stm32中TIM3_ETR 的使用

只看该作者 · 2012-3-30 15:54

使用stm32中TIM3_ETR 来对外部脉冲计数，可是总是发出的是0，求香主帮忙看看，下面是配置：
void TIM3_Configuration(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;
  TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
  //Config PD2 为浮空输入
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;//测左电机转速
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
  GPIO_Init(GPIOD, &GPIO_InitStructure);
//配置TIMER3作为计数器
  TIM_DeInit(TIM3);
  TIM_TimeBaseStructure.TIM_Period = 0xFFFF;
  TIM_TimeBaseStructure.TIM_Prescaler = 0x00;
  TIM_TimeBaseStructure.TIM_ClockDivision = 0x0;
//  TIM_TimeBaseStructure.TIM_channel = TIM_Channel_1;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
  TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure); // Time base configuration

  TIM_ETRClockMode2Config(TIM3, TIM_ExtTRGPSC_OFF, TIM_ExtTRGPolarity_Inverted, 0);
  //使用ETR时钟作为计数时钟需要设置为外部时钟模式2
//TIM_ExtTRGPSC_OFF: TIM ETRP 预分频 OFF(范围：0，2，4，6)
//TIM_ExtTRGPolarity_NonInverted: TIM外部触发极性非翻转：高电平或上升沿有
//ExtTRGFilter: 外部触发滤波器。该参数取值在0x0和0xF之间。
  TIM_SetCounter(TIM3, 0);
  TIM_Cmd(TIM3, ENABLE);
//  COUN3 = TIM_GetCounter(TIM3);

}

在main（）中将COUN3 = TIM_GetCounter(TIM3);
然后通过串口发出去！

求解答~~