void setup() {

  RCC->AHBENR |= (1 << 0); //0 -> GPIOA
  RCC->AHBENR |= (1 << 3); //1 -> GPIOD

  GPIOA->MODER = 0xAAAAAAAA;
  GPIOA->MODER = 0x55555555;
  GPIOD->MODER = 0xAAAAAAAA;
  GPIOD->MODER = 0x55555555;
}

int state;

void loop() {
  int state = random(1, 4);
  for (int i = 0; i < 20; i++) {
    switch (state) {
      case 1: leuchten();
      break;
      case 2: blinken();
      break;
      case 3: rgb();
      break;
    }
  }
  allOFF();
}

void blinken() {
  int led = random(0x00, 0xFF);
  int rgb = random(0x00, 0xFF);
  GPIOA->ODR = led;
  GPIOD->ODR = rgb;
  delay(100);
}

void leuchten() {
  GPIOA->ODR = 0xFF;
  GPIOD->ODR = 0xFF;
  delay(10);
}

void rgb() {
  for (int i = 0; i < 3; i++) {
    GPIOD->ODR = i;
    delay(100);
  }
}

void allOFF() {
  GPIOA->ODR = 0x00;
  GPIOD->ODR = 0x00;
}