2021年10月27日 | stm32专题二十四：ADC 标准库函数分析

ADC初始化结构体：

typedef struct

{

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

                                               dual mode. 

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

  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_ExternalTrigConv;          /*!< Defines the external trigger used to start the analog

                                               to digital conversion of regular channels. This parameter

                                               can be a value of @ref ADC_external_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_NbrOfChannel;               /*!< Specifies the number of ADC channels that will be converted

                                               using the sequencer for regular channel group.

                                               This parameter must range from 1 to 16. */

}ADC_InitTypeDef;

（1）ADC模式： 一般选择独立模式；

/** @defgroup ADC_mode 

  * @{

  */

// 独立模式，最为常用

#define ADC_Mode_Independent                       ((uint32_t)0x00000000)

// 剩下的都是双ADC模式，包括同步、交叉、交替、混合等，不常用

#define ADC_Mode_RegInjecSimult                    ((uint32_t)0x00010000)

#define ADC_Mode_RegSimult_AlterTrig               ((uint32_t)0x00020000)

#define ADC_Mode_InjecSimult_FastInterl            ((uint32_t)0x00030000)

#define ADC_Mode_InjecSimult_SlowInterl            ((uint32_t)0x00040000)

#define ADC_Mode_InjecSimult                       ((uint32_t)0x00050000)

#define ADC_Mode_RegSimult                         ((uint32_t)0x00060000)

#define ADC_Mode_FastInterl                        ((uint32_t)0x00070000)

#define ADC_Mode_SlowInterl                        ((uint32_t)0x00080000)

#define ADC_Mode_AlterTrig                         ((uint32_t)0x00090000)

（2）ADC扫描模式：单通道 AD转换使用 DISABLE，多通道 AD转换使用 ENABLE；

（3）ADC连续转换：一般都会启用；

（4）外部触发选择：一般选择软件触发，也可以使用定时器触发 or 外部中断事件触发；

（5）ADC数据对齐：右对齐；

（6）ADC转换通道数量；

常用的标准固件库函数：

（1）ADC初始化函数

// 初始化ADC

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

（2）ADC时钟设置函数（设置分频系数），通常设置为6分频，ADCCLK = 12MHz

/**

  * @brief  Configures the ADC clock (ADCCLK).

  * @param  RCC_PCLK2: defines the ADC clock divider. This clock is derived from 

  *   the APB2 clock (PCLK2).

  *   This parameter can be one of the following values:

  *     @arg RCC_PCLK2_Div2: ADC clock = PCLK2/2

  *     @arg RCC_PCLK2_Div4: ADC clock = PCLK2/4

  *     @arg RCC_PCLK2_Div6: ADC clock = PCLK2/6

  *     @arg RCC_PCLK2_Div8: ADC clock = PCLK2/8

  * @retval None

  */

void RCC_ADCCLKConfig(uint32_t RCC_PCLK2)

{

  uint32_t tmpreg = 0;

  /* Check the parameters */

  assert_param(IS_RCC_ADCCLK(RCC_PCLK2));

  tmpreg = RCC->CFGR;

  /* Clear ADCPRE[1:0] bits */

  tmpreg &= CFGR_ADCPRE_Reset_Mask;

  /* Set ADCPRE[1:0] bits according to RCC_PCLK2 value */

  tmpreg |= RCC_PCLK2;

  /* Store the new value */

  RCC->CFGR = tmpreg;

}

（3）ADC规则通道配置函数（配置通道、转换顺序、采样周期）

/**

  * @brief  Configures for the selected ADC regular channel its corresponding

  *         rank in the sequencer and its sample time.

  * @param  ADCx: where x can be 1, 2 or 3 to select the ADC peripheral.

  * @param  ADC_Channel: the ADC channel to configure. 

  *   This parameter can be one of the following values:

  *     @arg ADC_Channel_0: ADC Channel0 selected

  *     @arg ADC_Channel_1: ADC Channel1 selected

  *     @arg ADC_Channel_2: ADC Channel2 selected

  *     @arg ADC_Channel_3: ADC Channel3 selected

  *     @arg ADC_Channel_4: ADC Channel4 selected

  *     @arg ADC_Channel_5: ADC Channel5 selected

  *     @arg ADC_Channel_6: ADC Channel6 selected

  *     @arg ADC_Channel_7: ADC Channel7 selected

  *     @arg ADC_Channel_8: ADC Channel8 selected

  *     @arg ADC_Channel_9: ADC Channel9 selected

  *     @arg ADC_Channel_10: ADC Channel10 selected

  *     @arg ADC_Channel_11: ADC Channel11 selected

  *     @arg ADC_Channel_12: ADC Channel12 selected

  *     @arg ADC_Channel_13: ADC Channel13 selected

  *     @arg ADC_Channel_14: ADC Channel14 selected

  *     @arg ADC_Channel_15: ADC Channel15 selected

  *     @arg ADC_Channel_16: ADC Channel16 selected

  *     @arg ADC_Channel_17: ADC Channel17 selected

  * @param  Rank: The rank in the regular group sequencer. This parameter must be between 1 to 16.

  * @param  ADC_SampleTime: The sample time value to be set for the selected channel. 

  *   This parameter can be one of the following values:

  *     @arg ADC_SampleTime_1Cycles5: Sample time equal to 1.5 cycles

  *     @arg ADC_SampleTime_7Cycles5: Sample time equal to 7.5 cycles

  *     @arg ADC_SampleTime_13Cycles5: Sample time equal to 13.5 cycles

  *     @arg ADC_SampleTime_28Cycles5: Sample time equal to 28.5 cycles

  *     @arg ADC_SampleTime_41Cycles5: Sample time equal to 41.5 cycles

  *     @arg ADC_SampleTime_55Cycles5: Sample time equal to 55.5 cycles

  *     @arg ADC_SampleTime_71Cycles5: Sample time equal to 71.5 cycles

  *     @arg ADC_SampleTime_239Cycles5: Sample time equal to 239.5 cycles

  * @retval None

  */

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

{

  uint32_t tmpreg1 = 0, tmpreg2 = 0;

  /* Check the parameters */

  assert_param(IS_ADC_ALL_PERIPH(ADCx));

  assert_param(IS_ADC_CHANNEL(ADC_Channel));

  assert_param(IS_ADC_REGULAR_RANK(Rank));

  assert_param(IS_ADC_SAMPLE_TIME(ADC_SampleTime));

  /* if ADC_Channel_10 ... ADC_Channel_17 is selected */

  if (ADC_Channel > ADC_Channel_9)

  {

    /* Get the old register value */

    tmpreg1 = ADCx->SMPR1;

    /* Calculate the mask to clear */

    tmpreg2 = SMPR1_SMP_Set << (3 * (ADC_Channel - 10));

    /* Clear the old channel sample time */

    tmpreg1 &= ~tmpreg2;

    /* Calculate the mask to set */

    tmpreg2 = (uint32_t)ADC_SampleTime << (3 * (ADC_Channel - 10));

    /* Set the new channel sample time */

    tmpreg1 |= tmpreg2;

    /* Store the new register value */

    ADCx->SMPR1 = tmpreg1;

  }

  else /* ADC_Channel include in ADC_Channel_[0..9] */

  {

    /* Get the old register value */

    tmpreg1 = ADCx->SMPR2;

    /* Calculate the mask to clear */

    tmpreg2 = SMPR2_SMP_Set << (3 * ADC_Channel);

    /* Clear the old channel sample time */