Table of Contents

SD-card

Necessary knowledge: [HW] Controller module

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

Data types

  • 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.

Functions

  • 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.

 

Example

#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);	
}
en/software/homelab/library/module/sdcard.txt · Last modified: 2018/12/27 12:53 (external edit)
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