void tim2_configuration(void)
{
        TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
        TIM_DeInit(TIM2);
       
        TIM_TimeBaseStructure.TIM_Period=2000;     //ARR 的值 
        TIM_TimeBaseStructure.TIM_Prescaler=0;        
        TIM_TimeBaseStructure.TIM_ClockDivision=0; //时钟分频 
        TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up; //向上计数模式 
        TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure); 
 
         TIM_PrescalerConfig(TIM2,0x8C9F,TIM_PSCReloadMode_Immediate);//时钟分频系数 36000，所以定时器时钟为 2K 
 
        /* Clear TIM2 update pending flag[清除TIM2溢出中断标志] */
    TIM_ClearFlag(TIM2, TIM_FLAG_Update);
        /* Enable TIM2 Update interrupt [TIM2溢出中断允许]*/
    TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);
        TIM_ARRPreloadConfig(TIM2, DISABLE);//禁 止 ARR 预装载缓冲器
        TIM_Cmd(TIM2, ENABLE); //开启时钟
}
编译连接时总是有这种情况，，，，到底肿么了，两天了，苦恼中，3.5的库，比着别人的一句句抄都不行
.\Output\Project.axf: Error: L6218E: Undefined symbol TIM_ARRPreloadConfig (referred from system_init.o).
.\Output\Project.axf: Error: L6218E: Undefined symbol TIM_ClearFlag (referred from system_init.o).
.\Output\Project.axf: Error: L6218E: Undefined symbol TIM_Cmd (referred from system_init.o).
.\Output\Project.axf: Error: L6218E: Undefined symbol TIM_DeInit (referred from system_init.o).
.\Output\Project.axf: Error: L6218E: Undefined symbol TIM_ITConfig (referred from system_init.o).
.\Output\Project.axf: Error: L6218E: Undefined symbol TIM_PrescalerConfig (referred from system_init.o).
.\Output\Project.axf: Error: L6218E: Undefined symbol TIM_TimeBaseInit (referred from system_init.o).