Week 9 – Introduction to Interactive Media

Project: Dual-Control LED System with LDR Night Light and Button-Controlled LED

Concept

This project explores the integration of analog and digital controls using an LDR (Light Dependent Resistor) and a **button to control two LEDs. The first LED functions as an automatic night light, turning on in low-light conditions as detected by the LDR. The second LED is controlled by a button, which allows the user to toggle it on and off. This setup demonstrates the use of both analog and digital inputs to create interactive light control.

Design and Execution

Components
– LDR: Senses ambient light and provides analog input for the night light.
– Button: Serves as a digital switch for the second LED.
– LED 1: Acts as a night light that responds to light levels.
– LED 2: Controlled by the button for manual on/off functionality.
– 220Ω Resistors: Limit current to protect the LEDs.

Schematic Diagram

The circuit is designed on a breadboard, with the LDR setup on one side and the button on the other. Power and ground rails connect both sides to the Arduino.

1. LDR Circuit: Creates a voltage divider with a 10kΩ resistor connected to analog pin A0.
2. Button Circuit: Connected to digital pin 7 with an internal pull-up resistor enabled in the code.
3. LEDs: LED 1 is controlled by the LDR (analog), and LED 2 by the button (digital).

Code

// Dual-Control LED System: LDR and Button

// Pin definitions
const int led1 = 8;            // LED for night light (LDR-based)
const int sensorPin = A0;      // LDR sensor pin
const int buttonPin = 7;       // Button pin for second LED control
const int led2 = 9;            // Second LED pin (button-controlled)

// Threshold for LDR to turn on the night light
const int threshold = 500;     // Adjust based on ambient light

// Variables
int sensorValue;               // LDR sensor reading
int buttonState;               // Button state

void setup() {
  pinMode(led1, OUTPUT);             // Set LED1 as output
  pinMode(buttonPin, INPUT_PULLUP);  // Set button as input with pull-up
  pinMode(led2, OUTPUT);             // Set LED2 as output
  Serial.begin(9600);                // Initialize serial communication
}

void loop() {
  // LDR-controlled LED (Night Light)
  sensorValue = analogRead(sensorPin);  // Read LDR value
  Serial.println(sensorValue);          // Print for debugging
  
  if(sensorValue < threshold) {         // If below threshold, turn on LED1
    digitalWrite(led1, HIGH);
  } else {                              // Otherwise, turn off LED1
    digitalWrite(led1, LOW);
  }

  // Button-controlled LED
  buttonState = digitalRead(buttonPin); // Read button state
  if (buttonState == LOW) {             // If button is pressed
    digitalWrite(led2, HIGH);           // Turn on LED2
  } else {
    digitalWrite(led2, LOW);            // Turn off LED2
  }
  delay(100); // Small delay for stability
}

Observations

– Night Light Sensitivity: The LDR-based LED responds to ambient light, offering a basic “automatic night light” functionality. The threshold value can be adjusted to suit different lighting conditions.
– Button Responsiveness: The button controls the second LED reliably, allowing manual toggling.

Video Demonstration

https://drive.google.com/file/d/1wugSSY6orAYq02qOQg9335lDeIQAwCms/view?usp=drive_link

Reflection and Future Improvements

This project demonstrates the integration of analog and digital inputs for LED control, offering insights into how sensors can drive interactive behavior. Future improvements could include adding adjustable sensitivity for the night light or introducing more complex patterns for the button-controlled LED.

This project enhanced my understanding of basic sensor interactions, providing a foundation for more advanced input/output controls in Arduino projects.

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