在使用STM32F030K6T6时，现在只使用了ADC0和ADC1（PA0和PA1两个引脚），发现只要置位具有ADC功能的其他IO口中的任意一个（设置为推挽输出），正在采样的ADC引脚（PA0和PA1）就会被附加上一个26K左右的方波信号，幅值大概在2~3V。将选中的ADC引脚（PA0和PA1引脚）悬空，这个现象照样存在。ADC,DMA的代码使用DISCOVERY的例程，初始化如下： void ADC_CH_DMA_Config(void){ ADC_InitTypeDef ADC_InitStructure; DMA_InitTypeDef DMA_InitStructure; GPIO_InitTypeDef GPIO_InitStructure; /* ADC1 DeInit */ ADC_DeInit(ADC1); /* ADC1 Periph clock enable */ RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE); RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE); /* DMA1 clock enable */ RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1 , ENABLE); GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 ; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN; GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL; //GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz; GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL; GPIO_Init(GPIOA, &GPIO_InitStructure); GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2 | GPIO_Pin_3 ; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT; GPIO_InitStructure.GPIO_OType = GPIO_OType_PP; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz; //GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL; GPIO_Init(GPIOA, &GPIO_InitStructure); /* DMA1 Channel1 Config */ DMA_DeInit(DMA1_Channel1); DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)ADC1_DR_Address; DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)RegularConvData_Tab; DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC; DMA_InitStructure.DMA_BufferSize = 2; DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable; DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable; 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_M2M = DMA_M2M_Disable; DMA_Init(DMA1_Channel1, &DMA_InitStructure); /* DMA1 Channel1 enable */ DMA_Cmd(DMA1_Channel1, ENABLE); /* ADC DMA request in circular mode */ ADC_DMARequestModeConfig(ADC1, ADC_DMAMode_Circular); /* Enable ADC_DMA */ ADC_DMACmd(ADC1, ENABLE); /* Initialize ADC structure */ ADC_StructInit(&ADC_InitStructure); /* Configure the ADC1 in continous mode withe a resolutuion equal to 12 bits */ ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b; ADC_InitStructure.ADC_ContinuousConvMode = ENABLE; ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None; ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right; ADC_InitStructure.ADC_ScanDirection = ADC_ScanDirection_Backward; ADC_Init(ADC1, &ADC_InitStructure); /* Convert the ADC1 temperature sensor with 55.5 Cycles as sampling time */ ADC_ChannelConfig(ADC1, ADC_Channel_0 , ADC_SampleTime_55_5Cycles); ADC_TempSensorCmd(ENABLE); /* Convert the ADC1 Vref with 55.5 Cycles as sampling time */ ADC_ChannelConfig(ADC1, ADC_Channel_0 , ADC_SampleTime_55_5Cycles); ADC_VrefintCmd(ENABLE); /* ADC Calibration */ ADC_GetCalibrationFactor(ADC1); /* Enable ADC1 */ ADC_Cmd(ADC1, ENABLE); /* Wait the ADRDY falg */ while(!ADC_GetFlagStatus(ADC1, ADC_FLAG_ADRDY)); /* ADC1 regular Software Start Conv */ ADC_StartOfConversion(ADC1);} 我只要将PA2,或者PA3在初始化时做如下置位： ADC_CH_DMA_Config(); GPIO_SetBits(GPIOA, GPIO_Pin_3); 则PA0和PA1引脚上就会出现方波信号。
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