Algorithm For NAND Flash Bad Block Management And Design For Logical Layer Driver

Stepping into the 21st century, NAND Flash memory has been widely used in mobile portable devices and embbed systems. NAND Flash has become the mainstream of the storage medium of large capacity.Bad block is allowed existed when NAND Flash shipped and being used. Bad block management has always been the key point and difficult point in NAND Flash memory management. The traditional bad block management algorithm is no longer suitable for the NAND Flash of large capacity nowadays. So, it's in dire need of breaking through the traditional bad block management design ideology and of searching for the new bad block management algorithm and key technology. Replacing bad block and updating the logical to physical block mapping table are central to the bad block management. This thesis focuses on the bad block management algorithm and the design of logical layer driver in NAND Flash. The main research outputs are:(1)This thesis puts forward an optimal bad block management algorithm on the base of comprehensive analysis of bad block management of ST company. When a new bad block is encountered during writing or erasing a block, uses the dynamic bad block management to update the bad block table dynamicly.(2)Considering the situation that most of the popular embedded systems use FAT file system to manage NAND Flash memory, based on the dynamic bad block management, this thesis designs and implements NAND Flash logical layer driver, combining the operations that NAND Flash of new generation supports, which includes cache program,multi-page program, gives its concrete functions, also has verified the algorithm and driver on the platform of FPGA. This algorithm has been verified in HT3001 chip design, the chip has been taped out and is in volume production.Analyzed results indicate that the dynamic bad block management and logical layer driver can solve the bad block problems and reading-writing NAND Flash in using nand flash effectively. This thesis has important referenced signification in NAND Flash management of embedded system and mobile portable devices.