SD-card

Necessary knowledge: [HW] Controller module

This section of library contains functions for using HomeLab SD-card.

• static FATFS FATFS_Obj - FATFS_Obj is FATFS data structure instance. Consists of drive identificators.

• FIL fil_obj - File system data structure where to store file identificators.

• DSTATUS - Return codes for drive related functions.
  • RES_OK - (0) Procedure successful.
  • RES_ERROR - (1) R/W error.
  • RES_WRPRT - (2) Write protected.
  • RES_NOTRDY - (3) Drive not ready.
  • RES_PARERR - (4) Some parameters are false.

• FRESULT - Most important codes that are returned from file related functions.
  • FR_OK - (0) Procedure successful.
  • FR_DISK_ERR - (1) Drive I/O layer error
  • FR_INT_ERR - (2) General drive error
  • FR_NOT_READY - (3) Drive not ready for procedure.
  • FR_NO_FILE - (4) File not found.
  • FR_NO_PATH - (5) Address not found.
  • FR_INVALID_NAME - (6) Wrong file name format.
  • FR_DENIED - (7) Drive is full.
  • FR_EXIST - (8) Access is denied.
  • FR_INVALID_OBJECT - (9) File or folder object error.
  • FR_WRITE_PROTECTED - (10) Drive is write protected.
  • FR_INVALID_DRIVE - (11) Drive number is false.
  • FR_NO_FILESYSTEM - (13) Supported FAT file system not found.
  • FR_TIMEOUT - (15) Connection with drive failed.
  • FR_INVALID_PARAMETER - (19) Some parameters are false.

• ModeFlags - Possible modes to open files.
  • FA_READ - File open in read mode.
  • FA_WRITE - File open in write mode.
  • FA_OPEN_EXISTING - Opens file. If it does not exists then returns error code.
  • FA_OPEN_ALWAYS - Opens file. If it does not exists then creates it.
  • FA_CREATE_NEW - Creates new file. If files is already present, error code will be returned.
  • FA_CREATE_ALWAYS - Creates new file. If files is already present then overwrites it.

• DSTATUS disk_initialize (BYTE drv)
  

Initializes drive. Parameters:

• drv - Drive number. In most cases 0.
• Returns DSTATUS code.

• DSTATUS disk_status (BYTE drv)
  

Displays drive status. Parameters:

• drv - Drive number. In most cases 0.
• Returns DSTATUS code.

• FRESULT f_mount (BYTE Drive, FATFS* FileSystemObject)
  

Initializes file system. Parameters:

• Drive - Drive number. In most cases 0.
• FileSystemObject - File system object pointer.
• Returns FRESULT code.

• FRESULT f_open (FIL* FileObject, const TCHAR* FileName, BYTE ModeFlags)
  

Opens or creates file. Parameters:

• FileObject - File system object pointer.
• FileName - File name.
• ModeFlags - Open mode flag.
• Returns FRESULT code.

• FRESULT f_close (FIL* FileObject)
  

Closes file. Parameters:

• FileObject - File system object pointer.
• Returns FRESULT code.

• FRESULT f_read (FIL* FileObject, void* Buffer, UINT ByteToRead, UINT* ByteRead)
  

Reads required amount of bytes from file. Parameters:

• FileObject - File object pointer.
• Buffer - Buffer pointer where to store data.
• ByteToRead - Number of files to be read.
• ByteRead - Variable pointer where read bytes are returned.
• Returns FRESULT code.

• FRESULT f_write (FIL* FileObject, const void* Buffer, UINT ByteToWrite, UINT* ByteWritten)
  

Writes required amount of bytes to file. Parameters:

• FileObject - Point to file object.
• Buffer - Point to data being written into file.
• ByteToWrite - Number of bytes to be written.
• ByteWritten - Point to variable where written bytes are returned.
• Returns FRESULT code.

• FRESULT f_sync (FIL* FileObject)
  

Writes data from buffers to a file to save them from power loss. Used in applications where a file is open for a long time. Parameters:

• FileObject - Point to file object.
• Returns FRESULT code.

• FRESULT f_mkdir (const TCHAR* DirName)
  

Creates folder. Parameters:

• DirName - Folder name.
• Returns FRESULT code.

• FRESULT f_unlink (const TCHAR* FileName)
  

Deletes file or folder. Parameters:

• FileName - Object name.
• Returns FRESULT code.

• FRESULT f_rename (const TCHAR* OldName, const TCHAR* NewName)
  

Rename file or folder. Parameters:

• OldName - Object old name.
• NewName - Object new name.
• Returns FRESULT code.

• TCHAR* f_gets (TCHAR* Str, int Size, FIL* FileObject)
  

Reads string with given length from file. Parameters:

• Str - Buffer where to save read data.
• Size - Length of string.
• FileObject - Point to file object.
• Returns Str buffer if successful.

• int f_putc (TCHAR Chr, FIL* FileObject)
  

Adds a char to file. Parameters:

• Chr - Char to be added into file.
• FileObject - File object pointer .
• Returns 1 if successful.

• int f_printf (FIL* FileObject, const TCHAR* Foramt, …)
  

Adds a formated string to file. Parameters:

• FileObject - File object pointer.
• Foramt - String format.
• …
• Returns the number of written chars if successful.

• DWORD f_tell (FIL* FileObject)
  

Cursor position in file. Parameters:

• FileObject - File object pointer.
• Returns read/write cursor position in file as a pointer.

• FRESULT f_lseek (FIL* FileObject,DWORD Offset)
  

Move cursor to desired position in file. Parameters:

• FileObject - File object pointer.
• Offset - Desired position in bytes from the beginning of the file.
• Returns FRESULT code.

#include <stdio.h>
#include <homelab/module/ff.h>
#include <homelab/module/diskio.h>
 
int main (void)
{
    static FATFS FATFS_Obj;
    FIL fil_obj;
 
	// SD card initialization. 
	disk_initialize(0);
 
	// File system initialization. 
	f_mount(0, &FATFS_Obj);
 
	// Create text file "file.txt".
	f_open(&fil_obj, "/file.txt", FA_CREATE_NEW);
 
	// File to be open for writing.
	f_open(&fil_obj, "/file.txt", FA_WRITE);
 
	// Writing into file.
	f_printf(&fil_obj, "SD Card test");
 
 	// Close file.
	f_close(&fil_obj);	
}