stm32f030系统reset起来之后，电压采样，，为什么不精确，，，系统采样20次之后，才会变得稳定，，为什么！！！！！

1. #define ADC1_DR_Address                0x40012440
   
2. __IO uint32_t TempSensVoltmv = 0, VrefIntVoltmv = 0;
   
3. __IO uint16_t RegularConvData_Tab[10];
   
4. 
   
5. 
   
6. #if 1
   
7. void ADC1_CH_DMA_Config(void)
   
8. {
   
9.   ADC_InitTypeDef     ADC_InitStructure;
   
10.   DMA_InitTypeDef     DMA_InitStructure;
    
11.         GPIO_InitTypeDef    GPIO_InitStructure;
    
12.   
    
13.   /* ADC1 DeInit */  
    
14.   ADC_DeInit(ADC1);
    
15.           /* GPIOC Periph clock enable */
    
16.   RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);
    
17.   
    
18.   /* ADC1 Periph clock enable */
    
19.   RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);
    
20.   
    
21.   /* DMA1 clock enable */
    
22.   RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1 , ENABLE);
    
23.        
    
24.        
    
25.           /* Configure ADC Channel2 as analog input */
    
26.   GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2 ;
    
27.   GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
    
28.   GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;
    
29.   GPIO_Init(GPIOA, &GPIO_InitStructure);
    
30.   
    
31.   /* DMA1 Channel1 Config */
    
32.   DMA_DeInit(DMA1_Channel1);
    
33.   DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)ADC1_DR_Address;
    
34.   DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)RegularConvData_Tab;
    
35.   DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
    
36.   DMA_InitStructure.DMA_BufferSize = 10;
    
37.   DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
    
38.   DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
    
39.   DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
    
40.   DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
    
41.   DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
    
42.   DMA_InitStructure.DMA_Priority = DMA_Priority_High;
    
43.   DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
    
44.   DMA_Init(DMA1_Channel1, &DMA_InitStructure);
    
45.   
    
46.   /* DMA1 Channel1 enable */
    
47.   DMA_Cmd(DMA1_Channel1, ENABLE);
    
48.   
    
49.   /* ADC DMA request in circular mode */
    
50.   ADC_DMARequestModeConfig(ADC1, ADC_DMAMode_Circular);
    
51.   
    
52.   /* Enable ADC_DMA */
    
53.   ADC_DMACmd(ADC1, ENABLE);  
    
54.   
    
55.   /* Initialize ADC structure */
    
56.   ADC_StructInit(&ADC_InitStructure);
    
57.   
    
58.   /* Configure the ADC1 in continous mode withe a resolutuion equal to 12 bits  */
    
59.   ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;
    
60.   ADC_InitStructure.ADC_ContinuousConvMode = ENABLE;
    
61.   ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None;
    
62.   ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
    
63.   ADC_InitStructure.ADC_ScanDirection = ADC_ScanDirection_Backward;
    
64.   ADC_Init(ADC1, &ADC_InitStructure);
    
65. 
    
66.    /* Convert the ADC1 Channel 11 with 239.5 Cycles as sampling time */
    
67.   ADC_ChannelConfig(ADC1, ADC_Channel_2 , ADC_SampleTime_55_5Cycles);   
    
68. // ADC_TempSensorCmd(ENABLE);
    
69. 
    
70.   /* ADC Calibration */
    
71.   //ADC_GetCalibrationFactor(ADC1);
    
72.        
    
73.           /* Enable the auto delay feature */   
    
74.   //ADC_WaitModeCmd(ADC1, ENABLE);
    
75.   
    
76.   /* Enable the Auto power off mode */
    
77. //  ADC_AutoPowerOffCmd(ADC1, ENABLE);
    
78.   
    
79.   /* Enable ADC1 */
    
80.   ADC_Cmd(ADC1, ENABLE);     
    
81.   
    
82.   /* Wait the ADCEN falg */
    
83.   while(!ADC_GetFlagStatus(ADC1, ADC_FLAG_ADEN));
    
84.   
    
85.   /* ADC1 regular Software Start Conv */
    
86. // ADC_StartOfConversion(ADC1);
    
87. }
    
88. 
    
89. uint32_t Get_RF_Voltage(void)
    
90. {
    
91.        
    
92.         uint16_t i;
    
93.         uint32_t vol =0;
    
94.        
    
95.         ADC_StartOfConversion(ADC1);
    
96.                 /* Test DMA1 TC flag */
    
97.         while((DMA_GetFlagStatus(DMA1_FLAG_TC1)) == RESET );
    
98.        
    
99.         /* Clear DMA TC flag */
    
100.         DMA_ClearFlag(DMA1_FLAG_TC1);
     
101.        
     
102.         for(i=0;i<10;i++)
     
103.         {
     
104.                         vol += RegularConvData_Tab[i];
     
105.         }
     
106.         vol = vol*330/0xfff;
     
107.         return vol;
     
108. }

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各位大侠们，，有什么见解，，都帮忙看看！！！