/*#define DELAY 1000000
void setup() {
  volatile unsigned int *RCCA_clk_en=(volatile unsigned int*) 0x40023830;
  volatile unsigned int *GPIOA_dir=(volatile unsigned int*) 0x40020000;
  volatile unsigned int *GPIOA_out=(volatile unsigned int*) 0x40020014;
 *RCCA_clk_en |=(1<<0);  // Enable clock access to GPIOA
 *GPIOA_dir |= (1<<10);  //  19: Set bit 10 to 1
 *GPIOA_dir &= ~(1<<11); //  20: Set bit 11 to 0
 long int a;
 while(1)
 {
 //  22: Set PA5(LED_PIN) high
 *GPIOA_out |= (1<<5);
 for(a=0;a<DELAY;a++);
 *GPIOA_out &= ~(1<<5);
 for(a=0;a<DELAY;a++);
 }
}

void loop() {

}*/

#define DELAY 1000000

void setup() {
  Serial.begin(115200);

  volatile unsigned int *RCC_AHB1ENR = (volatile unsigned int*) 0x40021014;
  volatile unsigned int *GPIOA_MODER = (volatile unsigned int*) 0x48000000;
  volatile unsigned int *GPIOA_ODR   = (volatile unsigned int*) 0x48000014;

  *RCC_AHB1ENR |= (1 << 0); // Enable clock for GPIOA

  // Set PA5 as output
  *GPIOA_MODER &= ~(3 << (2 * 5)); // Clear mode bits for PA5
  *GPIOA_MODER |=  (1 << (2 * 5)); // Set PA5 to output mode

  long int a;
  while(1)
  {
    *GPIOA_ODR |= (1 << 5);  // Set PA5 high
    for (a = 0; a < DELAY; a++);
    *GPIOA_ODR &= ~(1 << 5); // Set PA5 low
    for (a = 0; a < DELAY; a++);
  }
}

void loop() {
  // Not used
}