急急急！定时器3外部计数，寄存器版本，计数器不工作！！！

2459878559 · 发表于 2015-9-13 13:41:46

D6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！

[mw_shl_code=c,true] //***************************************************** //*************************************************************** //************************************************* //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->

UPDR &= ((~(0x3 << 4))); GPIOD->

UPDR |= (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->

SC = 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); [/mw_shl_code]