定时器外部计数配置？这个哪里有问题？为什么一直显示计数0

22599967 · 发表于 2016-6-23 08:30:30

void TIM5_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
NVIC_InitTypeDef NVIC_InitStructure;

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM5,ENABLE);    //TIM5时钟使能
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE); //使能PORTA时钟

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0; //GPIOA0
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;//复用功能
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz; //速度100MHz
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP; //推挽复用输出
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_DOWN; //下拉
GPIO_Init(GPIOA,&GPIO_InitStructure); //初始化PA0

GPIO_PinAFConfig(GPIOA,GPIO_PinSource0,GPIO_AF_TIM5); //PA0复用位定时器5

NVIC_InitStructure.NVIC_IRQChannel = TIM5_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=2;//抢占优先级3
NVIC_InitStructure.NVIC_IRQChannelSubPriority =0; //子优先级3
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ通道使能
NVIC_Init(&NVIC_InitStructure); //根据指定的参数初始化VIC寄存器、


TIM_TimeBaseStructure.TIM_Prescaler=0;  //定时器分频
TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up; //向上计数模式
TIM_TimeBaseStructure.TIM_Period=0xFFFF; //自动重装载值
TIM_TimeBaseStructure.TIM_ClockDivision=0;
TIM_TimeBaseInit(TIM5,&TIM_TimeBaseStructure);

  TIM_ETRClockMode2Config(TIM5, TIM_ExtTRGPSC_OFF, TIM_ExtTRGPolarity_NonInverted, 0);
  //TIM_ITConfig(TIM5, TIM_IT_Update, ENABLE);
  TIM_SetCounter(TIM5, 0);
  TIM_Cmd(TIM5, ENABLE);

}

我讲我自己做好的PWM波接在PA0为什么计数还一直为0，串口助手打印的