mmc.h

this code is such as a test code of interfacing microcontroller with MMC card

/*! \file mmc.h \brief MultiMedia and SD Flash Card Interface. */
//*****************************************************************************
//
// File Name	: 'mmc.h'
// Title		: MultiMedia and SD Flash Card Interface
// Author		: Pascal Stang - Copyright (C) 2004
// Created		: 2004.09.22
// Revised		: 2004.09.22
// Version		: 0.1
// Target MCU	: Atmel AVR Series
// Editor Tabs	: 4
//
///	\ingroup driver_hw
/// \defgroup mmc MultiMedia and SD Flash Card Interface (mmc.c)
/// \code #include "mmc.h" \endcode
/// \par Description
///		This library offers some simple functions which can be used
///		to read and write data on a MultiMedia or SecureDigital (SD) Flash
///		Card.  Although MM and SD Cards are designed to operate with their own
///		special bus wiring and protocols, both types of cards also provide a
///		simple SPI-like interface mode which is exceptionally useful when 
///		attempting to use the cards in embedded systems.
///
/// \par Wiring
///		To work with this library, the card must be wired to the SPI port of
///		the Atmel microcontroller as described below.  Typical cards can
///		operate at up to 25MHz maximum SPI clock rate (thus faster than most
///		AVR's maximum SPI clock rate).
/// <pre>
///	      _________________
///	     /  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
///
///	    (*) you must define this chip select I/O pin in mmcconf.h
/// </pre>
/// \note This code is currently below version 1.0, and therefore is considered
/// to be lacking in some functionality or documentation, or may not be fully
/// tested.  Nonetheless, you can expect most functions to work.
//
// This code is distributed under the GNU Public License
//		which can be found at http://www.gnu.org/licenses/gpl.txt
//
//*****************************************************************************
//@{

#ifndef MMC_H
#define MMC_H

#include "global.h"
#include <spi.h>
// 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		///< 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

//! Initialize AVR<->MMC hardware interface.
/// Prepares hardware for MMC access.
void mmcInit(void);

//! Initialize the card and prepare it for use.
/// Returns zero if successful.
u08 mmcReset(void);

//! Send card an MMC command.
/// Returns R1 result code.
u08 mmcSendCommand(u08 cmd, u32 arg);

//! Read 512-byte sector from card to buffer
/// Returns zero if successful.
u08 mmcRead(u32 sector, u08* buffer);

//! Write 512-byte sector from buffer to card
/// Returns zero if successful.
u08 mmcWrite(u32 sector, u08* buffer);

//! Internal command function.
/// Issues a generic MMC command as specified by cmd and arg.
u08 mmcCommand(u08 cmd, u32 arg);

#endif

// Functions
#define Enable_CS()   PORTB.4 = 0;
#define Disable_CS()   PORTB.4 = 1;


void mmcInit(void)
{
	// initialize SPI interface
	//spiInit();
	// release chip select
	//sbi(MMC_CS_DDR, MMC_CS_PIN);
	//sbi(MMC_CS_PORT,MMC_CS_PIN);
	Disable_CS();
}

u08 mmcReset(void)
{
	u08 i;
	u08 retry;
	u08 r1=0;

	retry = 0;
	do
	{
	          // send dummy bytes with CS high before accessing
		for(i=0;i<10;i++) spi(0xFF);
		// resetting card, go to SPI mode
		r1 = mmcSendCommand(MMC_GO_IDLE_STATE, 0);
		
		printf("MMC_GO_IDLE_STATE: R1=0x%x\r\n", r1);
		
		// do retry counter
		retry++;
		if(retry>10) return -1;
	} while(r1 != 0x01);

	// TODO: check card parameters for voltage compliance
	// before issuing initialize command

	/*retry = 0;
	do
	{
		// initializing card for operation
		r1 = mmcSendCommand(0x58,0);//MMC_SEND_OP_COND, 0);
		
		printf("MMC_SEND_OP_COND: R1=0x%x\r\n", r1);
		
		// do retry counter
		retry++;
		if(retry>100) return -1;
	} while(r1);
	  */
		
	// turn off CRC checking to simplify communication
	r1 = mmcSendCommand(MMC_CRC_ON_OFF, 0);
	
	printf("MMC_CRC_ON_OFF: R1=0x%x\r\n", r1);
	

	// set block length to 512 bytes
	r1 = mmcSendCommand(MMC_SET_BLOCKLEN, 100);
	
	printf("MMC_SET_BLOCKLEN: R1=0x%x\r\n", r1);
	
	// return success
	return 0;
}

u08 mmcSendCommand(u08 cmd, u32 arg)
{
	u08 r1;

	// assert chip select
	///////////////////////////////cbi(MMC_CS_PORT,MMC_CS_PIN);
          Enable_CS()
	
	// issue the command
	r1 = mmcCommand(cmd, arg);
	// release chip select
	///////////////////////////////sbi(MMC_CS_PORT,MMC_CS_PIN);
          Disable_CS();
	return r1;
}

u08 mmcRead(u32 sector, u08* buffer)
{
	u08 r1;
	u16 i;

	// assert chip select
	///////////////////////////////////////////////////cbi(MMC_CS_PORT,MMC_CS_PIN);
	Enable_CS()
	
	// issue command
	r1 = mmcCommand(MMC_READ_SINGLE_BLOCK, sector<<9);
	
	printf("MMC Read Block R1=0x%x\r\n", r1);
	
	// check for valid response
	if(r1 != 0x00)
		return r1;
	// wait for block start
	while(spi(0xFF) != MMC_STARTBLOCK_READ);
	// read in data
	for(i=0; i<0x200; i++)
	{
		*buffer++ = spi(0xFF);
	}
	// read 16-bit CRC
	spi(0xFF);
	spi(0xFF);
	// release chip select
	//////////////////////////////////////////////////////sbi(MMC_CS_PORT,MMC_CS_PIN);
	Disable_CS();
	// return success
	return 0;
}

u08 mmcWrite(u32 sector, u08* buffer)
{
	u08 r1;
	u16 i;

	// assert chip select
	/////////////////////////////////////////////////////cbi(MMC_CS_PORT,MMC_CS_PIN);
	Enable_CS();
	
	// issue command
	r1 = mmcCommand(MMC_WRITE_BLOCK, sector<<9);
	
	printf("MMC Write Block R1=0x%x\r\n", r1);
	
	// check for valid response
	if(r1 != 0x00)
		return r1;
	// send dummy
	spi(0xFF);
	// send data start token
	spi(MMC_STARTBLOCK_WRITE);
	// write data
	for(i=0; i<0x200; i++)
	{
		spi(*buffer++);
	}
	// write 16-bit CRC (dummy values)
	spi(0xFF);
	spi(0xFF);
	// read data response token
	r1 = spi(0xFF);
	if( (r1&MMC_DR_MASK) != MMC_DR_ACCEPT)
		return r1;
	
	printf("Data Response Token=0x%x\r\n", r1);
	
	// wait until card not busy
	while(!spi(0xFF));
	// release chip select
	//////////////////////////////////sbi(MMC_CS_PORT,MMC_CS_PIN);
	Disable_CS();
	// return success
	return 0;
}

u08 mmcCommand(u08 cmd, u32 arg)
{
	u08 r1;
	u08 retry=0;
	// send command
	spi(cmd | 0x40);
	spi(arg>>24);
	spi(arg>>16);
	spi(arg>>8);
	spi(arg);
	spi(0x95);	// crc valid only for MMC_GO_IDLE_STATE
	// end command
	// wait for response
	// if more than 8 retries, card has timed-out
	// return the received 0xFF
	while((r1 = spi(0xFF)) == 0xFF)
		if(retry++ > 8) break;
	// return response
	return r1;
}