SD卡与fatfs文件系统(1)

    SD的优势之一是它的便携性，它可以自由插拔，可以在嵌入式设备和PC机之间交换数据。如果使用FAT(File Allocation Table)文件系统，它便可以方便在安装windows的PC和嵌入式设备之间交换数据。一个完整的FAT文件系统代码量非常庞大，不适合资源较少的嵌入式系统，于是就需要一个微型的FAT文件系统，FatFs就是基于这样的目的而开发的。

    FatFS是一个专为小型嵌入式系统设计的通用FAT文件系统模块。FatFs具有较高的可配置性，最小配置仅使用1K的RAM空间，非常适用于嵌入式系统。FatFs 的编写遵循ANSI C，并且完全与磁盘I/O层分开。因此，它独立(不依赖)于硬件架构。它可以被嵌入到低成本的微控制器中，如AVR, 8051, PIC, ARM, Z80, 68K 等等，而不需要做任何修改。

特点

• Windows兼容的FAT文件系统
• 不依赖于平台，易于移植
• 代码和工作区占用空间非常小
• 多种配置选项：

多卷(物理驱动器和分区)

多ANSI/OEM代码页，包括DBCS

在ANSI/OEM或Unicode中长文件名的支持

RTOS的支持

多扇区大小的支持

只读，最少API，I/O缓冲区等等

FatFs的源代码只有几个文件:diskio.c,ff.c,ff_util.c,tff.c及头文件。diskio.c是磁盘操作的代码文件(这个文件是移植时要实现的)，ff.c是一般FatFs的代码文件，tff.c是微型FatFs的代码文件，ff_util.c是几个辅助函数。integer.h是内部基本类型的定义，ff.h是一般FatFs包含的头文件，tff.h是微型FatFs包含的头文件。

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1. #if _FATFS_TINY != 1  
2. #include <fatfs/src/ff.h>  
3. #else  
4. #include <fatfs/src/tff.h>  
5. #endif  
6. #include <fatfs/src/ff_util.h>  

#if _FATFS_TINY != 1

#include <fatfs/src/ff.h>#else#include <fatfs/src/tff.h>#endif#include <fatfs/src/ff_util.h>

微型FatFs配置最小时仅占用内存1KB，但它是一个只读的FAT系统。

FatFs的配置文件是fatfs_config.h:

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1. //——————————————————————————  
2. //      General Definitions (previously in ff.h)  
3. //——————————————————————————  
4.   
5. #define _FATFS_TINY 0  
6. /* When _FATFS_TINY is set to 1, fatfs is compiled in Tiny mode 
7. / Else, it is compiled in normal mode  
8. / Tiny FatFs feature : Very low memory consumption, suitable for small memory  
9. / system. (1KB RAM) : Supports only single drive, no disk format,  
10. / only read functions, no write functions */  
11.   
12. //——————————————————————————  
13. //      Definitions for normal FATFS (previously in ff.h)  
14. //——————————————————————————  
15.   
16. #if _FATFS_TINY == 0  
17.   
18. #define _MCU_ENDIAN     2  
19. /* The _MCU_ENDIAN defines which access method is used to the FAT structure. 
20. /  1: Enable word access. 
21. /  2: Disable word access and use byte-by-byte access instead. 
22. /  When the architectural byte order of the MCU is big-endian and/or address 
23. /  miss-aligned access results incorrect behavior, the _MCU_ENDIAN must be set to 2. 
24. /  If it is not the case, it can also be set to 1 for good code efficiency. */  
25.   
26. #define _FS_READONLY    0  
27. /* Setting _FS_READONLY to 1 defines read only configuration. This removes 
28. /  writing functions, f_write, f_sync, f_unlink, f_mkdir, f_chmod, f_rename, 
29. /  f_truncate and useless f_getfree. */  
30.   
31. #define _FS_MINIMIZE    0  
32. /* The _FS_MINIMIZE option defines minimization level to remove some functions. 
33. /  0: Full function. 
34. /  1: f_stat, f_getfree, f_unlink, f_mkdir, f_chmod, f_truncate and f_rename are removed. 
35. /  2: f_opendir and f_readdir are removed in addition to level 1. 
36. /  3: f_lseek is removed in addition to level 2. */  
37.   
38. #define _USE_STRFUNC    0  
39. /* To enable string functions, set _USE_STRFUNC to 1 or 2. */  
40.   
41. #define _USE_FSINFO 1  
42. /* To enable FSInfo support on FAT32 volume, set _USE_FSINFO to 1. */  
43.   
44. #define _USE_SJIS   1  
45. /* When _USE_SJIS is set to 1, Shift-JIS code transparency is enabled, otherwise 
46. /  only US-ASCII(7bit) code can be accepted as file/directory name. */  
47.   
48. #define _USE_NTFLAG 1  
49. /* When _USE_NTFLAG is set to 1, upper/lower case of the file name is preserved. 
50. /  Note that the files are always accessed in case insensitive. */  
51.   
52. #define _USE_MKFS   1  
53. /* When _USE_MKFS is set to 1 and _FS_READONLY is set to 0, f_mkfs function is 
54. /  enabled. */  
55.   
56. #define _DRIVES     2  
57. /* Number of logical drives to be used. This affects the size of internal table. */  
58.   
59. #define _MULTI_PARTITION    0  
60. /* When _MULTI_PARTITION is set to 0, each logical drive is bound to same 
61. /  physical drive number and can mount only 1st primaly partition. When it is 
62. /  set to 1, each logical drive can mount a partition listed in Drives[]. */  
63.   
64. //——————————————————————————  
65. //      Definitions for normal FATFS TINY (previously in tff.h)  
66. //——————————————————————————  
67.   
68. #else  
69.   
70. #define _MCU_ENDIAN     2  
71. /* The _MCU_ENDIAN defines which access method is used to the FAT structure. 
72. /  1: Enable word access. 
73. /  2: Disable word access and use byte-by-byte access instead. 
74. /  When the architectural byte order of the MCU is big-endian and/or address 
75. /  miss-aligned access results incorrect behavior, the _MCU_ENDIAN must be set to 2. 
76. /  If it is not the case, it can also be set to 1 for good code efficiency. */  
77.   
78. #define _FS_READONLY    1  
79. /* Setting _FS_READONLY to 1 defines read only configuration. This removes 
80. /  writing functions, f_write, f_sync, f_unlink, f_mkdir, f_chmod, f_rename, 
81. /  f_truncate, f_getfree and internal writing codes. */  
82.   
83. #define _FS_MINIMIZE    0  
84. /* The _FS_MINIMIZE option defines minimization level to remove some functions. 
85. /  0: Full function. 
86. /  1: f_stat, f_getfree, f_unlink, f_mkdir, f_chmod, f_truncate and f_rename are removed. 
87. /  2: f_opendir and f_readdir are removed in addition to level 1. 
88. /  3: f_lseek is removed in addition to level 2. */  
89.   
90. #define _USE_STRFUNC    0  
91. /* To enable string functions, set _USE_STRFUNC to 1 or 2. */  
92.   
93. #define _USE_FSINFO 1  
94. /* To enable FSInfo support on FAT32 volume, set _USE_FSINFO to 1. */  
95.   
96. #define _USE_SJIS   1  
97. /* When _USE_SJIS is set to 1, Shift-JIS code transparency is enabled, otherwise 
98. /  only US-ASCII(7bit) code can be accepted as file/directory name. */  
99.   
100. #define _USE_NTFLAG 1  
101. /* When _USE_NTFLAG is set to 1, upper/lower case of the file name is preserved. 
102. /  Note that the files are always accessed in case insensitive. */  
103.   
104. #define _USE_FORWARD    0  
105. /* To enable f_forward function, set _USE_FORWARD to 1. */  
106.   
107. #define _FAT32  1  
108. /* To enable FAT32 support in addition of FAT12/16, set _FAT32 to 1. */  
109.   
110. #endif  
111.   
112. //——————————————————————————  
113. //      Other definitions  
114. //——————————————————————————  
115.   
116. /*———————————————————————–*/  
117. /* Correspondence between drive number and physical drive                */  
118. /* Note that Tiny-FatFs supports only single drive and always            */  
119. /* accesses drive number 0.                                              */  
120.   
121. #define DRV_MMC          0  
122. #define DRV_SDRAM        1  
123. #define DRV_ATA          2  
124. #define DRV_USB          3  
125.   
126.   
127. #define SECTOR_SIZE_SDRAM  512  
128. #define SECTOR_SIZE_SDCARD 512  

//------------------------------------------------------------------------------//      General Definitions (previously in ff.h)//------------------------------------------------------------------------------

#define _FATFS_TINY 0/* When _FATFS_TINY is set to 1, fatfs is compiled in Tiny mode/ Else, it is compiled in normal mode / Tiny FatFs feature : Very low memory consumption, suitable for small memory / system. (1KB RAM) : Supports only single drive, no disk format, / only read functions, no write functions *///------------------------------------------------------------------------------// Definitions for normal FATFS (previously in ff.h)//------------------------------------------------------------------------------#if _FATFS_TINY == 0#define _MCU_ENDIAN 2/* The _MCU_ENDIAN defines which access method is used to the FAT structure./ 1: Enable word access./ 2: Disable word access and use byte-by-byte access instead./ When the architectural byte order of the MCU is big-endian and/or address/ miss-aligned access results incorrect behavior, the _MCU_ENDIAN must be set to 2./ If it is not the case, it can also be set to 1 for good code efficiency. */#define _FS_READONLY 0/* Setting _FS_READONLY to 1 defines read only configuration. This removes/ writing functions, f_write, f_sync, f_unlink, f_mkdir, f_chmod, f_rename,/ f_truncate and useless f_getfree. */#define _FS_MINIMIZE 0/* The _FS_MINIMIZE option defines minimization level to remove some functions./ 0: Full function./ 1: f_stat, f_getfree, f_unlink, f_mkdir, f_chmod, f_truncate and f_rename are removed./ 2: f_opendir and f_readdir are removed in addition to level 1./ 3: f_lseek is removed in addition to level 2. */#define _USE_STRFUNC 0/* To enable string functions, set _USE_STRFUNC to 1 or 2. */#define _USE_FSINFO 1/* To enable FSInfo support on FAT32 volume, set _USE_FSINFO to 1. */#define _USE_SJIS 1/* When _USE_SJIS is set to 1, Shift-JIS code transparency is enabled, otherwise/ only US-ASCII(7bit) code can be accepted as file/directory name. */#define _USE_NTFLAG 1/* When _USE_NTFLAG is set to 1, upper/lower case of the file name is preserved./ Note that the files are always accessed in case insensitive. */#define _USE_MKFS 1/* When _USE_MKFS is set to 1 and _FS_READONLY is set to 0, f_mkfs function is/ enabled. */#define _DRIVES 2/* Number of logical drives to be used. This affects the size of internal table. */#define _MULTI_PARTITION 0/* When _MULTI_PARTITION is set to 0, each logical drive is bound to same/ physical drive number and can mount only 1st primaly partition. When it is/ set to 1, each logical drive can mount a partition listed in Drives[]. *///------------------------------------------------------------------------------// Definitions for normal FATFS TINY (previously in tff.h)//------------------------------------------------------------------------------#else#define _MCU_ENDIAN 2/* The _MCU_ENDIAN defines which access method is used to the FAT structure./ 1: Enable word access./ 2: Disable word access and use byte-by-byte access instead./ When the architectural byte order of the MCU is big-endian and/or address/ miss-aligned access results incorrect behavior, the _MCU_ENDIAN must be set to 2./ If it is not the case, it can also be set to 1 for good code efficiency. */#define _FS_READONLY 1/* Setting _FS_READONLY to 1 defines read only configuration. This removes/ writing functions, f_write, f_sync, f_unlink, f_mkdir, f_chmod, f_rename,/ f_truncate, f_getfree and internal writing codes. */#define _FS_MINIMIZE 0/* The _FS_MINIMIZE option defines minimization level to remove some functions./ 0: Full function./ 1: f_stat, f_getfree, f_unlink, f_mkdir, f_chmod, f_truncate and f_rename are removed./ 2: f_opendir and f_readdir are removed in addition to level 1./ 3: f_lseek is removed in addition to level 2. */#define _USE_STRFUNC 0/* To enable string functions, set _USE_STRFUNC to 1 or 2. */#define _USE_FSINFO 1/* To enable FSInfo support on FAT32 volume, set _USE_FSINFO to 1. */#define _USE_SJIS 1/* When _USE_SJIS is set to 1, Shift-JIS code transparency is enabled, otherwise/ only US-ASCII(7bit) code can be accepted as file/directory name. */#define _USE_NTFLAG 1/* When _USE_NTFLAG is set to 1, upper/lower case of the file name is preserved./ Note that the files are always accessed in case insensitive. */#define _USE_FORWARD 0/* To enable f_forward function, set _USE_FORWARD to 1. */#define _FAT32 1/* To enable FAT32 support in addition of FAT12/16, set _FAT32 to 1. */#endif//------------------------------------------------------------------------------// Other definitions//------------------------------------------------------------------------------/*-----------------------------------------------------------------------*//* Correspondence between drive number and physical drive *//* Note that Tiny-FatFs supports only single drive and always *//* accesses drive number 0. */#define DRV_MMC 0#define DRV_SDRAM 1#define DRV_ATA 2#define DRV_USB 3#define SECTOR_SIZE_SDRAM 512#define SECTOR_SIZE_SDCARD 512