// Task 1: Clock System and CPU Timing

// Pin assignments
const int ledDelayPin = 8;   // LED using delay()
const int ledMillisPin = 9;  // LED using millis()

// Variables for millis() timing
unsigned long previousMillis = 0;
const long interval = 1000; // 1 second

void setup() {
  pinMode(ledDelayPin, OUTPUT);
  pinMode(ledMillisPin, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  // -------------------------------
  // 1️⃣ Blocking LED using delay()
  // -------------------------------
  digitalWrite(ledDelayPin, HIGH);
  delay(1000);  // blocks CPU for 1 second
  digitalWrite(ledDelayPin, LOW);
  delay(1000);

  // -------------------------------
  // 2️⃣ Non-blocking LED using millis()
  // -------------------------------
  unsigned long currentMillis = millis();
  if (currentMillis - previousMillis >= interval) {
    previousMillis = currentMillis;
    digitalWrite(ledMillisPin, !digitalRead(ledMillisPin)); // toggle LED
  }

  // -------------------------------
  // 3️⃣ Measure elapsed time with micros()
  // -------------------------------
  static unsigned long lastToggleTime = micros();
  unsigned long now = micros();
  unsigned long elapsed = now - lastToggleTime;

  // Print every 2 seconds
  if (elapsed > 2000000) { // 2,000,000 µs = 2 sec
    Serial.print("Elapsed microseconds: ");
    Serial.println(elapsed);
    lastToggleTime = now;
  }
}