static unsigned long waktuSebelumnya = 0;
unsigned long interval = 2000;

int pinLed = 2;
int pinTombol = 3;

int counter = 1;  // iterasi tombol
unsigned long debounce = 0;
unsigned long delayDebounce = 200;

void setup() {
  pinMode(pinLed, OUTPUT);
  pinMode(pinTombol, INPUT_PULLUP);  // tombol aktif LOW
}

void loop() {

  // ------------------------------
  //  Bagian pengaturan interval via tombol
  // ------------------------------
  if (digitalRead(pinTombol) == LOW && millis() - debounce > delayDebounce) {
    debounce = millis();   // simpan waktu tombol ditekan

    counter++;             // iterasi tombol

    if (counter == 1) interval = 500;
    else if (counter == 2) interval = 1000;
    else if (counter == 3) interval = 2000;
    else {
      counter = 1;         // reset iterasi
      interval = 500;
    }
  }

//pengontrol LED
  if (millis() - waktuSebelumnya >= interval) {
    waktuSebelumnya = millis();
    digitalWrite(pinLed, !digitalRead(pinLed));  
  }

}