
void TIM2_Int_Init(u16 arr,u16 psc)
{
    TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
 NVIC_InitTypeDef NVIC_InitStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE); //时钟使能
 TIM_TimeBaseStructure.TIM_Period = arr; //设置在下一个更新事件装入活动的自动重装载寄存器周期的值  计数到5000为500ms
 TIM_TimeBaseStructure.TIM_Prescaler =psc; //设置用来作为TIMx时钟频率除数的预分频值  10Khz的计数频率  
 TIM_TimeBaseStructure.TIM_ClockDivision = 0; //设置时钟分割:TDTS = Tck_tim
 TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //TIM向上计数模式
 TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure); //根据TIM_TimeBaseInitStruct中指定的参数初始化TIMx的时间基数单位
 
 TIM_ITConfig(TIM2,TIM_IT_Update,ENABLE ); //使能指定的TIM2中断,允许更新中断
 NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;  //TIM3中断
 NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;  //先占优先级0级
 NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3;  //从优先级3级
 NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ通道被使能
 NVIC_Init(&NVIC_InitStructure);  //根据NVIC_InitStruct中指定的参数初始化外设NVIC寄存器
 TIM_Cmd(TIM2, ENABLE);  //使能TIMx外设
}
  
//定时器2中断服务程序
void TIM2_IRQHandler(void)   //TIM2中断
{
 if (TIM_GetITStatus(TIM2, TIM_IT_Update) != RESET) //检查指定的TIM中断发生与否:TIM 中断源 
 {
 TIM_ClearITPendingBit(TIM2, TIM_IT_Update  );  //清除TIMx的中断待处理位:TIM 中断源 
 if (add >= 3)
 {
 add = 1;
 }
 else
 add ;
 }
}

 
  
					
				
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