MMC ROOT Directory Writing

[patrikshah]

hi,
I am interfacing MMC card with LPC2148 SPI based . I have one application note from NXP which

shows how to interface SD /MMC (512 MB) card using SPI for FAT16.

using that code i am able to write & Read data . So i am able to read data from (Sector 0- Boot

sector , Sector 6 - FAT table sector , sector 528 - Data sector )

but when i am accessing or writing data to Root Directory sector , its not able to write or read data to

& from that secotr - 496 .

when i am writing it to sector - 496 data is getting stored on 432 =Difference 64
When i am writing it to sector - 498 data is getting stored on 434 = Difference 64
When i am writing it to sector - 510 data is getting stored on 445 = Difference 64



So can any one tell me Is there any other merhod to write data in to ROOT DIRECTORY .

I am attaching my code here


if ( mmc_write_block(495,rootdirectory_info) == 0 )
{
mmc_read_block (496);
Display_Read_parameter (496) ;
}
else
{
while ( 1 ); /* Very bad

happened */
}



int mmc_write_block(WORD block_number, BYTE* MMCWRDATA)
{
WORD varl, varh;
BYTE Status;

IOCLR0 = SPI_SEL; /* clear SPI SSEL */

/* block size has been set in mmc_init() */
varl=((block_number&0x003F)<<9);
varh=((block_number&0xFFC0)>>7);

/* send mmc CMD24(WRITE_SINGLE_BLOCK) to write the data to
MMC card */
MMCCmd[0] = 0x58;
/* high block address bits, varh HIGH and LOW */
MMCCmd[1] = varh >> 0x08;
MMCCmd[2] = varh & 0xFF;
/* low block address bits, varl HIGH and LOW */
MMCCmd[3] = varl >> 0x08;
MMCCmd[4] = varl & 0xFF;
/* checksum is no longer required but we always send 0xFF */
MMCCmd[5] = 0xFF;
SPI_Send(MMCCmd, MMC_CMD_SIZE );

/* if mmc_response returns 1 then we failed to get a 0x00
response */
if((mmc_response(0x00))==1)
{
MMCStatus = WRITE_BLOCK_TIMEOUT;
IOSET0 = SPI_SEL; /* set SPI SSEL */
return MMCStatus;
}

/* Set bit 0 to 0 which indicates the beginning of the data block */
MMCCmd[0] = 0xFE;
SPI_Send( MMCCmd, 1 );

/* send data, pattern as 0x00,0x01,0x02,0x03,0x04,0x05 ...*/
SPI_Send( MMCWRDATA, MMC_DATA_SIZE );

/* Send dummy checksum */
/* when the last check sum is sent, the response should come back
immediately. So, check the SPI FIFO MISO and make sure the status
return 0xX5, the bit 3 through 0 should be 0x05 */
MMCCmd[0] = 0xFF;
MMCCmd[1] = 0xFF;
SPI_Send( MMCCmd, 2 );

Status = SPI_ReceiveByte();
if ( (Status & 0x0F) != 0x05 )
{
MMCStatus = WRITE_BLOCK_FAIL;
IOSET0 = SPI_SEL; /* set SPI SSEL */
return MMCStatus;
}

/* if the status is already zero, the write hasn't finished
yet and card is busy */
if(mmc_wait_for_write_finish()==1)
{
MMCStatus = WRITE_BLOCK_FAIL;
IOSET0 = SPI_SEL; /* set SPI SSEL */
return MMCStatus;
}

IOSET0 = SPI_SEL; /* set SPI SSEL */
SPI_ReceiveByte();
return 0;
}





So Please help me how to solve this problem

Regards,
Pratik