ELM - Generic FAT Files System Module

FatFs module is an experimental project to implement 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 and each file. Suitable for fast multiple file accsess.
Optimized for 8/16 bit microcontrollers.
Low memory consumption
Supports FAT12, FAT16(+FAT64) and FAT32 (FAT64: FAT16 in 64KB/cluster)
Supports 8.3 format file name and NT lower capital flags
Supports two partitioning formats: FDISK (only 1st primariy partition) and SFD (only 512B/sector)

Features of Tiny-FatFs Module

Only a common buffer for FAT and each file to reduce memory consumption.
Optimized for 8/16 bit microcontrollers.
Low memory consumption, suitable for small memory system (1KB)
Supports FAT12 and FAT16(+FAT64)
Supports 8.3 format file name and NT lower capital flags
Supports two partitioning formats: FDISK (only 1st primariy partition) and SFD (only 512B/sector)

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.)	8526	6042
Program (R/O cfg.)	4172	3402
Static Work Area	2
Dynamic Work Area	548 + 540 * <files>

Tiny-FatFs
Section	Std cfg.	Min cfg.
Program (R/W cfg.)	7138	4862
Program (R/O cfg.)	3542	2778
Static Work Area	2
Dynamic Work Area	540 + 24 * <files>

Application Interface

FatFs/Tiny-FatFs module provides following functions.

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_mountdrv - Force Initialized FatFs Module

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.