Editing MMC Card Reader Development

This wiki describes the development of the [[MMC Card Reader]] Project

==Architecture==
*See [[Multi-purpose_Embedded_System#File_System | here]] for block diagram


==Development Roadmap==
===Phase 1===
*Create stdio.h wrapper for file system in freertos_posix
*Use existing I2C EEPROM driver for development
===Phase 2===
*Circuit design for interfacing MMC
===Phase 3===
*SPI driver for MMC
===Phase 4===
*Test for normal read/write function
*hotswap (should not hang or cause voltage dip)
*multiple file read/write (protection)


==Circuit and PCB==
*[http://multimedia.3m.com/mws/mediawebserver?66666UuZjcFSLXTtmXftMXMXEVuQEcuZgVs6EVs6E666666-- SD Card connector]
*SPI interface to main board


==Software Implementation==
*Use [http://elm-chan.org/fsw/ff/00index_e.html FatFs] for accessing FAT16 file system. 
*Create a stdio.h wrapper for [http://chungyan5.no-ip.org/vc/?root=freertos_posix freertos_posix]

===Comparison of FatFs and stdio API===
*selected list is described below
{| border="1" cellspacing="0" cellpadding="5"
|+ Comparison between FatFs and stdio API
! Function !! stdio.h !! FatFs !! Remarks
|- 
| Open
| 
  FILE * 
[http://www.cplusplus.com/reference/clibrary/cstdio/fopen/ fopen] ( 
  const char * filename, 
  const char * mode
  
);
| 
  FRESULT 
[http://elm-chan.org/fsw/ff/en/open.html f_open] (
  FIL* FileObject,       /* Pointer to the blank file object structure */
  const XCHAR* FileName, /* Pointer to the file neme */
  BYTE ModeFlags         /* Mode flags */
);
| 
*'''FILE''' matches '''FIL'''
*'''filename''' matches '''FileName'''
*'''mode''' matches '''ModeFlags'''
*stdio.h has no equivalent '''FRESULT'''
|-
| Read 
| 
  size_t 
[http://www.cplusplus.com/reference/clibrary/cstdio/fread/ fread] ( 
  void * ptr, 
  size_t size, 
  size_t count, 
  FILE * stream 
);
|
  FRESULT 
[http://elm-chan.org/fsw/ff/en/read.html f_read] (
  FIL* FileObject,    /* Pointer to the file object structure */
  void* Buffer,       /* Pointer to the buffer to store read data */
  UINT ByteToRead,    /* Number of bytes to read */
  UINT* ByteRead      /* Pointer to the variable to return number of bytes read */
);
|
*'''size_t''' matches '''ByteRead'''
*'''ptr''' matches '''Buffer'''
*'''count''' matches '''ByteToRead'''
*'''stream''' matches '''FileObject'''
*stdio.h has no equivalent '''FRESULT'''
|-
| Write
|
  size_t 
[http://www.cplusplus.com/reference/clibrary/cstdio/fwrite/ fwrite] ( 
  const void * ptr, 
  size_t size, 
  size_t count, 
  FILE * stream 
);
| 
  FRESULT 
[http://elm-chan.org/fsw/ff/en/write.html f_write] (
  FIL* FileObject,     /* Pointer to the file object structure */
  const void* Buffer,  /* Pointer to the data to be written */
  UINT ByteToWrite,    /* Number of bytes to write */
  UINT* ByteWritten    /* Pointer to the variable to return number of bytes written */
);
|
*'''size_t''' matches '''ByteWritten'''
*'''ptr''' matches '''Buffer'''
*'''count''' matches '''ByteToWrite'''
*'''stream''' matches '''FileObject'''
*stdio.h has no equivalent '''FRESULT'''
|- 
| Close
|
  int 
[http://www.cplusplus.com/reference/clibrary/cstdio/fclose/ fclose] ( 
  FILE * stream 
);
|
  FRESULT 
[http://elm-chan.org/fsw/ff/en/close.html f_close] (
  FIL* FileObject     /* Pointer to the file object structure */
);
|
*'''int''' matches '''FRESULT'''
*'''stream''' matches '''FileObject'''
|-
|}
@@ Line 7: / Line 7: @@
 ==Development Roadmap==
 ===Phase 1===
-*Create fatfs wrapper for file system in freertos_posix
+*Create stdio.h wrapper for file system in freertos_posix
-*Use existing I2C EEPROM driver for development purpose
+*Use existing I2C EEPROM driver for development
 ===Phase 2===
 *Circuit design for interfacing MMC
@@ Line 26: / Line 26: @@
 ==Software Implementation==
 *Use [http://elm-chan.org/fsw/ff/00index_e.html FatFs] for accessing FAT16 file system.
-*Create a FatFs Wrapper in [http://chungyan5.no-ip.org/vc/?root=freertos_posix freertos_posix] as an intermediate layer to map API in stdio.h to API in FatFs, for example:
+*Create a stdio.h wrapper for [http://chungyan5.no-ip.org/vc/?root=freertos_posix freertos_posix]
-  +--------------------------------------------+
-  | POSIX              fopen()                 |
-  |                       |                    |
-  |                      \|/                   |
-  |                     open()                 |
-  |                       |                    |
-  |                      \|/                   |
-  +--------------------------------------------+
-  | FatFs Wrapper    fatfs_open()              |
-  |                       |                    |
-  |                      \|/                   |
-  +--------------------------------------------+
-  | FatFs              f_open()                |
-  |                       |                    |
-  |                      \|/                   |
-  |                disk_initialize()           |
-  |                       |                    |
-  |                      \|/                   |
-  +--------------------------------------------+
-  | EEPROM         i2c_eeprom_open()           |
-  +--------------------------------------------+
+===Comparison of FatFs and stdio API===
-===Comparison of stdio and FatFs API===
+*selected list is described below
-*selected list for concern
 {| border="1" cellspacing="0" cellpadding="5"
+|+ Comparison between FatFs and stdio API
 ! Function !! stdio.h !! FatFs !! Remarks
 |-