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STM32F4 Disc - ADC sample time

Question asked by pano.samuele on Nov 14, 2014
Latest reply on Nov 15, 2014 by Clive One
Hi,
I have this code, copied from anothers 3d in this forum, for a multi channel ADC:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
    
#include "stm32f4xx.h"
    
//******************************************************************************
    
volatile uint16_t ADCConvertedValues[2];
    
//******************************************************************************
    
void GPIO_Configuration(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;
    
  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
    
  /* Configure ADC1 Channel3 & 5 pins as analog input ******************************/
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3 | GPIO_Pin_5;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
  GPIO_Init(GPIOA, &GPIO_InitStructure);
}
    
//******************************************************************************
    
void ADC1_Configuration(void)
{
  ADC_InitTypeDef       ADC_InitStructure;
  ADC_CommonInitTypeDef ADC_CommonInitStructure;
  DMA_InitTypeDef       DMA_InitStructure;
    
  /* Enable peripheral clocks *************************************************/
  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2, ENABLE);
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);
    
  /* DMA2_Stream0 channel0 configuration **************************************/
  DMA_DeInit(DMA2_Stream0);
  DMA_InitStructure.DMA_Channel = DMA_Channel_0;
  DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&ADC1->DR;
  DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&ADCConvertedValues[0];
  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);
    
  /* 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);
    
  /* 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_ExternalTrigConv = ADC_ExternalTrigConv_T1_CC1;
  ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
  ADC_InitStructure.ADC_NbrOfConversion = 2;
  ADC_Init(ADC1, &ADC_InitStructure);
    
  /* ADC1 regular channel configuration ******************************/
  ADC_RegularChannelConfig(ADC1, ADC_Channel_3, 1, ADC_SampleTime_480Cycles); // PA3
  ADC_RegularChannelConfig(ADC1, ADC_Channel_5, 2, ADC_SampleTime_480Cycles); // PA5
    
   /* Enable DMA request after last transfer (Single-ADC mode) */
  ADC_DMARequestAfterLastTransferCmd(ADC1, ENABLE);
    
  /* Enable ADC1 DMA */
  ADC_DMACmd(ADC1, ENABLE);
    
    /* Enable ADC1 **************************************************************/
  ADC_Cmd(ADC1, ENABLE);
    
    /* Start ADC1 Software Conversion */
  ADC_SoftwareStartConv(ADC1);
}
what is the value of the sample time? how to fix it?

thanks

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