///  MMC/SD Library. CopyLefted from Procyon AVRlib
///	      _________________
///	     /  1 2 3 4 5 6 78 |	<- view of MMC/SD card looking at contacts
///	    / 9                |	Pins 8 and 9 are present only on SD cards
///	    |    MMC/SD Card   |
///	    |                  |
///	    /\/\/\/\/\/\/\/\/\/\
///	    1 - CS   (chip select)          - wire to any available I/O pin(*)
///	    2 - DIN  (data in, card<-host)  - wire to SPI MOSI pin
///	    3 - VSS  (ground)               - wire to ground
///	    4 - VDD  (power, 3.3V only?)    - wire to power (MIGHT BE 3.3V ONLY!)
///	    5 - SCLK (data clock)           - wire to SPI SCK pin
///	    6 - VSS  (ground)               - wire to ground
///	    7 - DOUT (data out, card->host) - wire to SPI MISO pin
///         8,9 (SD card only) - PullUP to VDD





unsigned char spiTransferByte(unsigned char data);


unsigned char spiTransferByte(unsigned char data)
{
SPDR=data;
while ((SPSR & (1<<7))==0); 
return SPDR;

}


// constants/macros/typdefs
// MMC commands (taken from sandisk MMC reference)
#define MMC_GO_IDLE_STATE			0		///< initialize card to SPI-type access
#define MMC_SEND_OP_COND			1
#define MMC_SEND_CMD41                          0x41		///< set card operational mode
#define MMC_SEND_CSD				9		///< get card's CSD
#define MMC_SEND_CID				10		///< get card's CID
#define MMC_SEND_STATUS				13
#define MMC_SET_BLOCKLEN			16		///< Set number of bytes to transfer per block
#define MMC_READ_SINGLE_BLOCK			17		///< read a block
#define MMC_WRITE_BLOCK				24		///< write a block
#define MMC_PROGRAM_CSD				27
#define MMC_SET_WRITE_PROT			28
#define MMC_CLR_WRITE_PROT			29
#define MMC_SEND_WRITE_PROT			30
#define MMC_TAG_SECTOR_START			32
#define MMC_TAG_SECTOR_END			33
#define MMC_UNTAG_SECTOR			34
#define MMC_TAG_ERASE_GROUP_START 		35		///< Sets beginning of erase group (mass erase)
#define MMC_TAG_ERARE_GROUP_END			36		///< Sets end of erase group (mass erase)
#define MMC_UNTAG_ERASE_GROUP			37		///< Untag (unset) erase group (mass erase)
#define MMC_ERASE				38		///< Perform block/mass erase
#define MMC_CRC_ON_OFF				59		///< Turns CRC check on/off
// R1 Response bit-defines
#define MMC_R1_BUSY				0x80	///< R1 response: bit indicates card is busy
#define MMC_R1_PARAMETER			0x40
#define MMC_R1_ADDRESS				0x20
#define MMC_R1_ERASE_SEQ			0x10
#define MMC_R1_COM_CRC				0x08
#define MMC_R1_ILLEGAL_COM			0x04
#define MMC_R1_ERASE_RESET			0x02
#define MMC_R1_IDLE_STATE			0x01
// Data Start tokens
#define MMC_STARTBLOCK_READ			0xFE	///< when received from card, indicates that a block of data will follow
#define MMC_STARTBLOCK_WRITE		0xFE	///< when sent to card, indicates that a block of data will follow
#define MMC_STARTBLOCK_MWRITE		0xFC
// Data Stop tokens
#define MMC_STOPTRAN_WRITE			0xFD
// Data Error Token values
#define MMC_DE_MASK					0x1F
#define MMC_DE_ERROR				0x01
#define MMC_DE_CC_ERROR				0x02
#define MMC_DE_ECC_FAIL				0x04
#define MMC_DE_OUT_OF_RANGE			0x04
#define MMC_DE_CARD_LOCKED			0x04
// Data Response Token values
#define MMC_DR_MASK					0x1F
#define MMC_DR_ACCEPT				0x05
#define MMC_DR_REJECT_CRC			0x0B
#define MMC_DR_REJECT_WRITE_ERROR	0x0D

// functions
/* Definitions for MMC/SDC command */
#define CMD0	(0x40+0)	/* GO_IDLE_STATE */
#define CMD1	(0x40+1)	/* SEND_OP_COND */
#define CMD8	(0x40+8)	/* SEND_IF_COND */
#define CMD9	(0x40+9)	/* SEND_CSD */
#define CMD10	(0x40+10)	/* SEND_CID */
#define CMD12	(0x40+12)	/* STOP_TRANSMISSION */
#define CMD16	(0x40+16)	/* SET_BLOCKLEN */
#define CMD17	(0x40+17)	/* READ_SINGLE_BLOCK */
#define CMD18	(0x40+18)	/* READ_MULTIPLE_BLOCK */
#define CMD24	(0x40+24)	/* WRITE_BLOCK */
#define CMD25	(0x40+25)	/* WRITE_MULTIPLE_BLOCK */
#define CMD41	(0x40+41)	/* SEND_OP_COND (ACMD) */
#define CMD55	(0x40+55)	/* APP_CMD */
#define CMD58	(0x40+58)	/* READ_OCR */

#define CS PORTB.3
unsigned char mmcReset(void);
unsigned char mmcSendCommand(unsigned char cmd, unsigned long arg);
unsigned char mmcRead(unsigned long sector, unsigned char* buffer);
unsigned char mmcCommand(unsigned char cmd, unsigned long arg);



unsigned char mmcReset(void)
{
	
	unsigned int retry,rn;
	unsigned char r1=0,r2=0,chk;
        int i = 0;
        char ocr[31];
	retry = 0;
	CS=1;
        do
	{
		// send dummy bytes with CS high before accessing
		for (rn=0; rn<90;rn++) spiTransferByte(0xFF);
		delay_ms(1);
		// resetting card, go to SPI mode
	        r1 = mmcSendCommand(CMD0, 0);
		// do retry counter
		retry++;
		if(retry>10) return 100;
	} while(r1 != 0x01);

	retry = 0;
	do
	{       
	       delay_ms(1);
	        for(i=0;i<255;i++) { chk = spiTransferByte(0x0ff); if(chk!= 0xff) {return 120;};};
		// initializing card for operation
		//delay_ms(1);
		
		if(mmcSendCommand(58,0) == 1) {
		CS = 0;
		for(i=0;i!=31;i++){ocr[i] = spiTransferByte(0xff);};
		}
		delay_ms(1);
	        
	        for(i=0;i<255;i++) { chk = spiTransferByte(0xff); if(chk!= 0xff) {return 130;};};
	        delay_ms(5);
		 r1 = mmcSendCommand(55, 0); 
		 for(i=0;i<255;i++) { chk = spiTransferByte(0xff); if(chk!= 0xff) {return 140;};};
		 delay_ms(5);
		 r2 = mmcSendCommand(41, 0);
		 retry++;
		 if(retry>400) 
		 {
		   printf("R1 = %i || R2 = %i \r\n",r1,r2); 
		   for(i=0;i!=31;i++)
		    {      
		      printf("%x ",ocr[i]);
		    }
		   printf("\r\n");
		   return r2;
		  };
	}while(!(r2==0)); 
		
	 // turn off CRC checking to simplify communication
         //r1 = mmcSendCommand(MMC_CRC_ON_OFF, 0);
         r1=0;
	// set block length to 512 bytes
	do
	{
	 delay_ms(1);
	 for(i=0;i<255;i++) { chk = spiTransferByte(0xff); if(chk!= 0xff) {return 150;};};
	 r1 = mmcSendCommand(16,512);
         // return success
	retry++;
	if(retry > 400) return r1;
	}while(!(r1==0));
	return r1;
}              

unsigned char mmcSendCommand(unsigned char cmd, unsigned long arg)
{
	unsigned char r1;

	// assert chip select
	CS=0;
	// issue the command
	r1 = mmcCommand(cmd, arg);
	// release chip select
	CS=1;

	return r1;
}

unsigned char mmcRead(unsigned long sector, unsigned char* buffer)
{
	unsigned char r1,chk;
	unsigned int i;

	// assert chip select
	CS=0;
	// issue command
	do{
	delay_ms(1);
	 for(i=0;i<255;i++) { chk = spiTransferByte(0xff); if(chk!= 0xff) {return 150;};};
	r1 = mmcCommand(17, sector<<9);
	if(r1 != 0) return 23;
       }while(!(r1==0));	
	// wait for block start
	while(spiTransferByte(0xFF) != MMC_STARTBLOCK_READ);
	// read in data
	for(i=0; i<0x200; i++)
	{
		*buffer++ = spiTransferByte(0xFF);
	}
	// read 16-bit CRC
	spiTransferByte(0xFF);
	spiTransferByte(0xFF);
	// release chip select
	CS=1;
	// return success
	return 0;
}


unsigned char mmcCommand(unsigned char cmd, unsigned long arg)
{
	unsigned char r1;
	unsigned char retry=0;
	// send command
	spiTransferByte(cmd | 0x40);
	spiTransferByte(arg>>24);
	spiTransferByte(arg>>16);
	spiTransferByte(arg>>8);
	spiTransferByte(arg);
	delay_us(1);
	//spiTransferByte(0x95);	// crc valid only for MMC_GO_IDLE_STATE
	if (cmd == CMD0) spiTransferByte(0x95);			/* CRC for CMD0(0) */
	if (cmd == CMD8) spiTransferByte(0x87);			/* CRC for CMD8(0x1AA) */
	// end command
	// wait for response
	// if more than 8 retries, card has timed-out
	// return the received 0xFF
	while((r1 = spiTransferByte(0xFF)) == 0xFF)
		if(retry++ > 8) break;
	// return response
	return r1;
}