View source for 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 ===
# Connect LEDs and push buttons to Arduino.  
# Write a program to turn LEDs ON/OFF based on button press.  
# Observe the response on the Serial Monitor. 

<span style="background-color: #ffcccc; display: inline-block; padding: 5px; border-radius: 5px; font-weight: bold;">
⚠️ Disconnect your Arduino from the computer while making or removing component connections.
</span>

=== Circuit Diagram ===
[[File:Eecit-kit-01-circuit.png|center|thumb|400px|Circuit Diagram]]

=== Board Connections ===
[[File:Eecit-kit-01-board-connection.png|center|thumb|400px|Board Connections]]

=== Circuit Connections (Simple)===

{| class="wikitable" style="text-align:center;"
! Push Button !! Arduino Pin
|-
| Push Button 1 || 5
|-
| Push Button GND || GND
|-
| Push Button VCC || 5V
|}

{| class="wikitable" style="text-align:center;"
! LED Bar !! Arduino Pin
|-
| LED 1 || 7
|-
|LED GND || GND
|}
* '''Serial Communication:''' 9600 baud rate


=== Circuit Connections (Advanced)===

{| class="wikitable" style="text-align:center;"
! Push Button !! Arduino Pin
|-
| Push Button 1 || 5
|-
| Push Button 2 || 4
|-
| Push Button 3 || 2
|-
| Push Button 4 || 3
|-
| Push Button GND || GND
|-
| Push Button VCC || 5V
|}

{| class="wikitable" style="text-align:center;"
! LED Bar !! Arduino Pin
|-
| LED 1 || 7
|-
| LED 2 || 8
|-
| LED 3 || 9
|-
| LED 4 || 10
|-
|LED GND || GND
|}
* '''Serial Communication:''' 9600 baud rate

=== Arduino Code (Simple)===
<pre>
// © 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;

// Variables to store button states
int push1Value;

// Define LED output pins
int ledPin1 = 7;

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

  // Set push button pins as inputs
  pinMode(push1Pin, INPUT);
  // Set LED pins as outputs
  pinMode(ledPin1, OUTPUT);
  Serial.println("System Initialized: Monitoring Push Buttons and LEDs...");
}

void loop() {
  // Read the state of each push button (HIGH = pressed, LOW = not pressed)
  push1Value = digitalRead(push1Pin);

  // Determine LED states and print to Serial Monitor
  if(push1Value == HIGH) {
    digitalWrite(ledPin1, HIGH);
    Serial.println("Button1 PRESSED → LED1 ON");
  }
 
  else {
    // If no button is pressed, turn OFF all LEDs
    digitalWrite(ledPin1, LOW);
    Serial.println("No button pressed → All LEDs OFF");
  }
  // Print raw pushbutton states for debugging
  Serial.print("Buttons: ");
  Serial.print(push1Value);
  delay(500); // Small delay for better readability in Serial Monitor
}
</pre>

=== Arduino Code (Advanced)===
<pre>
// © 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);

  Serial.println("System Initialized: Monitoring Push Buttons and LEDs...");
}

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);

  // Determine LED states and print to Serial Monitor
  if(push1Value == HIGH) {
    digitalWrite(ledPin1, HIGH);
    digitalWrite(ledPin2, LOW);
    digitalWrite(ledPin3, LOW);
    digitalWrite(ledPin4, LOW);
    Serial.println("Button1 PRESSED → LED1 ON");
  }
  else if(push2Value == HIGH) {
    digitalWrite(ledPin1, LOW);
    digitalWrite(ledPin2, HIGH);
    digitalWrite(ledPin3, LOW);
    digitalWrite(ledPin4, LOW);
    Serial.println("Button2 PRESSED → LED2 ON");
  }
  else if(push3Value == HIGH) {
    digitalWrite(ledPin1, LOW);
    digitalWrite(ledPin2, LOW);
    digitalWrite(ledPin3, HIGH);
    digitalWrite(ledPin4, LOW);
    Serial.println("Button3 PRESSED → LED3 ON");
  }
  else if(push4Value == HIGH) {
    digitalWrite(ledPin1, LOW);
    digitalWrite(ledPin2, LOW);
    digitalWrite(ledPin3, LOW);
    digitalWrite(ledPin4, HIGH);
    Serial.println("Button4 PRESSED → LED4 ON");
  }
  else {
    // If no button is pressed, turn OFF all LEDs
    digitalWrite(ledPin1, LOW);
    digitalWrite(ledPin2, LOW);
    digitalWrite(ledPin3, LOW);
    digitalWrite(ledPin4, LOW);
    Serial.println("No button pressed → All LEDs OFF");
  }

  // Print raw pushbutton states for debugging
  Serial.print("Buttons: ");
  Serial.print(push1Value);
  Serial.print(" ");
  Serial.print(push2Value);
  Serial.print(" ");
  Serial.print(push3Value);
  Serial.print(" ");
  Serial.println(push4Value);

  delay(500); // Small delay for better readability in Serial Monitor
}
</pre>

=== 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.

=== Real Life Examples ===
Automated Assembly Line Control: Digital I/O is used to operate actuators, solenoids, and indicator lamps. For example, pressing a start button activates a conveyor motor, demonstrating machine automation control in manufacturing lines.