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What am I missing? ADC again...

Question asked by martinu.jiri on Apr 27, 2013
Latest reply on Apr 29, 2013 by Clive One
Hi all,

I've the following problem. I need to measure signal on the PC.00 pin and with the code bellow it doesn't work. :-( However, if I change the pin to PC.02 and Channel 12 , everything works fine and I get the proper value for voltage on the PC.02 pin. What am I missing that on PC.00 it doesn't work and od the PC.02 is everything OK? Note, I've created a new project for test and nothing else is using the PC.00 pin. The board in question is STM32F4 Discovery.

Code:

#include "stm32f4xx.h"
#include "stm32f4_discovery.h"

#define ADC_CDR_ADDRESS    ((uint32_t)0x40012308)


__IO uint16_t ADCTripleConvertedValueUS0[3];

uint16_t ADC_Val; //Stores the calculated ADC value
double voltage1; //Used to store the actual voltage calculated by ADC for the 1st channel
double voltage2; //Used to store the actual voltage calculated by ADC for the 2nd channel
double voltage3; //Used to store the actual voltage calculated by ADC for the 3rd channel

ADC_InitTypeDef       ADC_InitStructure;
ADC_CommonInitTypeDef ADC_CommonInitStructure;
DMA_InitTypeDef       DMA_InitStructure;
GPIO_InitTypeDef      GPIO_InitStructure;

int main(void)
{
  /* Enable peripheral clocks */
  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2 | RCC_AHB1Periph_GPIOC, ENABLE);
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1 | RCC_APB2Periph_ADC2 |
                         RCC_APB2Periph_ADC3, ENABLE);

  /* Configure ADC Channel 10 pin as analog input */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0; //GPIO C.00
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_DOWN;
  GPIO_Init(GPIOC, &GPIO_InitStructure);
    
  /* DMA2 Stream0 channel0 configuration */
  DMA_InitStructure.DMA_Channel = DMA_Channel_0;  
  DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)ADC_CDR_ADDRESS;
  DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&ADCTripleConvertedValueUS0;
  DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory;
  DMA_InitStructure.DMA_BufferSize = 3;
  DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
  DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
  DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Word;
  DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Word;
  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);
    
/******************************************************************************/
/*  ADCs configuration: triple interleaved with 5cycles delay to reach 6Msps  */
/******************************************************************************/

  /* ADC Common configuration *************************************************/
  ADC_CommonInitStructure.ADC_Mode = ADC_TripleMode_Interl;
  ADC_CommonInitStructure.ADC_TwoSamplingDelay = ADC_TwoSamplingDelay_5Cycles;
  ADC_CommonInitStructure.ADC_DMAAccessMode = ADC_DMAAccessMode_2;  
  ADC_CommonInitStructure.ADC_Prescaler = ADC_Prescaler_Div2;
  ADC_CommonInit(&ADC_CommonInitStructure);

  /* ADC1 regular channel 10 configuration ************************************/
  ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;
  ADC_InitStructure.ADC_ScanConvMode = DISABLE;
  ADC_InitStructure.ADC_ContinuousConvMode = ENABLE;
  ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None;
  ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
  ADC_InitStructure.ADC_NbrOfConversion = 1;
  ADC_Init(ADC1, &ADC_InitStructure);

  ADC_RegularChannelConfig(ADC1, ADC_Channel_10, 1, ADC_SampleTime_3Cycles); 
 
  /* Enable ADC1 DMA */
  ADC_DMACmd(ADC1, ENABLE);

  /* ADC2 regular channel 10 configuration ************************************/
  ADC_Init(ADC2, &ADC_InitStructure);
 
    /* ADC2 regular channel 10 configuration */
    ADC_RegularChannelConfig(ADC2, ADC_Channel_10, 1, ADC_SampleTime_3Cycles); 

  /* ADC3 regular channel 10 configuration ************************************/
  ADC_Init(ADC3, &ADC_InitStructure);
 
  /* ADC3 regular channel 10 configuration *************************************/
  ADC_RegularChannelConfig(ADC3, ADC_Channel_10, 1, ADC_SampleTime_3Cycles);   

  /* Enable DMA request after last transfer (multi-ADC mode) ******************/
  ADC_MultiModeDMARequestAfterLastTransferCmd(ENABLE);

  /* Enable ADC1 **************************************************************/
  ADC_Cmd(ADC1, ENABLE);

  /* Enable ADC2 **************************************************************/
  ADC_Cmd(ADC2, ENABLE);

  /* Enable ADC3 **************************************************************/
  ADC_Cmd(ADC3, ENABLE);
    
  /* Start ADC1 Software Conversion */
  ADC_SoftwareStartConv(ADC1);
    
    
    //Led Init
    STM_EVAL_LEDInit(LED3);
    STM_EVAL_LEDInit(LED4);
    STM_EVAL_LEDInit(LED5);
    STM_EVAL_LEDInit(LED6);
    

  while (1)
  {
     STM_EVAL_LEDOff(LED3);
     STM_EVAL_LEDOff(LED4);
     STM_EVAL_LEDOff(LED5);
     STM_EVAL_LEDOff(LED6);

     ADC_Val = ADCTripleConvertedValueUS0[0];
     voltage1 = (3.3 * ADC_Val) / 4096;

     ADC_Val = ADCTripleConvertedValueUS0[1];
     voltage2 = (3.3 * ADC_Val) / 4096;
        
     ADC_Val = ADCTripleConvertedValueUS0[1];
     voltage3 = (3.3 * ADC_Val) / 4096;    
        
     voltage1 = (voltage1 + voltage2 + voltage3)/3;    

     if ((voltage1 >= 0) && (voltage1 < 0.2)) {
         STM_EVAL_LEDOn(LED3);
     } else if ((voltage1 >= 0.2) && (voltage1 < 0.4)) {
         STM_EVAL_LEDOn(LED4);
     } else if ((voltage1 >= 0.4) && (voltage1 < 0.5)) {
         STM_EVAL_LEDOn(LED5);
     } else {//voltage1 >= 0.5
         STM_EVAL_LEDOn(LED6);
     }    
         
  }
}


Thank you for your answers.

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