# FatFs - Generic FAT File System Module (R0.12c)

FatFs is a generic FAT/exFAT file system module for small embedded systems. The FatFs module is written in compliance with ANSI C (C89) and completely separated from the disk I/O layer. Therefore it is independent of the platform. It can be incorporated into small microcontrollers with limited resource, such as 8051, PIC, AVR, ARM, Z80, 78K and etc. Also Petit FatFs module for tiny microcontrollers is available here.

#### Features

- DOS/Windows compatible FAT/exFAT file system.
- Platform independent. Easy to port.
- Very small footprint for program code and work area.
- Various configuration options to support for:
  - Multiple volumes (physical drives and partitions).
  - Multiple ANSI/OEM code pages including DBCS.
  - Long file name in ANSI/OEM or Unicode.
  - exFAT file system.
  - RTOS envilonment.
  - Fixed or variable sector size.
  - Read-only, optional API, I/O buffer and etc...

### Application Interface

FatFs provides various file control functions for the applications as shown below.

- File Access
  - f_open - Open/Create a file
  - f_close - Close an open file
  - f_read - Read data
  - f_write - Write data
  - f_lseek - Move read/write pointer, Expand size
  - f_truncate - Truncate size
  - f_sync - Flush cached data
  - f_forward - Forward data to the stream
  - f_expand - Allocate a contiguous block to the file
  - f_gets - Read a string
  - f_putc - Write a character
  - f_puts - Write a string
  - f_printf - Write a formatted string
  - f_tell - Get current read/write pointer
  - f_eof - Test for end-of-file
  - f_size - Get size
  - f_error - Test for an error
- Directory Access
  - f_opendir - Open a directory
  - f_closedir - Close an open directory
  - f_readdir - Read an directory item
  - f_findfirst - Open a directory and read first item matched
  - f_findnext - Read a next item matched
- File/Directory Management
  - f_stat - Check existance of a file or sub-directory
  - f_unlink - Remove a file or sub-directory
  - f_rename - Rename or move a file or sub-directory
  - f_chmod - Change attribute of a file or sub-directory
  - f_utime - Change timestamp of a file or sub-directory
  - f_mkdir - Create a sub-directory
  - f_chdir - Change current directory
  - f_chdrive - Change current drive
  - f_getcwd - Retrieve the current directory and drive
- Volume Management
  - f_mount - Register/Unregister a work area of a volume
  - f_mkfs - Create an FAT volume on the logical drive
  - f_fdisk - Create logical drives on the physical drive
  - f_getfree - Get total size and free size on the volume
  - f_getlabel - Get volume label
  - f_setlabel - Set volume label

### Media Access Interface

Since the FatFs module is just a file system layer independent of platform and storage device. It is completely separated from the physical devices, such as memory card, harddisk and any type of storage device. The low level device control module is not a part of FatFs module and it needs to be provided by implementer. FatFs accesses the storage devices via a simple media access interface shown below. Also sample implementations for some platforms are available in the downloads.

- disk_status - Get device status
- disk_initialize - Initialize device
- disk_read - Read sector(s)
- disk_write - Write sector(s)
- disk_ioctl - Control device dependent functions
- get_fattime - Get current time

### Resources

The FatFs module is a free software opened for education, research and development. You can use, modify and/or redistribute it for personal projects or commercial products without any restriction under your responsibility. For further information, refer to the application note.

- Read first: FatFs module application note
- Community: FatFs User Forum
- FAT32 Specification by Microsoft↗ (The authorized document on FAT file system)
- The basics of FAT file system [ja]
- How to Use MMC/SDC
- Playing with FlashAir and FatFs
- Read SD card with FatFs on STM32F4xx devices by Tilen Majerle↗ (Quick and easy implementation for STM32F4-Discovery)
- Nemuisan's Blog↗ (Well written implementations for STM32F/SPI & SDIO and LPC4088/SDMMC)
- ARM-Projects by Martin THOMAS↗ (Examples for LPC2000, AT91SAM and STM32)
- Benchmark 1 (ATmega1284/20MHz with MMC via USART in SPI, CFC via GPIO)
- Benchmark 2 (LPC2368/72MHz with MMC via MCI)

FatFs Homepage