MMC initialization steps (via SPI)

[vinodstanur]

Pls give me some working mmc initialization steps;
I tried CMD0 at first and got response 0x01 . But then i give CMD1 but not getting response!=0. Tried in loop untill the response !=0. But not getting response. Tried another MMC .Still same problem. Then i give command(16,0,512,0xfF)//CMD16
But not getting response 1;
Then i had given command(17,0,(512),0xff);//write enable command CMD17
The I could receive 0x05 as response!!!!!!! So i am getting some response as correct. So what is my problem? I think its initialization problem. So any one could give me the correct initialization steps?

 

[Ian Rogers]

Maybe this will help...

You have to initialise the MMC to SPI mode

nt mmc_init() 
	{
	DWORD i; 
	/* Generate a data pattern for write block */ 
	for(i=0;i<MMC_DATA_SIZE;i++) 
		{  
		MMCWRData[i] = i; 
		{  
	MMCStatus = 0; 
	IOSET0 = SPI_SEL; /* set SPI SSEL */ 
	/* initialise the MMC card into SPI mode by sending 80 clks on */ 
	/* Use MMCRDData as a temporary buffer for SPI_Send() */  
	for(i=0; i<10; i++)  
		{ 
		MMCRDData[i] = 0xFF; 
		}  
	SPI_Send( MMCRDData, 10 ); 
   
	IOCLR0 = SPI_SEL; /* clear SPI SSEL */ 
	/* send CMD0(RESET or GO_IDLE_STATE) command, all the arguments  
	are 0x00 for the reset command, precalculated checksum */ 
	MMCCmd[0] = 0x40; 
	MMCCmd[1] = 0x00; 
	MMCCmd[2] = 0x00; 
	MMCCmd[3] = 0x00; 
	MMCCmd[4] = 0x00; 
	MMCCmd[5] = 0x95; 
	SPI_Send( MMCCmd, MMC_CMD_SIZE );
	/* if = 1 then there was a timeout waiting for 0x01 from the MMC */ 
	if( mmc_response(0x01) == 1 ) 
		{  
		MMCStatus = IDLE_STATE_TIMEOUT; 
		IOSET0 = SPI_SEL; /* set SPI SSEL */ 
		return MMCStatus; 
		}  
	/* Send some dummy clocks after GO_IDLE_STATE */ 
	IOSET0 = SPI_SEL; /* set SPI SSEL */ 
	SPI_ReceiveByte(); 
	IOCLR0 = SPI_SEL; /* clear SPI SSEL */      
	
	/* must keep sending command until zero response ia back. */ 
    	i = MAX_TIMEOUT; 
	do  
		{  
		/* send mmc CMD1(SEND_OP_COND) to bring out of idle state */ 
		/* all the arguments are 0x00 for command one */ 
		MMCCmd[0] = 0x41; 
		MMCCmd[1] = 0x00; 
		MMCCmd[2] = 0x00; 
		MMCCmd[3] = 0x00; 
		MMCCmd[4] = 0x00; 
		/* checksum is no longer required but we always send 0xFF */ 
		MMCCmd[5] = 0xFF; 
		SPI_Send( MMCCmd, MMC_CMD_SIZE ); 
		i--; 
		} while ( (mmc_response(0x00) != 0) && (i>0) ); 
	/* timeout waiting for 0x00 from the MMC */ 
	if ( i == 0 ) 
		{  
		MMCStatus = OP_COND_TIMEOUT; 
		IOSET0 = SPI_SEL; /* set SPI SSEL */ 
		return MMCStatus; 
		}  
	/* Send some dummy clocks after SEND_OP_COND */ 
	IOSET0 = SPI_SEL; /* set SPI SSEL */ 
	SPI_ReceiveByte(); 
	IOCLR0 = SPI_SEL; /* clear SPI SSEL */ 
      
	/* send MMC CMD16(SET_BLOCKLEN) to set the block length */ 
	MMCCmd[0] = 0x50; 
	MMCCmd[1] = 0x00;  /* 4 bytes from here is the block length */ 
	/* LSB is first */   
	/* 00 00 00 10 set to 16 bytes */ 
	/* 00 00 02 00 set to 512 bytes */ 
	MMCCmd[2] = 0x00; 
	/* high block length bits - 512 bytes */ 
	MMCCmd[3] = 0x02; 
	/* low block length bits */ 
	MMCCmd[4] = 0x00; 
	/* checksum is no longer required but we always send 0xFF */ 
	MMCCmd[5] = 0xFF; 
	SPI_Send( MMCCmd, MMC_CMD_SIZE ); 
     
	if( (mmc_response(0x00))==1 ) 
		{  
		MMCStatus = SET_BLOCKLEN_TIMEOUT; 
		IOSET0 = SPI_SEL;  /* set SPI SSEL */
		return MMCStatus; 
		}
	IOSET0 = SPI_SEL;  /* set SPI SSEL */ 
	SPI_ReceiveByte(); 
	return 0; 
	}

Ian