STM32F334 ADC差分应用问题怎么解决

2019-07-14 16:26发布

一、硬件连接:
1.  +3.3V 串3个10k电阻到地 取中间电阻电压(1.10V)送AD 得到码数为:2610
2.     +5V 串3个10k电阻到地 取中间电阻电压(1.66V)送AD 得到码数为:2915
3.   ADC1_IN1->PA0 接信号+
      ADC1_IN2->PA1 接信号-

二、问题:为何电压和码数无法对应呢?

三、代码:(cube生成)
/** System Clock Configuration
*/
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct;
  RCC_ClkInitTypeDef RCC_ClkInitStruct;
  RCC_PeriphCLKInitTypeDef PeriphClkInit;
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = 16;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
  RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL16;
  HAL_RCC_OscConfig(&RCC_OscInitStruct);
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_SYSCLK|RCC_CLOCKTYPE_PCLK1;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
  HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2);
  PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_HRTIM1|RCC_PERIPHCLK_USART1
                              |RCC_PERIPHCLK_ADC12;
  PeriphClkInit.Usart1ClockSelection = RCC_USART1CLKSOURCE_PCLK1;
  PeriphClkInit.Adc12ClockSelection = RCC_ADC12PLLCLK_DIV1;
  PeriphClkInit.Hrtim1ClockSelection = RCC_HRTIM1CLK_PLLCLK;
  HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit);
  __SYSCFG_CLK_ENABLE();
}

*******************************************************

/* ADC1 init function */
void MX_ADC1_Init(void)
{
  ADC_ChannelConfTypeDef sConfig;
    /**Common config
    */
  hadc1.Instance = ADC1;
  hadc1.Init.ClockPrescaler = ADC_CLOCK_ASYNC;
  hadc1.Init.Resolution = ADC_RESOLUTION12b;
  hadc1.Init.ScanConvMode = ADC_SCAN_DISABLE;
  hadc1.Init.ContinuousConvMode = ENABLE;
  hadc1.Init.DiscontinuousConvMode = DISABLE;
  hadc1.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;
  hadc1.Init.DataAlign = ADC_DATAALIGN_RIGHT;
  hadc1.Init.NbrOfConversion = 1;
  hadc1.Init.DMAContinuousRequests = DISABLE;
  hadc1.Init.EOCSelection = EOC_SINGLE_CONV;
  hadc1.Init.LowPowerAutoWait = DISABLE;
  hadc1.Init.Overrun = OVR_DATA_OVERWRITTEN;
  HAL_ADC_Init(&hadc1);
    /**Configure Regular Channel
    */
  sConfig.Channel = ADC_CHANNEL_1;
  sConfig.Rank = 1;
  sConfig.SingleDiff = ADC_DIFFERENTIAL_ENDED;
  sConfig.SamplingTime = ADC_SAMPLETIME_1CYCLE_5;
  sConfig.OffsetNumber = ADC_OFFSET_NONE;
  sConfig.Offset = 0;
  HAL_ADC_ConfigChannel(&hadc1, &sConfig);
}

*******************************************************

  HAL_ADC_Start(&hadc1);
  while (1)
  {
    ADC_GetValue=HAL_ADC_GetValue(&hadc1);  
    printf("%d ", ADC_GetValue);  
   }
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