is designed to interface to any standard DOS file system compatible
device through standard interface routines (read_sector(),
write_sector() etc.). Provided with FAT is a set of reference drivers
for quick and risk free integration.
MultiMediaCard, Secure Digital and SDHC Cards
is probably the simplest method to add a DOS compatible file media to
your embedded device. HCC provide a range of drivers for interfacing to
SD, SDHC and MMC cards including standard SPI implemented in either
hardware or software. HCC provide hardware referecnce designs for
Compact Flash Cards
Compact Flash cards
require a more complex communication with a PC compatible media but
offers performance advantages because of the wider data bus thus
generally a higher throughput is achieved and in many cases a reduced
CPU load. HCC also provide hardware design information and CPLD logic
Hard Disk Drives
Sample Driver and
reference designs have been created for interfacing an IDE HDD to a FAT
file system. Also provided in the file system are caching options which
are essential when using a HDD. The caching mechanisms combined with
the efficiency of FAT and its mainly zero-copy reads and writes gives
the best possible performance when implementing a HDD on an embedded
Two types of driver are provided for use with all types of Atmel DataFlash.
A simple driver which does a direct mapping of Dataflash pages to the logical disk is provided as standard.
A more complex driver (DFML) which handles the DataFlash in a more reliable way may be ordered separately.
HCC have a complete Flash Translation Layer product (FTL) which may be ordered with FAT and which provides a complete, reliable interface for NAND flash.
RAM drive is provided as standard and is partuicularly useful in
getting a system up and running without any hardware dependencies.
HCC are always adding to their list of supported devices and will also develop specific drivers upon request - contact Nohau to discuss your requirements. HCC also provide bespoke development services
is designed to be easily portable - it has very few host system
dependencies. It is tested on several commercial RTOSs and also in a
stand-alone system with no RTOS. We are not aware of any RTOS it cannot
be easily ported to.
All the code is supplied in ANSI
compliant 'C', is built on 4 different development environments and run
through a syntax checker to ensure the highest level of compatibility.
Also supplied with the system is sample application code
(HTTP server and and FTP server) for easy exercise of the system - and
sample drivers for different media types with clear reference to their
The Developer's Guide gives detailed information on all
aspects of porting and indicates clearly the areas which may need to be
modified for a particular host system. In particular, the host system
- real time clock for time/date information - necessary if time/date information is to be stored with files written.
- random number - serial number generation during format - recommended only if formatting of media is required.
- semaphores for mutual exclusion - only required in a pre-emptive system.
HCC is also experienced to provide customised design and development work for your specific project.
Standard File API
General File System Functions
||Get File System Version Number
||Initialise a Volume
||Removes a Volume from the System
||Gets Number of Active Volumes
||List the Active Volumes
||Mount a Drive
||Format a Drive
||Hard Format a Drive
||Get Usage Information From a Drive
||Get Current Drive Number
||Change Current Drive
||Set the Label on a Volume
||Get the Label on a Volume
||Get Current Working Directory
||Get a Drives' Current Working Directory
||Make a Directory
||Remove a Directory
File Access Functions
||Open a File
||Close a File
||Write ro a File
||Read from a File
||Set Position in a File
||Get Current File Position
||Check if at End of File
||Move to Start of File
||Put a Character to a File
||Get a Character from a File
||Truncates a File
File Control Functions
||Rename a File of Directory
||Delete a File or Directory
||get the Current Length of a File
||Find a File or Directory in the Specified Path
||Find Next File or Directory in the Specified Path
||Set the Time and Date on a File or Directory
||Get the Time and Date from a File or Directory
||Set the Attributes on a File or Directory
||Get the Attributes from a File or Directory
Note: Although these functions have standard call formats, their names have
been prefixed differently to the standard file function definitions to
avoid compiler warnings and conflicts when working on systems with
another standard API installed. The developer can change these names
Unified API for EFFS-STD and EFFS-FAT
developers who require failsafe access to their NOR and NAND targeted
filesystems (EFFS-STD) and access to their PC compatible devices
(EFFS-FAT) we provide a Unified API.
The Unified API allows both file systems to be accessed
through a single interface - seemlessly giving all the advantages of
the failsafe system and the PC compatible system. The two systems work
entirely independently and a wrapper layer is provided to manage all
file system calls. This ensures that neither system's performance is
influenced by the alternate system.
The Unified API is provided free of charge to customers using bothe EFFS-FAT and EFFS-STD on a product.
file systems were not designed to be completely failsafe. Unexpected
power-loss can cause a variety of errors including lost directories,
lost chains, or damaged files.
To overcome these limitations HCC also provide a
checkdisk utility for use on your target system which may be used to
fix/recover from conditions which may occur. The checkdisk utility
ensures that the drive is returned to a usable state and allows the
recovery of lost data.
Some of the errors the checkdisk utility can handle
include lost-chains, cross-linked chains, invalid file lengths, damaged
directory entries, damaged FAT entries. It will also give the user the
option of recovering lost files.
A standard PC based checkdisk utility would use
considerable resources on an embedded system. This utility has been
specifically engineered to use minimal resources and resolve all issues
that may occur when using EFFS-FAT.
- Compact Flash Cards
- SD, SDv2 and SDHC Cards
- Hard disk drive
- RAM drive
- USB mass storage
- USB MTP (Media Transfer Protocol)
- NAND flash
- Atmel DataFlash