//This code toggle led state using interrupt

const int buttonPin = 2;  // Interrupt-capable pin on Uno
const int ledPin = 8;     // LED pin

volatile bool ledState = false;        // LED state
volatile bool interruptFlag = false;   // Set in ISR when triggered
unsigned long lastInterruptTime = 0;   // For software debounce
const unsigned long debounceDelay = 200; // in milliseconds

// Interrupt Service Routine
void handleInterrupt() {
  // Prevent bouncing: record time and ignore if too soon
  unsigned long currentTime = millis();

  if (currentTime - lastInterruptTime > debounceDelay) {
    interruptFlag = true; // mark that a valid press occurred
    lastInterruptTime = currentTime;
  }
}

void setup() {
  pinMode(ledPin, OUTPUT);
  pinMode(buttonPin, INPUT);  // External pull-up

  Serial.begin(9600);
  Serial.println("System Initialized - Waiting for Button Interrupt...");

  attachInterrupt(digitalPinToInterrupt(buttonPin), handleInterrupt, FALLING);
}

void loop() {
  if (interruptFlag) {
    ledState = !ledState;                 // Toggle LED state
    digitalWrite(ledPin, ledState);       // Update LED
    Serial.println("Interrupt Triggered: LED Toggled");
    interruptFlag = false;                // Clear flag
  }

  // Short delay to prevent Serial flooding
  delay(50);
}