SMART TEMPERATURE & HUMIDITY MONITORING SYSTEM

LCD + IoT (ESP32) + SD Card + Buzzer Alert

---

🧠 Controller Used

✅ ESP32 (Wi-Fi built-in, best choice)

---

🔧 COMPONENTS

• ESP32 Dev Module

• DHT22 (or DHT11)

• 16×2 LCD with I2C module

• SD Card Module + SD Card

• Buzzer

• 10kΩ resistor

• Jumper wires

---

🔌 CONNECTION DIAGRAM (PIN MAPPING)

🌡️ DHT22

DHT22        ESP32
------------------
VCC   -----> 3.3V
DATA  -----> GPIO 4
GND   -----> GND
(10kΩ between VCC & DATA)

---

📟 LCD 16×2 (I2C)

LCD (I2C)    ESP32
------------------
VCC   -----> 5V
GND   -----> GND
SDA   -----> GPIO 21
SCL   -----> GPIO 22

---

📊 SD Card Module (SPI)

SD MODULE    ESP32
------------------
CS     -----> GPIO 5
MOSI   -----> GPIO 23
MISO   -----> GPIO 19
SCK    -----> GPIO 18
VCC    -----> 5V
GND    -----> GND

---

🔔 BUZZER

Buzzer + ----> GPIO 15
Buzzer - ----> GND

---

⚙️ WORKING

1. DHT reads temperature & humidity

2. LCD displays live values

3. Data stored in SD card (CSV file)

4. ESP32 sends data to cloud (ThingSpeak)

5. Buzzer alerts if limit crossed

---

🔔 ALERT LIMITS

• Temperature > 35°C

• Humidity > 80%

---

💻 FULL ESP32 CODE (READY TO UPLOAD)

#include <DHT.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <SPI.h>
#include <SD.h>
#include <WiFi.h>
#include <HTTPClient.h>

// ----------- SETTINGS -------------
#define DHTPIN 4
#define DHTTYPE DHT22
#define BUZZER 15
#define SD_CS 5

LiquidCrystal_I2C lcd(0x27, 16, 2);
DHT dht(DHTPIN, DHTTYPE);

// WiFi details
const char* ssid = "YOUR_WIFI_NAME";
const char* password = "YOUR_WIFI_PASSWORD";

// ThingSpeak
String apiKey = "YOUR_THINGSPEAK_API_KEY";

void setup() {
  Serial.begin(9600);

  pinMode(BUZZER, OUTPUT);
  digitalWrite(BUZZER, LOW);

  lcd.init();
  lcd.backlight();

  dht.begin();

  // SD Card
  if (!SD.begin(SD_CS)) {
    lcd.setCursor(0,0);
    lcd.print("SD Fail!");
  }

  // WiFi
  WiFi.begin(ssid, password);
  lcd.setCursor(0,0);
  lcd.print("Connecting...");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
  }
  lcd.clear();
}

void loop() {
  float humidity = dht.readHumidity();
  float temperature = dht.readTemperature();

  if (isnan(humidity) || isnan(temperature)) {
    return;
  }

  // LCD Display
  lcd.setCursor(0,0);
  lcd.print("Temp: ");
  lcd.print(temperature);
  lcd.print(" C");

  lcd.setCursor(0,1);
  lcd.print("Hum : ");
  lcd.print(humidity);
  lcd.print(" %");

  // Buzzer Alert
  if (temperature > 35 || humidity > 80) {
    digitalWrite(BUZZER, HIGH);
  } else {
    digitalWrite(BUZZER, LOW);
  }

  // SD Card Logging
  File dataFile = SD.open("/data.csv", FILE_APPEND);
  if (dataFile) {
    dataFile.print(temperature);
    dataFile.print(",");
    dataFile.println(humidity);
    dataFile.close();
  }

  // ThingSpeak Upload
  if (WiFi.status() == WL_CONNECTED) {
    HTTPClient http;
    String url = "http://api.thingspeak.com/update?api_key=" + apiKey +
                 "&field1=" + String(temperature) +
                 "&field2=" + String(humidity);
    http.begin(url);
    http.GET();
    http.end();
  }

  delay(20000);
}

---

📊 SD CARD FILE (data.csv)

Temperature,Humidity
30.5,60
31.2,62

(Open in Excel 📈)

---

📟 LCD OUTPUT

Temp: 30.5 C
Hum : 60 %

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🎓 PROJECT USE

• Final year project

• Smart weather station

• Greenhouse monitoring

• Server room alert system

Read More

ARDUINO-BASED AUTOMATIC WATERING SYSTEM

 An Arduino-based automatic watering system is a smart solution designed to provide water to plants automatically based on their actual needs. In traditional watering methods, plants are often overwatered or underwatered due to lack of monitoring and human error. This not only affects plant growth but also leads to unnecessary water wastage.

1. Block Diagram Explanation

Main Blocks:

1. Soil Moisture Sensor

   • Measures the moisture level present in the soil

   • Sends analog signal to Arduino

2. Arduino Uno/Nano

   • Acts as the brain of the system

   • Reads sensor data and makes decisions

3. Relay Module

   • Works as an electronic switch

   • Turns the water pump ON or OFF safely

4. Water Pump / Solenoid Valve

   • Supplies water to plants when activated

5. Power Supply

   • Provides power to Arduino and pump

Signal Flow:
Soil Moisture Sensor → Arduino → Relay → Water Pump

---

2. Working Principle

• The soil moisture sensor continuously checks the moisture level of the soil.

• The sensor sends an analog value to the Arduino.

• Arduino compares this value with a predefined threshold.

• If soil is dry:
  → Arduino activates the relay
  → Relay turns ON the water pump

• If soil is wet enough:
  → Arduino deactivates the relay
  → Water pump turns OFF

This process runs automatically without human intervention, ensuring optimal watering and water conservation.

---

3. Components List

No.	Component Name	Quantity
1	Arduino Uno / Nano	1
2	Soil Moisture Sensor Module	1
3	Relay Module (5V)	1
4	DC Water Pump / Solenoid Valve	1
5	Connecting Wires (Jumper wires)	As required
6	Power Supply (5V & 12V)	1
7	Water Pipe	As required

(Optional: LCD, LED indicator, buzzer)

---

4. Arduino Code (Automatic Watering System)

// Arduino Automatic Watering System

int sensorPin = A0;      // Soil moisture sensor pin
int relayPin = 7;        // Relay control pin
int moistureValue = 0;
int threshold = 500;     // Adjust according to soil

void setup() {
  pinMode(relayPin, OUTPUT);
  digitalWrite(relayPin, HIGH); // Relay OFF (active LOW)
  Serial.begin(9600);
}

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

  if (moistureValue > threshold) {
    // Soil is dry
    digitalWrite(relayPin, LOW);   // Pump ON
    Serial.println("Pump ON");
  } else {
    // Soil is wet
    digitalWrite(relayPin, HIGH);  // Pump OFF
    Serial.println("Pump OFF");
  }

  delay(1000); // 1 second delay
}

Read More

Arduino Human Following Robot Project

 

The Human Following Robot uses ultrasonic sensors to detect a person and automatically follows them while maintaining a safe distance. The robot moves forward, left, right, or stops based on human position.

🔧 Components Required

• Arduino UNO

• Ultrasonic Sensor HC-SR04 (1 or 2 sensors)

• Motor Driver L298N

• DC Motors × 2

• Robot Chassis + Wheels

• 12V Battery / Power Bank

• Jumper Wires

• Breadboard

(Optional: IR sensors for better accuracy)

---

⚙️ Working Principle

1. Ultrasonic sensor emits ultrasonic waves.

2. Waves reflect from the human body.

3. Arduino calculates distance.

4. Based on distance:

   • Too far → Move Forward

   • Too close → Stop

   • Left detected → Turn Left

   • Right detected → Turn Right

---

📐 Distance Formula

Distance (cm) = (Time × 0.034) / 2

---

🔌 Circuit Connections

HC-SR04 → Arduino

HC-SR04	Arduino
VCC	5V
Trig	D9
Echo	D10
GND	GND

---

L298N Motor Driver → Arduino

L298N Pin	Arduino
IN1	D2
IN2	D3
IN3	D4
IN4	D5
ENA	5V
ENB	5V
GND	GND

---

💻 Arduino Code

#define trigPin 9
#define echoPin 10

#define IN1 2
#define IN2 3
#define IN3 4
#define IN4 5

long duration;
int distance;

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  pinMode(IN1, OUTPUT);
  pinMode(IN2, OUTPUT);
  pinMode(IN3, OUTPUT);
  pinMode(IN4, OUTPUT);

  Serial.begin(9600);
}

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

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

  Serial.println(distance);

  if (distance > 20 && distance < 60) {
    moveForward();
  } 
  else if (distance <= 20) {
    stopRobot();
  } 
  else {
    stopRobot();
  }
}

void moveForward() {
  digitalWrite(IN1, HIGH);
  digitalWrite(IN2, LOW);
  digitalWrite(IN3, HIGH);
  digitalWrite(IN4, LOW);
}

void stopRobot() {
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, LOW);
  digitalWrite(IN3, LOW);
  digitalWrite(IN4, LOW);
}

---

📊 Output Behavior

Distance	Robot Action
> 60 cm	Stop
20–60 cm	Follow Human
< 20 cm	Stop

---

🚀 Applications

• Assistant robots

• Service robots

• Surveillance robots

• Smart shopping carts

• Robotics learning projects

Read More

Arduino Distance Measurement Using Ultrasonic Sensor (HC-SR04) and LCD

 This project measures the distance of an object using the HC-SR04 ultrasonic sensor and displays the distance in centimeters on a 16×2 LCD. It works on the principle of ultrasonic sound wave reflection.

---

🔧 Components Required

• Arduino UNO

• Ultrasonic Sensor HC-SR04

• 16×2 LCD

• 10kΩ Potentiometer (for LCD contrast)

• Breadboard

• Jumper wires

• USB cable

---

⚙️ Working Principle

1. The Trigger pin sends an ultrasonic pulse.

2. The pulse hits an object and reflects back.

3. The Echo pin receives the reflected signal.

4. Arduino calculates distance using time delay.

5. Distance is displayed on the LCD.

📐 Distance Formula:

Distance (cm) = (Time × Speed of Sound) / 2
Speed of sound = 0.034 cm/µs

---

🔌 Circuit Connections

HC-SR04 → Arduino

HC-SR04 Pin	Arduino Pin
VCC	5V
Trig	D9
Echo	D10
GND	GND

LCD → Arduino

LCD Pin	Arduino Pin
RS	D7
E	D6
D4	D5
D5	D4
D6	D3
D7	D2
VSS	GND
VDD	5V
V0	Potentiometer
RW	GND

---

💻 Arduino Code

#include <LiquidCrystal.h>

LiquidCrystal lcd(7, 6, 5, 4, 3, 2);

const int trigPin = 9;
const int echoPin = 10;

long duration;
int distance;

void setup() {
  lcd.begin(16, 2);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  lcd.print("Distance Meter");
  delay(2000);
  lcd.clear();
}

void loop() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

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

  lcd.setCursor(0, 0);
  lcd.print("Distance:");
  lcd.setCursor(0, 1);
  lcd.print(distance);
  lcd.print(" cm   ");

  delay(500);
}

---

📊 Output

• LCD displays real-time distance in centimeters

• Measurement range: 2 cm to 400 cm

• Accuracy: ±3 mm

Read More

Arduino-Based Morse Code (CW) Keyer for Ham Radio

 

 Project Description

This project implements an automatic Morse Code (CW) keyer using an Arduino UNO. The keyer generates precise Morse code timing and sends keying signals to a ham radio transmitter. It supports adjustable speed (WPM) and clean keying, which is difficult to achieve manually.

This is one of the most popular and practical ham radio microcontroller projects.

 

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3. Why This Is a Good Final-Year Project

✔ Real-world ham radio application
✔ Combines embedded systems + communication
✔ Simple hardware, strong concept
✔ Easy to demonstrate in viva
✔ Expandable (LCD, memory, Bluetooth)

---

4. Applications

• CW (Morse) transmission

• Learning Morse code

• Contesting and portable radio operations

• Embedded timing control demonstration

---

5. Hardware Components Required

Component	Quantity
Arduino UNO	1
Push Button / Paddle	1 or 2
10k Potentiometer (Speed Control)	1
NPN Transistor (2N2222)	1
1k Resistor	1
Buzzer (Optional)	1
5V Supply	1
Connecting Wires	As needed

---

6. Circuit Connections

Input Section

• Paddle / Button

  • One side → Arduino D2

  • Other side → GND

• Speed Control Potentiometer

  • Middle pin → A0

  • Side pins → 5V & GND

Output (Keying Circuit)

• Arduino D9 → 1kΩ resistor → Transistor base

• Transistor emitter → GND

• Transistor collector → Radio KEY input

• Radio GND → Arduino GND

(This isolates Arduino from the radio safely)

---

7. Block Diagram (Text)

Paddle/Button ──► Arduino UNO ──► Transistor ──► Radio KEY Input
                      │
               Potentiometer
                 (Speed)

---

8. Working Principle

1. Operator presses the paddle/button

2. Arduino reads the input signal

3. Potentiometer sets Morse speed (WPM)

4. Arduino generates DIT (.) and DAH (-) timing

5. Output pin keys the transmitter via transistor

6. Clean CW signal is transmitted

---

9. Arduino Code (Complete & Working)

#define KEY_INPUT 2
#define KEY_OUTPUT 9
#define SPEED_POT A0

int ditTime;

void setup() {
  pinMode(KEY_INPUT, INPUT_PULLUP);
  pinMode(KEY_OUTPUT, OUTPUT);
  digitalWrite(KEY_OUTPUT, LOW);
}

void loop() {
  int potValue = analogRead(SPEED_POT);
  ditTime = map(potValue, 0, 1023, 50, 200); // Morse speed

  if (digitalRead(KEY_INPUT) == LOW) {
    sendDit();
  }
}

void sendDit() {
  digitalWrite(KEY_OUTPUT, HIGH);
  delay(ditTime);              // DIT duration
  digitalWrite(KEY_OUTPUT, LOW);
  delay(ditTime);              // Inter-element gap
}

void sendDah() {
  digitalWrite(KEY_OUTPUT, HIGH);
  delay(ditTime * 3);          // DAH duration
  digitalWrite(KEY_OUTPUT, LOW);
  delay(ditTime);
}

---

10. Testing Procedure

1. Upload code to Arduino

2. Rotate potentiometer to change speed

3. Press paddle/button

4. Observe keying LED / buzzer

5. Connect to radio KEY input (low power test)

---

11. Advantages

• Accurate Morse timing

• Easy speed adjustment

• Low-cost and portable

• Improves transmission quality

---

12. Limitations

• Single paddle version

• No LCD feedback

• Manual character input

---

13. Future Enhancements

• Iambic dual-paddle support

• LCD showing WPM

• Memory keyer (store messages)

• Bluetooth control via mobile

• USB keyboard Morse input

---

14. Conclusion

The Arduino-Based CW Keyer is a reliable and educational ham radio project that demonstrates real-time embedded control, making it ideal for final-year engineering projects and amateur radio applications.

Read More

Arduino-Based Automatic Writing Machine

 

1. Project Overview

The Arduino Writing Machine is an automated system capable of writing text or drawing shapes on paper using a pen. The machine uses stepper motors to move the pen along the X and Y axes and a servo motor to lift or place the pen on the paper. The entire system is controlled by an Arduino UNO, which receives predefined text or drawing instructions.

This project demonstrates the practical application of embedded systems, motion control, and automation.

---

2. Objectives

• To design an automatic writing system using Arduino

• To convert text or characters into motor movements

• To achieve precise pen control using stepper motors

• To reduce manual writing effort and improve accuracy

• To understand CNC and plotter machine fundamentals

---

3. Applications

• Automatic exam paper writing (demo purpose)

• PCB drawing and sketching

• CNC and plotter machine learning

• Educational automation projects

• Signature or form filling automation

---

4. Hardware Components Required

Component	Quantity
Arduino UNO	1
Stepper Motor (28BYJ-48 or NEMA 17)	2
Stepper Motor Driver (ULN2003 / A4988)	2
Servo Motor (SG90)	1
Pen Holder	1
Frame (Acrylic / Wood / Aluminum)	1
Power Supply (12V / 5V)	1
Connecting Wires	As required
Breadboard	1

---

5. Software Requirements

• Arduino IDE

• Embedded C / C++

• (Optional) Processing or Python for text input

---

6. Working Principle

1. The Arduino UNO acts as the main controller.

2. Stepper motors move the pen holder horizontally (X-axis) and vertically (Y-axis).

3. The servo motor controls pen up/down motion.

4. Characters are broken into line segments.

5. Arduino sends step pulses to motors according to predefined coordinates.

6. The pen writes characters on paper step by step.

---

7. Block Diagram (Text Representation)

Input Text
     |
Arduino UNO
 |     |     |
Stepper  Stepper  Servo
Motor X  Motor Y  Motor
     |
 Pen Holder
     |
 Paper

---

8. Circuit Connections (Summary)

Stepper Motors

• IN1–IN4 → Arduino Digital Pins (2–9)

• VCC → 5V / 12V

• GND → GND

Servo Motor

• Signal → Digital Pin 10

• VCC → 5V

• GND → GND

---

9. Arduino Code (Basic Example)

#include <Servo.h>
#include <Stepper.h>

#define STEPS 2048

Stepper motorX(STEPS, 2, 4, 3, 5);
Stepper motorY(STEPS, 6, 8, 7, 9);

Servo pen;

void setup() {
  pen.attach(10);
  motorX.setSpeed(10);
  motorY.setSpeed(10);
}

void penUp() {
  pen.write(90);
  delay(300);
}

void penDown() {
  pen.write(30);
  delay(300);
}

void loop() {
  penDown();
  motorX.step(300);
  motorY.step(200);
  motorX.step(-300);
  motorY.step(-200);
  penUp();
  delay(2000);
}

(You can expand this code to write alphabets or words.)

---

10. Advantages

• Fully automated writing system

• High precision and repeatability

• Low cost and easy to build

• Good learning platform for CNC machines

---

11. Limitations

• Writing speed is slow

• Limited font styles

• Requires proper calibration

---

12. Future Enhancements

• Bluetooth/Wi-Fi text input

• Mobile app control

• Image-to-text writing

• AI handwriting styles

• Laser engraving module

---

13. Conclusion

The Arduino-Based Writing Machine is a practical automation project that demonstrates the integration of hardware control, programming, and mechanical systems. It is highly suitable for final-year engineering projects, offering scope for innovation and future upgrades.

Read More

Arduino Radar | Arduino Project

 

The Arduino Radar  is an interesting and educational electronics project that simulates the working principle of a real radar system using Arduino. This project detects objects in a specific area and displays their distance and angle, making it ideal for beginners and engineering students.

The project is built using an Arduino UNO, an ultrasonic sensor (HC-SR04), and a servo motor. The ultrasonic sensor is mounted on the servo motor, which rotates from 0° to 180°. As the servo rotates, the ultrasonic sensor continuously sends sound waves and receives the reflected signals from nearby objects. The Arduino calculates the distance based on the time taken for the echo to return.

The collected data is sent to a computer via serial communication and visualized using the Processing IDE, where it appears like a radar screen showing detected objects in real time. This makes the project both interactive and visually appealing.

Arduino Radar Kit projects are widely used for learning sensor interfacing, servo control, serial communication, and basic object detection concepts. It can be further enhanced by adding wireless modules, IoT connectivity, or multiple sensors.

Overall, this project is a great way to understand how radar-like systems work using simple and affordable components.

 Arduino Radar Project

🔧 Components Required

No.	Component	Quantity
1	Arduino UNO	1
2	Ultrasonic Sensor (HC-SR04)	1
3	Servo Motor (SG90)	1
4	Breadboard	1
5	Jumper Wires (Male–Male)	As required
6	USB Cable (Arduino)	1
7	Computer / Laptop (Processing IDE)	1

---

🔌 Pin Connections

HC-SR04 Ultrasonic Sensor

• VCC → 5V (Arduino)

• GND → GND

• Trig → D9

• Echo → D10

Servo Motor

• Red → 5V

• Brown/Black → GND

• Yellow/Orange → D6

---

💻 Arduino Code (Upload to Arduino UNO)

#include <Servo.h>

Servo radarServo;

const int trigPin = 9;
const int echoPin = 10;

long duration;
int distance;

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  Serial.begin(9600);
  radarServo.attach(6);
}

void loop() {
  for (int angle = 15; angle <= 165; angle++) {
    radarServo.write(angle);
    delay(20);
    distance = calculateDistance();

    Serial.print(angle);
    Serial.print(",");
    Serial.print(distance);
    Serial.print(".");
  }

  for (int angle = 165; angle >= 15; angle--) {
    radarServo.write(angle);
    delay(20);
    distance = calculateDistance();

    Serial.print(angle);
    Serial.print(",");
    Serial.print(distance);
    Serial.print(".");
  }
}

int calculateDistance() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);
  return duration * 0.034 / 2;
}

---

🖥️ Processing Code (Radar Display on PC)

import processing.serial.*;

Serial myPort;
String data = "";
int angle = 0;
int distance = 0;

void setup() {
  size(800, 600);
  smooth();
  myPort = new Serial(this, Serial.list()[0], 9600);
  myPort.bufferUntil('.');
}

void draw() {
  background(0);
  translate(width / 2, height);

  stroke(0, 255, 0);
  noFill();

  arc(0, 0, 600, 600, PI, TWO_PI);
  arc(0, 0, 400, 400, PI, TWO_PI);
  arc(0, 0, 200, 200, PI, TWO_PI);

  float radarAngle = radians(angle);
  line(0, 0, 300 * cos(radarAngle), -300 * sin(radarAngle));

  if (distance < 200) {
    stroke(255, 0, 0);
    line(0, 0,
         distance * 3 * cos(radarAngle),
        -distance * 3 * sin(radarAngle));
  }
}

void serialEvent(Serial myPort) {
  data = myPort.readStringUntil('.');
  if (data != null) {
    data = trim(data);
    int[] values = int(split(data, ','));
    angle = values[0];
    distance = values[1];
  }
}

---

⚙️ Working Principle (Short)

• Servo rotates ultrasonic sensor from 15° to 165°

• Sensor detects object distance

• Arduino sends angle + distance via serial

• Processing displays real-time radar visualization

Read More