const int pinBt1 = 2;
const int pinBt2 = 3;

const int pinLED = 9;
void setup() {
pinMode(pinBt1, INPUT);
pinMode(pinBt2, INPUT);  
pinMode(pinLED, OUTPUT);

digitalWrite(pinBt1, HIGH);
digitalWrite(pinBt2, HIGH);
}
int brightness = 0;
void loop() {
if(digitalRead(pinBt1) == LOW){
  //jika pushbutton diyekan
  //tambahkan nilai brightness
brightness++;
}else if(digitalRead(pinBt2) == LOW){
  // jka pushbutton2 ditekan // kurangi nilai brightness
  brightness--;
}
//brightness dibatasi antara 0 - 255
//jika dibawah 0, maka diganti dengan 0
//jika di atas 255, maka ganti dengan 255
  brightness = constrain(brightness, 0,255);

  //pinlED diberi nilai antara 0 -255
  analogWrite(pinLED, brightness);
  //delay agar perubahannya bertahap
  delay(20);
}