STM32中断定时，控制LED灯

 #include "led.h"

 void TIM3_Int_Init(u16 arr,u16 psc)
 {
     TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
     NVIC_InitTypeDef NVIC_InitStructure;

     RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE); //设置TIM3时钟使能

     TIM_TimeBaseStructure.TIM_Period = arr; //设置重装载寄存器的周期
     TIM_TimeBaseStructure.TIM_Prescaler =psc; //设置时钟频率除数的预分频值
     TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; //设置时钟分割
     TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //向上的计数模式
     TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure); //TIM3的初始化

     TIM_ITConfig(TIM3,TIM_IT_Update,ENABLE ); //TIM3更新中断使能

     NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;  //TIM3中断
     NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = ;  //先占优先0级
     NVIC_InitStructure.NVIC_IRQChannelSubPriority = ;  //从占优先3级
     NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ通道使能
     NVIC_Init(&NVIC_InitStructure);  //初始化NVIC寄存器

     TIM_Cmd(TIM3, ENABLE);  //使能TIM3
 }
 //定时器3中断服务程序
 void TIM3_IRQHandler(void)   //TIM3中断
 {
     if (TIM_GetITStatus(TIM3, TIM_IT_Update) != RESET)  //检查TIM3更新中断发生与否
         {
         TIM_ClearITPendingBit(TIM3, TIM_IT_Update  );  //清除TIMx更新中断标志
         LED2=!LED2;  //取反
         }
 }

 #include "stm32f10x_conf.h"
 #include "led.h"
 #include "key.h"
 #include "delay.h"
 #include "timer.h"
 #include "usart.h"

 int main(void)
 {

     delay_init();
     LED_Init();
     NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);
     uart_init();
     TIM3_Int_Init(,);
     //((4999+1)*( 7199+1))/72=500000us=500ms  延时500ms
   while()
   {
         LED3=!LED3;
         delay_ms();
         /*当数值为2000时，延时时间变快。当数值为1500以下，
         延时时间为x/1000，只设了几个值。其他值都还没有尝试。
         */
   }

 }