ADC with multiple channels settings

Posted on December 12, 2012 at 13:33

You'd need to configure it to do your 3 ADC measurements via DMA, the length of the transfer being 3, and the list inside the ADC being the 3 channels you want.

You probably don't need it to be a circular transfer, as there is so long between each burst of 3 measurements. Use the DMA TC interrupt to call you when all 3 measurements have been completed.

Posted on December 12, 2012 at 14:48

Thanks,

I changed the previous code and now I don't get anything at all. The previous code allowed me to read the potentiometer on ADC3 (pf9). Now I get just zeroes.

  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 | RCC_AHB1Periph_GPIOA, ENABLE);////////RCC_AHB1Periph_GPIOF only

  

  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)&val;

  DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory;

  DMA_InitStructure.DMA_BufferSize = 3; ////1

  DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;

  DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable; ////////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 Channel7 pin as analog input ******************************/

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;

  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;

  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;

  GPIO_Init(GPIOF, &GPIO_InitStructure);

  

  //added

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1 | GPIO_Pin_2;

  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;

  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;

  GPIO_Init(GPIOA, &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_DataAlign = ADC_DataAlign_Right;

  ADC_InitStructure.ADC_NbrOfConversion = 3; ///1

  ADC_Init(ADC3, &ADC_InitStructure);

  /* ADC3 regular channel7 configuration *************************************/

  ADC_RegularChannelConfig(ADC3, ADC_Channel_7, 1, ADC_SampleTime_3Cycles);

  ADC_RegularChannelConfig(ADC3, ADC_Channel_4, 1, ADC_SampleTime_3Cycles); ///added

  ADC_RegularChannelConfig(ADC3, ADC_Channel_5, 1, ADC_SampleTime_3Cycles); ////added

 /* 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);

  

  ADC_SoftwareStartConv(ADC3);

Posted on December 12, 2012 at 17:12

Hi,

I think it remains to add the handler for DMA interrupt requests as recommended by Clive1.

Cheers,

STOne-32

Posted on December 12, 2012 at 18:32

I don't have a lot of time to invest in this, but a quick scan suggests

unsigned short val[3];

..

DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&val[0];

..

Longer time, and Rank#

 /* ADC3 regular channel7 configuration *************************************/

  ADC_RegularChannelConfig(ADC3, ADC_Channel_7, 1, ADC_SampleTime_56Cycles);

  ADC_RegularChannelConfig(ADC3, ADC_Channel_4, 2, ADC_SampleTime_56Cycles);

  ADC_RegularChannelConfig(ADC3, ADC_Channel_5, 3, ADC_SampleTime_56Cycles);

..

Posted on December 13, 2012 at 17:34

Thanks for the advice, now I have an interrupt each time conversion is done. 

I want to be able to scan the following pins:

Pin 9 on GPIOF  (potentiometer)

Pins 1 and 2 on GPIOA

I'm working on the stm3220g-eval board

I use __IO uint16_t val[3] variable to hold the data from the ADC.

I can see the correct data in  val[0] but as I turn the potentiometer I see that it affects the data I see in  val[1] and val[2]. I think I am missing something with the DMA configuration what results in overwriting my memory.

I have been ''playing'' with this almost the whole day and I just can’t figure this out.

The latest code is below:

__IO uint16_t val[3];

void ADC_HW_Init(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 | RCC_AHB1Periph_GPIOA, 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)&val[0];

  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_HalfWord;

  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);

 

  /* Configure ADC3 Channel7 pin as analog input ******************************/

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;

  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;

  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;

  GPIO_Init(GPIOF, &GPIO_InitStructure);

  

  

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_2;

  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;

  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;

  GPIO_Init(GPIOA, &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 = ENABLE;

  ADC_InitStructure.ADC_ContinuousConvMode = DISABLE;

  ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None;

  ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;

  ADC_InitStructure.ADC_NbrOfConversion = 3;

  ADC_InitStructure.ADC_ExternalTrigConv = 0;

  ADC_Init(ADC3, &ADC_InitStructure);

  /* ADC3 regular channel7 configuration *************************************/

  ADC_RegularChannelConfig(ADC3, ADC_Channel_7, 1, ADC_SampleTime_56Cycles);

  ADC_RegularChannelConfig(ADC3, ADC_Channel_1, 2, ADC_SampleTime_56Cycles);

  ADC_RegularChannelConfig(ADC3, ADC_Channel_2, 3, ADC_SampleTime_56Cycles);

 /* Enable DMA request after last transfer (Single-ADC mode) */

  ADC_DMARequestAfterLastTransferCmd(ADC3, ENABLE);

 

  DMA_ITConfig( DMA2_Stream0, DMA_IT_TC, ENABLE );

  DMA_Cmd(DMA2_Stream0, ENABLE);

 

  ADC_DMACmd(ADC3, ENABLE);

  ADC_Cmd(ADC3, ENABLE);

  ADC_ITConfig(ADC3, ADC_IT_EOC, ENABLE);

  

  NVIC_SetPriority(ADC_IRQn, 0);

  NVIC_EnableIRQ(ADC_IRQn);

 

  ADC_SoftwareStartConv(ADC3);

  

}

void ADC3_IRQHandler(void)

{

  

   ADC_ClearITPendingBit(ADC3, ADC_IT_EOC);

   

     /* Start ADC3 Software Conversion */ 

   ADC_SoftwareStartConv(ADC3);

}

Posted on December 13, 2012 at 18:24

If pin 1 and 2 are not connected to a low impedance signal, crosstalk from pin 9 can cause what you are observing. Connect pin 1 and 2 to ground and try again.

Cheers, Hal

Posted on December 13, 2012 at 18:25

If pin 1 and 2 are not connected to a low impedance signal, crosstalk from pin 9 can cause what you are observing. Connect pin 1 and 2 to ground and try again.

Cheers, Hal