Read Digital Input with Pushbutton

🔰 Introduction

In this project, you’ll learn how to use a pushbutton to read a digital input on Arduino UNO or ESP32. This project helps beginners understand how microcontrollers detect HIGH or LOW signals from components like buttons or switches.

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🔧 Components Needed

Component	Quantity	Notes
Arduino UNO or ESP32	1	Any compatible board
Pushbutton	1	Momentary type
Resistor	1	10kΩ for pull-down resistor
Breadboard	1	Optional but helpful
Jumper Wires	4

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📷 Circuit Diagram

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🧩 Schematic Diagram

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🛠️ Wiring Instructions

1. Place the pushbutton on the breadboard.
2. Connect one leg of the pushbutton to digital pin 2.
3. Connect the other leg of the pushbutton to GND.
4. Place a 10kΩ pull-down resistor between digital pin 2 and GND.
5. Plug the Arduino or ESP32 into your PC via USB.

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🔍 What is digitalRead()?

digitalRead() is a built-in Arduino function used to read the digital signal from a specified pin. It detects whether the pin is receiving a HIGH or LOW voltage.

➤ Syntax

Syntax

int state = digitalRead(pin);

• pin: The digital pin number to read
• Returns: HIGH (1) or LOW (0)

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🧾 Code

digital-read-pushbutton.ino

#define BUTTON (2)

void setup() {
  pinMode(BUTTON, INPUT);         // Set pin 2 as input
  Serial.begin(9600);        // Start serial communication
}

void loop() {
  int buttonState = digitalRead(BUTTON);  // Read pin 2 state
  Serial.println(buttonState);       // Print state to Serial Monitor
  delay(100);                        // Delay for stability
}

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🧠 Code Breakdown

void setup()
Runs once when the microcontroller starts.

Configures pin 2 as an **input**

pinMode(2, INPUT);

— Configures pin 2 as an input.

• Serial.begin(9600); — Starts serial communication at 9600 baud to print messages to the Serial Monitor.

void loop()
Runs continuously.

• int buttonState = digitalRead(2); — Reads the state of pin 2 (HIGH or LOW) and stores it in buttonState.
• Serial.println(buttonState); — Prints the state to the Serial Monitor (1 for HIGH, 0 for LOW).
• delay(100); — Waits for 100ms before reading again (adds stability and acts as basic debounce).

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💡 Applications of Digital Read

Reading digital input is widely used in real-world applications such as:

• 🕹️ Game controllers – detect button presses
• 🚪 Security systems – monitor door or motion sensors
• 🤖 Robotics – read limit switches or triggers
• 📟 User interfaces – control via keypads or pushbuttons
• 🛠️ Industrial automation – detect machine states
• 🧠 IoT sensors – handle smart triggers

If you need to detect ON/OFF, pressed/released, or open/closed states, digitalRead() is your go-to function.

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