1. STM32F103 ADC
本例使用STM32F103芯片的PA1引脚测试模拟输入的电压值。
查看文档《STM32F103X.pdf》第31页，引脚定义图：
得知PA1使用ADC1的通道1。
查看文档《STM32F103X.pdf》第13页，时钟树图：
得知ADC1可2,4,6,8分频,又ADC输入时钟不得超过14MHZ(参见STM32参考手册RM0008第11章ADC)。
//初始化ADC
//这里我们仅以规则通道为例
//我们默认将开启通道0~3
void Adc_Init(void)
{
ADC_InitTypeDef ADC_InitStructure;
GPIO_InitTypeDef GPIO_InitStructure; RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA |RCC_APB2Periph_ADC1, ENABLE ); //使能ADC1通道时钟 RCC_ADCCLKConfig(RCC_PCLK2_Div6); //设置ADC分频因子6 72M/6=12,ADC最大时间不能超过14M //PA1 作为模拟通道输入引脚
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AIN; //模拟输入引脚
GPIO_Init(GPIOA, &GPIO_InitStructure); ADC_DeInit(ADC1); //复位ADC1,将外设 ADC1 的全部寄存器重设为缺省值 ADC_InitStructure.ADC_Mode = ADC_Mode_Independent; //ADC工作模式:ADC1和ADC2工作在独立模式
ADC_InitStructure.ADC_ScanConvMode = DISABLE; //模数转换工作在单通道模式
ADC_InitStructure.ADC_ContinuousConvMode = DISABLE; //模数转换工作在单次转换模式
ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_None; //转换由软件而不是外部触发启动
ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right; //ADC数据右对齐
ADC_InitStructure.ADC_NbrOfChannel = 1; //顺序进行规则转换的ADC通道的数目
ADC_Init(ADC1, &ADC_InitStructure); //根据ADC_InitStruct中指定的参数初始化外设ADCx的寄存器 ADC_Cmd(ADC1, ENABLE); //使能指定的ADC1
ADC_ResetCalibration(ADC1); //使能复位校准
while(ADC_GetResetCalibrationStatus(ADC1)); //等待复位校准结束
ADC_StartCalibration(ADC1); //开启AD校准
while(ADC_GetCalibrationStatus(ADC1)); //等待校准结束
ADC_SoftwareStartConvCmd(ADC1, ENABLE); //使能指定的ADC1的软件转换启动功能
}
//获得ADC值
//ch:通道值 0~3
u16 Get_Adc(u8 ch)
{
//设置指定ADC的规则组通道，一个序列，采样时间
ADC_RegularChannelConfig(ADC1, ch, 1, ADC_SampleTime_239Cycles5 ); //ADC1,ADC通道,采样时间为239.5周期
ADC_SoftwareStartConvCmd(ADC1, ENABLE); //使能指定的ADC1的软件转换启动功能
while(!ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC ));//等待转换结束
return ADC_GetConversionValue(ADC1); //返回最近一次ADC1规则组的转换结果
} u16 Get_Adc_Average(u8 ch,u8 times)
{
u32 temp_val=0;
u8 t;
for(t=0;t<times;t++)
{
temp_val+=Get_Adc(ch);
delay_ms(5);
}
return temp_val/times;
} void ADCTask(void)
{
float vol, adcx;
while(1)
{
adcx=Get_Adc_Average(ADC_Channel_1,10); //ADC的值
vol=(float)adcx*(3300/4096); //电压值(mv)
delay_ms(200);
}
}
2、 STM32F407 ADC
本例使用STM32F407芯片的PF9引脚测试模拟输入的电压值。
查看文档《STM32F4x7-Datasheet.pdf》第43页，引脚定义图：
查看文档《STM32F4x7-Reference manual.pdf》第51页，内存映射：
点击链接查看ADC寄存器映射：
又查看数据寄存器偏移量：
得知数据寄存器地址：#define ADC3_DR_ADDRESS ((uint32_t)0x4001224C)
查看《STM32F4x7-Reference manual.pdf》第165页DMA2 request mapping:
得知使用DMA2 Stream0 通道2映射ADC3。
#define ADC3_DR_ADDRESS ((uint32_t)0x4001224C) __IO uint16_t ADC3ConvertedValue = 0;
__IO uint32_t ADC3ConvertedVoltage = 0; //ADC3 channel07 with DMA configuration
void ADC3_CH7_DMA_Config(void)
{
ADC_InitTypeDef ADC_InitStructure;
ADC_CommonInitTypeDef ADC_CommonInitStructure;
DMA_InitTypeDef DMA_InitStructure;
GPIO_InitTypeDef GPIO_InitStructure; /* Enable ADC3, DMA2 and GPIO clocks ****************************************/
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2 | RCC_AHB1Periph_GPIOF, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC3, ENABLE); /* DMA2 Stream0 channel2 configuration **************************************/
DMA_InitStructure.DMA_Channel = DMA_Channel_2;
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)ADC3_DR_ADDRESS;
DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&ADC3ConvertedValue;
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory;
DMA_InitStructure.DMA_BufferSize = 1;
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Disable;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
DMA_InitStructure.DMA_Priority = DMA_Priority_High;
DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;
DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_HalfFull;
DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
DMA_Init(DMA2_Stream0, &DMA_InitStructure);
DMA_Cmd(DMA2_Stream0, ENABLE); /* Configure ADC3 Channel7 pin as analog input ******************************/
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;
GPIO_Init(GPIOF, &GPIO_InitStructure); /* ADC Common Init **********************************************************/
ADC_CommonInitStructure.ADC_Mode = ADC_Mode_Independent;
ADC_CommonInitStructure.ADC_Prescaler = ADC_Prescaler_Div2;
ADC_CommonInitStructure.ADC_DMAAccessMode = ADC_DMAAccessMode_Disabled;
ADC_CommonInitStructure.ADC_TwoSamplingDelay = ADC_TwoSamplingDelay_5Cycles;
ADC_CommonInit(&ADC_CommonInitStructure); /* ADC3 Init ****************************************************************/
ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;
ADC_InitStructure.ADC_ScanConvMode = DISABLE;
ADC_InitStructure.ADC_ContinuousConvMode = ENABLE;
ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None;
ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_T1_CC1;
ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
ADC_InitStructure.ADC_NbrOfConversion = 1;
ADC_Init(ADC3, &ADC_InitStructure); /* ADC3 regular channel7 configuration *************************************/
ADC_RegularChannelConfig(ADC3, ADC_Channel_7, 1, ADC_SampleTime_3Cycles); /* Enable DMA request after last transfer (Single-ADC mode) */
ADC_DMARequestAfterLastTransferCmd(ADC3, ENABLE); /* Enable ADC3 DMA */
ADC_DMACmd(ADC3, ENABLE); /* Enable ADC3 */
ADC_Cmd(ADC3, ENABLE);
} int main(void)
{
/* ADC3 configuration *******************************************************/
/* - Enable peripheral clocks */
/* - DMA2_Stream0 channel2 configuration */
/* - Configure ADC Channel7 pin as analog input */
/* - Configure ADC3 Channel7 */
ADC3_CH7_DMA_Config(); /* Start ADC3 Software Conversion */
ADC_SoftwareStartConv(ADC3); while (1)
{
ADC3ConvertedVoltage = ADC3ConvertedValue *3300/0xFFF;
delay_ms(200);
}
}