const int led = 10; //LED pin on my big Cat Board
const int btn = 8; //Btn pin on my big Cat Board
int state = 0; //state variable for switch case
void setup() {
  // put your setup code here, to run once:
  pinMode(btn, INPUT_PULLUP); //Register Button pin as INPUT_PULLUP
  attachInterrupt(digitalPinToInterrupt(btn), buttonPress, FALLING); //Attach interrupt to pin which trigger function everytime the signal is in FALLING state
  pinMode(led, OUTPUT); //Register LED as OUTPUT
}

void loop() {
  //Switch case to keep track of current mode (Four modes available)
  switch(state%4){ //Since state can get bigger than three, just take mod of state to get current mode
    case 0: //LED is permanently OFF
      digitalWrite(led, LOW);
      break;
    case 1: //LED is permanently ON
      digitalWrite(led, HIGH);
      break;
    case 2: //LED is blinking with an intervall of 100 between ON and OFF states
      digitalWrite(led, HIGH);
      delay(100);
      digitalWrite(led, LOW);
      delay(100);
    case 3: //Dynamic intervall => LED blinks faster and faster
      for (int i = 1000; i >= 0; i -= 25) {
        digitalWrite(led, LOW);
        delay(i);
        digitalWrite(led, HIGH);
        delay(i);
      }
  }
  
}

//Function gets called at button interrupt, adds +1 to the current state
void buttonPress(){
  state += 1;
  
}