

• Use external 5V supply

• Check common ground

• Avoid powering from ESP32 5V

🔹 STEP 5 – Test Relay Modules

📌 Debug Code – Relay

#define AC_RELAY 26
#define PUMP_RELAY 27

void setup() {
Serial.begin(115200);
pinMode(AC_RELAY, OUTPUT);
pinMode(PUMP_RELAY, OUTPUT);

Serial.println("Relay Test Started...");
}

void loop() {

Serial.println("AC ON");
digitalWrite(AC_RELAY, LOW);
delay(3000);

Serial.println("AC OFF");
digitalWrite(AC_RELAY, HIGH);
delay(3000);

Serial.println("Pump ON");
digitalWrite(PUMP_RELAY, LOW);
delay(3000);

Serial.println("Pump OFF");
digitalWrite(PUMP_RELAY, HIGH);
delay(3000);
}

⚠ Important

Many relay modules are:

LOW = ON
HIGH = OFF

Test and confirm.

🧠 Why This Lesson Is Critical

If something fails in final integration:

You will know exactly which module is faulty.

This prevents:

• Blind debugging

• Frustration

• Random code editing

🎓 Learning Outcomes

After this lesson, students will:

• Test sensors individually

• Calibrate readings

• Debug hardware problems

• Build confidence

• Follow professional workflow