STM32采用定时器捕获的方法测低频信号很准确，我测高频100K-120K就误差太大了，大概200Hz,这儿的误差是个范围，不是某个值。有的人说两个定时器一个定时，，一个计数，这样太浪费资源了吧。我项目要采集两个地感线圈的频率，所以用两个定时器捕获，这儿只说一个定时器的方法，用的是定时器3通道2，下面是用捕获的方法计算频率：
void Time3_Configuration(){TIM_ICInitTypeDef TIM_ICInitStructure;TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;TIM_DeInit(TIM3); TIM_TimeBaseStructure.TIM_Period = 0xffff; TIM_TimeBaseStructure.TIM_Prescaler = 0; TIM_TimeBaseStructure.TIM_ClockDivision = 0; TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure); // Time base configuration/*TIM3输入捕获*/ TIM_ICInitStructure.TIM_Channel = TIM_Channel_2; TIM_ICInitStructure.TIM_ICPolarity = TIM_CounterMode_Up; TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI; TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1; /*输入预分频*/ TIM_ICInitStructure.TIM_ICFilter = 0; TIM_ICInit(TIM3, &TIM_ICInitStructure); TIM_PWMIConfig(TIM3, &TIM_ICInitStructure); /* Select the TIM3 Input Trigger: TI2FP2 */ TIM_SelectInputTrigger(TIM3, TIM_TS_TI2FP2); /* Select the slave Mode: Reset Mode */ TIM_SelectSlaveMode(TIM3, TIM_SlaveMode_Reset); /* Enable the Master/Slave Mode */ TIM_SelectMasterSlaveMode(TIM3, TIM_MasterSlaveMode_Enable); /* TIM enable counter */ TIM_Cmd(TIM3, ENABLE); /* Enable the CC2 Interrupt Request */ TIM_ITConfig(TIM3, TIM_IT_CC2, ENABLE);}中断部分计算频率：void TIM3_IRQHandler(void){ if(TIM_GetITStatus(TIM3, TIM_IT_CC2) == SET) {/* Clear TIM5 Capture compare interrupt pending bit */TIM_ClearITPendingBit(TIM3, TIM_IT_CC2);if(capture_number2 == 0){/* Get the Input Capture value */ic3_readvalue3 = TIM_GetCapture2(TIM3);capture_number2 = 1;}){/* Get the Input Capture value */ic3_readvalue4 = TIM_GetCapture2(TIM3);/* Capture computation */if (ic3_readvalue4 > ic3_readvalue3){CAPTURE2 = ic3_readvalue4 ;}/* Frequency computation */Frequency2 = (u32)72000000 / CAPTURE2;capture_number2 = 0;}else{Frequency2=0;} }}
还有一种方法就是用外部中断计算频率，不过我没用过。更精确的计算方法我得慢慢研究。接触STM32也不是太久。
人，也总是很难发现自己的错误，
