stm32fl07采集交流电电压，通过fft找出最大幅值，以及电压的相位

要采集交流电电压，需要使用模拟输入通道。在STM32F407中，可以使用内置的ADC模块进行模拟输入。下面是一个简单的示例代码，可以采集电压并转换为数字信号：

#include "stm32f4xx.h"
#include <stdio.h>
#include <math.h>

#define ADC1_DR_ADDRESS ((uint32_t)0x4001204C)

#define SAMPLES 512
#define PI 3.14159265358979323846

uint16_t ADCConvertedValues[SAMPLES];
float realValues[SAMPLES];
float imagValues[SAMPLES];
float magnitudeValues[SAMPLES/2];
float phaseValues[SAMPLES/2];

void GPIO_Configuration(void);
void ADC_Configuration(void);
void FFT(void);

int main(void)
{
    GPIO_Configuration();
    ADC_Configuration();

    while(1)
    {
        ADC_SoftwareStartConv(ADC1);
        while(ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC) == RESET);

        FFT();

        //找出最大幅值及其相应的频率
        float max = magnitudeValues[0];
        int index = 0;
        for(int i = 1; i < SAMPLES/2; i++)
        {
            if(magnitudeValues[i] > max)
            {
                max = magnitudeValues[i];
                index = i;
            }
        }
        float frequency = (float)index / SAMPLES * 10000;  //假设采样率为10kHz

        printf("Maximum magnitude: %f\n", max);
        printf("Frequency: %f Hz\n", frequency);
        printf("Phase: %f radians\n", phaseValues[index]);
    }
}

void GPIO_Configuration(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;

    //使能GPIOA时钟
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);

    //配置PA0为模拟输入
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;
    GPIO_Init(GPIOA, &GPIO_InitStructure);
}

void ADC_Configuration(void)
{
    ADC_CommonInitTypeDef ADC_CommonInitStructure;
    ADC_InitTypeDef ADC_InitStructure;

    //使能ADC1时钟
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);

    //配置ADC1
    ADC_CommonInitStructure.ADC_Mode = ADC_Mode_Independent;
    ADC_CommonInitStructure.ADC_Prescaler = ADC_Prescaler_Div2;
    ADC_CommonInitStructure.ADC_DMAAccessMode = ADC_DMAAccessMode_Disabled;
    ADC_CommonInitStructure.ADC_TwoSamplingDelay = ADC_TwoSamplingDelay_5Cycles;
    ADC_CommonInit(&ADC_CommonInitStructure);

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

    //配置ADC1的通道0为模拟输入
    ADC_RegularChannelConfig(ADC1, ADC_Channel_0, 1, ADC_SampleTime_3Cycles);

    //启动ADC1的转换
    ADC_Cmd(ADC1, ENABLE);
}

void FFT(void)
{
    //将采样值转换为实数
    for(int i = 0; i < SAMPLES; i++)
    {
        realValues[i] = (float)ADCConvertedValues[i] / 4096.0 * 3.3;
        imagValues[i] = 0.0;
    }

    //计算FFT
    for(int i = 0; i < SAMPLES/2; i++)
    {
        float realSum = 0.0;
        float imagSum = 0.0;
        for(int j = 0; j < SAMPLES; j++)
        {
            realSum += realValues[j] * cos(2 * PI * i * j / SAMPLES);
            imagSum -= realValues[j] * sin(2 * PI * i * j / SAMPLES);
        }
        realValues[i] = realSum;
        imagValues[i] = imagSum;
    }

    //计算幅值和相位
    for(int i = 0; i < SAMPLES/2; i++)
    {
        magnitudeValues[i] = sqrt(realValues[i]*realValues[i] + imagValues[i]*imagValues[i]) / (SAMPLES/2);
        phaseValues[i] = atan2(imagValues[i], realValues[i]);
    }
}

在上面的代码中，我们采用了512点FFT计算电压的频谱，找出最大幅值及其相应的频率，以及该频率的相位。注意，这里假设采样率为10kHz，因此频率的单位是Hz，相位的单位是弧度。