我用stm32F103RC定时器3通道2来采集频率,输入频率为1.8KHZ,测得为2KHZ。用示波器实测也是1.8KHz。程序如下.请问我这程序要怎么改才能采集到正确的数据。需要用运算放大器吗?
/***********************************************************************************************
//上升沿捕获
************************************************************************************************/
TIM_ICInitTypeDef TIM3_ICInitStructure;
void TIM3_counter_Init(u16 arr,u16 psc)
{
GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
NVIC_InitTypeDef NVIC_InitStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE); //使能TIM5时钟
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE); //使能GPIOA时钟
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7; //PA7 清除之前设置
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING; //PA7 浮空输入
GPIO_Init(GPIOA, &GPIO_InitStructure);
GPIO_ResetBits(GPIOA,GPIO_Pin_7); //PA7 下拉
//初始化定时器5 TIM5
TIM_TimeBaseStructure.TIM_Period = arr; //设定计数器自动重装值
TIM_TimeBaseStructure.TIM_Prescaler =psc; //预分频器
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; //设置时钟分割:TDTS = Tck_tim
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //TIM向上计数模式
TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure); //根据TIM_TimeBaseInitStruct中指定的参数初始化TIMx的时间基数单位
//初始化TIM5输入捕获参数
TIM3_ICInitStructure.TIM_Channel = TIM_Channel_2; // 选择输入端 IC1映射到TI1上
TIM3_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising; //上升沿捕获
TIM3_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI; //映射到TI1上
TIM3_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1; //配置输入分频,不分频
TIM3_ICInitStructure.TIM_ICFilter = 0x00; //IC1F=0000 配置输入滤波器 不滤波
TIM_ICInit(TIM3, &TIM3_ICInitStructure);
TIM_SelectInputTrigger(TIM3, TIM_TS_TI2FP2); //选择IC2为始终触发源
TIM_SelectSlaveMode(TIM3, TIM_SlaveMode_Reset);//TIM从模式:触发信号的上升沿重新初始化计数器和触发寄存器的更新事件
TIM_SelectMasterSlaveMode(TIM3, TIM_MasterSlaveMode_Enable); //启动定时器的被动触发
//中断分组初始化
NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn; //TIM3中断
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; //先占优先级2级
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; //从优先级0级
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ通道被使能
NVIC_Init(&NVIC_InitStructure); //根据NVIC_InitStruct中指定的参数初始化外设NVIC寄存器
TIM_ITConfig(TIM3,TIM_IT_CC2,ENABLE);//不能允许更新中断 ,允许CC2IE捕获中断
TIM_Cmd(TIM3,ENABLE); //使能定时器3
}
/***********************************************************************************************
************************************************************************************************/
u32 counter=0; // 每秒计数
int Frequency=0;
void TIM3_IRQHandler(void)
{
static int i =0;
if (TIM_GetITStatus(TIM3, TIM_IT_CC2) == SET)
{
TIM_ClearITPendingBit(TIM3, TIM_IT_CC2); //清楚TIM的中断待处理位
counter = (u32)TIM_GetCapture2(TIM3);
Frequency =72000000/counter;
printf("当前频率为:%d Hz\r\n",Frequency/7200); //打印数据
for(i=0;i<2000000;i++)
{
;
}
}
}
[07:49:19.112]收←◆当前频率为:2000 Hz
[07:49:20.189]收←◆当前频率为:2000 Hz
[07:49:21.266]收←◆当前频率为:2000 Hz
[07:49:22.343]收←◆当前频率为:2000 Hz
[07:49:23.420]收←◆当前频率为:2000 Hz
[07:49:24.497]收←◆当前频率为:2000 Hz
[07:49:25.574]收←◆当前频率为:2000 Hz
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