DMA Transfer Delay Problem

lpcware — Wed, 15 Jun 2016 17:51:16 GMT

Content originally posted in LPCWare by mrmehdi on Mon Sep 14 07:32:01 MST 2015
Hi Everyone
i have a problem with LPC1788 DMA
i want transfer data linked list from sram to gpio port by DMA.
i try this code and work correctly
but i have a big problem
in data logger result you can see huge time gap between each transfer completed.
[img]http://s2.postimg.org/lwwour0xl/image.jpg[/img]

my tested code:

void DMA_IRQHandler (void)
{
static uint32_t regVal;
regVal=LPC_GPDMA->IntTCStat;
LPC_GPDMA->IntTCClear |= regVal;
regVal=LPC_GPDMA->IntErrStat;
LPC_GPDMA->IntErrClr |= regVal;

// check GPDMA interrupt on channel DMA_CHANNEL_NO
//if (GPDMA_IntGetStatus(GPDMA_STAT_INT, DMA_CHANNEL_NO)){ //check interrupt status on channel DMA_CHANNEL_NO
// Check counter terminal status
//if(GPDMA_IntGetStatus(GPDMA_STAT_INTTC, DMA_CHANNEL_NO)){
// Clear terminate counter Interrupt pending
//GPDMA_ClearIntPending (GPDMA_STATCLR_INTTC, DMA_CHANNEL_NO);
//Channel0_TC++;
//}
//}
}

GPDMA_LLI_TypdGPDMA_LLI;

void DMA_Setup()
{
uint32_ti=0;
GPDMA_Channel_CFG_TypeGPDMACfg;

for (i=0;i<512;i+=2)
{
DMASrc_Buffer=0x00;
DMASrc_Buffer[i+1]=0xff;
}

NVIC_DisableIRQ(DMA_IRQn);

NVIC_SetPriority(DMA_IRQn, ((0x01<<3)|0x01));

GPDMA_Init();
//Setup DMA Channel

GPDMA_LLI.SrcAddr=(uint32_t)DMASrc_Buffer;
GPDMA_LLI.DstAddr=(uint32_t)&(LPC_GPIO0->PIN);
GPDMA_LLI.NextLLI=(uint32_t)&GPDMA_LLI;
GPDMA_LLI.Control= DMA_SIZE 
|(2<<18) //SW=32Bit
|(2<<21)//DW=32Bit
|(1<<26) //source incr
|(1<<31) ;

GPDMACfg.ChannelNum=DMA_CHANNEL_NO;
GPDMACfg.SrcMemAddr=(uint32_t)DMASrc_Buffer;
GPDMACfg.DstMemAddr=(uint32_t)(&LPC_GPIO0->PIN);

// Transfer size
GPDMACfg.TransferSize = DMA_SIZE;
// Transfer width
GPDMACfg.TransferWidth = GPDMA_WIDTH_WORD;
// Transfer type
GPDMACfg.TransferType = GPDMA_TRANSFERTYPE_M2M;
// Source connection - unused
GPDMACfg.SrcConn = 0;
// Destination connection - unused
GPDMACfg.DstConn = 0;
// Linker List Item - unused
GPDMACfg.DMALLI = (uint32_t)&GPDMA_LLI;
// Setup channel with given parameter
GPDMA_Setup(&GPDMACfg,0);

// Enable GPDMA channel DMA_CHANNEL_NO
GPDMA_ChannelCmd(DMA_CHANNEL_NO, ENABLE);

/* Enable GPDMA interrupt */
NVIC_EnableIRQ(DMA_IRQn);

}

my problem is huge time between each transition.
you can see in this picture
A section period time and B section is same.
i don't know why this time gap happened.
thanks for your help

Re: DMA Transfer Delay Problem

lpcware — Wed, 15 Jun 2016 17:51:16 GMT

Content originally posted in LPCWare by mshrestha789 on Wed Nov 04 07:47:56 MST 2015
Hi,

Did you solve the problem?

topic DMA Transfer Delay Problem in LPC Microcontrollers

DMA Transfer Delay Problem

Re: DMA Transfer Delay Problem