stm32f4adc采样fft

### STM32F4 ADC Sampling and FFT Implementation Example #### Overview of ADC Configuration on STM32F4 The configuration begins with setting up the ADC module, which involves configuring several registers to ensure proper operation. The `ADC_CDR` register is a read-only 32-bit register used specifically for storing regular conversion data in dual mode configurations where high 16 bits store ADC2's rule channel group conversion value while low 16 bits are reserved for ADC1’s conversions[^1]. For controlling general settings across multiple ADCs, one uses the `ADC_CCR`, including options like adjusting prescaler values (`ADCPRE`) that determine how much PCLK2 gets divided before reaching the ADC clock—ranging from no division (PCLK2/2) up to dividing by eight (PCLK2/8)[^1]. Considering system limitations, it should be noted that due to constraints imposed by maximum permissible frequencies within this microcontroller family, achieving an optimal balance between performance requirements such as desired sample rate versus achievable accuracy becomes crucial when tuning parameters related directly or indirectly through PLL adjustments affecting overall timing characteristics[^2]. #### Code Implementation for ADC Setup and FFT Execution Below demonstrates initializing single-channel continuous sampling at approximately 2 MHz using DMA transfer into buffer followed by applying Fast Fourier Transform algorithm over collected samples. ```c #include "stm32f4xx_hal.h" #define SAMPLES_COUNT 1024 // Number of points needed for accurate FFT analysis. uint16_t adcBuffer[SAMPLES_COUNT]; // Buffer holding raw ADC readings. float fftInput[SAMPLES_COUNT], magnitudeOutput[(SAMPLES_COUNT / 2)]; // Arrays required during processing stage. // Function prototypes declaration here... void SystemClock_Config(void); static void MX_GPIO_Init(void); static void MX_DMA_Init(void); static void MX_ADC1_Init(ADC_HandleTypeDef* hadc); int main(void){ HAL_Init(); SystemClock_Config(); // Configure system clocks according to application needs. /* Initialize peripherals */ MX_GPIO_Init(); MX_DMA_Init(); ADC_HandleTypeDef AdcHandle; MX_ADC1_Init(&AdcHandle); if(HAL_ADC_Start_DMA(&AdcHandle,(uint32_t*)adcBuffer,SAMPLES_COUNT)!=HAL_OK){ Error_Handler(__FILE__,__LINE__); // Handle potential errors gracefully. } while (1){} // Main loop does nothing since all operations occur via interrupts/DMA transfers. } /* Additional functions definitions go below... */ /** * @brief Initializes ADC peripheral based upon specified handle structure contents. */ static void MX_ADC1_Init(ADC_HandleTypeDef* hadc){ ADC_ChannelConfTypeDef sConfig = {0}; /** Common config */ hadc->Instance=ADC1; hadc->Init.ClockPrescaler=ADC_CLOCK_SYNC_PCLK_DIV4; // Set appropriate divider per project specs.[^1] hadc->Init.Resolution=ADC_RESOLUTION_12B; hadc->Init.ScanConvMode=DISABLE; hadc->Init.ContinuousConvMode=ENABLE; hadc->Init.DiscontinuousConvMode=DISABLE; hadc->Init.ExternalTrigConvEdge=ADC_EXTERNALTRIGCONVEDGE_NONE; hadc->Init.DataAlign=ADC_DATAALIGN_RIGHT; hadc->Init.NbrOfConversion=1; if (HAL_ADC_Init(hadc) != HAL_OK){ Error_Handler(__FILE__, __LINE__); } /** Channel-specific setup */ sConfig.Channel = ADC_CHANNEL_0; sConfig.Rank = 1; sConfig.SamplingTime = ADC_SAMPLETIME_3CYCLES; if (HAL_ADC_ConfigChannel(hadc,&sConfig) != HAL_OK){ Error_Handler(__FILE__, __LINE__); } } ``` After collecting sufficient data points inside `adcBuffer[]`, proceed with performing FFT calculations utilizing libraries compatible with your development environment: ```cpp for(int i = 0 ;i<SAMPLES_COUNT;i++){ fftInput[i]= static_cast<float>(adcBuffer[i]); } arm_rfft_fast_f32(&fftInst,fftInput,magnitudeOutput,ifftFlag,bitReverseFlag); // Assuming CMSIS-DSP library usage. ```