/* * Lab 1 - Task 2: Multitasking with Millis() and Pull-Down Switch
 * Objective: Blink Green LED continuously without blocking the Red LED button control.
 */

// Define Pins
const int buttonPin = 18;      // Push button connected to GPIO 18
const int ledBlinkPin = 5;     // Green LED for blinking
const int ledButtonPin = 2;    // Red LED for button status

// Variables for millis() timing
unsigned long previousMillis = 0;  // Stores last time LED was updated
const long interval = 500;         // Interval at which to blink (milliseconds)
int ledState = LOW;                // Current state of the blinking LED

void setup() {
  pinMode(ledBlinkPin, OUTPUT);
  pinMode(ledButtonPin, OUTPUT);
  
  // Initialize the pushbutton pin as an input
  // Note: We are using an external pull-down resistor in the circuit
  pinMode(buttonPin, INPUT); 
  
  Serial.begin(115200);
  Serial.println("Task 2 Ready: Multitasking with millis().");
}

void loop() {
  // ---------------------------------------------------------
  // TASK A: Blink the Green LED using millis() (Non-Blocking)
  // ---------------------------------------------------------
  unsigned long currentMillis = millis(); // Get the current time
  
  if (currentMillis - previousMillis >= interval) {
    // Save the last time you blinked the LED
    previousMillis = currentMillis;

    // Toggle the LED state
    if (ledState == LOW) {
      ledState = HIGH;
    } else {
      ledState = LOW;
    }
    digitalWrite(ledBlinkPin, ledState);
  }

  // ---------------------------------------------------------
  // TASK B: Read the Push Button instantly
  // ---------------------------------------------------------
  int buttonState = digitalRead(buttonPin);

  // Check if button is pressed. 
  // With Pull-Down resistor, Pressed = HIGH, Unpressed = LOW
  if (buttonState == HIGH) {
    digitalWrite(ledButtonPin, HIGH); // Turn Red LED ON
  } else {
    digitalWrite(ledButtonPin, LOW);  // Turn Red LED OFF
  }
}