空间图像存储器NAND Flash的可靠性

摘要

For the unreliable data storage problem caused by bad blocks and single event upsets for the NAND flash memory in a space camera, this paper explores a bad block management strategy and an error correction algorithm. Firstly, the bad block management strategy based on parallel double-traverse mechanism was proposed by analyzing the characteristics of structure and operation for the NAND flash memory, the design ideas of the double traverse mechanism were described and its effectiveness was analyzed. Then, the error correction algorithm based on the shortened code RS (246, 240) and RS (134,128) in the field GF (28) was proposed, and the encode/decode algorithm and corresponding circuits were given. Finally, the verification experiments on an image storage platform in the prototype machine for a space multi-spectral camera were carried out. The experimental results show that the bad block management strategy can fast and reliably dispose the bad block events, and the algorithm can identify the bad blocks in one system clock period. The error correction algorithm can correct 27 B error within the 2 KB/page with a encoder speed of 72. 53 MBps and a decoder speed of 54. 26 MBps. Proposed stratege effectively solve the problem of unreliable recording data in the NAND flash memory.%针对空间相机中的图像存储器NAND Flash由于坏块和单粒子翻转导致存储数据不可靠的问题,研究了Flash坏块的管理策略和纠错算法.分析了Flash结构和工作特点,提出了基于并行双遍历机制的坏块管理策略,阐述了双遍历机制的设计思想并分析了它的有效性.在分析Flash结构和纠错特点的基础上,提出了在域GF(28)上的缩短码RS(246,240)+RS(134,128)纠错算法,并说明了编解码算法思想和实现电路.最后,在一空间多光谱相机样机的图像存储设备上进行了试验验证.结果表明,管理策略能快速可靠地处理坏块事件,每次操作仅需1个系统时钟周期即可完成坏块判断.纠错算法在2 KB/page内可以纠正27 B错误,编码速度达到72.53 MBps,解码器速度达到54.26MBps.提出的管理策略和纠错算法有效地解决了Flash数据存储的不可靠问题.