DM642

Hi,

Can any body tell me whether DAT_cpy API uses "DMA" or "EDMA" ?

Can any body tell me the difference between DAT_cpy, DMA, EDMA and
QDMA??

Thanks,

Harsha Start a New Thread

Hello Harsha,
EDMA: in C64x DSP is a basically enhanced version of the DMA which was used in the C620x/C670x devices.The EDMA includes several enhancements to the DMA. For more details please refer spru234b.pdf literature.

QDMA: is an quick DMA which is local to the CPU. So, QDMA allows direct and quick CPU-initiated DMA submission without having to submit requests to the EDMA channel controller. A QDMA transfer is best suited for applications that require quick data transfers, such as data requests in a tight loop algorithm.

DAT module can be used to move data to/from external memory to CPU by DMA/EDMA hardware.
DAT_copy: -API Copies a linear block of data from Src to Dst using DMA or EDMA hardware. (Refer ch.6 in Spru401e.pdf lit)

An example code is given for your clarification.

void main(void)
{
byte *src; // source pointer
byte *dst; // destination pointer

int i; // loop counter
unsigned long id; // transfer id for dma

// initialise CSL
CSL_init();

// configure L2 cache
CACHE_reset();
CACHE_setL2Mode(CACHE_64KCACHE);
CACHE_enableCaching(CACHE_EMIFA_CE00);

// allocate memory
if ((src = calloc(256, sizeof(byte))) == NULL)
{
printf("Can't allocate src!\n");
exit(1);
}

if ((dst = calloc(256, sizeof(byte))) == NULL)
{
printf("Can't allocate dst!\n");
exit(1);
}

// initialise src data
for (i = 0; i < 256; i++)
src[i] = i;
printf("Performing DMA test.\n");

// open dma channel
if (!DAT_open(DAT_CHAANY, DAT_PRI_LOW, 0))
{
printf("Can't open DMA channel!\n");
exit(2);
}

// dma src to dst
id = DAT_copy(src, dst, 256); //linear copy of 256 bytes
DAT_wait(id);

// check result
for (i = 0; i < 256; i++)
if ((src[i] - dst[i]) != 0)
printf("src[%d] = %d, dst[%d] = %d\n", i, src[i], i, dst[i]);

printf("DMA test done.\n\n");

free(src);
free(dst);

DAT_close();

}

Thanks & Regards
---------------------------------
P. Prabhakar
Digital Video Group
GDA Technologies Ltd
32 & 46 North Phase
Thiru Ve Ka Industrial Estate
Ekkatuthangal
Chennai - 600 097 India
Email: p...@gdatech.co.in
Mobile: 09840517282
Office : 044-30613429

----- Original Message -----
From: Harsha, Manjunatha (IE10)
To: c...
Sent: Monday, August 28, 2006 12:45 PM
Subject: [c6x] DM642

Hi,

Can any body tell me whether DAT_cpy API uses "DMA" or "EDMA" ?

Can any body tell me the difference between DAT_cpy, DMA, EDMA and QDMA??

Thanks,

Harsha

------
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Version: 7.1.405 / Virus Database: 268.11.6/428 - Release Date: 8/25/2006 Start a New Thread

DAT_cpy uses QDMA or quick dma. Please refer to the DMA document, DMA is a
generic term used to describe a direct memory access

And is used to move data in the background, QDMA or quick DMA stands for CPU
triggered transfers, and EDMA stands for event synchronized

transfers triggered by hardware events.

Regds

JS

_____

From: c... [mailto:c...] On Behalf Of Harsha,
Manjunatha (IE10)
Sent: Monday, August 28, 2006 2:16 AM
To: c...
Subject: [c6x] DM642

Hi,

Can any body tell me whether DAT_cpy API uses "DMA" or "EDMA" ?

Can any body tell me the difference between DAT_cpy, DMA, EDMA and QDMA??

Thanks,

Harsha Start a New Thread