STM32-基本知识梳理8-FATFS文件系统移植

一、基本概念

1，为什么需要文件系统？

在没有文件系统的存储器中，一般通过手工记录，那些变量存放在那些位置，很难有系统的管理

难以记录有效数据的位置 、难以确定存储介质的剩余空间、 不明确应以何种格式来解读数据

加入文件系统后，就可以引导区、目录等对内部数据进行管控，并且对于数据可以命名，方便以各种格式对应的解析数据；

2，文件系统是什么？

1-嵌入式中，最常用的就是文件系统就是FATFS，是一种小型文件系统；

2-FATFS在初步搭建在外部flash或者内存中时，第一次需要进格式化（格式化的本质就是利用spi的读写功能，在存储介质建立了一些组织结构，这些结构包括操作系统引导区、目录和文件）

3，加入文件系统后的读写过程？

1- 数据都以文件的形式存储；

2- 写入新文件时，先在目录中创建一个文件索引，它指示了文件存放的物理地址，再把数据存储到该地址中；

3- 当需要读取数据时，可以从目录中找到该文件的索引，进而在相应的地址中读取出数据；

4，有文件系统和没有文件系统最大的差异

1-没有文件系统，写入数据和读取数据，需要指定明确的物理地址

2-有文件系统后，文件系统的存在使存取数据时，不再是简单地向某物理地址直接读写，而是要遵循它的读写格式。如经过逻辑转换，一个完整的文件可能被分开成多段存储到不连续的物理地址，使用目录或链表的方式来获知下一段的位置。

二、文件系统示意图说明

1，文件分配表，存放A.TXT     B.TXT     C.TXT

2，对应的目录分配表

主要参数：1：文件名 ；2，开始簇；3，文件大小；4，创建时间；5，读取属性；

3， 实际文件分配表：

文件 a.txt 我们根据目录 项中指定的 a.txt 的首簇为 2，然后找到文件分配表的第 2 簇记录，上面登记 的是 3，就能确定下一簇是 3。找到文件分配表的第 3 簇记录，上面登记的 是 4，就能确定下一簇是 4......直到指到第 11 簇，发现下一个指向是 FF，就是结束。文件便读取完毕。

在内存是删除B文件后，创建D.TXT后

文件D，在物理内存中被分为两块，目录示意图如下：

 实际文件分配如下:

至此文件系统的基本内容完毕，下面介绍FATFS文件系统及移植过程

三、FATFS文件管理系统介绍

1，FATFS系统在系统中的位置

APP接口----FATFS----底层接口

文件系统本质上，可以理解为一个函数B，外部可以通过函数A调用函数B，而函数B不接触底层操作，而是通过调用函数C对底层存储进行操作。

2，FATFS中重要的文件及其作用

1 - integer.h：文件中包含了一些数值类型定义，对一些类型进行typedef。

2 -  diskio.c：包含底层存储介质的操作函数，这些函数需要用户自己实现，主要添加底层驱动函数。我们主要的底层接口都要在这边调用执行

3 -  ff.c： FatFs核心文件，文件管理的实现方法。该文件独立于底层介质操作文件的函数，利用这些函数实现文件的读写，在主函数中要包含ff.h，从而执行fatfs文件系统

4- cc936.c：本文件在option目录下，是简体中文支持所需要添加的文件，包含了简体中文的GBK和Unicode相互转换功能函数。

5-ffconf.h:这个头文件包含了对FatFs功能配置的宏定义，通过修改这些宏定义就可以裁剪FatFs的功能。如需要支持简体中文，需要把ffconf.h中的_CODE_PAGE 的宏改成936并把上面的cc936.c文件加入到工程之中。

 至此，文件系统的基本介绍到此结束，下面开始移植

四、FATFS文件系统移植

1，文件系统移植，本质上就是把文件系统对于下层的硬件操作接口，与文件系统本身的操作给建立连接

2，移植需要借用spi-flash控制的源码，在spi-flash控制的源码的基础上，添加文件系统

3，主要的文件需要包含上述的6个c文件或者h文件，在文件文件中，需要调整主要是diskio.c \        ffconf.h

下面开始逐步说明

diskio.c的底层硬件操作的移植

1-头文件，包含flash的底层头文件

#include "diskio.h"		/* FatFs lower layer API */
#include "./flash/bsp_spi_flash.h"

2-宏定义，设备名称

#define SDCARD		0
#define FLASH_SPI	1
/*-----------------------------------------------------------------------*/
/* Get Drive Status                                                      */
/*-----------------------------------------------------------------------*/
//diskio是底层硬件和FATFs操作的连接渠道，主要的配置都在这边执行

3-设备状态确认

实际上是通过SPI_FLASH_ReadID()==sFLASH_ID 来判定设备是否正常

DSTATUS disk_status (
	BYTE pdrv		/* Physical drive nmuber to identify the drive */
)
{
	DSTATUS stat;
//	int result;

	switch (pdrv) {
	case SDCARD :
    

	case FLASH_SPI :
		//通过读取到flash id来确认状态 
		if(SPI_FLASH_ReadID()==sFLASH_ID) 
		{
			stat= 0;
		}
		else
		{
			stat= STA_NOINIT;
		}
		// translate the reslut code here

		return stat;


	}
	return STA_NOINIT;
}

4-设备初始化，实际上调用SPI_FLASH_Init();对GPIO接口、SPI1模块进行底层的初始化操作

DSTATUS disk_initialize (
	BYTE pdrv				/* Physical drive nmuber to identify the drive */
)
{
//	DSTATUS stat;
//	int result;

	switch (pdrv) {
	case SDCARD :

	

	case FLASH_SPI:
			SPI_FLASH_Init();


		return disk_status(FLASH_SPI);


	}
	return STA_NOINIT;
}

5-实际上是调用SPI_FLASH_BufferRead(buff, sector*4096, count*4096);

在 disk_read 中的参数要进行转变，每个扇区是4096个字节，所以物理初始地址=扇区号*4096；字节数=扇区数*4096

DRESULT disk_read (
	BYTE pdrv,		/* 型号：Flash 还是SD */
	BYTE *buff,		/* 指针传递回数据 */
	DWORD sector,	/* 扇区号 */
	UINT count		/* 要读取的扇区数 */
)
{
	DRESULT res;
//	int result;

	switch (pdrv) {
    case SDCARD :

	

	case FLASH_SPI:
			
		
		SPI_FLASH_BufferRead(buff, sector*4096, count*4096);
		
        res= RES_OK;
		return res;


	}

	return RES_PARERR;
}

6-本质上是调用了  、

SPI_FLASH_SectorErase(sector*4096)；

SPI_FLASH_BufferWrite((BYTE *)buff, sector*4096, count*4096);

在flash中，写入数据要先擦除再写入

ps：在写入时，建议加一个等待busy，（具体看我上一篇 ）这样更稳妥。但是我看野火源码中没有加，似乎问题不大？

#if _USE_WRITE
DRESULT disk_write (
	BYTE pdrv,			/* Physical drive nmuber to identify the drive */
	const BYTE *buff,	/* Data to be written */
	DWORD sector,		/* Sector address in LBA */
	UINT count			/* Number of sectors to write */
)
{
	DRESULT res;
//	int result;

	switch (pdrv) {
    case SDCARD :

	

	case FLASH_SPI:
			
		
		SPI_FLASH_SectorErase(sector*4096);
        SPI_FLASH_BufferWrite((BYTE *)buff, sector*4096, count*4096);
		
        res= RES_OK;
		return res;
	} 

	return RES_PARERR;
}
#endif

7-这边主要时杂项指令，调用这个函数，通过buff指针传递回去；

这边void*指针的数据传递，需关注

*(DWORD*) buff=2048; 

*(WORD*) buff=4096; 

/*-----------------------------------------------------------------------*/
/* Miscellaneous Functions                                               */
/*-----------------------------------------------------------------------*/

#if _USE_IOCTL
DRESULT disk_ioctl (
	BYTE pdrv,		/* Physical drive nmuber (0..) */
	BYTE cmd,		/* Control code */
	void *buff		/* Buffer to send/receive control data */
)
{
	DRESULT res;
//	int result;

	switch (pdrv) {
    case SDCARD :

	

	case FLASH_SPI:
		switch(cmd)
		{
			//扇区数量
			case GET_SECTOR_COUNT:
				*(DWORD*) buff=2048;  
				break;
			
			//每个扇区大小
			case GET_SECTOR_SIZE:
				*(WORD*) buff=4096;  
				break;
			
			//每次擦除扇区的最小个数
			
			case GET_BLOCK_SIZE:
				*(DWORD*) buff=1; 
				break;
			      
		}			

        
		
        res= RES_OK;
		return res;
	}

	return RES_PARERR;
}
#endif

8-时间项，理论上要关联rtc，但是这边直接return 0

DWORD get_fattime (void)
{

 return 0;
}

ffconf.h的底层硬件操作的移植

看英文注释即可

/*---------------------------------------------------------------------------/
/  FatFs - FAT file system module configuration file  R0.11a (C)ChaN, 2015
/---------------------------------------------------------------------------*/

#define _FFCONF 64180	/* Revision ID */

/*---------------------------------------------------------------------------/
/ Function Configurations
/---------------------------------------------------------------------------*/

#define _FS_READONLY	0
/* This option switches read-only configuration. (0:Read/Write or 1:Read-only)
/  Read-only configuration removes writing API functions, f_write(), f_sync(),
/  f_unlink(), f_mkdir(), f_chmod(), f_rename(), f_truncate(), f_getfree()
/  and optional writing functions as well. */


#define _FS_MINIMIZE	0
/* This option defines minimization level to remove some basic API functions.
/
/   0: All basic functions are enabled.
/   1: f_stat(), f_getfree(), f_unlink(), f_mkdir(), f_chmod(), f_utime(),
/      f_truncate() and f_rename() function are removed.
/   2: f_opendir(), f_readdir() and f_closedir() are removed in addition to 1.
/   3: f_lseek() function is removed in addition to 2. */


#define	_USE_STRFUNC	1
/* This option switches string functions, f_gets(), f_putc(), f_puts() and
/  f_printf().
/
/  0: Disable string functions.
/  1: Enable without LF-CRLF conversion.
/  2: Enable with LF-CRLF conversion. */


#define _USE_FIND		0
/* This option switches filtered directory read feature and related functions,
/  f_findfirst() and f_findnext(). (0:Disable or 1:Enable) */


#define	_USE_MKFS		1  //在格式化时刻，需要配置成1 
/* This option switches f_mkfs() function. (0:Disable or 1:Enable) */


#define	_USE_FASTSEEK	0
/* This option switches fast seek feature. (0:Disable or 1:Enable) */


#define _USE_LABEL		0
/* This option switches volume label functions, f_getlabel() and f_setlabel().
/  (0:Disable or 1:Enable) */


#define	 _USE_FORWARD	0
/* This option switches f_forward() function. (0:Disable or 1:Enable)
/  To enable it, also _FS_TINY need to be set to 1. */


/*---------------------------------------------------------------------------/
/ Locale and Namespace Configurations
/---------------------------------------------------------------------------*/

#define _CODE_PAGE	932
/* This option specifies the OEM code page to be used on the target system.
/  Incorrect setting of the code page can cause a file open failure.
/
/   1   - ASCII (No extended character. Non-LFN cfg. only)
/   437 - U.S.
/   720 - Arabic
/   737 - Greek
/   771 - KBL
/   775 - Baltic
/   850 - Latin 1
/   852 - Latin 2
/   855 - Cyrillic
/   857 - Turkish
/   860 - Portuguese
/   861 - Icelandic
/   862 - Hebrew
/   863 - Canadian French
/   864 - Arabic
/   865 - Nordic
/   866 - Russian
/   869 - Greek 2
/   932 - Japanese (DBCS)
/   936 - Simplified Chinese (DBCS)
/   949 - Korean (DBCS)
/   950 - Traditional Chinese (DBCS)
*/


#define	_USE_LFN	0
#define	_MAX_LFN	255
/* The _USE_LFN option switches the LFN feature.
/
/   0: Disable LFN feature. _MAX_LFN has no effect.
/   1: Enable LFN with static working buffer on the BSS. Always NOT thread-safe.
/   2: Enable LFN with dynamic working buffer on the STACK.
/   3: Enable LFN with dynamic working buffer on the HEAP.
/
/  When enable the LFN feature, Unicode handling functions (option/unicode.c) must
/  be added to the project. The LFN working buffer occupies (_MAX_LFN + 1) * 2 bytes.
/  When use stack for the working buffer, take care on stack overflow. When use heap
/  memory for the working buffer, memory management functions, ff_memalloc() and
/  ff_memfree(), must be added to the project. */


#define	_LFN_UNICODE	0
/* This option switches character encoding on the API. (0:ANSI/OEM or 1:Unicode)
/  To use Unicode string for the path name, enable LFN feature and set _LFN_UNICODE
/  to 1. This option also affects behavior of string I/O functions. */


#define _STRF_ENCODE	3
/* When _LFN_UNICODE is 1, this option selects the character encoding on the file to
/  be read/written via string I/O functions, f_gets(), f_putc(), f_puts and f_printf().
/
/  0: ANSI/OEM
/  1: UTF-16LE
/  2: UTF-16BE
/  3: UTF-8
/
/  When _LFN_UNICODE is 0, this option has no effect. */


#define _FS_RPATH	0
/* This option configures relative path feature.
/
/   0: Disable relative path feature and remove related functions.
/   1: Enable relative path feature. f_chdir() and f_chdrive() are available.
/   2: f_getcwd() function is available in addition to 1.
/
/  Note that directory items read via f_readdir() are affected by this option. */


/*---------------------------------------------------------------------------/
/ Drive/Volume Configurations
/---------------------------------------------------------------------------*/

#define _VOLUMES	2
/* Number of volumes (logical drives) to be used. */


#define _STR_VOLUME_ID	0
#define _VOLUME_STRS	"RAM","NAND","CF","SD1","SD2","USB1","USB2","USB3"
/* _STR_VOLUME_ID option switches string volume ID feature.
/  When _STR_VOLUME_ID is set to 1, also pre-defined strings can be used as drive
/  number in the path name. _VOLUME_STRS defines the drive ID strings for each
/  logical drives. Number of items must be equal to _VOLUMES. Valid characters for
/  the drive ID strings are: A-Z and 0-9. */


#define	_MULTI_PARTITION	0
/* This option switches multi-partition feature. By default (0), each logical drive
/  number is bound to the same physical drive number and only an FAT volume found on
/  the physical drive will be mounted. When multi-partition feature is enabled (1),
/  each logical drive number is bound to arbitrary physical drive and partition
/  listed in the VolToPart[]. Also f_fdisk() funciton will be available. */


#define	_MIN_SS		512
#define	_MAX_SS		4096
/* These options configure the range of sector size to be supported. (512, 1024,
/  2048 or 4096) Always set both 512 for most systems, all type of memory cards and
/  harddisk. But a larger value may be required for on-board flash memory and some
/  type of optical media. When _MAX_SS is larger than _MIN_SS, FatFs is configured
/  to variable sector size and GET_SECTOR_SIZE command must be implemented to the
/  disk_ioctl() function. */


#define	_USE_TRIM	0
/* This option switches ATA-TRIM feature. (0:Disable or 1:Enable)
/  To enable Trim feature, also CTRL_TRIM command should be implemented to the
/  disk_ioctl() function. */


#define _FS_NOFSINFO	0
/* If you need to know correct free space on the FAT32 volume, set bit 0 of this
/  option, and f_getfree() function at first time after volume mount will force
/  a full FAT scan. Bit 1 controls the use of last allocated cluster number.
/
/  bit0=0: Use free cluster count in the FSINFO if available.
/  bit0=1: Do not trust free cluster count in the FSINFO.
/  bit1=0: Use last allocated cluster number in the FSINFO if available.
/  bit1=1: Do not trust last allocated cluster number in the FSINFO.
*/



/*---------------------------------------------------------------------------/
/ System Configurations
/---------------------------------------------------------------------------*/

#define	_FS_TINY	0
/* This option switches tiny buffer configuration. (0:Normal or 1:Tiny)
/  At the tiny configuration, size of the file object (FIL) is reduced _MAX_SS
/  bytes. Instead of private sector buffer eliminated from the file object,
/  common sector buffer in the file system object (FATFS) is used for the file
/  data transfer. */


#define _FS_NORTC	0
#define _NORTC_MON	1
#define _NORTC_MDAY	1
#define _NORTC_YEAR	2015
/* The _FS_NORTC option switches timestamp feature. If the system does not have
/  an RTC function or valid timestamp is not needed, set _FS_NORTC to 1 to disable
/  the timestamp feature. All objects modified by FatFs will have a fixed timestamp
/  defined by _NORTC_MON, _NORTC_MDAY and _NORTC_YEAR.
/  When timestamp feature is enabled (_FS_NORTC == 0), get_fattime() function need
/  to be added to the project to read current time form RTC. _NORTC_MON,
/  _NORTC_MDAY and _NORTC_YEAR have no effect. 
/  These options have no effect at read-only configuration (_FS_READONLY == 1). */


#define	_FS_LOCK	0
/* The _FS_LOCK option switches file lock feature to control duplicated file open
/  and illegal operation to open objects. This option must be 0 when _FS_READONLY
/  is 1.
/
/  0:  Disable file lock feature. To avoid volume corruption, application program
/      should avoid illegal open, remove and rename to the open objects.
/  >0: Enable file lock feature. The value defines how many files/sub-directories
/      can be opened simultaneously under file lock control. Note that the file
/      lock feature is independent of re-entrancy. */


#define _FS_REENTRANT	0
#define _FS_TIMEOUT		1000
#define	_SYNC_t			HANDLE
/* The _FS_REENTRANT option switches the re-entrancy (thread safe) of the FatFs
/  module itself. Note that regardless of this option, file access to different
/  volume is always re-entrant and volume control functions, f_mount(), f_mkfs()
/  and f_fdisk() function, are always not re-entrant. Only file/directory access
/  to the same volume is under control of this feature.
/
/   0: Disable re-entrancy. _FS_TIMEOUT and _SYNC_t have no effect.
/   1: Enable re-entrancy. Also user provided synchronization handlers,
/      ff_req_grant(), ff_rel_grant(), ff_del_syncobj() and ff_cre_syncobj()
/      function, must be added to the project. Samples are available in
/      option/syscall.c.
/
/  The _FS_TIMEOUT defines timeout period in unit of time tick.
/  The _SYNC_t defines O/S dependent sync object type. e.g. HANDLE, ID, OS_EVENT*,
/  SemaphoreHandle_t and etc.. A header file for O/S definitions needs to be
/  included somewhere in the scope of ff.c. */


#define _WORD_ACCESS	0
/* The _WORD_ACCESS option is an only platform dependent option. It defines
/  which access method is used to the word data on the FAT volume.
/
/   0: Byte-by-byte access. Always compatible with all platforms.
/   1: Word access. Do not choose this unless under both the following conditions.
/
/  * Address misaligned memory access is always allowed to ALL instructions.
/  * Byte order on the memory is little-endian.
/
/  If it is the case, _WORD_ACCESS can also be set to 1 to reduce code size.
/  Following table shows allowable settings of some type of processors.
/
/  ARM7TDMI   0   *2          ColdFire   0    *1         V850E      0    *2
/  Cortex-M3  0   *3          Z80        0/1             V850ES     0/1
/  Cortex-M0  0   *2          x86        0/1             TLCS-870   0/1
/  AVR        0/1             RX600(LE)  0/1             TLCS-900   0/1
/  AVR32      0   *1          RL78       0    *2         R32C       0    *2
/  PIC18      0/1             SH-2       0    *1         M16C       0/1
/  PIC24      0   *2          H8S        0    *1         MSP430     0    *2
/  PIC32      0   *1          H8/300H    0    *1         8051       0/1
/
/  *1:Big-endian.
/  *2:Unaligned memory access is not supported.
/  *3:Some compilers generate LDM/STM for mem_cpy function.
*/

下面可以在mian中操作：

1 - 包含对应头文件，fatfs包含#include "ff.H"

#include "stm32f10x.h"                  // Device header
#include "./led/bsp_led.h"  
#include "BSP_USART.H"
#include "./flash/bsp_spi_flash.h"
#include "ff.H"

2 - 相关变量定义

1-一个文件系统对应一个系统对象FATFS。（这边不能定义在main函数中，容易栈溢出）

例如SD卡和flash中都要用FATFS，则需要定义两个系统对象

2- 文件对象FIL，具体的文件类型；

3- 状态，文件操作结果FRESULT

FATFS fs_falsh;              /* FatFs文件系统对象 */
uint8_t writebuf[]="这是fatfs写入测试";  
uint8_t readbuf[30]="";
FRESULT state;   /* 文件操作结果 */
FIL fp;   /* 文件对象 */

UINT write_size=0;
UINT read_size=0;

3-文件启动

1-启动首先第一步，是挂载系统。如果系统存在，挂载结果为FR_OK;如果系统不存在FR_NO_FILESYSTEM，则格式化处理；

2-格式化完成后，需要取消挂载一次，在重新挂载；

	printf("测试开始：\n");
	//启动文件系统
	state=f_mount (&fs_falsh,"1:",1);	
	if(state==FR_OK)
	{
	 printf("系统挂载完成：\n");	
		
	}
	else
	{
	  printf("系统挂载失败 ,%d：\n",state);	
	 
	}
    
	 
	if(state==FR_NO_FILESYSTEM)
	{
		printf("格式化处理\n");
		state=f_mkfs("1:",0,0);
		
		if(state==FR_OK)
		{
		//格式化后，先取消挂载再重新挂载
			printf("》FLASH已成功格式化文件系统。\r\n");
			
		f_mount (NULL,"1:",1);    //取消
		f_mount (&fs_falsh,"1:",1);  //重新挂栽
			LED_GREEN;
		}
		else
		{
			printf("《《格式化失败。》》\r\n");
			LED_RED;
		}
			
			
		//格式化后，先取消挂载再重新挂载
		f_mount (NULL,"1:",1);    //取消
		f_mount (&fs_falsh,"1:",1);  //重新挂栽
		
	} 

4，文件的读取，写入操作

1- 写入和读取文件，要先open，才能进行操作

2- 如果写入完成，立即读取，则需要调用lseek进行重新定位，才能读取，这是由文件光标位置决定，相当于退后光标；

3-如果先f_close,再进行读取，则无需lseek

4-

//打开文件fopen
	state=f_open (&fp,"1:abc.txt",FA_OPEN_ALWAYS|FA_WRITE|FA_READ );
	 if(state==FR_OK) 
     {
		 printf("open abc ok\n");
		 
		 state=f_write(&fp,writebuf,sizeof(writebuf),&write_size);
		  if(state==FR_OK) 
		  {
			printf("写入完成 %d 字节",write_size);
			printf("写入后立马读取\r\n");//写入后立即读取，需要lseek重新定位
			f_lseek(&fp,4);
			state=f_read(&fp,readbuf,f_size(&fp),&read_size);
			  if(state==FR_OK)
				 {
					printf("读取完成 %d 字节\n",read_size);
					printf("内容是：%s",readbuf);
					LED_RED;
				 }
		  }
		  
		  f_close(&fp);
	 }
	 else
	 {
		printf("not open");
	 }

	 printf("****** 即将进行文件读取测试... ******\r\n");
	 state=f_open (&fp,"1:abc.txt",FA_OPEN_ALWAYS|FA_READ);
	 if(state==FR_OK)
	 {
		printf("open abc ok with read\n");
		state=f_read(&fp,readbuf,f_size(&fp),&read_size);
		 if(state==FR_OK)
		 {
			printf("读取完成 %d 字节\n",read_size);
			printf("内容是：%s",readbuf);
			LED_RED;
		 }
	 }
	

以上，文件系统FATFS移植，主体部分完成。文章来源地址https://www.toymoban.com/news/detail-775692.html

到了这里，关于STM32-基本知识梳理8-FATFS文件系统移植的文章就介绍完了。如果您还想了解更多内容，请在右上角搜索TOY模板网以前的文章或继续浏览下面的相关文章，希望大家以后多多支持TOY模板网！