What's the source address when using DMA PER_2_MEM Mode?

[TBaue.1]

Hi Folks,

i'm working with the STM32H750 controller. At the moment i'm trying to get the ADC working with the DMA in a Peripheral to Memory Mode.

Since i've no idea how to do this, i've started to checking the HAL functions and found the HAL_DMA_Start() function which leads to the DMA_SetConfig() function.

Here's the code from that:

/**
  * @brief  Sets the DMA Transfer parameter.
  * @param  hdma:       pointer to a DMA_HandleTypeDef structure that contains
  *                     the configuration information for the specified DMA Stream.
  * @param  SrcAddress: The source memory Buffer address
  * @param  DstAddress: The destination memory Buffer address
  * @param  DataLength: The length of data to be transferred from source to destination
  * @retval None
  */
static void DMA_SetConfig(DMA_HandleTypeDef *hdma, uint32_t SrcAddress, uint32_t DstAddress, uint32_t DataLength)
{
  /* calculate DMA base and stream number */
  DMA_Base_Registers  *regs_dma  = (DMA_Base_Registers *)hdma->StreamBaseAddress;
  BDMA_Base_Registers *regs_bdma = (BDMA_Base_Registers *)hdma->StreamBaseAddress;
 
  if(IS_DMA_DMAMUX_ALL_INSTANCE(hdma->Instance) != 0U) /* No DMAMUX available for BDMA1 */
  {
    /* Clear the DMAMUX synchro overrun flag */
    hdma->DMAmuxChannelStatus->CFR = hdma->DMAmuxChannelStatusMask;
 
    if(hdma->DMAmuxRequestGen != 0U)
    {
      /* Clear the DMAMUX request generator overrun flag */
      hdma->DMAmuxRequestGenStatus->RGCFR = hdma->DMAmuxRequestGenStatusMask;
    }
  }
 
  if(IS_DMA_STREAM_INSTANCE(hdma->Instance) != 0U) /* DMA1 or DMA2 instance */
  {
    /* Clear all interrupt flags at correct offset within the register */
    regs_dma->IFCR = 0x3FUL << (hdma->StreamIndex & 0x1FU);
 
    /* Clear DBM bit */
    ((DMA_Stream_TypeDef *)hdma->Instance)->CR &= (uint32_t)(~DMA_SxCR_DBM);
 
    /* Configure DMA Stream data length */
    ((DMA_Stream_TypeDef *)hdma->Instance)->NDTR = DataLength;
 
    /* Peripheral to Memory */
    if((hdma->Init.Direction) == DMA_MEMORY_TO_PERIPH)
    {
      /* Configure DMA Stream destination address */
      ((DMA_Stream_TypeDef *)hdma->Instance)->PAR = DstAddress;
 
      /* Configure DMA Stream source address */
      ((DMA_Stream_TypeDef *)hdma->Instance)->M0AR = SrcAddress;
    }
    /* Memory to Peripheral */
    else
    {
      /* Configure DMA Stream source address */
      ((DMA_Stream_TypeDef *)hdma->Instance)->PAR = SrcAddress;
 
      /* Configure DMA Stream destination address */
      ((DMA_Stream_TypeDef *)hdma->Instance)->M0AR = DstAddress;
    }
  }
  else if(IS_BDMA_CHANNEL_INSTANCE(hdma->Instance) != 0U) /* BDMA instance(s) */
  {
    /* Clear all flags */
    regs_bdma->IFCR = (BDMA_ISR_GIF0) << (hdma->StreamIndex & 0x1FU);
 
    /* Configure DMA Channel data length */
    ((BDMA_Channel_TypeDef *)hdma->Instance)->CNDTR = DataLength;
 
    /* Peripheral to Memory */
    if((hdma->Init.Direction) == DMA_MEMORY_TO_PERIPH)
    {
      /* Configure DMA Channel destination address */
      ((BDMA_Channel_TypeDef *)hdma->Instance)->CPAR = DstAddress;
 
      /* Configure DMA Channel source address */
      ((BDMA_Channel_TypeDef *)hdma->Instance)->CM0AR = SrcAddress;
    }
    /* Memory to Peripheral */
    else
    {
      /* Configure DMA Channel source address */
      ((BDMA_Channel_TypeDef *)hdma->Instance)->CPAR = SrcAddress;
 
      /* Configure DMA Channel destination address */
      ((BDMA_Channel_TypeDef *)hdma->Instance)->CM0AR = DstAddress;
    }
  }
  else
  {
    /* Nothing To Do */
  }
}

First of all, the commentary is faulty. When it says /* Peripheral to Memory */ it is checking for "== MEMORY_TO_PERIPH" so that is wrong right away. But that's not the problem here: I don't quiet now, what address should be entered for the source of the DMA transfer. In my case a want to get a specific number of samples from ADC1_CH0 to a given memspace (initiatet with a variable and referenced by a pointer of course).

Can you maybee give me some input to get this done? =)

Thanks in advance,

kind regards

Tony

[Imen GH]

Hello,

Please refer to RM0433 Rev 6 ( page 101 and 128)

Regards

Imen