Keil MDK STM32系列(六) 基于抽象外设库HAL的ADC模数转换-电子工程世界

配置 ADC

模式: 如果只启用了一个ADC, 这里只能配置为Independent mode

时钟分频: 这个选项是ADC的预分频器, 可设置为2/4/6/8, 决定了一个ADC时钟周期. 加入设置为2, 由于ADC是挂载在APB2总线(84M)上, 所以一个ADC时钟便是84 * M/2=42M

分辨率: 最高为12位分辨率, 分辨率越高转换时间越长

数据对齐方式: 如果选择12位分辨率, 右对齐, 得到的结果最大便是4096.

扫描模式: 转换完一个通道会不会继续转换下一个通道

连续转换模式: 使能的话转换将连续进行

不连续转换模式: 当使能多个转换通道时, 可单独设置不连续转换通道.

DMA连续请求: 是否连续请求DMA.

EOC标志设置: 当有多个转换通道时, 是每转换完一个通道设置一次EOC标志还是所有通道都转换完设置一次EOC标志.

转换的通道数:

触发模式: 可选择软件触发, 外部触发或定时器事件触发

秩序列表: 设置转换周期数和转换顺序

注入通道设置

窗口看门狗模式

配置 ADC 为主动请求模式

while (1)

{

/*##-1- Start the conversion process #######################################*/

HAL_ADC_Start(&hadc1);

/*##-2- Wait for the end of conversion #####################################*/

/* Before starting a new conversion, you need to check the current state of

the peripheral; if it’s busy you need to wait for the end of current

conversion before starting a new one.

For simplicity reasons, this example is just waiting till the end of the

conversion, but application may perform other tasks while conversion

operation is ongoing. */

HAL_ADC_PollForConversion(&hadc1, 50);

/* Check if the continous conversion of regular channel is finished */

if(HAL_IS_BIT_SET(HAL_ADC_GetState(&hadc1), HAL_ADC_STATE_REG_EOC))

{

/*##-3- Get the converted value of regular channel ######################*/

AD_Value = HAL_ADC_GetValue(&hadc1);

printf("MCU Temperature : %.1f¡ærn",((AD_Value*3300/4096-760)/2.5+25));

}

HAL_Delay(1000);

}

配置 ADC 为多通道连续扫描DMA模式

开ADC的IN0/IN1两个通道

在Pinout图上, 将PA0和PA1设为ADC1_IN0和ADC2_IN1

配置时钟

ADC1相关配置

ADCs_Common_Settings

Mode: Independent mode

ADC_Settings

Clock Prescaler: PCLK2 divided by 4 可以在时钟配置页看到PCLK2的值

Resolution: 12bits (15 ADC Clock cycles) 采样精度12bit, 此时每次采样需要15个时钟周期, 8bit对应11个时钟周期

Data Alignment: Right alignment

Scan Conversion Mode: Enabled

Continuous Conversion Mode: Enabled --> for DMA

Discontinuous Conversion Mode: Disabled

DMA Continuous Requests: Enabled

End Of Conversion Selection: EOC flag at the end of single channel conversion

ADC_Regular_ConversionMode

Number of Conversion: 2 --> 2 channels

External Trigger Conversion Source: Regular Conversion launched by software

External Trigger Conversion Edge: None

Rank: 1: Choose channel 0

Rank: 2: Choose channel 1

ADC_Injected_ConversionMode

Number of Conversions: 0

DMA相关配置

ADC1

Stream: DMA2 Stream 4

Direction: Peripheral To Memory

Priority: High

DMA Request Settings

Mode: Circular

Increment Address: Memory

Datawidth: Peripheral->Half Word, Memory->Half Word

NVIC Settings

ADC1 global interrupt: Enabled unchecked

DMA2 stream4 global interrupt: Enabled checked

ADC+DMA配置, 体现在代码上的变化

stm32f4xx_hal_conf.h 去掉了ADC的注释

#define HAL_ADC_MODULE_ENABLED

stm32f4xx_it.h 增加了方法声明

void DMA2_Stream4_IRQHandler(void);

stm32f4xx_it.c 增加了对应的typeDef和方法定义

extern DMA_HandleTypeDef hdma_adc1;

void DMA2_Stream4_IRQHandler(void)

{

HAL_DMA_IRQHandler(&hdma_adc1);

}

stm32f4xx_hal_msp.c

extern DMA_HandleTypeDef hdma_adc1;

void HAL_ADC_MspInit(ADC_HandleTypeDef* hadc)

{

GPIO_InitTypeDef GPIO_InitStruct = {0};

if(hadc->Instance==ADC1)

{

__HAL_RCC_ADC1_CLK_ENABLE();

__HAL_RCC_GPIOA_CLK_ENABLE();

/**ADC1 GPIO Configuration

PA0-WKUP ------> ADC1_IN0

PA1 ------> ADC1_IN1

GPIO_InitStruct.Pin = GPIO_PIN_0|GPIO_PIN_1;

GPIO_InitStruct.Mode = GPIO_MODE_ANALOG;

GPIO_InitStruct.Pull = GPIO_NOPULL;

HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

/* ADC1 DMA Init */

/* ADC1 Init */

hdma_adc1.Instance = DMA2_Stream4;

hdma_adc1.Init.Channel = DMA_CHANNEL_0;

hdma_adc1.Init.Direction = DMA_PERIPH_TO_MEMORY;

hdma_adc1.Init.PeriphInc = DMA_PINC_DISABLE;

hdma_adc1.Init.MemInc = DMA_MINC_ENABLE;

hdma_adc1.Init.PeriphDataAlignment = DMA_PDATAALIGN_HALFWORD;

hdma_adc1.Init.MemDataAlignment = DMA_MDATAALIGN_HALFWORD;

hdma_adc1.Init.Mode = DMA_CIRCULAR;

hdma_adc1.Init.Priority = DMA_PRIORITY_HIGH;

hdma_adc1.Init.FIFOMode = DMA_FIFOMODE_DISABLE;

if (HAL_DMA_Init(&hdma_adc1) != HAL_OK)

{

Error_Handler();

}

__HAL_LINKDMA(hadc,DMA_Handle,hdma_adc1);

}

void HAL_ADC_MspDeInit(ADC_HandleTypeDef* hadc)

{

if(hadc->Instance==ADC1)

{

/* Peripheral clock disable */

__HAL_RCC_ADC1_CLK_DISABLE();

/**ADC1 GPIO Configuration

PA0-WKUP ------> ADC1_IN0

PA1 ------> ADC1_IN1

HAL_GPIO_DeInit(GPIOA, GPIO_PIN_0|GPIO_PIN_1);

/* ADC1 DMA DeInit */

HAL_DMA_DeInit(hadc->DMA_Handle);

}

main.c

ADC_HandleTypeDef hadc1;

DMA_HandleTypeDef hdma_adc1;

static void MX_ADC1_Init(void)

{

ADC_ChannelConfTypeDef sConfig = {0};

hadc1.Instance = ADC1;

hadc1.Init.ClockPrescaler = ADC_CLOCK_SYNC_PCLK_DIV4;

hadc1.Init.Resolution = ADC_RESOLUTION_12B;

hadc1.Init.ScanConvMode = ENABLE;

hadc1.Init.ContinuousConvMode = ENABLE;

hadc1.Init.DiscontinuousConvMode = DISABLE;

hadc1.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;

hadc1.Init.ExternalTrigConv = ADC_SOFTWARE_START;

hadc1.Init.DataAlign = ADC_DATAALIGN_RIGHT;

hadc1.Init.NbrOfConversion = 2;

hadc1.Init.DMAContinuousRequests = ENABLE;

hadc1.Init.EOCSelection = ADC_EOC_SINGLE_CONV;

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 = 1;

sConfig.SamplingTime = ADC_SAMPLETIME_3CYCLES;

if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != 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_1;

sConfig.Rank = 2;

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

{

Error_Handler();

}

/**

* Enable DMA controller clock

static void MX_DMA_Init(void)

{

__HAL_RCC_DMA2_CLK_ENABLE();

HAL_NVIC_SetPriority(DMA2_Stream4_IRQn, 0, 0);

HAL_NVIC_EnableIRQ(DMA2_Stream4_IRQn);

}

最后, 在main.c中增加用于存储DMA数据的数组, 将数组地址传给HAL_ADC_Start_DMA()开启DMA传输就可以得到数据了.

DMA数组大小和中断的问题

数组的大小与HAL_ADC_Start_DMA()方法第三个参数length一致, 这里length代表的是数据的个数. 在设置这个大小时, 如果开启了DMAx_Streamx_IRQn的中断, 要考虑sConfig.SamplingTime指定的采样时间不能太短, 太短的话会一直卡在中断里(因为中断什么都不做也需要时间). 这个与SYSCLK大小无关, 在两个通道采样时

如果这里指定的值为ADC_SAMPLETIME_3CYCLES, 这个数组大小至少为6, 如果等于4采样循环会卡住

如果指定的值为ADC_SAMPLETIME_15CYCLES, 这个数组大小至少为4

如果指定的值为ADC_SAMPLETIME_28CYCLES, 数组大小可以为2

如果不需要使用DMA中断, 可以在 MX_DMA_Init()方法中, 将HAL_NVIC_EnableIRQ(DMA2_Stream4_IRQn);这句注释掉或者改成HAL_NVIC_DisableIRQ(DMA2_Stream4_IRQn);指定禁用它, 这个数组就可以设到最小(和采样通道数一致)了.

uint16_t ADC_Value[6];

main(void) {

HAL_ADC_Start_DMA(&hadc1,(uint32_t*)&ADC_Value, 6); // Enable DMA transfer

while (1)

{

printf("%d %d %d %drn",

ADC_Value[0], ADC_Value[1], ADC_Value[2], ADC_Value[3]);

HAL_Delay(100);

}

DMA中断处理回调

查看代码可以看到, 在stm32f4xxx_hal_dma.h中, 定义的 DMA_HandleTypeDef 类型中, 包含了几个对应中断的处理方法

typedef struct __DMA_HandleTypeDef