Flash File System ¦Ìcos-ii-based Research And To Achieve

With the development of the embedded technology and the lower price ofthe hardware, the storage ability of the embedded system improve rapidly. Thereare so many complicated data resources need to be manage in theembedded system. So the importance of the embedded file system become moreand more prominent. It was a necessity direction of the RTOS developping.The filesystem make the embedded system becoming easily management,developing andportable.Its standard interface make the system transfer be independent of thememory device.The embedded system can establish the complicated applicationprogram in the helping that the file system manage lots of data. Unlike the generalfile system, the embedded file system is based on the kernel of the real timeoperation system. The design of the embedded file system should not only satisfy allkinds of requirement needed by data storage but also adapt to the badly environmentand the memory physical characteristic. This work is focused on the research ofthe crash/powerdown safe,the average wear leveling and the garbage collection ofthe file system.In this paper,embedded file system FFS is developed on thebasis of the real time operation systemμCOS-Ⅱand adopting FAT type andadapting to NandFlash memory. The FFS can be divided into three levels: thedrivers of the devices, the logical layer of the file system and the management layerof the file system.The deivers of the device designed the three interface functionsthat are page read,page write and block erase for strengthening the codeportable.The logical layer transform operating of the management layer to physicaloperating,for example,managing memory space,managing direntry of file, mapingaddress,writing file,reading file,deleting file,distributing the spare block,collectinggarbage block and referring these task to the drivers layer.The management layer ofthe file system provide with the standard interface to use the file management.This paper is based on the through analysis ofμCOS-Ⅱ,FAT file systemand flash characteristic to design the whole system frame, the reliability of theflash,the average wear-leveling, the garbage collecting and implementing FFS.These design improved the capability and the reliability of the file system.