#include "stm32f103xb.h"

#define LED_PIN GPIO_PIN_13
#define LED_PORT GPIOC

void delay(uint32_t count) {
    for(uint32_t i = 0; i < count; i++);
}

int main(void) {
    RCC->APB2ENR |= RCC_APB2ENR_IOPCEN; // Enable clock for GPIOC
    GPIOC->CRH &= ~(GPIO_CRH_CNF13 | GPIO_CRH_MODE13); // Clear CNF and MODE bits for pin 13
    GPIOC->CRH |= GPIO_CRH_MODE13_0; // Output mode, max speed 10 MHz

    while (1) {
        GPIOC->BSRR = LED_PIN; // Set pin high (turn LED on)
        delay(1000000); // Delay
        GPIOC->BSRR = LED_PIN << 16; // Reset pin (turn LED off)
        delay(1000000); // Delay
    }
}