#include "stm32f4xx.h"
#include "stm32f401_discovery.h"

void SysTick_Handler(void);

void LedSetup(void)
{
	GPIO_InitTypeDef GPIO_InitStructure;
	/* Enable the GPIO_LED Clock */
	RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);
	/* Configure the GPIO_LED pin */
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12;
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
	GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
	GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
	GPIO_Init(GPIOD, &GPIO_InitStructure);
}

void ButtonSetup(void)
{
	GPIO_InitTypeDef GPIO_InitStructure;
	NVIC_InitTypeDef NVIC_InitStructure;
	EXTI_InitTypeDef EXTI_InitStructure;
	/* Enable GPIOA clock */
	RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
	/* Configure PA0 pin as input floating */
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;
	GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
	GPIO_Init(GPIOA, &GPIO_InitStructure);

	RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE);
	/* Configure EXTI Line0 */
	EXTI_InitStructure.EXTI_Line = EXTI_Line0;
	EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
	EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising;
	EXTI_InitStructure.EXTI_LineCmd = ENABLE;
	EXTI_Init(&EXTI_InitStructure);
	/* Connect EXTI Line0 to PA0 pin */
	SYSCFG_EXTILineConfig(EXTI_PortSourceGPIOA, EXTI_PinSource0);
	/* Enable and set EXTI Line0 Interrupt to the lowest priority */
	NVIC_InitStructure.NVIC_IRQChannel = EXTI0_IRQn;
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x01;
	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x01;
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
	NVIC_Init(&NVIC_InitStructure);
}

void EXTI0_IRQHandler(void)
{
	//your code
	/* Clear the EXTI line 0 pending bit */
	EXTI_ClearITPendingBit(EXTI_Line0);
}

int main(void)
{
	LedSetup();
	ButtonSetup();

	if (SysTick_Config(SystemCoreClock / 1000))
				{
					/* Capture error */
					for(;;);
				}
	while(1)
	{
		//your code
	}

}


void SysTick_Handler(void)
{
	static u16 counter = 0;

	counter++;

	if (counter == 500)
	{
		// your code
		counter = 0;
	}

}