灵动微MM32F003硬件最小系统 --- 简单循环的单通道AD

MM32F003具有8路12位ADC，最高可以达到1Msps的转换速度。对于一般的电压检测是基本够用的。
这个例程通过while(1)循环的方式，持续将ADC采样值转换成电压值后，通过串口输出。
ADC的初始化分为两个步骤：GPIO配置和ADC参数的配置。

1 ADC管脚的GPIO相关配置

ADCConfig(ADCch ADC_Channel)函数实现ADC通道的设置，不同的ADC通道，通过GPIO_Config_AIN()函数调用不同的GPIO配置参数。

void ADCConfig(ADCch ADC_Channel)
{
    if( ADCch0 == ADC_Channel ) {
        GPIO_Config_AIN(GPIOA, GPIO_Pin_0);
    } else if( ADCch4 == ADC_Channel ) {
        GPIO_Config_AIN(GPIOA, GPIO_Pin_4);
    } else if( ADCch5 == ADC_Channel ) {
        GPIO_Config_AIN(GPIOA, GPIO_Pin_5);
    } else if( ADCch6 == ADC_Channel ) {
        GPIO_Config_AIN(GPIOA, GPIO_Pin_6);
    } else if( ADCch8 == ADC_Channel ) {
        GPIO_Config_AIN(GPIOB, GPIO_Pin_0);
    } else if( ADCch9 == ADC_Channel ) {
        GPIO_Config_AIN(GPIOB, GPIO_Pin_1);
    } else if( ADCch10 == ADC_Channel ) {
        GPIO_Config_AIN(GPIOB, GPIO_Pin_3);
    } else if( ADCch11 == ADC_Channel ) {
        GPIO_Config_AIN(GPIOB, GPIO_Pin_4);
    } else if( ADCch12 == ADC_Channel ) {
        GPIO_Config_AIN(GPIOB, GPIO_Pin_7);
    } else {
    }
    ADCSingleChannelInit(ADC_Channel);
}

GPIO_Config_AIN()函数将对应的GPIO配置为模拟输入模式。

void GPIO_Config_AIN(GPIO_TypeDef* GPIOx, u16 GPIO_Pin_n)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    if(GPIOx == GPIOA) {
        RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE); //GPIO clock starts
    }
    if(GPIOx == GPIOB) {
        RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOB, ENABLE); //GPIO clock starts
    }
    if(GPIOx == GPIOC) {
        RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOC, ENABLE);  //GPIO clock starts
    }
    if(GPIOx == GPIOD) {
        RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOD, ENABLE);  //GPIO clock starts
    }
    GPIO_InitStructure.GPIO_Pin  =  GPIO_Pin_n;   //pin
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;   //Output speed
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AIN;        //GPIO mode
    GPIO_Init(GPIOx, &GPIO_InitStructure);
}

2 配置ADC参数

void ADCSingleChannelInit(ADCch ADC_Channel_x)
{
    ADC_InitTypeDef  ADC_InitStructure;
    ADC_StructInit(&ADC_InitStructure);
    
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);  //Enable ADC clock

    ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;
    ADC_InitStructure.ADC_PRESCARE = ADC_PCLK2_PRESCARE_16; //ADC prescale factor
    ADC_InitStructure.ADC_Mode = ADC_Mode_Continuous_Scan;  //Set ADC mode to continuous conversion mode
    ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right; //AD data right-justified
    ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_T1_CC1;
    ADC_Init(ADC1, &ADC_InitStructure);

    ADC_RegularChannelConfig(ADC1, ADC_Channel_x, 0, ADC_SampleTime_239_5Cycles);//Enable the channel


    if(ADC_Channel_x == ADC_Channel_TempSensor) {
        ADC_TempSensorCmd(ENABLE);   //Enable internal temperature sensor
    }
    if(ADC_Channel_x == ADC_Channel_Vrefint) {
        ADC_VrefintCmd(ENABLE);          //Enable internal temperature sensor
    }
    //Enable ADCDMA
    ADC_Cmd(ADC1, ENABLE);             //Enable AD conversion
}

3 读取ADC值

u16 ADC1_SingleChannel_Get(void)
{
    u16 puiADData;
 
    ADC_SoftwareStartConvCmd(ADC1, ENABLE);
    while(ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC) == 0);
    ADC_ClearFlag(ADC1, ADC_FLAG_EOC);
    puiADData = ADC_GetConversionValue(ADC1);
    return puiADData;
}

4 将ADC值转为电压值，循环读取

多次读取ADC，取平均值。

u16 Get_Adc_Average(uint8_t times)
{
    u32 temp_val = 0;
    u8 t;
    u8 delay;
    for(t = 0; t < times; t++) {
        temp_val += ADC1_SingleChannel_Get();
        for(delay = 0; delay < 100; delay++);
    }
    return temp_val / times;
}

main()函数实现：

int main(void)
{
    delay_init();
      //init uart
      Uart_ConfigInit(9600);

    ADCConfig(ADCch10); //use PB3
    while(1) {
        ADCVAL = Get_Adc_Average(5);
        //fValue = ((float)ADCVAL / 4095) * 3.3; //use 3.3V as VDD
        fValue = (((float)ADCVAL)/4095)*5; //use 5V as VDD

        delay_ms(1000);
        UartSendGroup((u8*)printBuf, sprintf(printBuf, "adc value = 0x%4X \r\n",ADCVAL));
        UartSendGroup((u8*)printBuf, sprintf(printBuf, "voltage value = %f \r\n",fValue));
    }
}