急急急，STM32f429 TIM3外部计数ETR 计数器不计数！！！

只看该作者 · 2015-9-14 10:27

   PD6输出50K的波形，使用TIM3的ETR功能测量（PD2），将PD2于PD6连接，用示波器可以测得50K的波形，但是TIM3的计数器没有计数，一直为0！
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//*****************************************************
//***************************************************************
//*************************************************
//将外部IO连到ETR

//打开PD2  时钟  PD2 JP6
RCC->AHB1ENR |= (RCC_AHB1ENR_GPIODEN);

//使用复用功能AF2 TIME3 ETR  复用
GPIOD->AFR[0] &=  (~(0xF<<8));
GPIOD->AFR[0] |=  (0x2 << 8);

GPIOD->MODER &= (~(0x3 << 4));
GPIOD->MODER |= (0x0 << 4);//0x2
//推挽输入
GPIOD->OTYPER &= (~(1 << 2));
//输出速度高速
GPIOD->OSPEEDR &= ((~(0x3 << 4)));
GPIOD->OSPEEDR |= (0x2 << 4);
//悬浮
GPIOD->PUPDR &= ((~(0x3 << 4)));
GPIOD->PUPDR |= (0x0 << 4);

  //***********************************************
//初始化时钟 40M 输入
    RCC->APB1ENR |= (RCC_APB1ENR_TIM3EN);

//ETR设置
//不需要滤波器
temp = TIM3->SMCR;
temp &= ~(TIM_SMCR_ETF);
//预分频 0
temp &= ~(TIM_SMCR_ETPS);
//temp |= TIM_SMCR_ETF_1;
//上升沿检测
temp &= ~(TIM_SMCR_ETP);
//外部时钟模式2
temp |= TIM_SMCR_ECE;
  //外部触发输入
// temp |= TIM_SMCR_TS;
//从模式选择
//temp &= ~TIM_SMCR_SMS;
// temp |= TIM_SMCR_SMS;

   TIM3->SMCR = temp;
   temp = 0;
//TIM3->EGR |= TIM_EGR_UG;

UART1_Printf("timer3 init  TIM3->SMCR %x \r\n", TIM3->SMCR);
//***********************************************************

//禁止计数器
// TIM3->CR1 &= ~(TIM_CR1_CEN);
//手动清除计数器
//TIM3->EGR |= TIM_EGR_UG;
//设置预分频器  1KHZ
TIM3->PSC = 0;// 2分频
//自动重载寄存器 100ms 上溢  ？
TIM3->ARR = 0xffff;
   //计数初始为0
   TIM3->CNT = 0;
   //重复计数器
   TIM3->RCR =  (TIM3->RCR)&0xff;
//TIM3_CR1
   temp = TIM3->CR1;
//自动重装载
temp |= TIM_CR1_ARPE;
//多脉冲模式
temp &= ~(TIM_CR1_OPM);
//更新源设置
temp |= TIM_CR1_URS;
//更新禁止选择
temp &= (~TIM_CR1_UDIS);
//方向上
temp &= ~(TIM_CR1_DIR);
// 采样频率 Tdts = Tck_int 40M
temp &= ~(TIM_CR1_CKD);
//中心对齐模式选择单向
temp &= ~ TIM_CR1_CMS;

TIM3->CR1 = temp;

   //使能定时器6  100ms
TIM3->CR1 |= (TIM_CR1_CEN);

UART1_Printf("timer3 init TIM3->CR1 %x \r\n",TIM3->CR1);

UART1_Printf("timer3 init TIM3->CNT %d \r\n",TIM3->CNT);