Embedded FAT16/32 for CF cards

Full Description

The library was originally developed for a very high speed data logging system running on a c6000 DSP from Ti. The library was designed to read and write data to/from a compact flash interface.

The compact flash card is connected directly to the c6000 memory bus with only a few simple external logic gates required.

There are several methods of reading and writing to compact flash cards, including UDMA and memory mapped. To keep the electronic interface as simple as possible our library uses a standard memory mapped mode of interface. The system reads information from the card (the PIO mode) and using this information sets up the maximum speed of access possible.

All standard ANSI C disk operations are supported, making interfacing with existing code very simple indeed.


Overview of FAT16/32 library

Simultaneous Disk Access
FAT16/32 library can access files on unlimited number of disk volumes at the same time.

Unlimited Number of Files
FAT16/32 library can handle as many open files as required by the application.

Supports FAT16, and FAT32
FAT16/32 library supports the same FAT (File Allocation Table) formats as MS-DOS, Windows, and many other systems.

Supports Compact Flash
FAT16/32 library supports LBA (Logical Block Addressing) to read from disk drives and tested with many different Compact Flash cards.

Support for Fast Writes
FAT16/32 library can write large chunks of data at once making it to achieving the maximum possible data throughput for real-time writes.

Efficient Cache Support
FAT16/32 library will cache frequently accessed data such as a volume's FAT or directories. The application has full control over the size of the cache and how delayed write operations should be handled.

Optimised FAT operations
FAT16/32 library has its own native API consisting of about 20 functions highly optimised for maximum performance and control.

Compatible API
FAT16/32 library emulates about 32 file I/O related functions. These are written with the prefix of “fs_” to remove ambiguity with ANSI C Standard I/O functions.

Disk Format
FAT16/32 library supports FAT32 Disk Format according to the standards.

Performance Parameters

RAM requirements: xxkB minimum, typicall xxkB

Typical code space requirements: xxkB

Typical read speed: 10MB/s at xx% processor load (DM648 @900MHz)

Typical write speed: 8MB/s at xx% processor load (DM648 @900MHz)

FAT16/32 library Application Programming Interface

fs_InitFATFS - FS initializing function (should call before file operations)
fs_DoneFATFS - Close fs_FAT safely
fs_chdir - change directory
fs_getcwd - get current directory
fs_fopen - file open
fs_fclose - file close
fs_fcloseall - close all files
fs_fseek - seek to a specific place in the file given a starting position by 'whence'
fs_rewind - go to the beginning of a file
fs_ftell - get the current position of the file
fs_feof - check whether end of file
fs_fsize - get file size
fs_fgetpos - get current position
fs_fsetpos - set current position
fs_fread - read file
fs_fwrite - write file
fs_fwrite_fast - Write the maximum possible sectors at once
Limitations:
* Recommended to start with a new file (Partially written files may provide problems)
* Files with partially written clusters at end are not supported
* All writes restricted to begin at end of file

fs_fgetc - get character
fs_fputc - put character
fs_fgets - get string
fs_fputs - put string
fs_fflush - flush file buffers
fs_flushall - flush all file buffers
fs_remove - delete file
fs_mkdir - make directory
fs_rmdir - remove directory
fs_fstat - get statistics of a given file
fs_chmod - change file mode
fs_utime - change time of a given file
fs_filecount - return file count for given extension
fs_filename - return filename for given index
fs_init_file - Initialise file structure (need to call for every file structure before use)