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我用stm32F103RC定時(shí)器3通道2來(lái)采集頻率，輸入頻率為1.8KHZ，測(cè)得為2KHZ。用示波器實(shí)測(cè)也是1.8KHz。程序如下.請(qǐng)問(wèn)我這程序要怎么改才能采集到正確的數(shù)據(jù)。需要用運(yùn)算放大器嗎？
/***********************************************************************************************
//上升沿捕獲
************************************************************************************************/
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時(shí)鐘
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE); //使能GPIOA時(shí)鐘
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7; //PA7 清除之前設(shè)置
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING; //PA7 浮空輸入
GPIO_Init(GPIOA, &GPIO_InitStructure);
GPIO_ResetBits(GPIOA,GPIO_Pin_7); //PA7 下拉
//初始化定時(shí)器5 TIM5
TIM_TimeBaseStructure.TIM_Period = arr; //設(shè)定計(jì)數(shù)器自動(dòng)重裝值
TIM_TimeBaseStructure.TIM_Prescaler =psc; //預(yù)分頻器
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; //設(shè)置時(shí)鐘分割:TDTS = Tck_tim
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //TIM向上計(jì)數(shù)模式
TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure); //根據(jù)TIM_TimeBaseInitStruct中指定的參數(shù)初始化TIMx的時(shí)間基數(shù)單位
//初始化TIM5輸入捕獲參數(shù)
TIM3_ICInitStructure.TIM_Channel = TIM_Channel_2; // 選擇輸入端 IC1映射到TI1上
TIM3_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising; //上升沿捕獲
TIM3_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI; //映射到TI1上
TIM3_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1; //配置輸入分頻,不分頻
TIM3_ICInitStructure.TIM_ICFilter = 0x00; //IC1F=0000 配置輸入濾波器 不濾波
TIM_ICInit(TIM3, &TIM3_ICInitStructure);
TIM_SelectInputTrigger(TIM3, TIM_TS_TI2FP2); //選擇IC2為始終觸發(fā)源
TIM_SelectSlaveMode(TIM3, TIM_SlaveMode_Reset);//TIM從模式：觸發(fā)信號(hào)的上升沿重新初始化計(jì)數(shù)器和觸發(fā)寄存器的更新事件
TIM_SelectMasterSlaveMode(TIM3, TIM_MasterSlaveMode_Enable); //啟動(dòng)定時(shí)器的被動(dòng)觸發(fā)
//中斷分組初始化
NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn; //TIM3中斷
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; //先占優(yōu)先級(jí)2級(jí)
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; //從優(yōu)先級(jí)0級(jí)
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ通道被使能
NVIC_Init(&NVIC_InitStructure); //根據(jù)NVIC_InitStruct中指定的參數(shù)初始化外設(shè)NVIC寄存器
TIM_ITConfig(TIM3,TIM_IT_CC2,ENABLE);//不能允許更新中斷 ,允許CC2IE捕獲中斷
TIM_Cmd(TIM3,ENABLE); //使能定時(shí)器3
}
/***********************************************************************************************
************************************************************************************************/
u32 counter=0; // 每秒計(jì)數(shù)
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的中斷待處理位
counter = (u32)TIM_GetCapture2(TIM3);
Frequency =72000000/counter;
printf("當(dāng)前頻率為:%d Hz\r\n",Frequency/7200); //打印數(shù)據(jù)
for(i=0;i<2000000;i++)
{
;
}
}
}
[07:49:19.112]收←◆當(dāng)前頻率為:2000 Hz
[07:49:20.189]收←◆當(dāng)前頻率為:2000 Hz
[07:49:21.266]收←◆當(dāng)前頻率為:2000 Hz
[07:49:22.343]收←◆當(dāng)前頻率為:2000 Hz
[07:49:23.420]收←◆當(dāng)前頻率為:2000 Hz
[07:49:24.497]收←◆當(dāng)前頻率為:2000 Hz
[07:49:25.574]收←◆當(dāng)前頻率為:2000 Hz
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