stm32定时器

#include "timer.h"
#include "led.h"
void timer3_init(u16 arr,u16 psc)
{
TIM_TimeBaseInitTypeDef  TIM_TimeBaseyyy;
	NVIC_InitTypeDef  NVIC_SGDJY;
RCC_APB2PeriphClockCmd(RCC_APB1Periph_TIM3,ENABLE);  //使能定时器时钟
	
	TIM_TimeBaseyyy.TIM_ClockDivision=TIM_CKD_DIV1;
	TIM_TimeBaseyyy.TIM_CounterMode=TIM_CounterMode_Up;
	TIM_TimeBaseyyy.TIM_Period=arr;
	TIM_TimeBaseyyy.TIM_Prescaler=psc;
  TIM_TimeBaseInit(TIM3,&TIM_TimeBaseyyy);//初始化定时器配置arr，psc
	TIM_ITConfig(TIM3,TIM_IT_Update,ENABLE);
	
	
	
	NVIC_SGDJY.NVIC_IRQChannel=TIM3_IRQn;
	NVIC_SGDJY.NVIC_IRQChannelCmd=ENABLE;
	NVIC_SGDJY.NVIC_IRQChannelPreemptionPriority=0;
	NVIC_SGDJY.NVIC_IRQChannelSubPriority=3;
	NVIC_Init(&NVIC_SGDJY);//开启定时中断
	TIM_Cmd(TIM3,ENABLE);//使能定时器
	}
  void   TIM3_IRQHandler()//中断服务函数
{
if(TIM_GetITStatus(TIM3,TIM_IT_Update)==SET)//获取完中断信息后
{

LED1=!LED1;
	TIM_ClearITPendingBit(TIM3,TIM_IT_Update);//清楚中断

}
}

 int main(void)
 {	

	 
	 NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);//声明终端级别
	 delay_init();
	 LED_Init();
	 timer3_init(4999,7199);
	 while(1)
	 {
	 LED0=!LED0;
		 delay_ms(200);
	 
	 
	 
	 }