#include "stm32c031xx.h"

void delay(void)
{
    for (volatile unsigned int i = 0; i < 500000; i++)
    {
        ;
    }
}

int main(void)
{
    /* Enable GPIOA clock */
    RCC->IOPENR |= RCC_IOPENR_GPIOAEN;

    /* Configure PA5 as General Purpose Output
       MODER bits for PA5 = bits 11:10
       01 = Output */
    GPIOA->MODER &= ~(3U << (5 * 2));
    GPIOA->MODER |=  (1U << (5 * 2));

    while (1)
    {
        /* LED ON */
        GPIOA->ODR |= (1U << 5);

        delay();

        /* LED OFF */
        GPIOA->ODR &= ~(1U << 5);

        delay();
    }
}