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LPC1788 MCI systematic CRC error on block write

Hi,

During the migration of a project from LPC2478 to LPC1788 I get a near systematic issue when trying to write to an SD card.
After each write block attempt I get an DATA CRC error in MCI status reg. I also was able to check that data are really not written on the card.
The exception is when almost all byte are 0xFF. In that case, data are written and no CRC error occurs.

I tried to lower MCLK, PCLK and SD clock frequency (down to 2MHz) but it does not change anything.
I tried several SD card too.
I checked all errata sheet from NXP and did not find anything.

With an identical board with an LPC2478, I never get this issue. Has anyone already encountered a similar issue ?

I use a Keil RL-ARM library.

Here is the source code of the driver (MCI commands 25 send separately by the library before calling this function) :

/*--------------------------- WriteBlock -------------------------------------*/

static BOOL WriteBlock (U32 block, U8 *buf, U32 cnt) {
  /* Write a cnt number of 512 byte blocks to Flash Card. */
  U32 i,j;

  for (j = 0; j < cnt; buf += 512, j++) {
        /* Set MCI Transfer registers. */
        LPC_MCI->DATATMR  = DATA_WR_TOUT_VALUE;
        LPC_MCI->DATALEN  = 512;

    /* Start DMA Memory to Peripheral transfer. */
    DmaStart (DMA_WRITE, buf);
    LPC_MCI->DATACTRL = 0x99;

    for (i = DMA_TOUT; i; i--) {
      if (LPC_GPDMA->RawIntTCStat & 0x01) {
        /* Data transfer finished. */
        break;
      }
    }

    if (i == 0) {
      /* DMA Data Transfer timeout. */
      return (__FALSE);
    }

    if (cnt == 1) {
      break;
    }

    /* Wait until Data Block sent to Card. */
    while (LPC_MCI->STATUS != (MCI_DATA_END | MCI_DATA_BLK_END)) {
      if (LPC_MCI->STATUS & (MCI_DATA_CRC_FAIL | MCI_DATA_TIMEOUT)) {
        /* Error while Data Block sending occured. */
                return (__FALSE); <------------------------------------------------------ systematic error with LPC_MCI->STATUS = 0x02
      }
    }

    /* Wait 2 SD clocks */
    for (i = WAIT_2SD_CLK(__CPUCLK); i; i--);
  }

  return (__TRUE);
}

Thanks by advance and best regards.
Antoine Gardiol

0 Tamiryan Michael over 11 years ago

It has been a while for me since I last used this software, but I recall that there is a DMA timeout setting in one of the header files associated with the file system. I don't recall where exactly.
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0 Tamiryan Michael over 11 years ago in reply to Tamiryan Michael

DMA_TOUT ! Try increasing it.
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0 Antoine Gardiol over 11 years ago in reply to Tamiryan Michael

Hello.

Thanks for the tip, but I am aware of this point and it does not solve the problem. I fact DMA end with success (status bits checked) but it is the SD card that tell the MCI peripheral that the received CRC is bad.
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0 Antoine Gardiol over 11 years ago

Hello.

I found the problem. It is an hardware issue.

On the LPC2478, there is no need of extern pull-ups on the CMD and DATx lines. It is not the fact on the LPC1788.

So adding 5 pull-ups solves this issue.

Best regards.
Antoine Gardiol
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