Erik -
Class that combined FATFileSystem with a USBMSD device, similar to LocalFileSystem
Dependents: SD_USB_FS_HelloWorld S25FL216K_USBFileSystem USBFileSystem_RAMDISK_HelloWorld
Introduction
USBFileSystem is a combination of FATFileSystem and USB-MSD (Mass-Storage Device). This way it allows you to create a filesystem that is both accessible on your PC with the USB cable plugged in, and on the device itself. This is very similar to LocalFileSystem, only you can use any Serial Flash, SD, etc as storage medium.
If your code works with either FATFileSystem or USBMSD it will with very little modification also work with USBFileSystem.
Basic functionality
Since both FATFileSystem and USBMSD write binary data to a the storage medium, if both are writing somewhere at the same time we have a problem. This library makes the medium read only for the local side, if USB is writing, and vice versa. Local is considered to be writing as long as you have opened a file for write. USB is considered writing as soon as a write command comes from USB, and this continues for a short time after the last write command. This is needed because I cannot know when the last sector is written by USB, so I have to wait a little while to see if more data is written.
Reading
You can still read when the other one is writing. This can result in issues. Using the functions given you can easily make sure that won't happen. However regardless if you do that or not, it is a good idea to make sure your program can handle unexpected situations. For example if you open a file locally, and you get a NULL pointer, do not immediatly go into an error condition, but just try it again.
USB MSD on your PC
When you write to / read from a USB drive Windows (and I expect other OS's too) will cache everything. The result is that once you read a file on your PC, it will never change, even if your mbed does change the data. And if you write/delete a file when the mbed is locally using the file system, it will be read only, however your PC will tell you data was succesfully written/removed.
If this is a problem for your device, you can disconnect the USB part when the mbed is writing to the storage medium locally. The library can do this automatically for you.
Required code
The virtual functions that need to be implemented by you are:
virtual int disk_initialize() { return 0; }
virtual int _disk_status() { return 0; }
virtual int disk_read(uint8_t * buffer, uint64_t sector) { return 0;}
virtual int _disk_write(const uint8_t * buffer, uint64_t sector) = 0;
virtual int disk_sync() { return 0; }
virtual uint64_t disk_sectors() = 0;
Some of those are optional, but disk_read, _disk_write and disk_sectors have to be defined in the child class.
Sector size
The sector size must be 512 bytes. In USBMSD this requirement isn't present, but FATFileSystem has this requirement!
Function name
Note the '_' at the beginning of _disk_status and _disk_write. You may not inherit it without the '_', that will break the library. Since the parent libraries made it virtual I cannot block it from happening, so just watch out.
Available functions for the user
The USBFileSystem library allows for some extra functions the user can use. The API documentation lists them, but summarized: You can attach functions which are called once either USB is writing to the storage medium, or when this is done locally. There are two functions which will tell you if currently USB/local is writing to the storage medium, and you can set the usbMode. Set it to mode 0 and USB is read only when the storage is used locally, set it to mode 1 and it is disconnected (default and recommended).
Besides that there are of course the standard USB functions (connect/disconnect for example), and you can use 'fopen', 'mkdir', etc similar to FATFileSystem.
Hello World
Currently available:
RAM-disk for KL25Z and LPC1768 (this one disappeared for some reason, I re-published it, should still work):
Import programUSBFileSystem_RAMDISK_HelloWorld
RAMDisk example for the USBFileSystem
Last commit 18 Jan 2015 by 
Erik -
Wi-Go serial flash:
Import programS25FL216K_HelloWorld
Helloworld program for the S25FL216K flash memory in combination with USBFileSystem
Last commit 19 Nov 2013 by Erik -
SD card (different from others):
Note that this one is not mine, if you have problems with it check if there are updates for the library.
FATFileSystem/ChaN/ffconf.h
- Committer:
- Sissors
- Date:
- 2015-01-18
- Revision:
- 8:a9e1dffac4bd
- Parent:
- 6:15b73dae124e
File content as of revision 8:a9e1dffac4bd:
/*---------------------------------------------------------------------------/
/ FatFs - FAT file system module configuration file R0.09a (C)ChaN, 2012
/----------------------------------------------------------------------------/
/
/ CAUTION! Do not forget to make clean the project after any changes to
/ the configuration options.
/
/----------------------------------------------------------------------------*/
#ifndef _FFCONF
#define _FFCONF 4004 /* Revision ID */
#define FFS_DBG 0
/*---------------------------------------------------------------------------/
/ Functions and Buffer Configurations
/----------------------------------------------------------------------------*/
#define _FS_TINY 1 /* 0:Normal or 1:Tiny */
/* When _FS_TINY is set to 1, FatFs uses the sector buffer in the file system
/ object instead of the sector buffer in the individual file object for file
/ data transfer. This reduces memory consumption 512 bytes each file object. */
#define _FS_READONLY 0 /* 0:Read/Write or 1:Read only */
/* 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 /* 0 to 3 */
/* 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 1.
/ 3: f_lseek is removed in addition to 2. */
#define _USE_STRFUNC 0 /* 0:Disable or 1-2:Enable */
/* To enable string functions, set _USE_STRFUNC to 1 or 2. */
#define _USE_MKFS 1 /* 0:Disable or 1:Enable */
/* To enable f_mkfs function, set _USE_MKFS to 1 and set _FS_READONLY to 0 */
#define _USE_FORWARD 0 /* 0:Disable or 1:Enable */
/* To enable f_forward function, set _USE_FORWARD to 1 and set _FS_TINY to 1. */
#define _USE_FASTSEEK 0 /* 0:Disable or 1:Enable */
/* To enable fast seek feature, set _USE_FASTSEEK to 1. */
/*---------------------------------------------------------------------------/
/ Locale and Namespace Configurations
/----------------------------------------------------------------------------*/
#define _CODE_PAGE 858
/* The _CODE_PAGE specifies the OEM code page to be used on the target system.
/ Incorrect setting of the code page can cause a file open failure.
/
/ 932 - Japanese Shift-JIS (DBCS, OEM, Windows)
/ 936 - Simplified Chinese GBK (DBCS, OEM, Windows)
/ 949 - Korean (DBCS, OEM, Windows)
/ 950 - Traditional Chinese Big5 (DBCS, OEM, Windows)
/ 1250 - Central Europe (Windows)
/ 1251 - Cyrillic (Windows)
/ 1252 - Latin 1 (Windows)
/ 1253 - Greek (Windows)
/ 1254 - Turkish (Windows)
/ 1255 - Hebrew (Windows)
/ 1256 - Arabic (Windows)
/ 1257 - Baltic (Windows)
/ 1258 - Vietnam (OEM, Windows)
/ 437 - U.S. (OEM)
/ 720 - Arabic (OEM)
/ 737 - Greek (OEM)
/ 775 - Baltic (OEM)
/ 850 - Multilingual Latin 1 (OEM)
/ 858 - Multilingual Latin 1 + Euro (OEM)
/ 852 - Latin 2 (OEM)
/ 855 - Cyrillic (OEM)
/ 866 - Russian (OEM)
/ 857 - Turkish (OEM)
/ 862 - Hebrew (OEM)
/ 874 - Thai (OEM, Windows)
/ 1 - ASCII only (Valid for non LFN cfg.)
*/
#define _USE_LFN 1 /* 0 to 3 */
#define _MAX_LFN 255 /* Maximum LFN length to handle (12 to 255) */
/* The _USE_LFN option switches the LFN support.
/
/ 0: Disable LFN feature. _MAX_LFN and _LFN_UNICODE have no effect.
/ 1: Enable LFN with static working buffer on the BSS. Always NOT reentrant.
/ 2: Enable LFN with dynamic working buffer on the STACK.
/ 3: Enable LFN with dynamic working buffer on the HEAP.
/
/ The LFN working buffer occupies (_MAX_LFN + 1) * 2 bytes. To enable LFN,
/ Unicode handling functions ff_convert() and ff_wtoupper() must be added
/ to the project. When enable to use heap, memory control functions
/ ff_memalloc() and ff_memfree() must be added to the project. */
#define _LFN_UNICODE 0 /* 0:ANSI/OEM or 1:Unicode */
/* To switch the character code set on FatFs API to Unicode,
/ enable LFN feature and set _LFN_UNICODE to 1. */
#define _FS_RPATH 0 /* 0 to 2 */
/* The _FS_RPATH option configures relative path feature.
/
/ 0: Disable relative path feature and remove related functions.
/ 1: Enable relative path. f_chdrive() and f_chdir() are available.
/ 2: f_getcwd() is available in addition to 1.
/
/ Note that output of the f_readdir fnction is affected by this option. */
/*---------------------------------------------------------------------------/
/ Physical Drive Configurations
/----------------------------------------------------------------------------*/
#define _VOLUMES 1
/* Number of volumes (logical drives) to be used. */
#define _MAX_SS 512 /* 512, 1024, 2048 or 4096 */
/* Maximum sector size to be handled.
/ Always set 512 for memory card and hard disk but a larger value may be
/ required for on-board flash memory, floppy disk and optical disk.
/ When _MAX_SS is larger than 512, it configures FatFs to variable sector size
/ and GET_SECTOR_SIZE command must be implememted to the disk_ioctl function. */
#define _MULTI_PARTITION 0 /* 0:Single partition, 1/2:Enable multiple partition */
/* When set to 0, each volume is bound to the same physical drive number and
/ it can mount only first primaly partition. When it is set to 1, each volume
/ is tied to the partitions listed in VolToPart[]. */
#define _USE_ERASE 0 /* 0:Disable or 1:Enable */
/* To enable sector erase feature, set _USE_ERASE to 1. CTRL_ERASE_SECTOR command
/ should be added to the disk_ioctl functio. */
/*---------------------------------------------------------------------------/
/ System Configurations
/----------------------------------------------------------------------------*/
#define _WORD_ACCESS 0 /* 0 or 1 */
/* Set 0 first and it is always compatible with all platforms. The _WORD_ACCESS
/ option defines which access method is used to the word data on the FAT volume.
/
/ 0: Byte-by-byte access.
/ 1: Word access. Do not choose this unless following condition is met.
/
/ When the byte order on the memory is big-endian or address miss-aligned word
/ access results incorrect behavior, the _WORD_ACCESS must be set to 0.
/ If it is not the case, the value can also be set to 1 to improve the
/ performance and code size.
*/
/* A header file that defines sync object types on the O/S, such as
/ windows.h, ucos_ii.h and semphr.h, must be included prior to ff.h. */
#define _FS_REENTRANT 0 /* 0:Disable or 1:Enable */
#define _FS_TIMEOUT 1000 /* Timeout period in unit of time ticks */
#define _SYNC_t HANDLE /* O/S dependent type of sync object. e.g. HANDLE, OS_EVENT*, ID and etc.. */
/* The _FS_REENTRANT option switches the reentrancy (thread safe) of the FatFs module.
/
/ 0: Disable reentrancy. _SYNC_t and _FS_TIMEOUT have no effect.
/ 1: Enable reentrancy. 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. */
#define _FS_LOCK 0 /* 0:Disable or >=1:Enable */
/* To enable file lock control feature, set _FS_LOCK to 1 or greater.
The value defines how many files can be opened simultaneously. */
#define FLUSH_ON_NEW_CLUSTER 0 /* Sync the file on every new cluster */
#define FLUSH_ON_NEW_SECTOR 1 /* Sync the file on every new sector */
/* Only one of these two defines needs to be set to 1. If both are set to 0
the file is only sync when closed.
Clusters are group of sectors (eg: 8 sectors). Flushing on new cluster means
it would be less often than flushing on new sector. Sectors are generally
512 Bytes long. */
#endif /* _FFCONFIG */