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stm32f4 Discovery multiple potentiometers

Question asked by Kenny on Nov 11, 2012
Latest reply on Nov 11, 2012 by Kenny
Hi everyone,

I'm trying to get a accurate reading out of 2 potentiometers but they keep affecting each other.
Also when I press my touchpanel (XPT2046) the readout is affected....
Does anyone have any idea how to fix this?

Here is my ADC and DMA configuration
Maybe you can tell that i tried a few things, but up till now i have very limited results.

Thanks in advance,

Kenny

void ADC1_DMA_Config(void)
{
  ADC_InitTypeDef       ADC_InitStructure;
  ADC_CommonInitTypeDef ADC_CommonInitStructure;
  DMA_InitTypeDef       DMA_InitStructure;
   
  /* Enable peripheral clocks *************************************************/
  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2 | RCC_AHB1Periph_GPIOB, ENABLE);
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);
 
  /* DMA2_Stream0 channel0 configuration **************************************/
  DMA_DeInit(DMA2_Stream0);
  DMA_InitStructure.DMA_Channel = DMA_Channel_0; 
  //The adress of the analog to digital converter 1
  #define ADC1_DR_ADDRESS    ((uint32_t)0x4001204C)
  DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)ADC1_DR_ADDRESS;
  DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&ADCConvertedValue;
  DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory;
  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_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);
  /* DMA2_Stream0 enable */
  DMA_Cmd(DMA2_Stream0, ENABLE);
   
  /* Configure GPIO pins as analog input ******************************/
  GPIO_InitTypeDef      GPIO_InitStructure;
  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_Init(GPIOB, &GPIO_InitStructure);
  
  /* ADC Common Init **********************************************************/
  ADC_CommonInitStructure.ADC_Mode = ADC_Mode_Independent;
  ADC_CommonInitStructure.ADC_Prescaler = ADC_Prescaler_Div8;
  ADC_CommonInitStructure.ADC_DMAAccessMode = ADC_DMAAccessMode_Disabled;
  ADC_CommonInitStructure.ADC_TwoSamplingDelay = ADC_TwoSamplingDelay_5Cycles;
  ADC_CommonInit(&ADC_CommonInitStructure);
 
  /* ADC1 Init ****************************************************************/
  ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;
  ADC_InitStructure.ADC_ScanConvMode = ENABLE;
  ADC_InitStructure.ADC_ContinuousConvMode = ENABLE;
  ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None;
  ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
  ADC_InitStructure.ADC_NbrOfConversion = 2;
  ADC_InitStructure.ADC_ExternalTrigConv=0x00;
  ADC_Init(ADC1, &ADC_InitStructure);
 
  /* Enable ADC1 DMA */
  ADC_DMACmd(ADC1, ENABLE);
   
  /* ADC1 regular channels configuration **************************************/
  ADC_RegularChannelConfig(ADC1, ADC_Channel_8, 1, ADC_SampleTime_3Cycles);
  ADC_RegularChannelConfig(ADC1, ADC_Channel_9, 2, ADC_SampleTime_3Cycles);
 
 
  /* Enable DMA request after last transfer (Single-ADC mode) */
  ADC_DMARequestAfterLastTransferCmd(ADC1, ENABLE);
 
  /* Enable ADC1 **************************************************************/
  ADC_Cmd(ADC1, ENABLE);
}

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