ELM - Generic FAT Files System Module

FatFs module is an experimental project to implement a FAT file system to small embdded systems. The FatFs module is written in compliance with ANSI C, therefore it is independent of hardware architecture. It can be incorporated into most small microcontrollers, such as 8051, PIC, AVR, H8, Z80 and etc..., without any change. I created two modules in different configurations in consideration of various use. To use the FatFs module, low level disk I/O functions for each media must be provided by user.

Features of FatFs Module

Separated buffer for FAT/DIR and each file, suitable for fast multiple file accsess.
Supports FAT12, FAT16(+FAT64) and FAT32 (FAT64: FAT16 in 64KB/cluster)
Supports multiple drives.
Supports 8.3 format file name and NT lower capital flags
Supports two partitioning rules: FDISK (only 1st primariy partition) and SFD
Optimized for 8/16 bit microcontrollers.

Features of Tiny-FatFs Module (different to FatFs)

Very low memory consumption, suitable for small memory system (RAM:1KB)
Supports only single drive.

Memory Usage

There are some configuration options to eliminate unused functions to reduce module size. Following tables are the memory consumption in unit of byte on avr-gcc.

FatFs
Section	Std cfg.	Min cfg.
Program (R/W cfg.)	8574	6094
Program (R/O cfg.)	4268	3494
Static Work Area	2 + 2*<drives>
Dynamic Work Area	550<drives> + 544<files>

Tiny-FatFs
Section	Std cfg.	Min cfg.
Program (R/W cfg.)	7164	4890
Program (R/O cfg.)	3660	2946
Static Work Area	4
Dynamic Work Area	542 + 28*<files>

Application Interface

FatFs/Tiny-FatFs module provides following functions.

f_mount - Register/Unregister a Work Area
f_open - Open/Create a File
f_close - Close a File
f_read - Read File
f_write - Write File
f_lseek - Move R/W Pointer
f_sync - Flush Cached Data
f_opendir - Open a Directory
f_readdir - Read a Directory Item
f_getfree - Get Free Clusters
f_stat - Get File Status
f_mkdir - Create a Directory
f_unlink - Remove a File or Directory
f_chmod - Change Attribute
f_rename - Rename/Move a File or Directory
f_mkfs - Create a File System on the Drive

Disk I/O Interface

Since the FatFs/Tiny-FatFs module is completely separated from disk I/O layer, it requires following functions to lower layer to read/write physical disk and to get current time. These functions must be provided by user.

disk_initialize - Initialize disk drive
disk_status - Get disk status
disk_read - Read sector(s)
disk_write - Write sector(s)
get_fattime - Get current time

Resources

The FatFs/Tiny-FatFs module is a free software and is opened for education, research and development. You can use, modify and/or republish it for personal, non-profit or profit use without any restriction under your responsibility.