const int ledDelay = 8;
const int ledMillis = 9;

unsigned long previousMillis = 0;
const long interval = 1000;

void setup() {
  pinMode(ledDelay, OUTPUT);
  pinMode(ledMillis, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  // Blocking LED using delay()
  digitalWrite(ledDelay, HIGH);
  delay(1000);
  digitalWrite(ledDelay, LOW);
  delay(1000);

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

  // Measure time between toggles using micros()
  static unsigned long lastToggleMicros = 0;
  static bool toggleState = false;
  if (currentMillis % 2000 < 10) { // every ~2s
    unsigned long nowMicros = micros();
    unsigned long elapsed = nowMicros - lastToggleMicros;
    lastToggleMicros = nowMicros;
    toggleState = !toggleState;
    digitalWrite(ledMillis, toggleState);
    Serial.print("Elapsed time (µs): ");
    Serial.println(elapsed);
  }
}


/*
const int ledMillis = 9;
unsigned long previousMillis = 0;
const long interval = 1000;

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

void loop() {
  unsigned long currentMillis = millis();
  unsigned long difference = currentMillis - previousMillis;

  // Print timing values
  Serial.print("Current millis: ");
  Serial.print(currentMillis);
  Serial.print(" | Previous millis: ");
  Serial.print(previousMillis);
  Serial.print(" | Difference: ");
  Serial.println(difference);

  // Non-blocking LED toggle
  if (difference >= interval) {
    previousMillis = currentMillis;
    digitalWrite(ledMillis, !digitalRead(ledMillis));
  }

  // Small delay to avoid flooding Serial Monitor
  delay(200);
}
*/