Control devices are integral to various applications, from home automation to industrial systems. Using Arduino, a versatile and user-friendly microcontroller platform, you can control devices such as lights, motors, and sensors with ease. This article will guide you through the process of setting up and controlling devices using Arduino, highlighting its importance in simplifying complex control systems. Adjustments have been made to ensure compatibility with the Arduino environment, providing code examples and detailed instructions.

Project: In this example project, we will create a simple home automation system to control a light and a fan using an Arduino. The objectives of this project are to understand how to interface relays with Arduino, control devices through digital signals, and implement basic automation logic. The functionalities include turning the light and fan on or off based on specific conditions, such as a button press or a temperature threshold.

Components List:

• Arduino Uno (1)
• Relay Module (2-channel) (1)
• Push Button (2)
• DHT11 Temperature and Humidity Sensor (1)
• LED (1)
• Fan (1)
• 220Ω Resistor (1)
• Breadboard (1)
• Jumper Wires (various)

Examples:

// Include necessary libraries
#include <DHT.h>

// Define pin connections
#define LIGHT_RELAY_PIN 2
#define FAN_RELAY_PIN 3
#define BUTTON_PIN 4
#define DHT_PIN 5
#define DHT_TYPE DHT11

// Initialize the DHT sensor
DHT dht(DHT_PIN, DHT_TYPE);

void setup() {
  // Initialize serial communication
  Serial.begin(9600);

  // Set relay pins as output
  pinMode(LIGHT_RELAY_PIN, OUTPUT);
  pinMode(FAN_RELAY_PIN, OUTPUT);

  // Set button pin as input
  pinMode(BUTTON_PIN, INPUT_PULLUP);

  // Initialize the DHT sensor
  dht.begin();

  // Initially turn off the relays
  digitalWrite(LIGHT_RELAY_PIN, HIGH);
  digitalWrite(FAN_RELAY_PIN, HIGH);
}

void loop() {
  // Read the button state
  int buttonState = digitalRead(BUTTON_PIN);

  // Read temperature and humidity
  float temperature = dht.readTemperature();
  float humidity = dht.readHumidity();

  // Print temperature and humidity values to the serial monitor
  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.print(" °C, Humidity: ");
  Serial.print(humidity);
  Serial.println(" %");

  // Control light based on button press
  if (buttonState == LOW) {
    digitalWrite(LIGHT_RELAY_PIN, LOW); // Turn on the light
  } else {
    digitalWrite(LIGHT_RELAY_PIN, HIGH); // Turn off the light
  }

  // Control fan based on temperature threshold
  if (temperature > 25.0) {
    digitalWrite(FAN_RELAY_PIN, LOW); // Turn on the fan
  } else {
    digitalWrite(FAN_RELAY_PIN, HIGH); // Turn off the fan
  }

  // Add a small delay to avoid bouncing issues
  delay(200);
}

Explanation:

1. Libraries and Pin Definitions: The DHT library is included for temperature and humidity sensing. Pin numbers for the relays, button, and DHT sensor are defined.
2. Setup Function: Serial communication is initialized for debugging. Relay pins are set as outputs, and the button pin is set as an input with an internal pull-up resistor. The DHT sensor is initialized, and the relays are turned off initially.
3. Loop Function: The button state is read, and temperature and humidity values are obtained from the DHT sensor. These values are printed to the serial monitor for debugging. The light is controlled based on the button state, and the fan is controlled based on a temperature threshold.