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

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

Objective

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

Task

1. Connect LEDs and push buttons to Arduino.
2. Write a program to turn LEDs ON/OFF based on button press.
3. Observe the response on the Serial Monitor.

Circuit Connections

• **Push Buttons (Inputs):** Pins 5, 4, 2, 3
• **LEDs (Outputs):** Pins 7, 8, 9, 10
• **Serial Communication:** 9600 baud rate

Arduino Code

<syntaxhighlight lang="cpp"> // © 2025, Cognifront. Member of The IoT Kits Family.

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

// Define push button input pins int push1Pin = 5; int push2Pin = 4; int push3Pin = 2; int push4Pin = 3;

// Variables to store button states int push1Value; int push2Value; int push3Value; int push4Value;

// Define LED output pins int ledPin1 = 7; int ledPin2 = 8; int ledPin3 = 9; int ledPin4 = 10;

void setup() {

 // Start serial communication at 9600 baud for debugging
 Serial.begin(9600);

 // Set push button pins as inputs
 pinMode(push1Pin, INPUT);
 pinMode(push2Pin, INPUT);
 pinMode(push3Pin, INPUT);
 pinMode(push4Pin, INPUT);

 // Set LED pins as outputs
 pinMode(ledPin1, OUTPUT);
 pinMode(ledPin2, OUTPUT);
 pinMode(ledPin3, OUTPUT);
 pinMode(ledPin4, OUTPUT);

}

void loop() {

 // Read the state of each push button (HIGH = pressed, LOW = not pressed)
 push1Value = digitalRead(push1Pin);
 push2Value = digitalRead(push2Pin);
 push3Value = digitalRead(push3Pin);
 push4Value = digitalRead(push4Pin);

 // Check which button is pressed and turn ON the corresponding LED
 // Only one LED will turn ON at a time because of the else-if structure
 if(push1Value == HIGH) {
   digitalWrite(ledPin1, HIGH); // Turn ON LED1 if button1 is pressed
 }
 else if(push2Value == HIGH) {
   digitalWrite(ledPin2, HIGH); // Turn ON LED2 if button2 is pressed
 }
 else if(push3Value == HIGH) {
   digitalWrite(ledPin3, HIGH); // Turn ON LED3 if button3 is pressed
 }
 else if(push4Value == HIGH) {
   digitalWrite(ledPin4, HIGH); // Turn ON LED4 if button4 is pressed
 }
 else {
   // If no button is pressed, turn OFF all LEDs
   digitalWrite(ledPin1, LOW);
   digitalWrite(ledPin2, LOW);
   digitalWrite(ledPin3, LOW);
   digitalWrite(ledPin4, LOW);
 } 

} </syntaxhighlight>

Observation

• Pressing any button will turn ON the corresponding LED.
• Only one LED lights up at a time because of the else-if structure.
• Serial Monitor can be used to confirm button press readings.

Conclusion

This experiment demonstrates basic digital input and output control using Arduino.