DMA normal buffer

Posted on March 13, 2015 at 14:50

Hi

I have attached a piece of code in which DMA is configures as circular buffer. I have configured a total buffer complete interrupt. when I get into the interrupt I want to change the BUFF_SIZE In data shet it is mentioned that before doing we have to disable the stream. I am doing exactly the same  but when I give a break point  in case 1 value it always posses the value in the BUFF_SIZE which is initialized before for e.g if BUFF_SIZE while prior initialization  is initialized to 240(value = 204)  anf the total buffer complete interrupt occurs in case 0 I initialized the BUFF_SIZE to 120(value = 103)  again but when I give a break point at value = DAC->DHR12R1. it always have the 204 ehich was initialized before what is the problem. One more thing is I want to configure as normal buffer not a circular one I mean I want to update the MOAR register too how to do that Please help

for your reference I have paste the code below

void DMA1_Stream5_IRQHandler(void)

{

  if(DMA_GetITStatus(DMA1_Stream5, DMA_IT_TCIF5))

    {

        DMA_ClearITPendingBit(DMA1_Stream5, DMA_IT_TCIF5);

    

          switch(index)

          {

          case 0:

              DMA1_Stream5->CR &= ~0x00000001;  // disabling the stream          

        

              DMA1_Stream5->M0AR = (uint32_t)& aSine12bit;

        

              DMA1_Stream5->NDTR = 160;           

             DMA1_Stream5->CR |= 0x00000001; //enabling the stream    

              index ++;

              break;

          case 1:

                       value = DAC->DHR12R1;

                       DMA1_Stream5->CR &= ~0x00000001;            // disabling the stream

              

                     DMA1_Stream5->M0AR = (uint32_t)& aSine12bit;

                     DMA1_Stream5->NDTR = 120;           

                      DMA1_Stream5->CR |= 0x00000001;     //enabling the stream

               

                   index ++;

                      break;

          case 2:

            

                 if ( flag_onetime == 1)

              {

               DMA1_Stream5->CR &= ~0x00000001;            // disabling the stream

               DMA1_Stream5->M0AR = (uint32_t)& aSine12bit;

               DMA1_Stream5->NDTR = 240;            /

               DMA1_Stream5->CR |= 0x00000001;     //enabling the stream

               flag_onetime = 0;

              }

          break;

          }

    }

  }