A file system which can mount, read, and enumerate a file system image which has been appended to the compiled .bin code file before being uploaded to the mbed device.

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FlashFileSystem Class Reference

FlashFileSystem Class Reference

A filesystem for accessing a read-only file system placed in the internal
FLASH memory of the mbed board. More...

#include <FlashFileSystem.h>

Detailed Description

A filesystem for accessing a read-only file system placed in the internal
FLASH memory of the mbed board.

The file system to be mounted by this file system should be created through
the use of the fsbld utility on the PC.

As fsbld creates two output files (a binary and a header file), there are two
ways to add the resulting file system image:

  1. Concatenate the binary file system to the end of the .bin file created
    by the mbed online compiler before uploading to the mbed device.
  2. Import the header file into your project, include this file in your main
    file and add 'roFlashDrive' to the FlashfileSystem constructor call.
    eg : static FlashFileSystem flash("flash", roFlashDrive);

A third (optional) parameter in the FlashfileSystem constructor call allows
you to specify the size of the FLASH (KB) on the device (default = 512).
eg (for a KL25Z device) : static FlashFileSystem flash("flash", NULL, 128);
Note that in this example, the pointer to the header file has been omitted,
so we need to append the binary file system ourselves (see above).
When you use the binary file system header in your main file, you can
use the roFlashDrive pointer.
eg (for a KL25Z device) : static FlashFileSystem flash("flash", roFlashDrive, 128);

NOTE: This file system is case-sensitive. Calling fopen("/flash/INDEX.html")
won't successfully open a file named index.html in the root directory
of the flash file system.


#include <mbed.h>
#include "FlashFileSystem.h"
// Uncomment the line below when you imported the header file built with fsbld
// and replace <Flashdrive> with its correct filename
//#include "<FlashDrive>.h"

static void _RecursiveDir(const char* pDirectoryName, DIR* pDirectory = NULL)
    DIR* pFreeDirectory = NULL;
    size_t DirectoryNameLength = strlen(pDirectoryName);
    // Open the specified directory.
    if (!pDirectory)
        pDirectory = opendir(pDirectoryName);
        if (!pDirectory)
            error("Failed to open directory '%s' for enumeration.\r\n", 
        // Remember to free this directory enumerator.
        pFreeDirectory = pDirectory;
    // Determine if we should remove a trailing slash from future *printf()
    // calls.
    if (DirectoryNameLength && '/' == pDirectoryName[DirectoryNameLength-1])
    // Iterate though each item contained within this directory and display
    // it to the console.
    struct dirent* DirEntry;
    while((DirEntry = readdir(pDirectory)) != NULL) 
        char RecurseDirectoryName[256];
        DIR* pSubdirectory;

        // Try opening this file as a directory to see if it succeeds or not.
        snprintf(RecurseDirectoryName, sizeof(RecurseDirectoryName),
        pSubdirectory = opendir(RecurseDirectoryName);
        if (pSubdirectory)
            _RecursiveDir(RecurseDirectoryName, pSubdirectory);
            printf("    %.*s/%s\n", 
    // Close the directory enumerator if it was opened by this call.
    if (pFreeDirectory)

int main() 
    static const char* Filename = "/flash/index.html";
    char*              ReadResult = NULL;
    int                SeekResult = -1;
    char               Buffer[128];

    // Create the file system under the name "flash".
    // NOTE : When you include the the header file built with fsbld,
    //        disable the first static FlashFileSystem... line
    //        and enable the second static FlashFileSystem... line.
    static FlashFileSystem flash("flash");
//    static FlashFileSystem flash("flash, roFlashDrive");
    if (!flash.IsMounted())
        error("Failed to mount FlashFileSystem.\r\n");

    // Open "index.html" on the file system for reading.
    FILE *fp = fopen(Filename, "r");
    if (NULL == fp)
        error("Failed to open %s\r\n", Filename);
    // Use seek to determine the length of the file
    SeekResult = fseek(fp, 0, SEEK_END);
    if (SeekResult)
        error("Failed to seek to end of %s.\r\n", Filename);
    long FileLength = ftell(fp);
    printf("%s is %ld bytes in length.\r\n", Filename, FileLength);
    // Reset the file pointer to the beginning of the file
    SeekResult = fseek(fp, 0, SEEK_SET);
    if (SeekResult)
        error("Failed to seek to beginning of %s.\r\n", Filename);
    // Read the first line into Buffer and then display to user.
    ReadResult = fgets(Buffer, sizeof(Buffer)/sizeof(Buffer[0]), fp);
    if (NULL == ReadResult)
        error("Failed to read first line of %s.\r\n", Filename);
    printf("%s:1  %s", Filename, Buffer);
    // Done with the file so close it.

    // Enumerate all content on mounted file systems.
    printf("\r\nList all files in /flash...\r\n");
    printf("\r\nFlashFileSystem example has completed.\r\n");

Definition at line 283 of file FlashFileSystem.h.