模数转换器（ADC）

概述

本章描述 12 位逐次逼近寄存器（SAR）型模数转换器（ADC）的使用方法，ADC 转换结果存储在结果寄存器中，支持按需读取。

ADC 的相关参数如下：

  • 分辨率：12 位

  • ENOB：10 位

  • 采样频率：31.25 kHz ~ 250 kHz，建议值为 166.67 kHz（默认）

  • 采样电容：2.4 pF ~ 2.93 pF

  • 参考电压：固定，不可外供

  • 内部阻抗：500 kΩ左右

  • FIFO：64 * 16 位

  • 通道切换列表长度：1 ~ 16

  • 通道参数如下表所示：

RTL8721Dx:

通道

通道号

引脚

输入电压（V）

常规通道

CH0~CH6

PB13~PB19

0 ~ 3.3

电池测量通道

CH7

BAT_MEAS

0 ~ 5

备注

ADC 多通道采样分时复用同一个 ADC 采样电路。上述采样频率是针对单个通道的参数，当通道切换列表中设置多个不同的通道时，对单个通道的采样频率会同比成倍降低。

ADC 采样模式

RTL8721Dx:

ADC 仅支持 连续采样模式。该模式下，ADC 不间断地按序对通道列表的通道进行采样，开关均可控，适合短时间内对电压连续采样。

ADC 支持 多通道采样，用户可以配置 通道切换列表 ，参数包括 采样通道数量 和 采样通道切换顺序。

ADC 采样顺序为：每当触发信号产生，ADC 会对通道列表中的所有通道按序进行采样。

使用 ADC 连续采样模式的步骤如下：

  1. 启用 ADC 模块的时钟与功能

    RCC_PeriphClockCmd(APBPeriph_ADC, APBPeriph_ADC_CLOCK, ENABLE);
RCC_PeriphClockCmd(APBPeriph_CTC, APBPeriph_CTC_CLOCK, ENABLE);

  2. 根据 Pinmux 映射表配置 ADC 引脚复用

    例如：调用以下函数来使用 ADC0 通道。

    Pinmux_Config(ADC_CH0_PIN, PINMUX_FUNCTION_xxx); // 参考 pinmux table 配置 function ID
PAD_InputCtrl(ADC_CH0_PIN, DISABLE);
PAD_PullCtrl(ADC_CH0_PIN, GPIO_PuPd_NOPULL);
PAD_SleepPullCtrl(ADC_CH0_PIN, GPIO_PuPd_NOPULL);

    备注

    BAT_MEAS 引脚为专用引脚，不需要执行该步骤。

  3. 设置默认参数，并修改 ADC 工作模式。默认 ADC 对所有通道按序采样

    ADC_StructInit(ADC_InitTypeDef *ADC_InitStruct);
ADC_InitStruct->ADC_OpMode = ADC_AUTO_MODE; // 设置采样模式为连续采样

  4. 如有需要，修改 ADC_InitStruct 结构体，调整通道列表及其他参数

    例如：用户设置通道切换列表的长度为 3 ，分别对通道 0、通道 2 和通道 4 进行采样。

    ADC_InitStruct->ADC_CvlistLen = 3 - 1; // 设置通道列表长度
ADC_InitStruct->ADC_Cvlist[0] = ADC_CH0; // 设置第一个通道号
ADC_InitStruct->ADC_Cvlist[1] = ADC_CH2; // 设置第二个通道号
ADC_InitStruct->ADC_Cvlist[2] = ADC_CH4; // 设置第三个通道号

  5. 初始化 ADC，并启用 ADC

    ADC_Init(ADC_InitTypeDef *ADC_InitStruct);
ADC_Cmd(ENABLE);

  6. 通过轮询模式或中断模式读取 ADC 采样数据

    • 轮询模式：

      ADC_ReceiveBuf(u16 *pBuf, u32 len);

    • 中断模式：

      ADC_INTConfig(ADC_BIT_IT_FIFO_OVER_EN | ADC_BIT_IT_FIFO_FULL_EN, ENABLE);
InterruptRegister((IRQ_FUN)ADCIrqHandle, ADC_IRQ, NULL, INT_PRI_MIDDLE);
InterruptEn(ADC_IRQ, INT_PRI_MIDDLE);
ADC_AutoCSwCmd(ENABLE);

    其中， ADCIrqHandle 的定义为：

    u32 ADCIrqHandle(void *para)
{
   (void)para;
   u32 status = ADC_GetISR();

   if (status & ADC_BIT_IT_FIFO_FULL_STS) {
      while (ADC_Readable()) {
         u32 sample_value = ADC_Read(); // 读出采样值
         if (sample_cnt ++ > MAX_SAMPLE_CNT) { // 读到足够多的采样值
            ADC_AutoCSwCmd(DISABLE);
            ADC_INTConfig(ADC_BIT_IT_FIFO_OVER_EN | ADC_BIT_IT_FIFO_FULL_EN, DISABLE);
            InterruptDis(ADC_IRQ);
            break;
         }
      }
   }

   ADC_INTClearPendingBits(status);
   return 0;
}

备注

采样结果由 4 位通道号和 12 位采样值组成。用户可以分别通过以下宏获取：

  • ADC_GET_CH_NUM_GLOBAL(sample_data)：获取 4 位通道号

  • ADC_GET_DATA_GLOBAL(sample_data)：获取 12 位采样值

ADC 校准

ADC 电压校准

  • 为了改善 ADC 输入/输出特性的线性度，在工厂阶段对每颗芯片进行 ADC 的偏移误差与增益误差校准。

  • 用户可分别通过以下 API 获取校准电压：

    • ADC_GetVoltage(u32 chan_data)：获取校准后的常规通道电压

    • ADC_GetVBATVoltage(u32 vbat_data)：获取校准后的电池测量通道电压

ADC 内部电阻校准

  • 不同芯片的 ADC 内部电阻 R 存在差异

  • 用户可直接通过 ADC_GetInterR() 获取内部电阻

ADC 数字比较器

ADC 包含数字比较器，如果指定通道的采样数值在设置的范围内，会产生对应中断，用户可以在中断处理程序中进行特定的操作，如读取当前电压等。

数字比较器在 ADC 的所有采样模式下都可以工作。

数字比较器支持以下 比较模式 ：

  • 小于低阈值

  • 大于高阈值

  • 大于等于低阈值 且 小于等于高阈值

  • 小于低阈值 或 大于高阈值

备注

低阈值和高阈值的取值范围为 0 ~ 4095 ，低阈值不能大于高阈值。

以连续采样模式为例，如果要使用 ADC 数字比较器，请按照以下步骤操作：

  1. 启用 ADC 模块的时钟与功能。

    RCC_PeriphClockCmd(APBPeriph_ADC, APBPeriph_ADC_CLOCK, ENABLE);
RCC_PeriphClockCmd(APBPeriph_CTC, APBPeriph_CTC_CLOCK, ENABLE);

  2. 根据 Pinmux 映射表配置 ADC 引脚复用。

    例如，调用以下函数使用 ADC0：

    Pinmux_Config(ADC_CH0_PIN, PINMUX_FUNCTION_xxx); // 请参考 Pinmux 表获取 function ID
PAD_InputCtrl(ADC_CH0_PIN, DISABLE);
PAD_PullCtrl(ADC_CH0_PIN, GPIO_PuPd_NOPULL);
PAD_SleepPullCtrl(ADC_CH0_PIN, GPIO_PuPd_NOPULL);

  3. 指定通道并设置比较器的低阈值、高阈值和比较模式。

    例如：调用以下函数来设置 ADC0 通道的比较模式，当采样值大于等于 2000 且小于等于 3000 时会有中断产生。

    ADC_SetComp(ADC_CH0, 3000, 2000, ADC_COMP_WITHIN_THL_AND_THH);
InterruptRegister((IRQ_FUN)ADCIrqHandle, ADC_IRQ, NULL, INT_PRI_MIDDLE);
InterruptEn(ADC_IRQ, INT_PRI_MIDDLE);

    其中，ADCIrqHandle 的定义如下：

    u32 ADCIrqHandle(void *para)
{
   (void)para;
   u32 status = ADC_GetISR();
   u32 value;
   if (status & ADC_BIT_IT_COMP_ALL_STS) {
      printf("ISR:0x%x, Comp status:0x%x\n", status, ADC->ADC_COMP_STS); // ADC 在指定通道的采样值落在设置范围内
      while (ADC_Readable() == 0);
      value = ADC_Read();
   }
   ADC_INTClearPendingBits(status);
   return 0;
}

  4. 设置默认参数，并修改 ADC 工作模式。默认情况下，ADC 按序对所有通道进行采样。

    ADC_StructInit(ADC_InitTypeDef *ADC_InitStruct);
ADC_InitStruct->ADC_OpMode = ADC_AUTO_MODE; // 设置为自动模式

  5. 如有需要，修改 ADC_InitStruct 结构体，调整通道列表及其他参数。

    例如，将通道切换列表长度设为 3，并按顺序采样 ADC0/ADC2/ADC4：

    ADC_InitStruct->ADC_CvlistLen = 3 - 1; // 设置通道切换列表长度
ADC_InitStruct->ADC_Cvlist[0] = ADC_CH0; // 设置第 1 个通道 ID
ADC_InitStruct->ADC_Cvlist[1] = ADC_CH2; // 设置第 2 个通道 ID
ADC_InitStruct->ADC_Cvlist[2] = ADC_CH4; // 设置第 3 个通道 ID

  6. 初始化 ADC，并启用 ADC。

    ADC_Init(ADC_InitTypeDef *ADC_InitStruct);
ADC_Cmd(ENABLE);

  7. 建议通过轮询模式读取 ADC 采样数据。

ADC 常见问题排查

采样电压偏移

现象

采样电压偏移

原因

  • 校准参数不适用

  • 输入阻抗不匹配

解决方法

  • 重新校准

  • 调整输入阻抗，使得信号源内阻远小于ADC输入阻抗

备注

  • 如果条件满足，可以考虑将应用电路一起校准。

  • 参考硬件设计手册，获取 ADC 内部阻抗值。

通道间串扰

现象

通道间串扰

原因

  • 输入阻抗不匹配，输入源驱动能力差

  • 采样率太高

解决方法

  • 降低信号源内阻

  • 降低采样率

采样电压干扰

现象

采样电压干扰，信噪比低

原因

PCB布局不合理

解决方法

  • 检查PCB布局，如是否临近开关电源、高速信号等

  • 如果接受软件滤波，可以进行多点采样值平均

Raw API

ADC Exported Types

struct ADC_CalParaTypeDef

ADC Calibration Parameter Structure Definition.

Public Members

s32 cal_a

Calibration coefficient A.

s32 cal_b

Calibration coefficient B.

s32 cal_c

Calibration coefficient C.

u8 init_done

Calibration parameter initialization done flag.

RTL8721Dx:
struct ADC_InitTypeDef

ADC Init Structure Definition.

Public Members

u8 ADC_OpMode

Specifies ADC operation mode. This parameter can be a value of ADC Operation Mode

u8 ADC_CvlistLen

The number of valid items in the ADC conversion channel list is (ADC_CvlistLen + 1). This parameter can be set to 0~15

u8 ADC_Cvlist[16]

Specifies the ADC channel conversion order. Each member should be a value of ADC Channel Selection

u8 ADC_ClkDiv

Specifies ADC clock divider. This parameter can be a value of ADC Clock Divider

u8 ADC_RxThresholdLevel

Specifies the receive FIFO threshold level. When the number of rx FIFO entries is greater than or equal to this value +1, the receive FIFO full interrupt is triggered.

u8 ADC_SpecialCh

Specifies ADC particular channel. This parameter defines that ADC module should send interrupt signal to system when a conversion which of channel number is the same as this parameter. Default 0xFF means there is no need to set particular channel.

u32 ADC_ChanInType

Specifies CH0~5 input type. Default all channels are in single-end mode. If some channels need to be set to differential mode, use a value or combination of ADC Channel Input Type.

enum ADC_OS_Mode

ADC Oversample Mode.

Values:

/* All oversampling conversions done in staggered sequence */
ADC_OS_STAGGERED = 0x00

/* All oversampling conversions done in regular sequence */
ADC_OS_REGULAR = 0x01
enum ADC_OS_Ratio

ADC Oversample Ratio.

Values:

/* 2x */
ADC_OSR_2 = 0x00

/* 4x */
ADC_OSR_4 = 0x01

/* 8x */
ADC_OSR_8 = 0x02

/* 16x */
ADC_OSR_16 = 0x03

/* 32x */
ADC_OSR_32 = 0x04

/* 64x */
ADC_OSR_64 = 0x05

/* 128x */
ADC_OSR_128 = 0x06

/* 256x */
ADC_OSR_256 = 0x07
enum ADC_OS_Shift

ADC Oversample Right Shift.

Values:

/* No shift */
ADC_OSF_NONE = 0x00

/* Right shift 1 bit */
ADC_OSF_1 = 0x01

/* Right shift 2 bits */
ADC_OSF_2 = 0x02

/* Right shift 3 bits */
ADC_OSF_3 = 0x03

/* Right shift 4 bits */
ADC_OSF_4 = 0x04

/* Right shift 5 bits */
ADC_OSF_5 = 0x05

/* Right shift 6 bits */
ADC_OSF_6 = 0x06

/* Right shift 7 bits */
ADC_OSF_7 = 0x07

ADC Exported Constants

ADC Channel Switch List

/* Bit shift for channel switch list 0 entry x. */
#define ADC_SHIFT_CHSW0 (4*(x))

/* Bit shift for channel switch list 1 entry x. */
#define ADC_SHIFT_CHSW1 (4*((x) - 8))

ADC Channel Input Type

/* Set channel x to differential input mode. */
#define ADC_DIFFERENTIAL_CH ((u32)0x00000001 << (x))

ADC Channel Selection

/* ADC channel 0 index. */
#define ADC_CH0 ((u8)0x00)

/* ADC channel 1 index. */
#define ADC_CH1 ((u8)0x01)

/* ADC channel 2 index. */
#define ADC_CH2 ((u8)0x02)

/* ADC channel 3 index. */
#define ADC_CH3 ((u8)0x03)

/* ADC channel 4 index. */
#define ADC_CH4 ((u8)0x04)

/* ADC channel 5 index. */
#define ADC_CH5 ((u8)0x05)

/* ADC channel 6 index. */
#define ADC_CH6 ((u8)0x06)

/* ADC channel 7 index. */
#define ADC_CH7 ((u8)0x07)

/* ADC channel 8 index. */
#define ADC_CH8 ((u8)0x08)

/* ADC channel 9 index. */
#define ADC_CH9 ((u8)0x09)

/* Global ADC channel identifier. */
#define ADC_GLOBAL ((u8)0xFF)
RTL8721Dx: 
/* ADC channel 10 index (internal). */
#define ADC_CH10 ((u8)0x0A)

/* ADC dummy cycle channel. */
#define ADC_DUMMY_CYCLE ((u8)0x0F)

/* Total number of ADC channels. */
#define ADC_CH_NUM (11)

/* Number of external ADC channels. */
#define ADC_EXT_CH_NUM (7)

/* Check if ADC channel selection is valid. */
#define IS_ADC_CHN_SEL (((SEL) == ADC_CH0) || \
    ((SEL) == ADC_CH1) || \
    ((SEL) == ADC_CH2) || \
    ((SEL) == ADC_CH3) || \
    ((SEL) == ADC_CH4) || \
    ((SEL) == ADC_CH5) || \
    ((SEL) == ADC_CH6) || \
    ((SEL) == ADC_CH7) || \
    ((SEL) == ADC_CH8) || \
    ((SEL) == ADC_CH9) || \
    ((SEL) == ADC_CH10) || \
    ((SEL) == ADC_DUMMY_CYCLE))

ADC Compare Control

/* Compare criterion: Vin below lower threshold. */
#define ADC_COMP_SMALLER_THAN_THL ((u8)0x00)

/* Compare criterion: Vin above upper threshold. */
#define ADC_COMP_GREATER_THAN_THH ((u8)0x01)

/* Compare criterion: Vin within lower and upper thresholds. */
#define ADC_COMP_WITHIN_THL_AND_THH ((u8)0x02)

/* Compare criterion: Vin outside lower and upper thresholds. */
#define ADC_COMP_OUTSIDE_THL_AND_THH ((u8)0x03)

/* Check if ADC comparison criteria is valid. */
#define IS_ADC_COMP_CRITERIA (((rule) == ADC_COMP_SMALLER_THAN_THL) || \
    ((rule) == ADC_COMP_GREATER_THAN_THH) || \
    ((rule) == ADC_COMP_WITHIN_THL_AND_THH) || \
    ((rule) == ADC_COMP_OUTSIDE_THL_AND_THH))

ADC Comparison Setting

/* Bit shift for comparison control of channel x. */
#define ADC_SHIFT_COMP_CTRL_CH (2*x)

/* Bitmask for comparison control of channel x. */
#define ADC_MASK_COMP_CTRL_CH (u32)(0x00000003 << ADC_SHIFT_COMP_CTRL_CH(x))

/* Bit shift for comparison status of channel x. */
#define ADC_SHIFT_COMP_STS_CH (2*x)

/* Bitmask for comparison status of channel x. */
#define ADC_MASK_COMP_STS_CH (u32)(0x00000003 << ADC_SHIFT_COMP_STS_CH(x))

/* Comparison interrupt enable bit for channel x. */
#define ADC_IT_COMP_CH_EN ((u32)0x00000001 << ((8+x)))
RTL8721Dx: 
/* Comparison interrupt detection mode: level. */
#define ADC_COMP_LEVEL_DETECT (0x0)

/* Comparison interrupt detection mode: edge. */
#define ADC_COMP_EDGE_DETECT (0x1)

ADC Operation Mode

/* ADC software-trigger operation mode. */
#define ADC_SW_TRI_MODE ((u8)0x00)

/* ADC automatic operation mode. */
#define ADC_AUTO_MODE ((u8)0x01)

/* ADC timer-trigger operation mode. */
#define ADC_TIM_TRI_MODE ((u8)0x02)
RTL8721Dx: 
/* ADC comparator-assist operation mode. */
#define ADC_COMP_ASSIST_MODE ((u8)0x03)

/* Check if ADC operation mode is valid. */
#define IS_ADC_MODE (((mode) == ADC_SW_TRI_MODE) || \
    ((mode) == ADC_AUTO_MODE) || \
    ((mode) == ADC_TIM_TRI_MODE) || \
    ((mode) == ADC_COMP_ASSIST_MODE))

ADC Valid Timer

/* Check if ADC timer index value is valid. */
#define IS_ADC_VALID_TIM ((idx) < 8)

ADC Channel Pad Selection

RTL8721Dx: 
/* Pin mapping for ADC channel 0. */
#define ADC_CH0_PIN (_PB_19)

/* Pin mapping for ADC channel 1. */
#define ADC_CH1_PIN (_PB_18)

/* Pin mapping for ADC channel 2. */
#define ADC_CH2_PIN (_PB_17)

/* Pin mapping for ADC channel 3. */
#define ADC_CH3_PIN (_PB_16)

/* Pin mapping for ADC channel 4. */
#define ADC_CH4_PIN (_PB_15)

/* Pin mapping for ADC channel 5. */
#define ADC_CH5_PIN (_PB_14)

/* Pin mapping for ADC channel 6. */
#define ADC_CH6_PIN (_PB_13)

ADC Clock Divider

RTL8721Dx: 
/* ADC clock divided by 4. */
#define ADC_CLK_DIV_4 ((u8)0x00)

/* ADC clock divided by 8. */
#define ADC_CLK_DIV_8 ((u8)0x01)

/* ADC clock divided by 16. */
#define ADC_CLK_DIV_16 ((u8)0x02)

/* ADC clock divided by 24. */
#define ADC_CLK_DIV_24 ((u8)0x03)

/* ADC clock divided by 32. */
#define ADC_CLK_DIV_32 ((u8)0x04)

/* ADC clock divided by 64. */
#define ADC_CLK_DIV_64 ((u8)0x05)

/* ADC clock divided by 128. */
#define ADC_CLK_DIV_128 ((u8)0x06)

/* Check if ADC sample clock divider is valid. */
#define IS_ADC_SAMPLE_CLK ((CLK) == ADC_CLK_DIV_4) || \
    ((CLK) == ADC_CLK_DIV_8) || \
    ((CLK) == ADC_CLK_DIV_16) || \
    ((CLK) == ADC_CLK_DIV_24) || \
    ((CLK) == ADC_CLK_DIV_32) || \
    ((CLK) == ADC_CLK_DIV_64) || \
    ((CLK) == ADC_CLK_DIV_128)

ADC Compare Threshold

RTL8721Dx: 
/* Check if ADC comparison threshold value is valid. */
#define IS_ADC_VALID_COMP_TH ((x) < 0x10000)

ADC Interrupt Control

RTL8721Dx: 
/* Bitmask enabling all ADC interrupts. */
#define ADC_BIT_IT_ALL_EN (ADC_BIT_IT_COMP_CH10_EN  |\
    ADC_BIT_IT_COMP_CH9_EN   |\
    ADC_BIT_IT_COMP_CH8_EN   |\
    ADC_BIT_IT_COMP_CH7_EN   |\
    ADC_BIT_IT_COMP_CH6_EN   |\
    ADC_BIT_IT_COMP_CH5_EN   |\
    ADC_BIT_IT_COMP_CH4_EN   |\
    ADC_BIT_IT_COMP_CH3_EN   |\
    ADC_BIT_IT_COMP_CH2_EN   |\
    ADC_BIT_IT_COMP_CH1_EN   |\
    ADC_BIT_IT_COMP_CH0_EN   |\
    ADC_BIT_IT_ERR_EN        |\
    ADC_BIT_IT_DAT_OVW_EN    |\
    ADC_BIT_IT_FIFO_EMPTY_EN |\
    ADC_BIT_IT_FIFO_OVER_EN  |\
    ADC_BIT_IT_FIFO_FULL_EN  |\
    ADC_BIT_IT_CHCV_END_EN   |\
    ADC_BIT_IT_CV_END_EN     |\
    ADC_BIT_IT_CVLIST_END_EN)

ADC Interrupt Status

RTL8721Dx: 
/* Bitmask of all channel comparison interrupt status bits. */
#define ADC_BIT_IT_COMP_ALL_STS (ADC_BIT_IT_COMP_CH0_STS | \
    ADC_BIT_IT_COMP_CH1_STS | \
    ADC_BIT_IT_COMP_CH2_STS | \
    ADC_BIT_IT_COMP_CH3_STS | \
    ADC_BIT_IT_COMP_CH4_STS | \
    ADC_BIT_IT_COMP_CH5_STS | \
    ADC_BIT_IT_COMP_CH6_STS | \
    ADC_BIT_IT_COMP_CH7_STS | \
    ADC_BIT_IT_COMP_CH8_STS | \
    ADC_BIT_IT_COMP_CH9_STS | \
    ADC_BIT_IT_COMP_CH10_STS)

/* Bitmask of all ADC interrupt status bits. */
#define ADC_BIT_IT_ALL_STS (ADC_BIT_IT_COMP_ALL_STS | \
    ADC_BIT_IT_ERR_STS | \
    ADC_BIT_IT_DAT_OVW_STS |\
    ADC_BIT_IT_FIFO_EMPTY_STS |\
    ADC_BIT_IT_FIFO_OVER_STS |\
    ADC_BIT_IT_FIFO_FULL_STS |\
    ADC_BIT_IT_CHCV_END_STS |\
    ADC_BIT_IT_CV_END_STS |\
    ADC_BIT_IT_CVLIST_END_STS)

ADC Data Setting

RTL8721Dx: 
/* Extract channel ID and conversion data from ADC register value. */
#define ADC_ID_AND_DATA ((u32)((x) & 0x000FFFFF))

ADC OTP Address Setting

RTL8721Dx: 
/* OTP address for normal channel voltage calibration. */
#define NORM_VOL_ADDR 0x704

/* OTP address for VBAT channel voltage calibration. */
#define VBAT_VOL_ADDR 0x70A

/* OTP address for voltage reference selection. */
#define VREF_SEL_ADDR 0x7EB

/* OTP address for internal resistance calibration. */
#define INTER_R_ADDR 0x7EC

ADC Vref Selection

RTL8721Dx:

Not supported.

ADC Exported Functions

void ADC_AutoCSwCmd(u32 NewState)

Enable or disable the automatic channel switch.

参数:

  • NewState --

    This parameter can be one of the following values:

    • ENABLE: Enable the automatic channel switch.

    • DISABLE: Disable the automatic channel switch.

备注

  • Used in Automatic Mode.

  • When setting this bit, an automatic channel switch starts from the first channel in the channel switch list.

  • If an automatic channel switch is in progress, writing 0 will terminate the automatic channel switch.

void ADC_ClearFIFO(void)

Clear ADC FIFO.

void ADC_Cmd(u32 NewState)

Enable or disable the ADC peripheral.

参数:

  • NewState -- New state of the ADC peripheral. This parameter can be ENABLE or DISABLE.

u32 ADC_GetCompStatus(u8 ADC_Channel)

Get comparison result of ADC channel.

参数:

  • ADC_Channel -- ADC channel index.

返回:

The comparison result of specified ADC channel.

u32 ADC_GetISR(void)

Get ADC interrupt status.

返回:

Current interrupt status.

u32 ADC_GetInterR(void)

Get internal R resistance of V33 channels(CH0~CH5) in divided mode.

返回:

Internal R resistance value in Kohm.

u32 ADC_GetLastChan(void)

Get the last ADC used channel.

返回:

The last ADC used channel index.

u32 ADC_GetRawISR(void)

Get ADC raw interrupt status.

返回:

Current raw interrupt status.

u32 ADC_GetRxCount(void)

Get the number of valid entries in ADC receive FIFO.

返回:

The number of valid entries in receive FIFO.

u32 ADC_GetStatus(void)

Get ADC status.

返回:

Current status.

s32 ADC_GetVoltage(u32 chan_data)

Get normal channel voltage value in mV.

参数:

  • chan_data -- ADC conversion data.

返回:

ADC voltage value in mV.

void ADC_INTClear(void)

Clear all the ADC interrupt pending bits.

备注

This function can also be used to clear raw interrupt status.

void ADC_INTClearPendingBits(u32 ADC_IT)

Clear specified ADC interrupt pending bits.

参数:

  • ADC_IT -- Pending bits to be cleared. This parameter is a bitmask of the ADC_INTR_STS register bits.

void ADC_INTConfig(u32 ADC_IT, u32 NewState)

Enable or disable ADC interrupt(s).

参数:

  • ADC_IT -- ADC interrupt(s) to be enabled or disabled. This parameter is a bitmask of the ADC_INTR_CTRL register bits.

  • NewState -- ENABLE or DISABLE.

void ADC_Init(ADC_InitTypeDef *ADC_InitStruct)

Initialize ADC according to the specified parameters in ADC_InitStruct.

参数:

  • ADC_InitStruct -- Pointer to an ADC_InitTypeDef structure that contains the configuration information of the ADC peripheral.

u32 ADC_Read(void)

Read data from ADC receive FIFO .

返回:

The conversion data with the channel index that the data belongs to.

u32 ADC_Readable(void)

Determine ADC FIFO is readable or not.

返回:

ADC FIFO is readable or not:

  • 0: Not readable

  • 1: Readable

void ADC_ReceiveBuf(u32 *pBuf, u32 len)

Read data in auto mode continuously.

参数:

  • pBuf -- Pointer to buffer to keep sample data.

  • len -- Number of sample data to be read.

void ADC_SetComp(u8 ADC_channel, u16 CompThresH, u16 CompThresL, u8 CompCtrl)

Set ADC channel threshold and criteria for comparison.

参数:

  • ADC_channel -- This parameter can be a value of ADC Channel Selection.

  • CompThresH -- Higher threshold of channel for ADC automatic comparison.

  • CompThresL -- Lower threshold of channel for ADC automatic comparison.

  • CompCtrl --

    This parameter can be a value of ADC Compare Control as following:

    • ADC_COMP_SMALLER_THAN_THL: less than the lower threshold

    • ADC_COMP_GREATER_THAN_THH: greater than the higher threshold

    • ADC_COMP_WITHIN_THL_AND_THH: between the lower and higher threshold

    • ADC_COMP_OUTSIDE_THL_AND_THH: out the range of the higher and lower threshold

void ADC_StructInit(ADC_InitTypeDef *ADC_InitStruct)

Initialize the parameters in the ADC_InitStruct with default values.

参数:

  • ADC_InitStruct -- Pointer to an ADC_InitTypeDef structure that contains the configuration information of the ADC peripheral.

RTL8721Dx:
u32 ADC_GetSampleValue(s32 VolMV, u8 IsVBatChan)

Get normal or vbat sample value according to voltage in mV.

参数:

  • VolMV -- ADC Voltage in mV.

  • IsVBatChan --

    Calibration parameter belongs to vbat channel or normal channel. This parameter can be one of the following values:

    • TRUE: Calibration parameter belongs to vbat channel.

    • FALSE: Calibration parameter belongs to normal channel.

返回:

ADC conversion data.

void ADC_InitCalPara(ADC_CalParaTypeDef *CalPara, u8 IsVBatChan)

Initialize ADC calibration parameters according to EFuse.

参数:

  • CalPara -- Pointer to ADC calibration parameter structure.

  • IsVBatChan --

    Calibration parameter belongs to vbat channel or normal channel. This parameter can be one of the following values:

    • TRUE: Calibration parameter belongs to vbat channel.

    • FALSE: Calibration parameter belongs to normal channel.

s32 ADC_GetVBATVoltage(u32 vbat_data)

Get VBAT voltage value in mV.

参数:

  • vbat_data -- ADC conversion data from VBAT channel.

返回:

ADC voltage value in mV.

备注

This function is only for VBAT channel.

void ADC_OverSampleCmd(u32 NewState)

Control ADC oversample function.

参数:

  • NewState --

    This parameter can be one of the following values:

    • ENABLE: Enable ADC oversample.

    • DISABLE: Disable ADC oversample.

void ADC_SetChList(u8 *ChanIdBuf, u8 ChanLen)

Set list length and channel ID of ADC channel switch list.

参数:

  • ChanIdBuf -- Pointer to ADC channel ID buffer, which contains value of ADC Channel Selection.

  • ChanLen -- ADC channel list length, which can be 1 ~ 16.

void ADC_SetCompMode(u8 det_mode)

Set ADC comparison detection mode.

参数:

  • det_mode --

    This parameter can be one of the following values:

    • ADC_COMP_LEVEL_DETECT: Level detection mode.

    • ADC_COMP_EDGE_DETECT: Edge detection mode.

void ADC_SetOverSample(ADC_OS_Shift OS_Shift, ADC_OS_Ratio OS_Ratio, ADC_OS_Mode OS_Mode)

Set ADC oversample parameters.

参数:

  • OS_Shift -- Oversample right shift bit. This parameter can be a value of ADC_OS_Shift.

  • OS_Ratio -- Oversample ratio. This parameter can be a value of ADC_OS_Ratio.

  • OS_Mode -- Oversample mode. This parameter can be a value of ADC_OS_Mode.

Mbed API

MBED_ADC Exported Types

Enumeration Type

enum AnalogInCallback

Analog input (ADC) callback event types.

Values:

/* DMA RX transfer complete event. */
ANALOGIN_RX_DMA_COMPLETE = 0

MBED_ADC Exported Functions

void analogin_deinit(analogin_t *obj)

Deinitialize the ADC device, including clock, function and ADC registers.

参数:

  • obj -- ADC object defined in application software.

void analogin_init(analogin_t *obj, PinName pin)

Initialize the ADC device, including clock, function and ADC registers.

参数:

  • obj -- ADC object defined in application software.

  • pin -- ADC PinName according to pinmux spec.

float analogin_read(analogin_t *obj)

Read data from the specified ADC channel FIFO.

参数:

  • obj -- ADC object defined in application software.

返回:

ADC channel data(float).

uint16_t analogin_read_u16(analogin_t *obj)

Read data from the specified ADC channel FIFO.

参数:

  • obj -- ADC object defined in application software.

返回:

16b ADC channel data(int).

uint32_t analogin_voltage_norm(uint32_t adc_data)

Get channel voltage in mV according to conversion data from normal channel.

参数:

  • adc_data -- ADC conversion data from normal channel.

返回:

Normal channel voltage in mV.

RTL8721Dx:
uint32_t analogin_voltage_vbat(uint32_t adc_data)

Get channel voltage in mV according to conversion data from VBAT channel.

参数:

  • adc_data -- ADC conversion data from VBAT channel.

返回:

VBAT channel voltage in mV.