STM32使用捕获功能，计算输入PWM信号周期，误差很大，求帮忙？？
我用的TIMER2的CH1通道，PWM信号接在PA0脚。我输入100Hz信号，根据捕获得到的结果是105Hz,这误差也太大了吧！！求各位高手帮忙解决一下，万分感谢！！下面是我的初始化程序：
1：时钟初始化，我的TIMER2上的时钟频率为36M
RCC_PCLK1Config(RCC_HCLK_Div2); //设置低速AHB时钟=系统时钟/2
RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9); //倍频系数为9 PLLCLK=8*9=72
2：TIMER2初始化
TIM_DeInit(TIM2);
TIM_TimeBaseStructure.TIM_Period = 65535;
TIM_TimeBaseStructure.TIM_Prescaler = 18;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
TIM_ICInitStructure.TIM_Channel = TIM_Channel_1;
TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV4;
TIM_ICInitStructure.TIM_ICFilter = 0x0;
TIM_PWMIConfig(TIM2, &TIM_ICInitStructure);
TIM_SelectInputTrigger(TIM2, TIM_TS_TI1FP1);
TIM_SelectSlaveMode(TIM2, TIM_SlaveMode_Reset); //复位模式为从模式
TIM_SelectMasterSlaveMode(TIM2, TIM_MasterSlaveMode_Enable); //使能主从模式
TIM_Cmd(TIM2, ENABLE); //使能TIM2计数器
TIM_ITConfig(TIM2, TIM_IT_CC2, ENABLE); //使能CC2中断请求
3，中断部分程序
void TIM2_IRQHandler(void)
{
/* Clear TIM2 Capture compare interrupt pending bit */
TIM_ClearITPendingBit(TIM2, TIM_IT_CC2);
/* Get the Input Capture value */
IC2_Value = TIM_GetCapture2(TIM2);
}
回复:STM32使用捕获功能，计算输入PWM信号周期，误差很大，求帮忙？？
回复第 1 楼 studentzf972于2009-06-09 01:24:10发表:我用的TIMER2的CH1通道，PWM信号接在PA0脚。我输入100Hz信号，根据捕获得到的结果是105Hz,这误差也太大了吧！！求各位高手帮忙解决一下，万分感谢！！
下面是我的初始化程序：
1：时钟初始化，我的TIMER2上的时钟频率为36M
RCC_PCLK1Config(RCC_HCLK_Div2); //设置低速AHB时钟=系统时钟/2
RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9); //倍频系数为9 PLLCLK=8*9=72
2：TIMER2初始化
TIM_DeInit(TIM2);
TIM_TimeBaseStructure.TIM_Period = 65535;
TIM_TimeBaseStructure.TIM_Prescaler = 18;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
TIM_ICInitStructure.TIM_Channel = TIM_Channel_1;
TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV4;
TIM_ICInitStructure.TIM_ICFilter = 0x0;
TIM_PWMIConfig(TIM2, &TIM_ICInitStructure);
TIM_SelectInputTrigger(TIM2, TIM_TS_TI1FP1);
TIM_SelectSlaveMode(TIM2, TIM_SlaveMode_Reset); //复位模式为从模式
TIM_SelectMasterSlaveMode(TIM2, TIM_MasterSlaveMode_Enable); //使能主从模式
TIM_Cmd(TIM2, ENABLE); //使能TIM2计数器
TIM_ITConfig(TIM2, TIM_IT_CC2, ENABLE); //使能CC2中断请求
3，中断部分程序
void TIM2_IRQHandler(void)
{
/* Clear TIM2 Capture compare interrupt pending bit */
TIM_ClearITPendingBit(TIM2, TIM_IT_CC2);
/* Get the Input Capture value */
IC2_Value = TIM_GetCapture2(TIM2);
}
回复:STM32使用捕获功能，计算输入PWM信号周期，误差很大，求帮忙？？
Prescaler = 18: 分频为19 .
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