Arduino-Button-LED-Toggle-With-Debounce

Learn how to use a pushbutton to toggle an LED on and off with simple software debouncing in Arduino.

🎯 Introduction / Objective

This project demonstrates how to control an LED using a pushbutton on an Arduino board.
Unlike a basic circuit where the LED stays ON only while the button is pressed, this version introduces a toggle feature —
pressing the button once turns the LED ON, and pressing it again turns it OFF.

To make the input more reliable, the project also includes simple debouncing logic, which prevents false triggers caused by the mechanical “bounce” of the button.

🔹 Goal: Learn how to use digital inputs and outputs together, implement state change detection, and apply software debouncing in Arduino.

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⚙️ Components Used

Component	Quantity	Description
Arduino UNO	1	Microcontroller board used to run the code
Breadboard	1	For connecting the circuit without soldering
LED (any color)	1	Visual output indicator
Pushbutton	1	Input device to control the LED
Resistor 220Ω	1	Limits current to the LED
Resistor 10kΩ	1	Used as a pull-down resistor for the button
Jumper Wires	As needed	For making connections

💡 Note: In my prototype, I used a 10 kΩ resistor for the LED because I didn’t have a 220 Ω one available.
The LED still worked but was very dim. Recommended value: 220 Ω.

🔌 Circuit Diagram / Wiring

Connections:

• Digital Pin 13 → Resistor (220Ω) → LED Anode (+)
• LED Cathode (–) → GND
• Pushbutton one side → +5V
• Pushbutton other side → Digital Pin 2
• 10kΩ resistor between Pin 2 and GND (pull-down resistor)

🔌 Circuit Diagram / Wiring

Breadboard View

Schematic View

⚙️ How It Works

This project demonstrates how a pushbutton switch can be used to toggle an LED ON and OFF using an Arduino, even after the button is released.

Unlike a simple circuit where the LED only lights while the button is held down, this version uses state change detection and debouncing logic so each press changes the LED’s state cleanly — once ON, once OFF.

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🔹 Step-by-Step Explanation

1. LED Connection:
   The LED is connected to digital pin 13 through a 220 Ω resistor to limit current and protect the LED.

2. Pushbutton Connection:
   The pushbutton is connected to digital pin 2.

3. Pull-down Resistor (10 kΩ):
   Keeps the input pin LOW (0) when the button isn’t pressed, preventing random signals.

4. Button Press:
   When the button is pressed, the pin reads HIGH (1) because it connects to 5V.

5. Toggle Logic:
   The Arduino detects a change from LOW → HIGH.

   • If the LED was OFF, it turns ON.
   • If it was ON, it turns OFF.

6. Debouncing:
   A short delay (500 ms) filters out the quick “noise” signals caused by the button’s mechanical bounce, ensuring the LED toggles only once per press.

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🧠 In Short:

🟢 Press button → LED turns ON (and stays ON)
⚫ Press button again → LED turns OFF

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💡 Additional Note:

In this version also, a 10 kΩ resistor has been temporarily used in place of the LED’s 220 Ω resistor due to component availability.
The LED still worked but appeared dim. For proper brightness and safety, use a 220 Ω resistor for the LED.

🔄 Simple Logic Flow

Start -> (Button Pressed? (Yes → Change LED State? If LED was OFF → Turn ON: If LED was ON → Turn OFF)) -> Wait briefly to debounce -> Return to checking button -> End

💻 Code Explanation

// Turn on LED when the button is pressed
// and keep it on after it is released
// including simple de-bouncing

const int LED = 13;      // Pin connected to the LED
const int BUTTON = 2;    // Pin connected to the pushbutton

int val = 0;             // Current reading from the button
int old_val = 0;         // Previous button reading
int state = 0;           // LED state: 0 = OFF, 1 = ON

void setup() {
  pinMode(LED, OUTPUT);     // Set LED pin as OUTPUT
  pinMode(BUTTON, INPUT);   // Set button pin as INPUT
}

void loop() {
  val = digitalRead(BUTTON);      // Read the current button state

  // Check for a state change (LOW → HIGH)
  if ((val == HIGH) && (old_val == LOW)) {
    state = 1 - state;            // Toggle LED state (0→1 or 1→0)
    delay(500);                   // Simple debounce delay
  }

  old_val = val;                  // Update old value for next loop

  // Control LED based on state
  if (state == 1) {
    digitalWrite(LED, HIGH);      // Turn LED ON
  } else {
    digitalWrite(LED, LOW);       // Turn LED OFF
  }
}

🎬 Demo / Result

▶️ Watch Demo Video

🧩 Challenges & Learning

🔹 Challenges Faced:

• Multiple LED toggles on a single press:
  At first, the LED turned ON and OFF rapidly due to the button’s “bouncing” effect — tiny quick ON/OFF signals caused by the physical button.
• Remembering LED state:
  Initially, the LED would turn OFF as soon as the button was released. Implementing a state variable helped the LED stay ON until the next press.
• Timing and Debouncing:
  Finding the right delay value (like delay(500)) was tricky — too short caused double toggles, too long made the button feel slow.

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🔹 Key Learnings:

• Learned how to detect state changes (LOW → HIGH) instead of constantly reading button status.
• Understood how to toggle outputs using a simple logic formula: state = 1 - state.
• Gained practical knowledge of button debouncing and how to make input signals more stable.
• Strengthened understanding of how Arduino loops continuously to check inputs and update outputs.

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💡 This project was a great step forward from the basic button-LED control — introducing state management, reliable input handling, and smarter logic.

🧩 Challenges Faced & Learnings

🔹 Challenges Faced:

• Understanding the button toggle logic:
  It was tricky to make the LED stay ON even after releasing the button.
  Learning how to store and update the LED’s state (state = 1 - state) helped solve this.

• Dealing with button bounce:
  The LED sometimes toggled multiple times with a single press.
  Adding a simple debounce delay (delay(500)) fixed this by ignoring fast unwanted signals.

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🔹 What I Learned:

• How to make an LED toggle ON/OFF using state change detection in Arduino.
• How debouncing logic prevents false readings from mechanical button noise.
  Clear understanding of digital input (button) and digital output (LED) operations.
• Improved skills in debugging breadboard connections and reading Arduino circuit layouts.

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💡 This upgraded version deepened my understanding of digital I/O handling, button logic, and clean signal reading — a key foundation for more advanced Arduino projects.

Add a Buzzer or Multiple LEDs:

• Make the circuit more interactive — for example, light up multiple LEDs in sequence or play a sound when the button is pressed.

Use Internal Pull-up Resistor:

• Modify the code to use Arduino’s built-in INPUT_PULLUP mode instead of an external resistor.
• Learn how logic levels invert (pressed = LOW, released = HIGH).

Experiment with Different Components:

• Replace the LED with a relay module or motor driver to control higher-power devices.

Create a Mini Project:

• Build a “Night Lamp” or “Touch Switch” system using the same principles.