LPC4370 M2M DMA Transfer Speed

hairy_lee — Thu, 24 Nov 2016 17:01:00 GMT

Hi,

I am using the GPDMA to transfer a block of data out via a GPIO port and I'm trying, with no success, to discover the theoretical frequency at which this should occur based on the system core frequency.

I have measured the transfer using a scope at a core frequency of 204MHz and 120MHz. I get a sensible looking answer on the scope given the ration between the 2, however it would really help to discover the actual speed and tolerance.

Thanks.

Re: LPC4370 M2M DMA Transfer Speed

soledad — Thu, 29 Dec 2016 18:46:13 GMT

Hello Hairy Lee,

You can try something like this 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_Typd                         GPDMA_LLI;  void DMA_Setup() {           uint32_t     i=0;           GPDMA_Channel_CFG_Type     GPDMACfg;                 for (i=0;i<512;i+=2)           {                DMASrc_Buffer[i]=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);  }

Best Regards,

Sol

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LPC4370 M2M DMA Transfer Speed

Re: LPC4370 M2M DMA Transfer Speed