// System-2: 2 LEDs & 2 Buttons
// LED1 on while Button1 pressed
// LED2 blinking while Button2 pressed

const int LED1 = 13;    // D13 -> PA5 (user LED biasa)
const int LED2 = 12;    // D12 (pilih pin bebas yang tersedia)
const int BTN1 = 2;     // Button1
const int BTN2 = 3;     // Button2

unsigned long previousMillis = 0;
const unsigned long blinkInterval = 500; // ms (LED2 toggle every 500ms)

void setup() {
  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);

  pinMode(BTN1, INPUT_PULLUP); // tombol ke GND: pressed = LOW
  pinMode(BTN2, INPUT_PULLUP);

  digitalWrite(LED1, LOW);
  digitalWrite(LED2, LOW);
}

void loop() {
  bool btn1Pressed = (digitalRead(BTN1) == LOW);
  bool btn2Pressed = (digitalRead(BTN2) == LOW);

  // LED1 mirrors Button1 (on while pressed)
  if (btn1Pressed) digitalWrite(LED1, HIGH);
  else digitalWrite(LED1, LOW);

  // LED2 blinks while Button2 pressed
  if (btn2Pressed) {
    unsigned long current = millis();
    if (current - previousMillis >= blinkInterval) {
      previousMillis = current;
      digitalWrite(LED2, !digitalRead(LED2)); // toggle
    }
  } else {
    // ensure LED2 off when button not pressed
    digitalWrite(LED2, LOW);
    // reset timer so blink starts fresh next time pressed
    previousMillis = millis();
  }
}