分享一个FFT实现频谱仪的例子

#include "main.h"

#include "arm_math.h"



#define N 256 // FFT长度

#define Fs 10000 // 采样率

#define ADC_BUF_LEN 512 // ADC缓存长度

#define OLED_WIDTH 128 // OLED宽度

#define OLED_HEIGHT 64 // OLED高度



uint16_t ADC_Buffer[ADC_BUF_LEN]; // ADC采样缓存

uint16_t FFT_Input[N]; // FFT输入缓存

float32_t FFT_Output[N]; // FFT输出缓存

float32_t FFT_Mag[N/2]; // FFT幅值缓存

uint8_t OLED_Buffer[OLED_WIDTH*OLED_HEIGHT/8]; // OLED显示缓存



extern SPI_HandleTypeDef hspi1; // OLED所用SPI口



void SystemClock_Config(void);

static void MX_GPIO_Init(void);

static void MX_DMA_Init(void);

static void MX_ADC1_Init(void);

static void MX_SPI1_Init(void);



void HAL_ADC_ConvCpltCallback(ADC_HandleTypeDef* hadc) { // ADC完成一次转换的回调函数

    uint32_t i, j;



    for(i=0, j=0; i<N; i+=2, j++) { // 交错采样，同时处理两个ADC采样值

        FFT_Input[j] = ADC_Buffer[i];

    }



    arm_rfft_fast_instance_f32 S; // 初始化FFT结构体

    arm_rfft_fast_init_f32(&S, N);



    arm_rfft_fast_f32(&S, FFT_Input, FFT_Output, 0); // 执行FFT

    arm_cmplx_mag_f32(FFT_Output, FFT_Mag, N/2); // 计算幅值



    for(i=0; i<OLED_WIDTH; i++) { // 将频谱转换为显示格式

        uint8_t row_data = 0;

        for(j=i*OLED_HEIGHT/OLED_WIDTH; j<(i+1)*OLED_HEIGHT/OLED_WIDTH; j++) {

            if(FFT_Mag[j] > 20000) { // 限制幅值范围

                FFT_Mag[j] = 20000;

            }

            uint8_t bit = (FFT_Mag[j] * OLED_HEIGHT / 20000.0) * 255 / 8; // 将幅值映射到OLED高度

            row_data |= (bit << (j % 8)); // 存储到OLED缓存中

        }

        OLED_Buffer[i*OLED_HEIGHT/8] = row_data;

    }



    HAL_SPI_Transmit(&hspi1, OLED_Buffer, OLED_WIDTH*OLED_HEIGHT/8, 10); // 将OLED缓存发送到OLED显示屏

}



int main(void) {

    HAL_Init();

    SystemClock_Config();

    MX_GPIO_Init();

    MX_DMA_Init();

    MX_ADC1_Init();

    MX_SPI1_Init();

    HAL_ADC_Start_DMA(&hadc1, (uint32_t*)ADC_Buffer, ADC_BUF_LEN); // 启动ADC采样



    while (1) {



    }

}



void SystemClock_Config(void) {

    RCC_OscInitTypeDef RCC_OscInitStruct = {0};

    RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};



/** Initializes the RCC Oscillators according to the specified parameters

* in the RCC_OscInitTypeDef structure.

*/

RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;

RCC_OscInitStruct.HSEState = RCC_HSE_ON;

RCC_OscInitStruct.HSEPredivValue = RCC_HSE_PREDIV_DIV1;

RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;

RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;

RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;

if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) {

    Error_Handler();

}



/** Initializes the CPU, AHB and APB buses clocks

*/

RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK

                            |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;

RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;

RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;

RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;

RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;



if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK) {

    Error_Handler();

}

PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_ADC|RCC_PERIPHCLK_SPI1;

PeriphClkInit.AdcClockSelection = RCC_ADCPCLK2_DIV6;

PeriphClkInit.Spi1ClockSelection = RCC_SPI1CLKSOURCE_PCLK2;

if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK) {

    Error_Handler();

}

}



static void MX_ADC1_Init(void) {

ADC_ChannelConfTypeDef sConfig = {0};

/** Configure the global features of the ADC (Clock, Resolution, Data Alignment and number of conversion)

*/

hadc1.Instance = ADC1;

hadc1.Init.ScanConvMode = ENABLE;

hadc1.Init.ContinuousConvMode = ENABLE;

hadc1.Init.DiscontinuousConvMode = DISABLE;

hadc1.Init.ExternalTrigConv = ADC_SOFTWARE_START;

hadc1.Init.DataAlign = ADC_DATAALIGN_RIGHT;

hadc1.Init.NbrOfConversion = 1;

if (HAL_ADC_Init(&hadc1) != HAL_OK) {

    Error_Handler();

}



/** Configure for the selected ADC regular channel its corresponding rank in the sequencer and its sample time.

*/

sConfig.Channel = ADC_CHANNEL_0;

sConfig.Rank = ADC_REGULAR_RANK_1;

sConfig.SamplingTime = ADC_SAMPLETIME_13CYCLES_5;

if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK) {

    Error_Handler();

}

}



static void MX_DMA_Init(void) {

/* DMA controller clock enable */

__HAL_RCC_DMA1_CLK_ENABLE();

/* DMA interrupt init */

/* DMA1_Channel1_IRQn interrupt configuration */

HAL_NVIC_SetPriority(DMA1_Channel1_IRQn, 0, 0);

HAL_NVIC_EnableIRQ(DMA1_Channel1_IRQn);

HAL_NVIC_SetPriority(SysTick_IRQn, 0, 0);

}



static void MX_SPI1_Init(void) {

/* SPI1 parameter configuration*/

hspi1.Instance = SPI1;

hspi1.Init.Mode= SPI_MODE_MASTER;

hspi1.Init.Direction = SPI_DIRECTION_1LINE;

hspi1.Init.DataSize = SPI_DATASIZE_8BIT;

hspi1.Init.CLKPolarity = SPI_POLARITY_LOW;

hspi1.Init.CLKPhase = SPI_PHASE_1EDGE;

hspi1.Init.NSS = SPI_NSS_SOFT;

hspi1.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_256;

hspi1.Init.FirstBit = SPI_FIRSTBIT_MSB;

hspi1.Init.TIMode = SPI_TIMODE_DISABLE;

hspi1.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;

hspi1.Init.CRCPolynomial = 10;

if (HAL_SPI_Init(&hspi1) != HAL_OK) {

Error_Handler();

}

}



void Error_Handler(void) {

/* USER CODE BEGIN Error_Handler_Debug /

/ User can add his own implementation to report the HAL error return state /

while(1) {

}

/ USER CODE END Error_Handler_Debug */

}



#ifdef USE_FULL_ASSERT



void assert_failed(uint8_t file, uint32_t line) {

/ USER CODE BEGIN 6 /

/ User can add his own implementation to report the file name and line number,

ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) /

/ USER CODE END 6 */

}



#endif