STM32 关于ADC采交直流问题探讨(一)

前沿

关于STM32采样问题，相信很多人曾遇到过这样的问题，无论是关于ADC底层相关的配置还是ADC采样方案的抉择，或者是ADC软硬件滤波算法，这里博主就自己曾做过的训练题为引申，探讨ADC采样过程中的问题。

1.ADC的认识

1.1 ADC初始化参数

/* Exported types ------------------------------------------------------------*/

/**

  * @brief   ADC Init structure definition  

  */

typedef struct

{

  uint32_t ADC_Resolution;                                 /*!< Configures the ADC resolution dual mode. This parameter can be a value of @ref ADC_resolution */                                   

  FunctionalState ADC_ScanConvMode;             /*!< Specifies whether the conversion is performed in Scan (multichannels)or Single (one channel) mode.

                                                                                   This parameter can be set to ENABLE or DISABLE */

  FunctionalState ADC_ContinuousConvMode;  /*!< Specifies whether the conversion is performed in Continuous or Single mode.

                                                                                   This parameter can be set to ENABLE or DISABLE. */

  uint32_t ADC_ExternalTrigConvEdge;          /*!< Select the external trigger edge and enable the trigger of a regular group.

                                                                           This parameter can be a value of

                                                                       @ref ADC_external_trigger_edge_for_regular_channels_conversion */

  uint32_t ADC_ExternalTrigConv;                  /*!< Select the external event used to trigger the start of conversion of a regular group.

                                                                           This parameter can be a value of

                                                                       @ref ADC_extrenal_trigger_sources_for_regular_channels_conversion */

  uint32_t ADC_DataAlign;                 /*!< Specifies whether the ADC data  alignment is left or right. This parameter can be

                                                                       a value of @ref ADC_data_align */

  uint8_t  ADC_NbrOfConversion;           /*!< Specifies the number of ADC conversions  that will be done using the sequencer for

                                                                       regular channel group.This parameter must range from 1 to 16. */

}ADC_InitTypeDef;

涉及的相关参数：ADC分辨率（6/8/10/12位）、扫描或非扫描模式、连续或不连续转换、触发方式、对齐方式等。 

       这里值得注意的是规则组转化序列不能超过16。

1.2 ADC通用初始化参数

/**

  * @brief   ADC Common Init structure definition  

  */

typedef struct

{

  uint32_t ADC_Mode;                      /*!< Configures the ADC to operate in

                                               independent or multi mode.

                                               This parameter can be a value of @ref ADC_Common_mode */                                              

  uint32_t ADC_Prescaler;                 /*!< Select the frequency of the clock

                                               to the ADC. The clock is common for all the ADCs.

                                               This parameter can be a value of @ref ADC_Prescaler */

  uint32_t ADC_DMAAccessMode;             /*!< Configures the Direct memory access

                                              mode for multi ADC mode.

                                               This parameter can be a value of

                                               @ref ADC_Direct_memory_access_mode_for_multi_mode */

  uint32_t ADC_TwoSamplingDelay;          /*!< Configures the Delay between 2 sampling phases.

                                               This parameter can be a value of

                                               @ref ADC_delay_between_2_sampling_phases */

}ADC_CommonInitTypeDef;

这里涉及相关ADC单独/多重模式选择，两采样阶段采样间隔，DMA使能/失能，ADC分屏系数（注意ADC的时钟频率不超过36Mhz）

1.3 ADC相关配置库函数

/*  Function used to set the ADC configuration to the default reset state *****/  

void ADC_DeInit(void);

/* Initialization and Configuration functions *********************************/

void ADC_Init(ADC_TypeDef* ADCx, ADC_InitTypeDef* ADC_InitStruct);

void ADC_StructInit(ADC_InitTypeDef* ADC_InitStruct);

void ADC_CommonInit(ADC_CommonInitTypeDef* ADC_CommonInitStruct);

void ADC_CommonStructInit(ADC_CommonInitTypeDef* ADC_CommonInitStruct);

void ADC_Cmd(ADC_TypeDef* ADCx, FunctionalState NewState);

/* Analog Watchdog configuration functions ************************************/

void ADC_AnalogWatchdogCmd(ADC_TypeDef* ADCx, uint32_t ADC_AnalogWatchdog);

void ADC_AnalogWatchdogThresholdsConfig(ADC_TypeDef* ADCx, uint16_t HighThreshold,uint16_t LowThreshold);

void ADC_AnalogWatchdogSingleChannelConfig(ADC_TypeDef* ADCx, uint8_t ADC_Channel);

/* Temperature Sensor, Vrefint and VBAT management functions ******************/

void ADC_TempSensorVrefintCmd(FunctionalState NewState);

void ADC_VBATCmd(FunctionalState NewState);

/* Regular Channels Configuration functions ***********************************/

void ADC_RegularChannelConfig(ADC_TypeDef* ADCx, uint8_t ADC_Channel, uint8_t Rank, uint8_t ADC_SampleTime);

void ADC_SoftwareStartConv(ADC_TypeDef* ADCx);

FlagStatus ADC_GetSoftwareStartConvStatus(ADC_TypeDef* ADCx);

void ADC_EOCOnEachRegularChannelCmd(ADC_TypeDef* ADCx, FunctionalState NewState);

void ADC_ContinuousModeCmd(ADC_TypeDef* ADCx, FunctionalState NewState);

void ADC_DiscModeChannelCountConfig(ADC_TypeDef* ADCx, uint8_t Number);

void ADC_DiscModeCmd(ADC_TypeDef* ADCx, FunctionalState NewState);

uint16_t ADC_GetConversionValue(ADC_TypeDef* ADCx);

uint32_t ADC_GetMultiModeConversionValue(void);

/* Regular Channels DMA Configuration functions *******************************/

void ADC_DMACmd(ADC_TypeDef* ADCx, FunctionalState NewState);

void ADC_DMARequestAfterLastTransferCmd(ADC_TypeDef* ADCx, FunctionalState NewState);

void ADC_MultiModeDMARequestAfterLastTransferCmd(FunctionalState NewState);

/* Injected channels Configuration functions **********************************/

void ADC_InjectedChannelConfig(ADC_TypeDef* ADCx, uint8_t ADC_Channel, uint8_t Rank, uint8_t ADC_SampleTime);

void ADC_InjectedSequencerLengthConfig(ADC_TypeDef* ADCx, uint8_t Length);

void ADC_SetInjectedOffset(ADC_TypeDef* ADCx, uint8_t ADC_InjectedChannel, uint16_t Offset);

void ADC_ExternalTrigInjectedConvConfig(ADC_TypeDef* ADCx, uint32_t ADC_ExternalTrigInjecConv);

void ADC_ExternalTrigInjectedConvEdgeConfig(ADC_TypeDef* ADCx, uint32_t ADC_ExternalTrigInjecConvEdge);

void ADC_SoftwareStartInjectedConv(ADC_TypeDef* ADCx);

FlagStatus ADC_GetSoftwareStartInjectedConvCmdStatus(ADC_TypeDef* ADCx);

void ADC_AutoInjectedConvCmd(ADC_TypeDef* ADCx, FunctionalState NewState);

void ADC_InjectedDiscModeCmd(ADC_TypeDef* ADCx, FunctionalState NewState);

uint16_t ADC_GetInjectedConversionValue(ADC_TypeDef* ADCx, uint8_t ADC_InjectedChannel);