#include "stm32f4xx.h"                  // Device header
void delay(int delayms);
int counter=0;
int main(void)
{
__disable_irq();
RCC->AHB1ENR |=RCC_AHB1ENR_GPIOAEN ;
RCC->AHB1ENR |=RCC_AHB1ENR_GPIOCEN;
GPIOC->PUPDR|=0x4002000;
//RCC->AHB1ENR |=4;//enable gpio a clock
GPIOA->MODER|= GPIO_MODER_MODER5_0; //PA5 as output
GPIOA->MODER|= GPIO_MODER_MODER6_0; //PA6 as output
RCC->APB2ENR|=RCC_APB2ENR_SYSCFGEN ;
SYSCFG->EXTICR[3]|=SYSCFG_EXTICR4_EXTI13_PC;
EXTI->IMR|=EXTI_IMR_MR13;
//EXTI->IMR|=0x2000;
EXTI->FTSR|=EXTI_RTSR_TR13;
//EXTI->FTSR|=0x2000;
NVIC_EnableIRQ(EXTI15_10_IRQn);
__enable_irq();
while(1)
{
GPIOA->BSRR|=GPIO_BSRR_BS6;
delay(300);
GPIOA->BSRR|=GPIO_BSRR_BR6;
delay(300);
counter++;
}
}

void EXTI15_10_IRQHandler(void){

GPIOA->BSRR|=GPIO_BSRR_BS5;
    delay(300);
GPIOA->BSRR|=GPIO_BSRR_BR5;
delay(300);
GPIOA->BSRR|=GPIO_BSRR_BS5;
    delay(300);
GPIOA->BSRR|=GPIO_BSRR_BR5;
delay(300);
EXTI->PR=EXTI_PR_PR13;
}
void delay(int ms)
{
    SysTick->LOAD=16000-1;
    SysTick->VAL=0;
    SysTick->CTRL=0x5;
        for (int i=0;i<ms;i++)
        {
            while(!(SysTick->CTRL &0x10000)){}
        }
    SysTick->CTRL=0;
}