//想请问下用TIM3的ETR输入触发引脚（PD2），来检测旋转编码器的脉冲，但是没有触发计数是怎么回事？
//TIM3配置如下

void TIM3_Init(void)
{
        TIM_TimeBaseInitTypeDef        TIM_TimeBaseStrcture;
        RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3,ENABLE);
       
        TIM_DeInit(TIM3);
        TIM_TimeBaseStrcture.TIM_Period = 0xFFFF-1;
       
        TIM_TimeBaseStrcture.TIM_Prescaler = 0x00;
        TIM_TimeBaseStrcture.TIM_ClockDivision = 0x0;
        TIM_TimeBaseStrcture.TIM_CounterMode = TIM_CounterMode_Up;
        TIM_TimeBaseInit(TIM3,&TIM_TimeBaseStrcture);
        //TIM_ITRxExternalClockConfig(TIM3,TIM_TS_ETRF);
        TIM_ETRClockMode2Config(TIM3,TIM_ExtTRGPSC_OFF,TIM_ExtTRGPolarity_NonInverted,0);
        TIM_SetCounter(TIM3,0);
        TIM_Cmd(TIM3,ENABLE);
       
}