Experiment 1: Introduction to Arduino and Digital I/O Control

Objective

To understand digital input/output operations by interfacing LEDs and push buttons with an Arduino board.

Theory

Arduino digital pins can act as INPUT or OUTPUT.

INPUT mode detects HIGH (5V) or LOW (0V) signals.
OUTPUT mode drives devices like LEDs using HIGH or LOW logic.

Push buttons provide user input, while LEDs indicate output response.

Components Required

Arduino Uno (or compatible board)
USB cable, Breadboard, Jumper wires
2 × LEDs (with 220Ω resistors)
2 × Push buttons (with 10kΩ pull-down resistors)

Task

Connect LEDs and push buttons to Arduino.
Write a program to turn LEDs ON/OFF based on button press.
Observe the LED response and monitor button status using Serial Monitor.

Arduino Code

<syntaxhighlight lang="cpp"> int led1 = 8, led2 = 9; int button1 = 2, button2 = 3;

void setup() {

 pinMode(led1, OUTPUT); pinMode(led2, OUTPUT);
 pinMode(button1, INPUT); pinMode(button2, INPUT);
 Serial.begin(9600);

}

void loop() {

 int b1 = digitalRead(button1), b2 = digitalRead(button2);
 Serial.print("B1: "); Serial.print(b1);
 Serial.print(" | B2: "); Serial.println(b2);
 digitalWrite(led1, b1); digitalWrite(led2, b2);
 delay(100);

} </syntaxhighlight>

Observation

Button press → corresponding LED ON
Serial Monitor → displays button state

Conclusion

Demonstrates basic digital I/O control using Arduino.