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no one can help me understand how to use the DMA? please: '(

Question asked by capasso.ornella on Oct 8, 2012
Latest reply on Oct 9, 2012 by baird.hal.001
hi,
I modified an example of the ST microcontroller STM32F4xx need to acquire three channels with a single ADC and using the DMA, but I do not know how to retrieve the data.
can you give me a hand? I'll post the code! Thank you and sorry for the English

/* Includes ------------------------------------------------------------------*/
#include "stm32f4xx.h"
#include "stm324xg_eval.h"
#include "stm324xg_eval_lcd.h"
#include <stdio.h>
 
/** @addtogroup STM32F4xx_StdPeriph_Examples
  * @{
  */
 
/** @addtogroup ADC_ADC3_DMA
  * @{
  */
 
/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/
/* used to display the ADC converted value on LCD */
#define PRINT_ON_LCD
   
 
#define ADC3_DR_ADDRESS    ((uint32_t)0x4001224C)
 
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
__IO uint16_t ADC3ConvertedValue = 0;
__IO uint16_t ADC3ConvertedValue2 = 0;
__IO uint32_t ADC3ConvertedVoltage = 0;
__IO uint32_t ADC3ConvertedVoltage2 = 0;
 
/* Private function prototypes -----------------------------------------------*/
/* Private functions ---------------------------------------------------------*/
void ADC3_CH_9_14_15_DMA_Config(void);
 
#ifdef PRINT_ON_LCD
void Display_Init(void);
void Display(void);
#endif /* PRINT_ON_LCD */
 
/**
  * @brief  Main program
  * @param  None
  * @retval None
  */
int main(void)
{
  
#ifdef PRINT_ON_LCD
  /* LCD Display init  */
  Display_Init();
#endif
 
  /* ADC3 configuration *******************************************************/
  /*  - Enable peripheral clocks                                              */
  /*  - DMA2_Stream0 channel2 configuration                                   */
  /*  - Configure ADC Channe9 14 15 pin as analog input                            */
  /*  - Configure ADC3 Channe9 14 15                                               */
ADC3_CH_9_14_15_DMA_Config();
 
  /* Start ADC3 Software Conversion */
  ADC_SoftwareStartConv(ADC3);
 
  while (1)
  {
         
#ifdef PRINT_ON_LCD
  /* Display ADC3 converted value on LCD */
    Display();
#endif
  }
}
 
 
/**
  * @brief  ADC3 channel07 with DMA configuration
  * @param  None
  * @retval None
  */
void ADC3_CH_9_14_15_DMA_Config(void)
{
  ADC_InitTypeDef       ADC_InitStructure;
  ADC_CommonInitTypeDef ADC_CommonInitStructure;
  DMA_InitTypeDef       DMA_InitStructure;
  GPIO_InitTypeDef      GPIO_InitStructure;
 
  /* Enable ADC3, DMA2 and GPIO clocks ****************************************/
  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2 | RCC_AHB1Periph_GPIOF, ENABLE);
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC3, ENABLE);
 
  /* DMA2 Stream0 channel2 configuration **************************************/
  DMA_InitStructure.DMA_Channel = DMA_Channel_2; 
  DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)ADC3_DR_ADDRESS;
  DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&ADC3ConvertedValue;
  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_Disable;
  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);
  DMA_Cmd(DMA2_Stream0, ENABLE);
     
     
     
 
 
  /* Configure ADC3 Channe 9 14 15 pin as analog input ******************************/
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3|GPIO_Pin_4|GPIO_Pin_5;              
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;
  GPIO_Init(GPIOF, &GPIO_InitStructure);
 
  /* ADC Common Init **********************************************************/
  ADC_CommonInitStructure.ADC_Mode = ADC_Mode_Independent;
  ADC_CommonInitStructure.ADC_Prescaler = ADC_Prescaler_Div2;
  ADC_CommonInitStructure.ADC_DMAAccessMode = ADC_DMAAccessMode_Disabled;
  ADC_CommonInitStructure.ADC_TwoSamplingDelay = ADC_TwoSamplingDelay_5Cycles;
  ADC_CommonInit(&ADC_CommonInitStructure);
 
  /* ADC3 Init ****************************************************************/
  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_ExternalTrigConv = ADC_ExternalTrigConv_T1_CC1;
  ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
  ADC_InitStructure.ADC_NbrOfConversion = 3; //Perchè effettuo ttue e tre le conversioni dall'ADC3
  ADC_Init(ADC3, &ADC_InitStructure);
 
  /* ADC3 regular channel7 configuration *************************************/
 /****MODIFICATO*****/
    ADC_RegularChannelConfig(ADC3, ADC_Channel_9, 1, ADC_SampleTime_3Cycles);   /****MODIFICATO*****/
    ADC_RegularChannelConfig(ADC3, ADC_Channel_14, 2, ADC_SampleTime_3Cycles);  /****MODIFICATO*****/
    ADC_RegularChannelConfig(ADC3, ADC_Channel_15, 3, ADC_SampleTime_3Cycles);  /****MODIFICATO*****/
  
 /* Enable DMA request after last transfer (Single-ADC mode) */
  ADC_DMARequestAfterLastTransferCmd(ADC3, ENABLE);
 
  /* Enable ADC3 DMA */
  ADC_DMACmd(ADC3, ENABLE);
 
  /* Enable ADC3 */
  ADC_Cmd(ADC3, ENABLE);
}
 
#ifdef PRINT_ON_LCD
/**
  * @brief  Display ADC converted value on LCD
  * @param  None
  * @retval None
  */
void Display(void)
{
  uint32_t v=0,mv=0,v2,mv2;
  uint8_t text[50];
 
    ADC3ConvertedVoltage = ADC3ConvertedValue *3300/0xFFF;
  v=(ADC3ConvertedVoltage)/1000;
  mv = (ADC3ConvertedVoltage%1000)/100;
  sprintf((char*)text,"   ADC = %d,%d V   ",v,mv);
  LCD_DisplayStringLine(LINE(6),text);
     
    // I do not know how to take the data from channel 14 or 15 ... Help!//
    v2=(ADC3ConvertedVoltage2)/1000;
  mv2 = (ADC3ConvertedVoltage2%1000)/100;
  sprintf((char*)text,"   ADC = %d,%d V   ",v2,mv2);
  LCD_DisplayStringLine(LINE(7),text);
}
 
/**
  * @brief  Display Init (LCD)
  * @param  None
  * @retval None
  */
void Display_Init(void)
{
  /* Initialize the LCD */
  STM324xG_LCD_Init();
 
  /* Clear the LCD */
  LCD_Clear(White);
 
  /* Set the LCD Text size */
  LCD_SetFont(&Font8x12);
 
  /* Set the LCD Back Color and Text Color*/
  LCD_SetBackColor(Blue);
  LCD_SetTextColor(White);
 
  /* Display */
  LCD_DisplayStringLine(LINE(0x13), " ADC conversion w/ DMA transfer example ");
 
  /* Set the LCD Text size */
  LCD_SetFont(&Font16x24);
 
  /* Display */
  LCD_DisplayStringLine(LINE(0), "ADC Ch7 Conv @2.4Msps");
 
 
  /* Set the LCD Back Color and Text Color*/
  LCD_SetBackColor(White);
  LCD_SetTextColor(Blue);
 
  /* Display */
  LCD_DisplayStringLine(LINE(2),"  Turn RV1(PF.09)    ");
  LCD_DisplayStringLine(LINE(4),"   Potentiometer     ");
}
#endif /* PRINT_ON_LCD */
 
#ifdef  USE_FULL_ASSERT
 
/**
  * @brief  Reports the name of the source file and the source line number
  *         where the assert_param error has occurred.
  * @param  file: pointer to the source file name
  * @param  line: assert_param error line source number
  * @retval None
  */
void assert_failed(uint8_t* file, uint32_t line)
{
  /* User can add his own implementation to report the file name and line number,
     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
 
  /* Infinite loop */
  while (1)
  {
  }
}
#endif
 
/**
  * @}
  */
 
/**
  * @}
  */
 
/******************* (C) COPYRIGHT 2011 STMicroelectronics *****END OF FILE****/

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