stm32标准库低通滤波代码

以下是一个基于STM32标准库的低通滤波器代码示例：

#include "stm32f4xx.h"

#define SAMPLE_RATE 100   // 采样率
#define CUTOFF_FREQ 10    // 截止频率

int main(void)
{
    // 初始化时钟
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

    // 配置GPIO引脚
    GPIO_InitTypeDef GPIO_InitStruct;
    GPIO_InitStruct.GPIO_Pin = GPIO_Pin_0;
    GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AN;
    GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOA, &GPIO_InitStruct);

    // 配置定时器
    TIM_TimeBaseInitTypeDef TIM_InitStruct;
    TIM_InitStruct.TIM_Prescaler = SystemCoreClock / (SAMPLE_RATE * 2) - 1;   // 定时器时钟频率为采样率的2倍
    TIM_InitStruct.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_InitStruct.TIM_Period = 1000 - 1;   // 定时器周期为1ms
    TIM_InitStruct.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseInit(TIM2, &TIM_InitStruct);

    // 配置ADC
    ADC_InitTypeDef ADC_InitStruct;
    ADC_CommonInitTypeDef ADC_CommonInitStruct;
    ADC_CommonInitStruct.ADC_Mode = ADC_Mode_Independent;   // 独立模式
    ADC_CommonInitStruct.ADC_Prescaler = ADC_Prescaler_Div2;   // ADC时钟频率为APB2时钟频率的1/2
    ADC_CommonInitStruct.ADC_DMAAccessMode = ADC_DMAAccessMode_Disabled;
    ADC_CommonInitStruct.ADC_TwoSamplingDelay = ADC_TwoSamplingDelay_5Cycles;
    ADC_CommonInit(&ADC_CommonInitStruct);

    ADC_InitStruct.ADC_Resolution = ADC_Resolution_12b;
    ADC_InitStruct.ADC_ScanConvMode = DISABLE;
    ADC_InitStruct.ADC_ContinuousConvMode = ENABLE;
    ADC_InitStruct.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None;
    ADC_InitStruct.ADC_DataAlign = ADC_DataAlign_Right;
    ADC_InitStruct.ADC_NbrOfConversion = 1;
    ADC_Init(ADC1, &ADC_InitStruct);

    ADC_RegularChannelConfig(ADC1, ADC_Channel_0, 1, ADC_SampleTime_15Cycles);

    // 配置DMA
    DMA_InitTypeDef DMA_InitStruct;
    DMA_InitStruct.DMA_Channel = DMA_Channel_0;
    DMA_InitStruct.DMA_PeripheralBaseAddr = (uint32_t)&(ADC1->DR);
    DMA_InitStruct.DMA_Memory0BaseAddr = (uint32_t)&adc_value;
    DMA_InitStruct.DMA_DIR = DMA_DIR_PeripheralToMemory;
    DMA_InitStruct.DMA_BufferSize = 1;
    DMA_InitStruct.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
    DMA_InitStruct.DMA_MemoryInc = DMA_MemoryInc_Enable;
    DMA_InitStruct.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
    DMA_InitStruct.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
    DMA_InitStruct.DMA_Mode = DMA_Mode_Circular;
    DMA_InitStruct.DMA_Priority = DMA_Priority_High;
    DMA_InitStruct.DMA_FIFOMode = DMA_FIFOMode_Disable;
    DMA_InitStruct.DMA_FIFOThreshold = DMA_FIFOThreshold_HalfFull;
    DMA_InitStruct.DMA_MemoryBurst = DMA_MemoryBurst_Single;
    DMA_InitStruct.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
    DMA_Init(DMA2_Stream0, &DMA_InitStruct);

    // 配置NVIC
    NVIC_InitTypeDef NVIC_InitStruct;
    NVIC_InitStruct.NVIC_IRQChannel = DMA2_Stream0_IRQn;
    NVIC_InitStruct.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStruct.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStruct.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStruct);

    // 启动DMA
    DMA_Cmd(DMA2_Stream0, ENABLE);

    // 启动ADC
    ADC_Cmd(ADC1, ENABLE);

    // 启动定时器
    TIM_Cmd(TIM2, ENABLE);

    while(1)
    {
        // 等待DMA传输完成
        while(!DMA_GetFlagStatus(DMA2_Stream0, DMA_FLAG_TCIF0));
        DMA_ClearFlag(DMA2_Stream0, DMA_FLAG_TCIF0);

        // 计算低通滤波器系数
        float RC = 1.0 / (2 * 3.14159265358979323846 * CUTOFF_FREQ);
        float dt = 1.0 / SAMPLE_RATE;
        float alpha = dt / (RC + dt);

        // 应用低通滤波器
        filtered_value = alpha * adc_value + (1 - alpha) * filtered_value;
    }
}

// DMA传输完成中断处理函数
void DMA2_Stream0_IRQHandler(void)
{
    if(DMA_GetITStatus(DMA2_Stream0, DMA_IT_TCIF0))
    {
        DMA_ClearITPendingBit(DMA2_Stream0, DMA_IT_TCIF0);
    }
}

此代码实现了一个基于RC低通滤波器的实时滤波器，用于去除选定频率以下的噪声。它使用DMA和定时器来实现连续的ADC采样，并计算和应用低通滤波器。请注意，此代码仅是示例，实际实现可能需要进行调整以适应特定的硬件和应用程序要求。