Bug in DMA transfers

aliasadzadeh — Sun, 24 Feb 2013 14:12:15 GMT

Dear All

I want to put a 4 element int to another 16 element int with DMA,

Here is the code

static uint32_t test_source[4]={1,2,3,4};
static uint32_t test_dest[16]={0};

//DMA
//Enable DMA MUX
SIM->SCGC6 |= SIM_SCGC6_DMAMUX_MASK;
// Disable DMA MUX channel first
DMAMUX0->CHCFG[0] = 0x00;
// Clear pending errors and/or the done bit
if (((DMA0->DMA[0].DSR_BCR & DMA_DSR_BCR_DONE_MASK) == DMA_DSR_BCR_DONE_MASK)
  | ((DMA0->DMA[0].DSR_BCR & DMA_DSR_BCR_BES_MASK) == DMA_DSR_BCR_BES_MASK)
  | ((DMA0->DMA[0].DSR_BCR & DMA_DSR_BCR_BED_MASK) == DMA_DSR_BCR_BED_MASK)
  | ((DMA0->DMA[0].DSR_BCR & DMA_DSR_BCR_CE_MASK) == DMA_DSR_BCR_CE_MASK))
DMA0->DMA[0].DSR_BCR |= DMA_DSR_BCR_DONE_MASK;

// Set Source Address
  DMA0->DMA[0].SAR = (uint32_t )&test_source;
// Set destination address
  DMA0->DMA[0].DAR = (uint32_t )&test_dest;
  // Set BCR to know how many bytes to transfer
  DMA0->DMA[0].DSR_BCR = DMA_DSR_BCR_BCR(64);
  // Clear Source size and Destination size fields.
  DMA0->DMA[0].DCR &= ~(DMA_DCR_SSIZE_MASK | DMA_DCR_DSIZE_MASK);
// Set DMA as follows:
  // Source size is byte size
  // Destination size is byte size
  // D_REQ cleared automatically by hardware
  // Destination address will be incremented after each transfer
  // Cycle Steal mode
  // External Requests are enabled
  // Asynchronous DMA requests are enabled.
  DMA0->DMA[0].DCR |= (DMA_DCR_SSIZE(0)
  | DMA_DCR_DSIZE(0)
  | DMA_DCR_D_REQ_MASK
  | DMA_DCR_DINC_MASK
  | DMA_DCR_SINC_MASK
  | DMA_DCR_ERQ_MASK
  //| DMA_DCR_CS_MASK
  | DMA_DCR_ERQ_MASK
  | DMA_DCR_EADREQ_MASK
  | DMA_DCR_EINT_MASK
  | DMA_DCR_SMOD(3)
  );
  // Enables the DMA channel and select the DMA Channel Source
  //DMAMUX0->CHCFG[0] = 0x02; // Select UART0 as the Channel Source
  DMAMUX0->CHCFG[0] |= DMAMUX_CHCFG_ENBL_MASK; // Enable the DMA MUX channel
  NVIC_EnableIRQ(DMA0_IRQn);

  DMA0->DMA[0].DCR |= DMA_DCR_START_MASK;






void DMA0_IRQHandler()
{
  // Clear pending errors and/or the done bit
  if (((DMA0->DMA[0].DSR_BCR & DMA_DSR_BCR_DONE_MASK) == DMA_DSR_BCR_DONE_MASK)
  | ((DMA0->DMA[0].DSR_BCR & DMA_DSR_BCR_BES_MASK) == DMA_DSR_BCR_BES_MASK)
  | ((DMA0->DMA[0].DSR_BCR & DMA_DSR_BCR_BED_MASK) == DMA_DSR_BCR_BED_MASK)
  | ((DMA0->DMA[0].DSR_BCR & DMA_DSR_BCR_CE_MASK) == DMA_DSR_BCR_CE_MASK))
  DMA0->DMA[0].DSR_BCR |= DMA_DSR_BCR_DONE_MASK;
  // Set BCR to know how many bytes to transfer
  DMA0->DMA[0].DSR_BCR = DMA_DSR_BCR_BCR(64);
  // Set Source Address (this is the UART0_D register
  DMA0->DMA[0].SAR = (uint32_t )&test_source;
  // Set destination address
  DMA0->DMA[0].DAR = (uint32_t )&test_dest;
}

But After I run the code instead of getting 1,2,3,4,1,2,3,4... in test_dest I will get

1,2,3,4,0,1,2,3,4,0,1,2,3,4,0x02DC6C00,0

what is wrong with this Code?

Re: Bug in DMA transfers

JimDon — Mon, 25 Feb 2013 02:28:16 GMT

Just wondering did you mean | or || in your if statements?

Re: Bug in DMA transfers

aliasadzadeh — Mon, 25 Feb 2013 05:15:05 GMT

I meant | (or) in my if statement, Do you know what's wrong?

Re: Bug in DMA transfers

lothar — Mon, 02 Nov 2020 13:04:47 GMT

Ali Asadzadeh schrieb:

static uint32_t test_source[4]={1,2,3,4};
static uint32_t test_dest[16]={0};

I would write:

static uint32_t test_source[]={1,2,3,4}; // Compiler counts the array size itself
static uint32_t test_dest[16]; // I think they are initialized to 0 anyway and like that you only put the first element to 0

Ali Asadzadeh schrieb:

// Set Source Address
  DMA0->DMA[0].SAR = (uint32_t )&test_source;

Im not sure about this one. Your variable test_source is an array. Therefor in test_source[0] there is a one. But test_source without [] is a pointer, pointing to the first value of your array (*test_source is also = 1). So you probably like to write:

DMA0->DMA[0].DAR = (uint32_t )test_source;

DMA0->DMA[0].DAR = (uint32_t )&test_source[0];

At the moment you give an address of a variable in which a address is stored.

Maybe I'm wrong

greez

Re: Bug in DMA transfers

Monica — Tue, 19 Mar 2013 18:04:59 GMT

Ali, was this helpful?

Please let us know! :smileywink:

Regards

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