求助~我ADC转换的最大电压只有2.5v

arronmahone · 发表于 2013-8-10 15:50:39

我用ADC转换出来的电压到2.5v的时候数据就已经达到4096了，这是什么问题？

augustedward · 发表于 2013-8-10 15:58:22

回复【楼主位】arronmahone:
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什么芯片，电压是外部基准，还是内部基准？查资料看一下！

arronmahone · 发表于 2013-8-10 16:04:27

回复【2楼】augustedward:
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我用的是stm32F103的

配置是这样的：

void ADC_Configuration(void) //DMA1_Channel1--ADC1\DMA2_Channel5--ADC3
{
DMA_InitTypeDef DMA_InitStructure;
ADC_InitTypeDef ADC_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;

GPIO_Config(GPIO_Pin_5, GPIO_Mode_AIN, GPIO_Speed_2MHz, GPIOA);
GPIO_Config(GPIO_Pin_6, GPIO_Mode_AIN, GPIO_Speed_2MHz, GPIOA);

RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);

/* DMA channel1 configuration */
DMA_DeInit(DMA1_Channel1);
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&(ADC1->DR); //ADC地址
DMA_InitStructure.DMA_MemoryBaseAddr = (u32)&ADC_Value;//内存地址
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
DMA_InitStructure.DMA_BufferSize = 2;
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;//外设地址固定
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable; //内存地址固定
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord; //半字
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
DMA_InitStructure.DMA_Mode = DMA_Mode_Circular; //循环传输
DMA_InitStructure.DMA_Priority = DMA_Priority_High;
DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
DMA_Init(DMA1_Channel1, &DMA_InitStructure);
DMA_ITConfig(DMA1_Channel1,DMA_IT_TC,ENABLE);
/* Enable DMA channel1 */
DMA_Cmd(DMA1_Channel1, ENABLE);
NVIC_InitStructure.NVIC_IRQChannel = DMA1_Channel1_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 4;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);

/* ADC1 configuration */
ADC_InitStructure.ADC_ContinuousConvMode = ENABLE; //是否工作在连续或单一模式
ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right; //数据右对齐
ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_None; //由软件控制开始转换，而不是外部触发器
ADC_InitStructure.ADC_Mode = ADC_Mode_Independent; //ADC工作在独立模式（ADC1与ADC2之间）
ADC_InitStructure.ADC_ScanConvMode = ENABLE; //是否工作在多信道或单一信道
ADC_InitStructure.ADC_NbrOfChannel = 2; //要进行转换的ADC信道号，范围是1-16
ADC_Init(ADC1, &ADC_InitStructure);
/*配置ADC时钟，为PCLK2的8分频，即9Hz*/
// RCC_ADCCLKConfig(RCC_PCLK2_Div8);

ADC_RegularChannelConfig(ADC1, ADC_Channel_5, 1, ADC_SampleTime_239Cycles5);
ADC_RegularChannelConfig(ADC1, ADC_Channel_6, 2, ADC_SampleTime_239Cycles5);
//ADC1与ADC2、ADC的信道0-17、常规组音序器的等级1-16、采样时间为28.5个周期
ADC_DMACmd(ADC1, ENABLE); // Enable ADC1 DMA
ADC_Cmd(ADC1, ENABLE);

ADC_ResetCalibration(ADC1); //复位校准寄存器
while(ADC_GetResetCalibrationStatus(ADC1)); //等待校准寄存器复位完成

ADC_StartCalibration(ADC1); // ADC校准
while(ADC_GetCalibrationStatus(ADC1)); // 等待校准完成

// ADC_SoftwareStartConvCmd(ADC1, ENABLE); //由于没有采用外部触发，所以使用软件触发ADC转换
}