Multi Media Card Library

The Multi Media Card (MMC) is a Flash memory card standard. MMC cards are currently available in sizes up to and including 32 GB and are used in cellular phones, digital audio players, digital cameras and PDA’s.
mikroC PRO for AVR provides a library for accessing data on Multi Media Card via SPI communication. This library also supports SD (Secure Digital) and high capacity SDHC (Secure Digital High Capacity) memory cards .

Secure Digital Card

Secure Digital (SD) is a Flash memory card standard, based on the older Multi Media Card (MMC) format.
SD cards are currently available in sizes of up to and including 2 GB, and are used in digital cameras, digital camcorders, handheld computers, media players, mobile phones, GPS receivers, video games and PDAs.

Secure Digital High Capacity Card

SDHC (Secure Digital High Capacity, SD 2.0) is an extension of the SD standard which increases card's storage capacity up to 32 GB by using sector addressing instead of byte addressing in the previous SD standard.
SDHC cards share the same physical and electrical form factor as older (SD 1.x) cards, allowing SDHC-devices to support both newer SDHC cards and older SD-cards. The current standard limits the maximum capacity of an SDHC card to 32 GB.

Important :

Routines for file handling can be used only with FAT16 file system.
Library functions create and read files from the root directory only.
Library functions populate both FAT1 and FAT2 tables when writing to files, but the file data is being read from the FAT1 table only; i.e. there is no recovery if the FAT1 table gets corrupted.
If MMC/SD card has Master Boot Record (MBR), the library will work with the first available primary (logical) partition that has non-zero size. If MMC/SD card has Volume Boot Record (i.e. there is only one logical partition and no MBRs), the library works with entire card as a single partition. For more information on MBR, physical and logical drives, primary/secondary partitions and partition tables, please consult other resources, e.g. Wikipedia and similar.
Before write operation, make sure you don’t overwrite boot or FAT sector as it could make your card on PC or digital camera unreadable. Drive mapping tools, such as Winhex, can be of a great assistance.
Library uses SPI module for communication. The user must initialize the appropriate SPI module before using the MMC Library.

The SPI module has to be initialized through SPIx_Init_Advanced routine with the following parameters:

SPI Master
Primary prescaler 64
Data sampled in the middle of data output time
Clock idle low
Serial output data changes on transition form low to high edge

Tip : Once the MMC/SD card is initialized, SPI module can be reinitialized at higher a speed. See the Mmc_Init and Mmc_Fat_Init routines.

Library Dependency Tree

External dependencies of MMC Library

The following variable must be defined in all projects using MMC library:	Description :	Example :
`extern sfr sbit Mmc_Chip_Select;`	Chip select pin.	`sbit Mmc_Chip_Select at PORTG1_bit;`
`extern sfr sbit Mmc_Chip_Select_Direction;`	Direction of the chip select pin.	`sbit Mmc_Chip_Select_Direction at DDG1_bit;`

Routines for file handling:

Mmc_Fat_Init
Mmc_Fat_QuickFormat
Mmc_Fat_Assign
Mmc_Fat_Reset
Mmc_Fat_Read
Mmc_Fat_Rewrite
Mmc_Fat_Append
Mmc_Fat_Delete
Mmc_Fat_Write
Mmc_Fat_Set_File_Date
Mmc_Fat_Get_File_Date
Mmc_Fat_Get_File_Date_Modified
Mmc_Fat_Get_File_Size
Mmc_Get_File_Write_Sector
Mmc_Fat_Get_Swap_File
Mmc_Fat_Tell
Mmc_Fat_Seek
Mmc_Fat_Rename
Mmc_Fat_MakeDir
Mmc_Fat_RenameDir
Mmc_Fat_RemoveDir
Mmc_Fat_ChangeDir
Mmc_Fat_Exists
Mmc_Fat_Dir
Mmc_Fat_ReadDir
Mmc_Fat_Activate
Mmc_Fat_ReadN
Mmc_Fat_Open
Mmc_Fat_Close
Mmc_Fat_EOF

Mmc_Init

Prototype	unsigned char Mmc_Init();
Returns	`0` - if MMC/SD card was detected and successfully initialized `1` - otherwise
Description	Initializes MMC through hardware SPI interface. Mmc_Init needs to be called before using other functions of this library.
Requires	The appropriate hardware SPI module must be previously initialized. Global variables : `Mmc_Chip_Select`: Chip Select line `Mmc_Chip_Select_Direction`: Direction of the Chip Select pin must be defined before using this function. The appropriate hardware SPI module must be previously initialized. See the SPI1_Init, SPI1_Init_Advanced routines.
Example	// MMC module connections sfr sbit Mmc_Chip_Select at PORTG1_bit; sfr sbit Mmc_Chip_Select_Direction at DDG1_bit; // MMC module connections SPI1_Init_Advanced(_SPI_MASTER, _SPI_FCY_DIV2, _SPI_CLK_LO_LEADING); error = Mmc_Init(); // Init with CS line at PORTG1

Mmc_Read_Sector

Prototype	unsigned char Mmc_Read_Sector(unsigned long sector, char *dbuff);
Returns	`0` - if reading was successful `1` - if an error occurred
Description	The function reads one sector (512 bytes) from MMC card. Parameters: `sector:` MMC/SD card sector to be read. `dbuff:` buffer of minimum 512 bytes in length for data storage.
Requires	MMC/SD card must be initialized. See Mmc_Init.
Example	// read sector 510 of the MMC/SD card unsigned int error; unsigned long sectorNo = 510; char dataBuffer[512]; ... error = Mmc_Read_Sector(sectorNo, dataBuffer);

Mmc_Write_Sector

Prototype	unsigned char Mmc_Write_Sector(unsigned long sector, char *dbuff);
Returns	`0` - if writing was successful `1` - if there was an error in sending write command `2` - if there was an error in writing (data rejected)
Description	The function writes 512 bytes of data to one MMC card sector. Parameters: `sector:` MMC/SD card sector to be written to. `dbuff:` data to be written (buffer of minimum 512 bytes in length).
Requires	MMC/SD card must be initialized. See Mmc_Init.
Example	// write to sector 510 of the MMC/SD card unsigned int error; unsigned long sectorNo = 510; char dataBuffer[512]; ... error = Mmc_Write_Sector(sectorNo, dataBuffer);

Mmc_Read_Cid

Prototype	unsigned char Mmc_Read_Cid(char *data_cid);
Returns	`0` - if CID register was read successfully `1` - if there was an error while reading
Description	The function reads 16-byte CID register. Parameters: `data_cid:` buffer of minimum 16 bytes in length for storing CID register content.
Requires	MMC/SD card must be initialized. See Mmc_Init.
Example	unsigned int error; char dataBuffer[16]; ... error = Mmc_Read_Cid(dataBuffer);

Mmc_Read_Csd

Prototype	unsigned char Mmc_Read_Csd(char *data_csd);
Returns	`0` - if CSD register was read successfully `1` - if there was an error while reading
Description	The function reads 16-byte CSD register. Parameters: `data_csd:` buffer of minimum 16 bytes in length for storing CSD register content.
Requires	MMC/SD card must be initialized. See Mmc_Init.
Example	unsigned int error; char dataBuffer[16]; ... error = Mmc_Read_Csd(dataBuffer);

Mmc_Multi_Read_Start

Prototype	unsigned int Mmc_Multi_Read_Start(unsigned long sector);
Description	The function starts multi read mode, sectors are sequentially read starting from the sector given in the function argument.
Parameters	`sector:` starting sector number.
Returns	`0` - if multi read start was successful. `1` - ir error occured.
Requires	MMC/SD card must be initialized. See Mmc_Init.
Example	unsigned int error; char sector; ... error = Mmc_Multi_Read_Start(sector);
Notes	None.

Mmc_Multi_Read_Sector

Prototype	void Mmc_Multi_Read_Sector(char *dbuff);
Description	The function reads sectors in multi read mode and places them in the buffer given as the function argument. Next function call reads the subsequent sector. Buffer size should be 512B.
Parameters	`dbuff:` buffer for holding the sector data.
Returns	Nothing.
Requires	MMC/SD card must be initialized. See Mmc_Init.
Example	unsigned int error; ... Mmc_Multi_Read_Sector(buffer);
Notes	None.

Mmc_Multi_Read_Stop

Prototype	unsigned int Mmc_Multi_Read_Stop();
Description	The function stops multi read mode sequence.
Parameters	None.
Returns	`0` - if stop was successful. `1` - ir error was detected.
Requires	MMC/SD card must be initialized. See Mmc_Init.
Example	Mmc_Multi_Read_Stop;
Notes	None.

Mmc_Fat_Init

Prototype	unsigned short Mmc_Fat_Init();
Returns	`0` - if MMC/SD card was detected and successfully initialized `1` - if FAT16 boot sector was not found `255` - if MMC/SD card was not detected
Description	Initializes MMC/SD card, reads MMC/SD FAT16 boot sector and extracts necessary data needed by the library. Note : MMC/SD card has to be formatted to FAT16 file system.
Requires	Global variables : `Mmc_Chip_Select`: Chip Select line `Mmc_Chip_Select_Direction`: Direction of the Chip Select pin must be defined before using this function. The appropriate hardware SPI module must be previously initialized. See the SPI1_Init, SPI1_Init_Advanced routines.
Example	// MMC module connections sfr sbit Mmc_Chip_Select at PORTG_bit1; sfr sbit Mmc_Chip_Select_Direction at DDG1_bit; // MMC module connections // Initialize SPI1 module SPI1_Init_Advanced(_SPI_MASTER, _SPI_FCY_DIV128, _SPI_CLK_LO_LEADING); // use fat16 quick format instead of init routine if a formatting is needed if (!Mmc_Fat_Init()) { // reinitialize SPI1 at higher speed SPI1_Init_Advanced(_SPI_MASTER, _SPI_FCY_DIV2, _SPI_CLK_LO_LEADING); ... }

Mmc_Fat_QuickFormat

Prototype	unsigned char Mmc_Fat_QuickFormat(char *mmc_fat_label);
Returns	`0` - if MMC/SD card was detected, successfully formated and initialized `1` - if FAT16 format was unsuccessful `255` - if MMC/SD card was not detected
Description	Formats to FAT16 and initializes MMC/SD card. Parameters: `mmc_fat_label:` volume label (11 characters in length). If less than 11 characters are provided, the label will be padded with spaces. If null string is passed volume will not be labeled Note : This routine can be used instead or in conjunction with Mmc_Fat_Init routine. If MMC/SD card already contains a valid boot sector, it will remain unchanged (except volume label field) and only FAT and ROOT tables will be erased. Also, the new volume label will be set.
Requires	The appropriate hardware SPI module must be previously initialized.
Example	// Format and initialize MMC/SD card and MMC_FAT16 library globals if (!Mmc_Fat_QuickFormat(&mmc_fat_label)) { ... }

Mmc_Fat_Assign

Prototype

unsigned short Mmc_Fat_Assign(char *filename, char file_cre_attr);

Returns

2 - if there are no more free file handlers, currently opened file is closed in order to free space.
1 - if file already exists or file does not exist but a new file is created.
0 - if file does not exist and no new file is created.

Description

Assigns file for file operations (read, write, delete...). All subsequent file operations will be applied on an assigned file.

Parameters:

filename: name of the file that should be assigned for file operations. File name should be in DOS 8.3 (file_name.extension) format. The file name and extension will be automatically padded with spaces by the library if they have less than length required (i.e. "mikro.tx" -> "mikro .tx "), so the user does not have to take care of that. The file name and extension are case insensitive. The library will convert them to proper case automatically, so the user does not have to take care of that.
file_cre_attr: file creation and attributs flags. Each bit corresponds to the appropriate file attribut:

Bit Mask Description

0 0x01 Read Only

1 0x02 Hidden

2 0x04 System

3 0x08 Volume Label

4 0x10 Subdirectory

5 0x20 Archive

6 0x40 Device (internal use only, never found on disk)

7 0x80 File creation flag. If file does not exist and this flag is set, a new file with specified name will be created.

Note : Long File Names (LFN) are not supported.

Requires

MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init.

Example

// create file with archive attribute if it does not already exist
Mmc_Fat_Assign("MIKRO007.TXT",0xA0);

Mmc_Fat_Reset

Prototype	void Mmc_Fat_Reset(unsigned long *size);
Returns	Nothing.
Description	Procedure resets the file pointer (moves it to the start of the file) of the assigned file, so that the file can be read. Parameters: `size:` buffer to store file size to. After file has been open for reading, its size is returned through this parameter.
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init. The file must be previously assigned. See Mmc_Fat_Assign.
Example	unsigned long size; ... Mmc_Fat_Reset(&size);

Mmc_Fat_Read

Prototype	void Mmc_Fat_Read(unsigned short *bdata);
Returns	Nothing.
Description	Reads a byte from the currently assigned file opened for reading. Upon function execution, file pointers will be set to the next character in the file. Parameters: `bdata:` buffer to store read byte to. Upon this function execution read byte is returned through this parameter.
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init. The file must be previously assigned. See Mmc_Fat_Assign. The file must be opened for reading. See Mmc_Fat_Reset.
Example	char character; ... Mmc_Fat_Read(&character);

Mmc_Fat_Rewrite

Prototype	void Mmc_Fat_Rewrite();
Returns	Nothing.
Description	Opens the currently assigned file for writing. If the file is not empty its content will be erased.
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init. The file must be previously assigned. See Mmc_Fat_Assign.
Example	// open file for writing Mmc_Fat_Rewrite();

Mmc_Fat_Append

Prototype	void Mmc_Fat_Append();
Returns	Nothing.
Description	Opens the currently assigned file for appending. Upon this function execution file pointers will be positioned after the last byte in the file, so any subsequent file writing operation will start from there.
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init. The file must be previously assigned. See Mmc_Fat_Assign.
Example	// open file for appending Mmc_Fat_Append();

Mmc_Fat_Delete

Prototype	char Mmc_Fat_Delete();
Returns	`1` - if there are no assigned files `2` - if an error occured during deleting `0` - if deleting was successful
Description	Deletes currently assigned file from MMC/SD card.
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init. The file must be previously assigned. See Mmc_Fat_Assign.
Example	// delete current file if (Mmc_Fat_Delete() == 0) ...

Mmc_Fat_Write

Prototype	void Mmc_Fat_Write(char fdata, unsigned* data_len);
Returns	Nothing.
Description	Writes requested number of bytes to the currently assigned file opened for writing. Parameters: `fdata:` data to be written. `data_len:` number of bytes to be written.
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init. The file must be previously assigned. See Mmc_Fat_Assign. The file must be opened for writing. See Mmc_Fat_Rewrite or Mmc_Fat_Append.
Example	Mmc_Fat_Write(txt,255); Mmc_Fat_Write("Hello world",255);

Mmc_Fat_Set_File_Date

Prototype	void Mmc_Fat_Set_File_Date(unsigned int year, unsigned short month, unsigned short day, unsigned short hours, unsigned short mins, unsigned short seconds);
Returns	Nothing.
Description	Sets the date/time stamp. Any subsequent file writing operation will write this stamp to the currently assigned file's time/date attributs. Parameters: `year:` year attribute. Valid values: 1980-2107 `month:` month attribute. Valid values: 1-12 `day:` day attribute. Valid values: 1-31 `hours:` hours attribute. Valid values: 0-23 `mins:` minutes attribute. Valid values: 0-59 `seconds:` seconds attribute. Valid values: 0-59
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init. The file must be previously assigned. See Mmc_Fat_Assign. The file must be opened for writing. See Mmc_Fat_Rewrite or Mmc_Fat_Append.
Example	// April 1st 2005, 18:07:00 Mmc_Fat_Set_File_Date(2005, 4, 1, 18, 7, 0);

Mmc_Fat_Get_File_Date

Prototype	void Mmc_Fat_Get_File_Date(unsigned int year, unsigned short* month, unsigned short* day, unsigned short* hours, unsigned short* *mins);
Returns	Nothing.
Description	Reads time/date attributes of the currently assigned file. Parameters: `year:` buffer to store year attribute to. Upon function execution year attribute is returned through this parameter. `month:` buffer to store month attribute to. Upon function execution month attribute is returned through this parameter. `day:` buffer to store day attribute to. Upon function execution day attribute is returned through this parameter. `hours:` buffer to store hours attribute to. Upon function execution hours attribute is returned through this parameter. `mins:` buffer to store minutes attribute to. Upon function execution minutes attribute is returned through this parameter.
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init. The file must be previously assigned. See Mmc_Fat_Assign.
Example	// get Date/time of file unsigned yr; char mnth, dat, hrs, mins; ... file_Name = "MYFILEABTXT"; Mmc_Fat_Assign(file_Name); Mmc_Fat_Get_File_Date(&yr, &mnth, &day, &hrs, &mins);

Mmc_Fat_Get_File_Date_Modified

Prototype	void Mmc_Fat_Get_File_Date_Modified(unsigned int year, unsigned short* month, unsigned short* day, unsigned short* hours, unsigned short* *mins);
Returns	Nothing.
Description	Retrieves the last modification date/time for the currently selected file. Parameters: `year:` buffer to store year of modification attribute to. Upon function execution year of modification attribute is returned through this parameter. `month:` buffer to store month of modification attribute to. Upon function execution month of modification attribute is returned through this parameter. `day:` buffer to store day of modification attribute to. Upon function execution day of modification attribute is returned through this parameter. `hours:` buffer to store hours of modification attribute to. Upon function execution hours of modification attribute is returned through this parameter. `mins:` buffer to store minutes of modification attribute to. Upon function execution minutes of modification attribute is returned through this parameter.
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init. The file must be previously assigned. See Mmc_Fat_Assign.
Example	// get modification Date/time of file unsigned yr; char mnth, dat, hrs, mins; ... file_Name = "MYFILEABTXT"; Mmc_Fat_Assign(file_Name); Mmc_Fat_Get_File_Date_Modified(&yr, &mnth, &day, &hrs, &mins);

Mmc_Fat_Get_File_Size

Prototype	unsigned long Mmc_Fat_Get_File_Size();
Returns	This function returns size of active file (in bytes).
Description	This function reads size of the currently assigned file in bytes.
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init. The file must be previously assigned. See Mmc_Fat_Assign.
Example	// get Date/time of file unsigned yr; char mnth, dat, hrs, mins; ... file_name = "MYFILEXXTXT"; Mmc_Fat_Assign(file_name); mmc_size = Mmc_Fat_Get_File_Size;

Mmc_Get_File_Write_Sector

Prototype	unsigned long Mmc_Get_File_Write_Sector();
Description	This function returns the current file write sector.
Parameters	None.
Returns	This function returns the current file write sector.
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init. The file must be previously assigned. See Mmc_Fat_Assign.
Example	unsigned long sector; ... sector = Mmc_Get_File_Write_Sector();
Notes	None.

Mmc_Fat_Get_Swap_File

Prototype

unsigned long Mmc_Fat_Get_Swap_File(unsigned long sectors_cnt, char* filename, char file_attr);

Returns

Number of the start sector for the newly created swap file, if there was enough free space on the MMC/SD card to create file of required size.
0 - otherwise.

Description

This function is used to create a swap file of predefined name and size on the MMC/SD media. If a file with specified name already exists on the media, search for consecutive sectors will ignore sectors occupied by this file. Therefore, it is recommended to erase such file if it already exists before calling this function. If it is not erased and there is still enough space for a new swap file, this function will delete it after allocating new memory space for a new swap file.

The purpose of the swap file is to make reading and writing to MMC/SD media as fast as possible, by using the Mmc_Read_Sector() and Mmc_Write_Sector() functions directly, without potentially damaging the FAT system. The swap file can be considered as a "window" on the media where the user can freely write/read data. Its main purpose in the library is to be used for fast data acquisition; when the time-critical acquisition has finished, the data can be re-written into a "normal" file, and formatted in the most suitable way.

Parameters:

sectors_cnt: number of consecutive sectors that user wants the swap file to have.
filename: name of the file that should be assigned for file operations. File name should be in DOS 8.3 (file_name.extension) format. The file name and extension will be automatically padded with spaces by the library if they have less than length required (i.e. "mikro.tx" -> "mikro .tx "), so the user does not have to take care of that. The file name and extension are case insensitive. The library will convert them to proper case automatically, so the user does not have to take care of that.
Also, in order to keep backward compatibility with the first version of this library, file names can be entered as UPPERCASE string of 11 bytes in length with no dot character between file name and extension (i.e. "MIKROELETXT" -> MIKROELE.TXT). In this case the last 3 characters of the string are considered to be file extension.
file_attr: file creation and attributs flags. Each bit corresponds to the appropriate file attribut:

Note : Long File Names (LFN) are not supported.

Requires

MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init.

Example

//-------------- Tries to create a swap file, whose size will be at least 100 sectors.
//If it succeeds, it sends the No. of start sector over UART
void M_Create_Swap_File(){
  size = Mmc_Fat_Get_Swap_File(100);
  if (size <> 0) {
    UART1_Write(0xAA);
    UART1_Write(Lo(size));
    UART1_Write(Hi(size));
    UART1_Write(Higher(size));
    UART1_Write(Highest(size));
    UART1_Write(0xAA);
  } 
}

Mmc_Fat_Tell

Prototype	unsigned long Mmc_Fat_Tell();
Description	This routine is used to retrieve the cursor position within an opened file.
Parameters	None.
Returns	Returns the cursor position in currently assigned file.
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init. The file must be previously assigned. See Mmc_Fat_Assign.
Example	unsigned long position; position = Mmc_Fat_Tell();
Notes	None.

Mmc_Fat_Seek

Prototype	unsigned long Mmc_Fat_Seek(unsigned long position);
Description	This routine is used to set the cursor position within an opened file and returns the cursor's new position within an opened file.
Parameters	`position:` desired position on which we want to place the cursor.
Returns	Returns the cursor's new position in currently assigned file.
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init. The file must be previously assigned. See Mmc_Fat_Assign.
Example	unsigned long position; position = Mmc_Fat_Seek(1000);
Notes	If the desired cursor position exceeds file size, the cursor will be placed at the end of the file.

Mmc_Fat_Rename

Prototype	char Mmc_Fat_Rename(char *newname);
Description	This function renames the currently assigned file.
Parameters	`newname:` new file name.
Returns	`1` - if there are no assigned files `2` - if the new name in invalied `3` - if the file with the new name already exists `4` - if an error occurred during renaming `0` - if renaming was successful
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init. The file must be previously assigned. See Mmc_Fat_Assign.
Example	if (0 == Mmc_Fat_Rename("NEWNAME.TXT")) { // if rename operation was successful... ... }
Notes	None.

Mmc_Fat_MakeDir

Prototype

char Mmc_Fat_MakeDir(char *name, char attrib);

Description

This function creates a new directory.

Parameters

name: directory name.
attrib: directory creation and attributs flags. Each bit corresponds to the appropriate directory attribute :

Bit Mask Description

0 0x01 Read Only

1 0x02 Hidden

2 0x04 System

3 0x08 Volume Label

4 0x10 Subdirectory

5 0x20 Archive

6 0x40 Device (internal use only, never found on disk)

7 0x80 Directory creation flag. If directory does not exist and this flag is set, a new directory with specified name will be created.

Returns

0 - directory creation was successful
255 - if an error occurred

Requires

MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init.

Example

if (0 == Mmc_Fat_MakeDir("DIR_A", 0xA0)) {  // create DIR_A directory
  ...
}

Notes

None.

Mmc_Fat_RenameDir

Prototype	char Mmc_Fat_RenameDir(char oldname, char* *newname);
Description	This function renames a directory.
Parameters	`oldname:` old directory name. `newname:` new directory name.
Returns	`1` - if directory name is invalid `2` - if there is no directry with the old name `3` - if an entry with the new name already exits `4` - if an error occurred during renaming `0` - if renaming was successful
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init.
Example	if (0 == Mmc_Fat_RenameDir("DIR_A", "DIR_B")) { // if rename operation was successful... ... }
Notes	None.

Mmc_Fat_RemoveDir

Prototype	char Mmc_Fat_RemoveDir(char *name);
Description	This function removes directory entry from current directory.
Parameters	`name:` directory name.
Returns	`1` - if directory name is invalid `2` - if directory name is non-existant `3` - if directory is not empty `4` - if an error occurred while writing `0` - if operation was successful
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init.
Example	if (0 == Mmc_Fat_RemoveDir("DIR_A")) { // if removing operation was successful... ... }
Notes	Recursive removing is not supported, i.e. the directory must be empty before it can be removed.

Mmc_Fat_ChangeDir

Prototype	char Mmc_Fat_ChangeDir(char *name);
Description	This function changes the current directory to `name`.
Parameters	`name:` directory name.
Returns	`0` - if operation was successful `1` - if there is no entry with given directory name `2` - if an entry with the given name is not a directory
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init.
Example	// enter DIR_A directory if (0 == Mmc_Fat_ChangeDir("DIR_A")) { ... } // go to parent directory if (0 == Mmc_Fat_ChangeDir("..")) { ... } // go to root directory if (0 == Mmc_Fat_ChangeDir("\\")) { ... }
Notes	Special directory names like "`.`" and "`..`" are also supported.

Mmc_Fat_Exists

Prototype	char Mmc_Fat_Exists(char *name);
Description	This function returns information on file/directory existence.
Parameters	`name:` file/directory name.
Returns	`0` - if file/directory doesn't exist `1` - if file/directory exists
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init.
Example	status = Mmc_Fat_Exists("X_FILES.TXT"); if (1 == status) { ... } // if the file was found... else if (0 == status) { ... } // or if the file was not found... else { ... } // or if there was an error during function call, // which needs to be handled separately.
Notes	None.

Mmc_Fat_Dir

Prototype	char Mmc_Fat_Dir(void (print)(char* ch))
Description	This routine displays contents of the current directory via user-defined medium (i.e. UART module, a file on FAT16 file system). The function displays character by character.
Parameters	`ch:` function pointer to a routine which will display contents of the current directory.
Returns	`1` - if file nema is invalid `2` - if file already exists `3` - if error occured while writing `0` - if operation was successful
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init.
Example	// Displaying routine void PrintChar(char ch) { UART1_Write(ch); } ... Mmc_Fat_Dir(PrintChar);
Notes	None.

Mmc_Fat_ReadDir

Prototype	static short Mmc_Fat_ReadDir(DIR *d);
Description	This function gets next directory entry from current directory.
Parameters	`d:` directory entry (valid if return value equals 1), consisted of the following fields : Copy Code To Clipboard typedef struct { unsigned char name[13]; // directory name unsigned char attrib; // directory attribute unsigned char ctime[6]; // create time and date unsigned char mtime[6]; // modification time and date unsigned long size; // directory size unsigned int first; // directory start cluster unsigned long sect; // directory entry sector unsigned int entry; // derectory entry number in the entry sector } DIR;
Returns	`< 0` - if an error occurred `0` - if no more entries `1` - if a valid entry is returned
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init.
Example	if (1 == Mmc_Fat_ReadDir("DIR_A")) { ... }
Notes	None.

Mmc_Fat_Activate

Prototype	char Mmc_Fat_Activate(short fileHandle);
Description	This function selects active file of currently opened files.
Parameters	`fileHandle:` file handle of the file which need to be activated.
Returns	`0` - if activation was successful `1` - if file handle is out of scope `2` - if file handle is empty
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init.
Example	short fhandle; fhandle = Mmc_Fat_Open("X_FILES.TXT", FILE_READ, 0x01); if (Mmc_Fat_Activate(fhandle)) == 0) { }
Notes	Use Mmc_Fat_Open function to get file handles.

Mmc_Fat_ReadN

Prototype	unsigned int Mmc_Fat_ReadN(char fdata, unsigned int* n);
Description	This function reads multiple bytes.
Parameters	`fdata:` data buffer. `n:` number of bytes to read.
Returns	Number of read bytes.
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init.
Example	char data_buffer[512]; unsigned int no_bytes; ... no_bytes = Mmc_Fat_ReadN(&data_buffer, 500);
Notes	None.

Mmc_Fat_Open

Prototype

short Mmc_Fat_Open(unsigned char *name, unsigned short mode, char attrib);

Description

This function opens a new file.

Parameters

name: file name.
mode: file handling mode, FILE_WRITE, FILE_READ or FILE_APPEND.
attrib: file creation and attributes flags. Each bit corresponds to the appropriate file attribute :

Returns

< 0 - if an error occurred
file handle for opened file otherwise

Requires

MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init.

Example

short fhandle;

fhandle = Mmc_Fat_Open("X_FILES.TXT", FILE_READ, 0x01);

Notes

None.

Mmc_Fat_Close

Prototype	char Mmc_Fat_Close();
Description	This function closes currently opened file.
Parameters	None.
Returns	`0` - if closing was successful `1` - if there are no assigned files
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init.
Example	if (Mmc_Fat_Close() == 0) { }
Notes	None.

Mmc_Fat_EOF

Prototype	short Mmc_Fat_EOF();
Description	This function check if the end of file is reached.
Parameters	None.
Returns	`-1` - if an error occurred `0` - if end of file was not reached `1` - if end of file was reached
Requires	MMC/SD card and MMC library must be initialized for file operations. See Mmc_Fat_Init.
Example	if (Mmc_Fat_EOF() == 0) { }
Notes	None.

Library Example

The following example demonstrates usage of the MMC and MMC_FAT routines.

Copy Code To Clipboard

// MMC module connections
sbit Mmc_Chip_Select at PORTG1_bit;
sbit Mmc_Chip_Select_Direction at DDG1_bit;
// eof MMC module connections

// Variables for MMC routines
unsigned char SectorData[512];             // Buffer for MMC sector reading/writing
unsigned char data_for_registers[16];      // buffer for CID and CSD registers

// UART1 write text and new line (carriage return + line feed)
void UART1_Write_Line(char *uart_text) {
  UART1_Write_Text(uart_text);
  UART1_Write(13);
  UART1_Write(10);
}

// Display byte in hex
void PrintHex(unsigned char i) {
  unsigned char hi,lo;
  
  hi = i & 0xF0;                           // High nibble
  hi = hi >> 4;
  hi = hi + '0';
  if (hi>'9') hi=hi+7;
  lo = (i & 0x0F) + '0';                   // Low nibble
  if (lo>'9') lo=lo+7;
  
  UART1_Write(hi);
  UART1_Write(lo);
}

void main() {

  const char   FILL_CHAR = 'm';
  unsigned int i, SectorNo;
  char         mmc_error;
  bit          data_ok;

  // Initialize UART1 module
  UART1_Init(19200);
  Delay_ms(10);

  UART1_Write_Line("MCU-Started");         // MCU present report

  // Initialize SPI1 module
  SPI1_Init_Advanced(_SPI_MASTER, _SPI_FCY_DIV2, _SPI_CLK_LO_LEADING);

  // initialise a MMC card
  mmc_error = Mmc_Init();
  if(mmc_error == 0)
    UART1_Write_Line("MMC Init-OK");       // If MMC present report
  else
    UART1_Write_Line("MMC Init-error");    // If error report

  // Fill MMC buffer with same characters
  for(i=0; i<=511; i++)
    SectorData[i] = FILL_CHAR;

  // Choose sector
  SectorNo = 590;

  // Write sector
  mmc_error = Mmc_Write_Sector(SectorNo, SectorData);
  if(mmc_error == 0)
    UART1_Write_Line("Write-OK");
  else  // if there are errors.....
    UART1_Write_Line("Write-Error");

  // Reading of CID register
  mmc_error = Mmc_Read_Cid(data_for_registers);
  if(mmc_error == 0) {
    UART1_Write_Text("CID : ");
    for(i=0; i<=15; i++)
      PrintHex(data_for_registers[i]);
    UART1_Write_Line("");
  }
  else
    UART1_Write_Line("CID-error");

  // Reading of CSD register
  mmc_error = Mmc_Read_Csd(data_for_registers);
  if(mmc_error == 0) {
    UART1_Write_Text("CSD : ");
    for(i=0; i<=15; i++)
      PrintHex(data_for_registers[i]);
    UART1_Write_Line("");
  }
  else
    UART1_Write_Line("CSD-error");

  // Read sector
  mmc_error = Mmc_Read_Sector(SectorNo, SectorData);
  if(mmc_error == 0) {
    UART1_Write_Line("Read-OK");
    // Chech data match
    data_ok = 1;
    for(i=0; i<=511; i++) {
      UART1_Write(SectorData[i]);
      if (SectorData[i] != FILL_CHAR) {
        data_ok = 0;
        break;
      }
    }
    UART1_Write_Line("");
    if (data_ok)
      UART1_Write_Line("Content-OK");
    else
      UART1_Write_Line("Content-Error");
  }
  else  // if there are errors.....
    UART1_Write_Line("Read-Error");

  // Signal test end
  UART1_Write_Line("Test End.");
}

HW Connection

MMC interface

MMC back view

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