void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello, STM32!");
  uint32_t *GPIOA_BASEADDRESS=(uint32_t)0x5000 0000;
  uint32_t *GPIOA_MODER=GPIOA_BASEADDRESS;
  uint32_t *GPIOA_OTYPER=GPIOA_BASEADDRESS + (0x04);
  uint32_t *GPIOA_ODR=GPIOA_BASEADDRESS + (0x14);

  *GPIOA_MODER &= ~(1<<0);
  *GPIOA_MODER |= (1<<0);
  
  *GPIOA_OTYPER &= ~(1<<0);

  *GPIOA_ODR |= (1<<0);
  
}

void loop() {
 *GPIOA_ODR &= ~(1<<0);
 delay(500);
*GPIOA_ODR |= (1<<0);
delay(1000);
}