SHDesigns: Embedded Systems Design, Consulting and Developer Resources

Page hits:

SHDesigns File system Libraries for Softools

These Libraries Do Not Work with Dynamic C

SHDesigns FAT Library:

SHDesigns Embedded File System Library (SHD/EFS):

Written for speed and ease of use. PC-Compatible file system. Supports FAT12, FAT16 and devices with no partition table. Uses Softools sfash.lib. Minimizes Flash wear. Cached reads and writes for speed. Stream interface. Stdio (FILE *) support. Supports RCM3700, RCM3300, SF1000 Flash chips Can use generic Atmel Serial Flash Chip Supports Atmel DataFlash Cards Supports MMC/Secure Digital Cards No cached data after files are closed Does not require battery-backed RAM Supports Long File Names Includes HTTP server sample Tested on RCM3300, RCM3700, Atmel DataFlash, MMC, Compact Flash and IDE. Includes source to library, driver source and example programs. Supports SHDesigns SPI-200 chip for fast data transfers. Tested with MMC/SD cards up to 2GB Purchase with MMC/SPI Adapter board and save $10:

Note: Not recommended where the FAT library will work  Written for speed and ease of use. Optimized for larger files. Excellent Flash wear prevention. File names up to 64 characters Can have multiple extensions. Subdirectories can be simulated. I.e. logfiles\daily.log is a valid file name. A search for logfiles\* would find all files in the simulated directory. Supports Large drives up to 128 Gig. Block, Stream and Stdio interfaces. Uses XMEM for file buffering and File data Uses Softools slfash.lib Supports RCM3700, RCM3300, SF1000 Flash chips Can use generic Atmel Serial Flash Chip Supports Atmel DataFlash Cards No cached data after files are closed Does not require battery-backed RAM Simple ATA interface library, easy to port to IDE or Compact Flash. Tested on RCM3300, RCM3700, Atmel DataFlash, MMC, Compact Flash and IDE. Includes binary library, driver source and example programs.

Comparison of File systems.

Feature List	SHD FAT	SHD/EFS	ZWorld FAT
Read Speed, 50k file, 512-byte reads	300.2kB/sec	226kB/sec	193kB/sec
Write Speed, 50k File, 512-byte writes	30.5kB/sec	29kB/sec	31.5kB/sec
File Names	up to 128 chars	64 char	8.3 only
Subdirectories	Yes	Emulated	Yes
Long File Name Support	Yes	Yes	No
Device Size	Up to 2 Gig	Up to 128 Gig	1 Gig?
PC-Compatible File system	Yes	No	No, non-standard partition table
Stdio support	Yes	Yes	No
Stream Support	Yes	Yes	No
Far data read/writes	No	Yes	Limited
Sample Root Code/const	2k	2k	17k
Sample Root Data	2.5k	4k	7.7k
Available Root space	43k	42k	19.3k
Sample program size	29K	35K	110K
ZServer/Http support	Via CGI function	No	Yes
Requires BBRAM	No	No	Yes
Flush command	Yes	Yes	Requires Unmount of Partition
Corruption due to power loss.	Open Files Truncated	Open Files Truncated	May recover last write. Often File System Corrupted.
MMC/SD Card Support	Yes	Future	With DC Version 9.5 and later
RCM3700/RCM3300/RCM3800 and SF1000 support	Yes	Yes	SF1000 requires custom driver settings
Atmel DataFlash Support	Yes	Yes	Requires Lib change.
RAM Filesystem Support	Yes	No	No
Compact Flash / IDE Support	Yes (sample drivers.)	Yes	No
Softools Support	Yes	Yes	No
License Cost	$75.00	$75.00	$149.00 (Now Free in 9.5x and up)
Free Updates	Yes	Yes	Yes
Full Source	Yes	Optional	Yes

ZW HTTP server support:

The ZW HTTP code is hardcoded to their FAT library. It does not allow long file names. Adding support for either of SHDesigns file systems would be a major rewrite of their code. The FAT library includes a CGI script that allows files to be served from the file system.

Test Parameters:

• All tests done on an RCM3300, no debug options, optimized for speed.
• Test program has code to display file list, read/write files and format device.
• kB/sec = Kilobytes/sec
• Stdio Support = supports fprintf(), fread(), fwrite()

File system Corruption:

All file systems were tested for corruption on a power loss. The ZW FAT corrupted the entire File system if the RAM was not battery-backed. Even with backup, loading a new program would somehow cause the partition to fail to mount.

The SHD/FAT Library would truncate files that were open for writing on a reset with files open.

The SHD/EFS library would truncate files that were open on write on a reset. SHD/EFS has no FAT table on disk. This data is rebuilt on reboot and is kept in RAM

MMC/Secure Digital Flash Card support Support

SHDesigns has tested an MMC interface on an RCM3200. This has worked well. Testing was done on a KingMax 128MB card.

MMC/SD is the best option for removable storage. It has distinct advantages:

• Small size, about 1/4 the size of a credit card. Mini and MicroSD even smaller.
• Inexpensive, only requires an MMC/SD connector added to your board.
• Low Pin Count. Only 4 signals + Power/ground. SPI Interface.
• Inexpensive readers available for read/write files from a PC.
• Write-Protect option on some cards.
• Very Low power requirements
• Fast interface, 20mbit/sec minimum (Rabbit only supports up to CLK/4 for SPI.)

MMC/SD Read/write speeds (SHD/FAT):

	Rabbit SPI	SPI-200
Read Speed	315 kB/sec	930 kB/sec
Write Speed	211.2 kB/sec	425 kB/sec

Tests done with RCM3200, 512-byte reads and writes.

MMC/SD provides much faster data transfer than the Atmel serial flash. The SPI-200 adds additional hardware accelleration due to reduced code and higher bit clock. MMC is also removable and can be read on a PC. An easy way to transfer files between a PC and a Rabbit board.

Compact Flash / IDE support:

A sample library is included for CF/IDE. It was used for testing only. IDE is 16-bit only. External hardware is needed for 16-bit read/writes. IDE Speeds of 500kbytes/sec and higher have been achieved with the IDE interface. CF is just as fast for read.