stm32 ADC模数转换 ADC多通道 ADC DMA

缺乏、安全感 2022-06-10 07:50 351阅读 0赞

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通过调节电位器，改变AD转换值和电压值

**STM32F1 ADC 配置步骤**

> 1.使能GPIO时钟和ADC时钟  
> 2.配置引脚模式为模拟输入  
> 3.配置ADC的分频因子  
> 4.初始化ADC参数，ADC\_InitTypeDef  
> 5.使能ADC  
> 6.执行ADC校准  
> 7.设置ADC软件启动  
> 8.读取ADC转换值  
> 9.设置ADC规则，采样时间等  
> 10.使能ADC的软件转换  
> 11.读取ADC转换结果

**举例**

u16 ADC_value(u8 time)
    {
        u8 i = 0;
        u16 value;
    
        for(i = 0; i < time; i++)
        {
            ADC_SoftwareStartConvCmd(ADC1, ENABLE); //使能ADC的软件转换
    
            while(ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC) != SET);
    
            value += ADC_GetConversionValue(ADC1); //读取ADC转换结果
        }
    
        return value/time;
    }
    
    typedef struct
    {
        uint32_t ADC_Mode; //双模式选择
        FunctionalState ADC_ScanConvMode; //扫描模式 
        FunctionalState ADC_ContinuousConvMode; //连续转换
        uint32_t ADC_ExternalTrigConv;  //注入通道的外部触发转换模式
        uint32_t ADC_DataAlign; //数据对齐
        uint8_t ADC_NbrOfChannel; //规则通道序列长度
    }ADC_InitTypeDef;
    
    void ADC_init()
    {
        GPIO_InitTypeDef gpio = 
        {
            GPIO_Pin_1,
            GPIO_Speed_50MHz,
            GPIO_Mode_AIN //模拟输入
        };
    
        ADC_InitTypeDef adc =
        {
            ADC_Mode_Independent, //独立模式
            DISABLE, //关闭扫描模式
            DISABLE, //单次转换模式
            ADC_ExternalTrigConv_None, //不用外部事件启动转换
            ADC_DataAlign_Right, //右对齐
            1, //通道数目1
        };
    
        RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_ADC1, ENABLE); //使能GPIO时钟和ADC时钟
    
        GPIO_Init(GPIOA, &gpio); //配置引脚模式
    
        RCC_ADCCLKConfig(RCC_PCLK2_Div6); //配置ADC的分频因子 72/6=12（通常）
    
        ADC_RegularChannelConfig(ADC1, ADC_Channel_1, 1, ADC_SampleTime_55Cycles5); //设置ADC规则，采样周期
    
        ADC_Init(ADC1, &adc); //初始化ADC参数
    
        ADC_Cmd(ADC1, ENABLE); //使能ADC
    
        ADC_ResetCalibration(ADC1); //执行ADC复位校准
        while(ADC_GetResetCalibrationStatus(ADC1) == SET); //等待校准完成
    
        ADC_StartCalibration(ADC1); //执行ADC校准
        while(ADC_GetCalibrationStatus(ADC1) == SET);
    
        ADC_SoftwareStartConvCmd(ADC1, ENABLE); //ADC软件启动
    }
    
    int main(void)
    {
        ADC_init();
    
        while(1)
        {
            adc = ADC_value(15); //15次平均值
            printf("ADC_value is %d.\n", adc);
            printf("vol is %.3fV.\n", adc * (3.3 / 4096)); //电压值
            delay_ms(500);
            led1 = ~led1;
        }
    }

**电压计算**

vol = ADC * (3.3 / 4096);

ADC的参考电压VREF+为3.3V。ADC为12位转换精度， 2^12为4096

**DMA方式**  
ADC\_DMACmd开启DMA，在ADC初始化之后  
ADC\_RegularChannelConfig通道配置，在ADC初始化之后  
DMA\_MemoryInc要设置为DMA\_MemoryInc\_Enable，存储器地址递增

DMA\_BufferSize大小，是定义DMA\_MemoryBaseAddr内存的大小。根据DMA\_MemoryDataSize存储器数据宽度，HalfWord占16bit

#define CHANNEL_NUM 4
    
    volatile u16 AD_Bufer[4];
    volatile u8 adc1_ok;
    
    //多通道配置。4路输入
    void ADC_init()
    {
        ...
    
        ADC_InitTypeDef adc =
        {
            ADC_Mode_Independent, //独立模式
            ENABLE, //开启扫描模式
            ENABLE, //开启连续转换模式
            ADC_ExternalTrigConv_None, //不用外部事件启动转换
            ADC_DataAlign_Right, //右对齐
            CHANNEL_NUM, //通道数目4
        };
    
        ADC_Init(ADC1, &adc);
    
        ADC_RegularChannelConfig(ADC1, ADC_Channel_1, 1, ADC_SampleTime_55Cycles5);
        ADC_RegularChannelConfig(ADC1, ADC_Channel_2, 2, ADC_SampleTime_55Cycles5);
        ADC_RegularChannelConfig(ADC1, ADC_Channel_3, 3, ADC_SampleTime_55Cycles5);
        ADC_RegularChannelConfig(ADC1, ADC_Channel_4, 4, ADC_SampleTime_55Cycles5);
    
        DMA_adc_init(ADC1, (u32)AD_Bufer, CHANNEL_NUM);
    
        ...
    }
    
    void DMA_adc_init(ADC_TypeDef *ADCx, u32 mem_addr, u32 size)
    {
       DMA_InitTypeDef DMA_InitStructure;
       NVIC_InitTypeDef NVIC_InitStructure;
    
       RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE); //使能DMA控制器时钟
    
       NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);
       NVIC_InitStructure.NVIC_IRQChannel = DMA1_Channel1_IRQn;
       NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
       NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
       NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
       NVIC_Init(&NVIC_InitStructure);
    
       DMA_InitStructure.DMA_PeripheralBaseAddr = (u32)&ADCx->DR; //外设地址
       DMA_InitStructure.DMA_MemoryBaseAddr = mem_addr; //内存地址
       DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
       DMA_InitStructure.DMA_BufferSize = size; //4个缓存大小
       DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
       DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
       DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Word;
       DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
       DMA_InitStructure.DMA_Mode = DMA_Mode_Circular; //循环模式
       DMA_InitStructure.DMA_Priority = DMA_Priority_High;
       DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
       DMA_Init(DMA1_Channel1, &DMA_InitStructure);
    
       DMA_ITConfig(DMA1_Channel1, DMA1_IT_TC1, ENABLE); //开启中断
    
       DMA_Cmd(DMA1_Channel1, ENABLE);
    
       ADC_DMACmd(ADCx, ENABLE); //开启ADC1 DMA采集
    }
    
    void DMA1_Channel1_IRQHandler(void)
    {
        if(DMA_GetITStatus(DMA1_IT_TC1) != RESET)
        {
            DMA_ClearITPendingBit(DMA1_IT_TC1);
            adc1_ok = 1;
        }
    }
    
    int main(void)
    {
        ADC_init();
    
        while(1)
        {
            if(adc1_ok == 1)
            {
                v0 = AD_Bufer[0];
                v1 = AD_Bufer[1];
                v2 = AD_Bufer[2];
                v3 = AD_Bufer[3];
    
                printf("v0 is %.3fV.\n", v0 * (3.3 / 4096)); //电压值
                printf("v1 is %.3fV.\n", v1 * (3.3 / 4096));
                printf("v2 is %.3fV.\n", v2 * (3.3 / 4096));
                printf("v3 is %.3fV.\n", v3 * (3.3 / 4096));
    
                led1 = ~led1;
                adc1_ok = 0;
            }
    
            delay_ms(500);
        }
    }

[1]: https://img-blog.csdn.net/20170814134133271?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvemhhbmd4dWVjaGFvXw==/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/SouthEast
[2]: /images/20220610/51d0a12897f748d9af9e09348113a907.png