8. Arduino Projects

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5.1 Weather Monitoring Station Using Temperature and Humidity Sensor

💧 Humidity Sensor (DHT22)

• The DHT-22 is a digital-output sensor for measuring relative humidity and temperature.
• Utilizes a capacitive humidity sensor and a thermistor.
• Outputs a digital signal via the data pin.
• This section guides on integrating this sensor with an Arduino UNO to display room temperature and humidity on the serial monitor.

Code:

// Include the DHT library to interact with the humidity and temperature sensor

#include “dht.h”

// Define the pin the DHT sensor is connected to (Analog Input A1)

#define dht_apin A1

// Include the Wire library for I2C devices (not used in this example, but typically required for sensor communication)

#include <Wire.h>

 

// Initialize the DHT library with the sensor type

dht DHT;

 

void setup(){

  // Begin serial communication at 9600 baud rate for output

  Serial.begin(9600);

  // Short delay to ensure that the serial communication is established

  delay(500);

  // Print a message to the serial monitor indicating the start of the program

  Serial.println(“DHT11 Humidity & temperature Sensor\n\n”);

  // Delay to ensure the sensor is ready for data reading

  delay(1000);

}

void loop(){

  // Read humidity and temperature data from the sensor

  DHT.read11(dht_apin);

 

  // Print the current humidity reading to the serial monitor

  Serial.print(“Current humidity = “);

  Serial.print(DHT.humidity);

  Serial.print(“%  “);

  // Print the current temperature reading to the serial monitor

  Serial.print(“temperature = “);

  Serial.print(DHT.temperature);

  Serial.println(“C “);

 

  // Wait 1 second before reading from the sensor again to prevent data flooding

  delay(1000);

}

📝 Arduino Code Overview

Initial Setup

#include “dht.h”

#define dht_apin A1 (Analog Pin connection)

#include <Wire.h>

Initialization:

Begin serial communication at 9600 baud rates.

Initial delays to stabilize system before sensor readout.

Setup message: “DHT11 Humidity & temperature Sensor\n\n”

Main Loop

Sensor reading with DHT.read11(dht_apin).

Displays current humidity (DHT.humidity) and temperature (DHT.temperature) in Celsius to the serial monitor.

Includes a 1-second delay before each sensor readout for data stability.

🔄 Operational Details

The program is crafted for both temperature and humidity data acquisition from a DHT11 sensor.

Unique points include:

Connection to an analog pin A1.

Sequential process: Initialize ➡ Print Setup Message ➡ Sensor Data Acquisition ➡ Display on Serial Monitor.

Utilizes delay for accurate and stable readings.

A practical application for environmental monitoring, potentially useful for climate control or environmental change detection.

Fire Alarm

🚨 Overview:

• An electronic device known as a fire alarm detects fire and alerts people to evacuate.
• 🔥 A flame sensor detects fire by sensing infrared radiation from flames.
• 🧠 An Arduino, a programmable small computer, can control electronic devices.
• 🔄 By connecting a flame sensor to an Arduino, the system can detect fire and trigger an alarm.

🚒 Operation:

• If the flame sensor detects fire, it sends a signal to the Arduino.
• 🎶 The Arduino then activates a buzzer, alerting people to the danger.
• This setup helps in extinguishing the fire early, preventing harm and damage.
• 

Arduino Code

//define variables to store the pin numbers for each component

int FLAME_SENSOR = 2; //digital pin 2

int BUZZER = 11; //digital pin 11

 

void setup() {

  //set the pinMode for each component

  pinMode(FLAME_SENSOR, INPUT); //flame sensor as input

  pinMode(BUZZER, OUTPUT); //buzzer as output

}

 

void loop() {

  //if the flame sensor detects a flame, turn on the buzzer and water pump

  if(digitalRead(FLAME_SENSOR)) {

    digitalWrite(BUZZER, HIGH); //turn on the buzzer

  }

  //if the flame sensor does not detect a flame, turn off the buzzer and water pump

  else {

    digitalWrite(BUZZER, LOW); //turn off the buzzer

  }

}

👨‍💻 Arduino Code Overview:

📌 Variable Definitions:

• int FLAME_SENSOR = 2; for the flame sensor connected to digital pin 2.
• int BUZZER = 11; for the buzzer connected to digital pin 11.

🛠 Setup Function:

• pin Mode (FLAME_SENSOR, INPUT); sets the flame sensor as input.
• pin Mode (BUZZER, OUTPUT); sets the buzzer as output.

🔁 Loop Function:

• If flame is detected (digital Read (FLAME_SENSOR) is TRUE), digital Write (BUZZER, HIGH); turns the buzzer on.
• If no flame is detected, digital Write (BUZZER, LOW); turns the buzzer off.

📖 Explanation:

• The code specifies pin connections for components and sets their modes (input or output).
• It continuously checks for flames, turning the buzzer on or off accordingly.
• This ensures the buzzer is activated upon fire detection, alerting for action

Flex sensor

🔍 Flex Sensor Overview

• 🌟 A flex sensor is a type of sensor that detects material bending.
• 📌 Typically made from flexible materials like plastic.
• 🔄 Can be bent to a certain degree, altering its resistance.
• 🛠️ Measured by Arduino to detect changes in bending.

🏗️ Applications

• 🤖 Robotics: Control movements of arms or hands.
• 🩺 Medical Devices: Monitor human body or limb movements.
• 🎮 Gaming: Control character movements with a flex sensor controller.
• 🎵 Musical Instruments: Adjust instrument sounds.

Arduino code to glow the LED in proportion to the bending of the flex sensor:

Arduino Code

int FLEX_PIN = A0; // connect the flex sensor to analog pin A0

int LED_PIN = 11; // connect the LED to digital pin 11

int flexValue = 0; // variable to store the value of the flex sensor

 

void setup() {

  pinMode(LED_PIN, OUTPUT); // set the LED pin as an output

  Serial.begin(9600); // initialize the serial communication

}

 

void loop() {

  flexValue = analogRead(FLEX_PIN); // read the value from the flex sensor

  Serial.print(“Flex Value: “); // print the value to the serial monitor

  Serial.println(flexValue);

 

  flexValue = map(flexValue, 0, 1023, 0, 255); // map the value to a range of 0-255

 

  analogWrite(LED_PIN, flexValue); // set the brightness of the LED based on the mapped value

  delay(100); // wait for 100 milliseconds

}

 

💻 Arduino Implementation

📝 Code Setup:

• int FLEX_PIN = A0; Connect flex sensor to analog pin A0.
• int LED_PIN = 11; Connect LED to digital pin 11.
• int flexValue = 0; Store flex sensor value.

🛠️ Function Setup:

• setup() Method:
• pinMode(LED_PIN, OUTPUT); Set LED pin as output.
• Serial.begin(9600); Start serial communication.

loop () Method:

• Read flex sensor: flexValue = analogRead(FLEX_PIN);
• Print value: Serial.print(“Flex Value: “); Serial.println(flexValue);
• Map sensor value: flexValue = map(flexValue, 0, 1023, 0, 255);
• Adjust LED brightness: analogWrite(LED_PIN, flexValue);
• Wait 100ms: delay(100);

🔧 Code Explanation:

• The flex sensor’s bending is read by analog pin A0.
• The LED’s brightness changes with the sensor’s bending.
• analogRead() reads the sensor, map() scales the value, analogWrite() sets LED brightness.
• Serial communication displays the sensor value on the monitor.
• The process repeats every 100 milliseconds.

Force sensor

🌐 Description:

• 🤖 A force sensor is an electronic device designed to measure force.
• 🔌 It converts force into an electrical signal for measurement and various applications.

📌 Applications:

• 🦾 In robotics, it gauges the force exerted by robot arms on objects.
• 🏥 In medical devices, it monitors force during surgery or rehabilitation exercises.

Here’s an example code that explains how to use a force sensor with Arduino:

Arduino Code

int forceSensorPin = A0; // connect force sensor to analog pin A0

int ledPin = 11; // connect LED to digital pin 11

 

void setup() {

  Serial.begin(9600); // initialize serial communication

  pinMode(ledPin, OUTPUT); // set LED pin as output

}

 

void loop() {

  int sensorValue = analogRead(forceSensorPin); // read force sensor value

  Serial.print(“Force sensor value: “);

  Serial.println(sensorValue); // print sensor value to serial monitor

 

  int brightness = map(sensorValue, 0, 1023, 0, 255); // map sensor value to LED brightness

 

  analogWrite(ledPin, brightness); // set LED brightness

}

Arduino Code Structure:

📂 Variables:

• int forceSensorPin = A0; ➡️ Connect force sensor to analog pin A0.
• int ledPin = 11; ➡️ Connect LED to digital pin 11.

🛠 Setup Function:

• Serial.begin(9600); ➡️ Initialize serial communication.
• pinMode(ledPin, OUTPUT); ➡️ Set LED pin as output.

🔁 Loop Function:

• Read sensor value: int sensorValue = analogRead(forceSensorPin);
• Print to serial: Serial.print(“Force sensor value: “); Serial.println(sensorValue);
• Map sensor value to brightness: int brightness = map(sensorValue, 0, 1023, 0, 255);
• Set LED brightness: analogWrite(ledPin, brightness);

📐 Tilt Sensor

• 🌐 A tilt sensor detects the orientation or tilt of an object.
• 🛠 Consists of a small metal ball or a mercury switch inside a metal canister.
• 🔁 When tilted, the ball/switch moves, altering an electrical connection to signal a change in orientation.

Here is an Arduino code with comments that explains how to use a tilt sensor to light up an LED when the sensor is tilted:

int tiltPin = 2;    // the digital pin connected to the tilt sensor

int ledPin = 11;    // the digital pin connected to the LED

 

void setup() {

  pinMode(tiltPin, INPUT);   // set the tilt sensor pin as input

  pinMode(ledPin, OUTPUT);   // set the LED pin as output

  Serial.begin(9600);        // initialize serial communication

}

 

void loop() {

  int tiltValue = digitalRead(tiltPin);   // read the tilt sensor value

 

  if (tiltValue == HIGH) {    // if the tilt sensor is tilted

    digitalWrite(ledPin, HIGH);   // turn on the LED

    Serial.println(“Tilted”);     // print “Tilted” on the serial monitor

  }

  else {                    // if the tilt sensor is not tilted

    digitalWrite(ledPin, LOW);    // turn off the LED

    Serial.println(“Not tilted”);   // print “Not tilted” on the serial monitor

  }

 

  delay(100);   // wait for 100 milliseconds before reading again

}

🔌 Arduino Code for Tilt Sensor

📝 Setup:

• 🔵 int tiltPin = 2; ➡️ Digital pin for the tilt sensor.
• 🔴 int ledPin = 11; ➡️ Digital pin for the LED.
• 🔄 void setup():
• 📥 Sets tilt sensor pin as input.
• 💡 Sets LED pin as output.
• 📡 Initializes serial communication.

♾ Loop:

• void loop ():
• 📊 Reads tilt sensor value.
• 🚦 If tilted:
• 💡 Turns on the LED.
• 🖨 Prints “Tilted” on the serial monitor.
• 🚦 If not tilted:
• 💡 Turns off the LED.
• 🖨 Prints “Not tilted” on the serial monitor.
• ⏲ Waits 100 milliseconds before the next read.

🔧 Functionality:

• 🔄 When tilted, digitalRead() from tiltPin is HIGH ➡️ LED turns on.
• 🔄 When not tilted, digitalRead() is LOW ➡️ LED turns off.
• 📋 Uses Serial.println() to indicate tilt status on the serial monitor.

Smart streetlight

🚦 Smart Street Light

🛠 Smart Street Light Project using Arduino, LDR, and IR Sensors

• 🌞 Daytime Detection: Utilizes LDR (Light Dependent Resistor) to detect sunlight, automatically turning off LED street lights.
• 🌜 Nighttime Activation: Employs an IR (Infrared Sensor) to detect darkness, subsequently turning on LED street lights.

 

int OUTPIN = 13;

int INPIN = 2;

//LiquidCrystal lcd( 8,9,4,5,6,7 );  //interfacing pins

void setup() {

  //put your setup code here, to run once:

  pinMode(INPIN, INPUT);

  pinMode(OUTPIN, OUTPUT);

 

  Serial.begin(9600); // // Serial Communication is starting with 9600 of baudrate speed

  Serial.println(“LDR Sensor DEMO”); // print some text in Serial Monitor

}

void loop() {

  //put your main code here, to run repeatedly:

  if(digitalRead(INPIN)) {

    digitalWrite(OUTPIN, false);

    Serial.println(“1”);

  }

  else {

    digitalWrite(OUTPIN, true);

    Serial.println(“0”);

  }

}

🔍 Applications of LDR

• 🌌 Astronomy: Used in infrared astronomy.
• 🚨 Safety Alarms: Integral to light failure alarm circuits and light meters.
• 🚒 Smoke Detection: A key component in smoke detectors.
• 📺 Television: Enhances automatic contrast and brightness control in TVs.
• 🔄 Relays: Found in photosensitive relays.
• 🔑 Security: Utilized in optical coding.

🚀 Smart Blind Stick

🔍 Project Overview:

🎯 Main Goal:

• Detect obstacles in front of the electronic stick and trigger an alarm.

🚶 User Assistance:

• Helps blind individuals during walks by providing an alarm if any hurdle is detected within the set range.

📏 Distance Measurement:

• Utilizes an ultrasonic sensor to determine the distance of obstacles.

🔊 Alarm Intensity:

• Slow beep for far obstacles (e.g., 100 cm), faster beep as obstacles get closer, aiding in understanding the obstacle’s distance.
• The main aim of this project is to detect the obstacle in front of the electronic stick and giving the alarm.

#define trigPin 2 //attach pin D2 Arduino to pin Trig of HC-SR04

#define echoPin 3 // attach pin D3 Arduino to pin Echo of HC-SR04

#define buzzerPin 11

// defines variables

long duration; // variable for the duration of sound wave travel

int distance; // variable for the distance measurement

void setup() {

  pinMode(trigPin, OUTPUT); // Sets the trigPin as an OUTPUT

  pinMode(echoPin, INPUT); // Sets the echoPin as an INPUT

  pinMode(buzzerPin, OUTPUT); // Sets the echoPin as an INPUT

  Serial.begin(9600); // // Serial Communication is starting with 9600 of baudrate speed

  Serial.println(“Ultrasonic Sensor HC-SR04 Test”); // print some text in Serial Monitor

  Serial.println(“with Arduino UNO R3”);

}

void loop() {

  // Clears the trigPin condition

  digitalWrite(trigPin, LOW);

  delayMicroseconds(2);

  // Sets the trigPin HIGH (ACTIVE) for 10 microseconds

  digitalWrite(trigPin, HIGH);

  delayMicroseconds(10);

  digitalWrite(trigPin, LOW);

  // Reads the echoPin, returns the sound wave travel time in microseconds

  duration = pulseIn(echoPin, HIGH);

  // Calculating the distance

  distance = duration * 0.034 / 2; // Speed of sound wave divided by 2 (go and back)

  // Displays the distance on the Serial Monitor

  if (distance < 30)

  {

      digitalWrite(buzzerPin, HIGH);

      delay(30);

      digitalWrite(buzzerPin, LOW);

      delay(30); 

  }

  if (distance > 30 && distance < 50)

  {

      digitalWrite(buzzerPin, HIGH);

      delay(60);

      digitalWrite(buzzerPin, LOW);

      delay(60); 

  }

  if (distance > 50 && distance < 70)

  {

      digitalWrite(buzzerPin, HIGH);

      delay(100);

      digitalWrite(buzzerPin, LOW);

      delay(100); 

  }

  if (distance > 70 && distance < 100)

  {

      digitalWrite(buzzerPin, HIGH);

      delay(200);

      digitalWrite(buzzerPin, LOW);

      delay(200)        ;

  }

  Serial.print(“Distance: “);

  Serial.print(distance);

  Serial.println(” cm”);

  delay(50);

}

💻 Code Setup:

📌 Pin Configuration:

• #define trigPin 2 : D2 on Arduino to Trig on HC-SR04.
• #define echoPin 3 : D3 on Arduino to Echo on HC-SR04.
• #define buzzerPin 11

📊 Variables:

• long duration; : Duration of sound wave travel.
• int distance; : Distance measurement.

🔄 Initialization:

🔧 Setup Function:

• Sets trigPin as OUTPUT.
• Sets echoPin as INPUT.
• Sets buzzerPin as OUTPUT.
• Starts Serial Communication at 9600 baudrate.
• Prints test message on Serial Monitor.

🔄 Main Loop:

📡 Triggering Ultrasonic Sensor:

• Clears trigPin, sets it HIGH for 10 microseconds, then LOW.

📏 Distance Calculation:

• Reads echoPin, calculates distance using sound wave speed.

🔊 Distance-Based Buzzer Alert:

• <30 cm: Buzzer HIGH for 30ms intervals.
• 30-50 cm: Buzzer HIGH for 60ms intervals.
• 50-70 cm: Buzzer HIGH for 100ms intervals.
• 70-100 cm: Buzzer HIGH for 200ms intervals.

🖥️ Serial Monitor Display:

• Prints distance in cm.

⏲️ Loop Delay: 50ms.