topic Re: SSP DMA in ARM LPC2388 in LPC Microcontrollers

SSP DMA in ARM LPC2388

mohammadfaizan — Thu, 27 Dec 2018 06:55:55 GMT

Hi,

I am working on a project, in which I want to copy a data from SD card (on SSP0) to a USB flash drive, I want to reduce the time span required to copy data from SD card to USB drive,so I decided to use a DMA. No such provision to access the DMA, to copy data from SD card to USB directly , I must first need to copy few bytes in memory buffer, then transfer that bytes from memory buffer to USB drive repeatedly to copy 8GB. I also explore the sample DMA example in code bundle LPC23xx-24xx Sample Software. Can you suggest a simpler way to accomplish this DMA transfer. It will be more helpful if you could provide a other code example

Re: SSP DMA in ARM LPC2388

CarlosCasillas — Mon, 07 Jan 2019 18:46:24 GMT

Hi Mohammad,

For additional DMA usage/details, you could take a look to the following link:

https://www.embeddedrelated.com/showthread/lpc2000/29543-1.php

Additionally, please consider that the procedure would vary if you are performing DMA transfers from raw data vs. files. If you are transferring files from the SD card to a USB thumb drive, the files may be fragmented, so, the DMA should be integrated on the File System library.

Hope this will be useful for you.
Best regards!
/Carlos
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Re: SSP DMA in ARM LPC2388

mohammadfaizan — Tue, 15 Jan 2019 11:17:16 GMT

Thanks CarlosCasillas,

I have gone throw the link, and also refer another post on the embeddedexplorer

lpc2000 | DMA->SSP/SPI Mystery on LPC2468

void callPer2Mem(void)
{
      DWORD i;
      char FIFOSIZE = 8;
      DMA_Init(0,P2M);
      GPDMA_CH0_CFG |= 0X08001 | (0X01 << 1) | (0X06 <<11); // need your help here access the SSP0 Rx To //USBmemory
      SSP0DMACR = 0X03; // ENB DMA RTX SSP0

      src_addr = DMA_SRC;
      dest_addr = DMA_DST;
      i=0;
         while(i<= SSP_BUFSIZE)
         {
            SPI_Write(src_addr);
            SPI_Write(dest_addr);
            src_addr += FIFOSIZE;
            dest_addr += FIFOSIZE;
            i+= FIFOSIZE;
         }
            for(i=0; i<SSP_BUFSIZE; i++)
               {
                 if(src_addr != dest_addr)
                  {
                     // while(1) ;
                  }
      return;
              }

}

I am not getting a data from sd card into a USB RAM, when I call the above function.Please help, I refer the code bundle

warm regards

Mohammad Faizan