void setup() {
  // put your setup code here, to run once:

    RCC->IOPENR |= RCC_IOPENR_GPIODEN;

    // Set PD1 as output (MODER register - bits [3:2] for PD1)
    GPIOD->MODER &= ~(3U << (1 * 2)); // Clear bits
    GPIOD->MODER |= (1U << (1 * 2));  // Set as output (01)
  
  Serial.begin(115200);
  Serial.println("Hello, STM32!");
}

void loop() {
  // put your main code here, to run repeatedly:
  delay(10); // this speeds up the simulation
}