基于嵌入式USB主机的飞控数据记录器设计及实现

针对无人机飞行训练的需要,设计了一种基于嵌入式USB主机的飞行数据固态记录器。介绍了飞控数据固态数据器的工作原理、三星NAND FLASH芯片(K91G08U0M)的嵌入式文件系统和嵌入式USB主机的软件设计。实验证明,该数据记录器设计方案可行,且与传统的数据记录器相比:一方面,具有NAND FLASH存储块管理的FAT文件系统,实现对NAND FLASH数据存储的保护;另一方面,实现了USB主机接口直接与大容量设备进行文件和数据交换,极大地方便数据卸载。     

嵌入式文件系统在移动数据采集器中的实现

介绍基于Flash存储器的嵌入式文件系统的基本结构和特点,设计了一个应用于手持式移动数据采集器的方案。采用ATMega128和8MB的AT45DB081来实现,通过对文件系统数据存储过程的分析,给出了浮动位置法提高可靠性和交换缓冲区法降低系统资源开销,并已在实际应用中得到了验证。     

Non-Volatile Memories for Removable Media

NAND Flash memory has become the preferred nonvolatile choice for portable consumer electronic devices. Features such as high density, low cost, and fast write times make NAND perfectly suited for media applications where large files of sequential data need to be loaded into the memory quickly and repeatedly. When compared to a hard disk drive, a limitation of the Flash memory is the finite number of erase/write cycles: most of commercially available NAND products are guaranteed to withstand 10$^{5}$ programming cycles at most. As a consequence, special care (remapping, bad block management algorithms, etc.) has to be taken when hard-drive based, read/write intensive applications, such as operating systems, are migrated to Flash-memory based devices. One of the basic requirements of the consumer market for data storage is the portability of stored data from one device to the other. Flash cards are the actual solution. A Flash card is a nonvolatile “system in package” in which a NAND Flash memory is embedded with a dedicated controller. This paper presents the basic features of the NAND Flash memory and the basic architecture of Flash cards. We provide an outlook on opportunities and challenges of future Flash systems.      

The Real-Time Compression Layer for Flash Memory in Mobile Multimedia Devices

Flash memory is used for storage in mobile multimedia and embedded systems such as mobile phones, digital cameras, and MP3 players because of its small size, light weight, nonvolatile operation, vibration resistance, high capacity, and low power consumption. Data compression is one effective method for increasing capacity and reducing data transfer, however real-time performance is necessary for mobile multimedia device applications. We propose a mechanism that uses contiguous packing and a read/write ping-pong buffer along with the X-match and run-length compression/decompression algorithm to create a real-time compression layer. Compared to the internal packing scheme and best-fit method of Yim et al., our mechanism increases the compression ratio, improves the write response time by 60%, and stabilizes the read response time to make it suitable for real-time applications.     

FTL algorithms for NAND-type flash memories

Flash memory is being rapidly deployed as data storage for embedded devices such as PDAs, MP3 players, mobile phones and digital cameras due to its low electronic power, non-volatile storage, high performance, physical stability and portability. The most prominent characteristic of flash memory is that prewritten data can only be dynamically updated via the time consuming erase operation. Furthermore, every block in flash memory has a limited program/erase cycle. In order to manage these issues, the flash memory controller can be integrated with a software module called the flash translation layer (FTL). This paper surveys the state-of-art FTL algorithms. The FTL algorithms can be classified by the complexity of the algorithms: basic and advance. Furthermore, they can be classified by their corresponding tasks: performance enhancement and durability enhancement. The FTL algorithms corresponding to each classification are further broken down into various schemes depending on the methods they adopt. This paper also provides the information of hardware features of flash memory for FTL programmers.     

基于VDK的嵌入式文件系统实现

针对实验室开发的基于Nand Flash的高速、大容量存储系统,阐述了利用BF537及其集成开发环境Visual DSP++的内核VDK,实现嵌入式文件系统的具体方案。同时简要介绍了通过虚拟地址映射和坏块标记的方法,来管理Nand Flash芯片中的坏块,以此实现文件系统的地址传输。     

一种基于差分进化的Flash文件系统垃圾回收算法

垃圾回收算法对于Flash文件系统具有十分重要的意义.本文针对已有垃圾回收算法在存储容量剩余较小时垃圾回收性能急剧下降进而影响写入速率的问题,采用最优化方法,提出并实现了一种基于差分进化的垃圾回收算法.该算法能够使得垃圾回收的代价均匀化,在保证性能和损耗均衡的前提下,减少擦除次数,延长Flash寿命.实验结果验证了该算...     

提高测速系统存储速率及可靠性的方法

针对破片测速系统对数据存储速率快、可靠性高的要求,提出了基于流水线设计的数据快速存储方案和基于FPGA片内建立虚拟存储器来管理FLASH坏块列表的方法。 该方法有效降低存储系统的平均响应时间,将数据流的存储速率提高了近2倍;并且有效地屏蔽FLASH的坏块,保证了破片数据存储的可靠性。 试验表明：该方法使数据存储速率提高到2.4Mbytes/S,为原始速率的3倍。数据存储的可靠性为100%。     

WinCE系统上大容量NAND Flash驱动设计与优化

NAND Flash具有存取速度快、体积小、成本低的特点,适宜作为海量数据的存储设备.本文设计了一种大容量NAND FLASH在WinCE系统上的实现方案.通过动态扇区分配、坏块管理和数据缓存等技术,提高了Flash驱动的安全性、稳定性和读写性能.经过优化后,平均读取速度2Mbyte/s,写入速度3Mbyte1/s.整个驱动通过了微软测试工具CETK(WinCE Test kit)的测试.     

K9MDG08U5M在航拍相机中的应用

存储系统在现代数字系统尤其是在便携设备中具有重要地位,它的容量、体积等指标也有严格要求,对此文中提出了一种新的解决方案。介绍Samsung公司的128Gbit位闪速存储器K9MDG08U5M的特性和主要功能,详细讨论其在高分辨率航拍相机系统中的硬件设计和相关的软件编程。该系统经过实验验证：错、漏数据现象极少,并可以方便地应用于各种图象、语音等数据存储系统。     

一种高可靠大容量星载存储器的设计与研究

凭借着存储密度大和存储速率高的特点,基于NANDFlash的大容量存储器在星载存储领域得到了广泛的应用,由于NAND Flash本身存在缺陷,基于NAND Flash的大容量存储器在恶劣环境下的可靠性难以保证.提出了通过FPGA设计SRAM对关键数据三模冗余读取和缓冲、NAND Flash阵列热备份和数据的回放校验以及合理的坏块管理等措施,实现了高可靠性的大容量存储器.实验说明该系统不会因为外在偶然因素而造成数据的不完整,而且整个存储系统的成本开销相对于目前的星载存储器也非常低.     

Performance study of iSCSI-based storage subsystems

iISCSI is emerging as an end-to-end protocol for transporting storage I/O block data over IP networks. By exploiting the ubiquitous Internet infrastructure, iSCSI greatly facilitates remote storage, remote backup, and data mirroring. This article evaluates the performance of two typical iSCSI storage subsystems by measuring and analyzing block-level I/O access performance and file-level access performance. In the file-level performance study, we compare file access performance in an NAS scheme with that in an iSCSI-based SAN scheme. Our test results show that Gigabit Ethernet-based iSCSI can reach very high bandwidth, close to that of a direct FC disk access in block I/O access. However, when the iSCSI traverses through longer distance, throughput relies heavily on the available bandwidth between the initiator and the target. On the other hand, the file-level performance shows that iSCSI-based file access (SAN scheme) provides higher performance than using NFS protocol in Linux and SMB protocol in Windows (NAS scheme). However, the advantage of using iSCSI-based file accesses decreases as the file size increases. The obtained experimental results shed some light on the performance of applications based on iSCSI storage.     

一种基于FAT文件系统的NAND Flash坏块处理方法

NAND Flash具有高存储密度和高存储速率的特点,在嵌入式系统领域得到了广泛应用.但其固有的擦除机制和存在有坏块这一致命弱点,成为其在应用中的主要障碍.本文提出了一种应用于FAT文件系统上的坏块处理方法,使用Flash上其他的空闲块或者空闲空间来代替坏块,并将坏块在FAT表中作出标记以后不作使用.这种方法彻底屏蔽了坏块对上层应用的影响,并对存储介质没有造成任何不良影响,从而很好地克服了上述障碍.工程项目中的应用证明了其较高的可靠性.     

基于FRAM和Flash混合数据存储方案的氨气检测仪研究与设计

针对某些嵌入式系统中数据存储量大且改写频繁,以及Flash存储器寿命有限的问题,结合氨氮检测仪的实际应用,提出了一种基于铁电存储器和Flash的混合数据存储方案。给出了基于主控制器STM32F407的氨氮检测仪的整体设计,着重分析了混合数据存储系统的软硬件设计,并在此基础上制订了数据存储协议,提高存储效率。同传统的存储方案相比,基于FRAM和Flash的混合数据存储系统提高了仪器的数据存储速度和效率,延长了使用寿命,提高了仪器整体的稳定性和可靠性。     

基于NAND Flash的海量存储器的设计

针对存储系统中对存储容量和存储带宽的要求不断提高,设计了一款高性能的超大容量数据存储器。该存储器采用NAND Flash作为存储介质,单板载有144片芯片,分为3组,每组48片,降低了单片的存储速度,实现了576 Gbyte的海量存储。设计采用FPGA进行多片NAND Flash芯片并行读写来提高读写带宽,使得大容量高带宽的存储器得以实现。针对NAND Flash存在坏块的缺点,提出了相应的管理方法,保证了数据的可靠性。     

基于嵌入式电池检测的文件系统的实现

为了有效地管理嵌入式电池检测系统的历史数据和运行数据,设计了基于嵌入式NAND Flash存储器的文件系统。充分利用NAND Flash存储器的特点,通过在内存中建立索引表,采用多种策略的无效块回收机制等方式,有效地降低了存储器的擦除次数,均衡了存储器的磨损,提高了文件的检索速度。该文件系统在μC／OS-Ⅱ操作系统中予以实现,并进行了性能测试。     

基于闪存阵列的缓存容量确定方法

针对低成本、小型化的数据记录系统的应用,提出了一种数据缓存技术解决方案。存储模块是由闪速存储器芯片（NAND Flash）组成的存储阵列,以FPGA为载体的SOPC系统作为存储模块的控制核心。分析存储系统的结构及控制平台的实现过程,并对系统工作原理及并行分路技术进行讨论。深入研究Flash阵列的存储过程,提出最小FIF...     

基于ARM的SD卡文件系统设计

ARM以其高性能、低功耗、易扩展的特点成为了嵌入式系统全球领先的16／32位RISC微处理器内核。但由于嵌入式系统中数据量的增加,对存储设备的要求也越来越高。在众多存储卡中,SD卡占有越来越多的市场份额。丈中介绍了基于ARM7平台设计的SD卡读写系统,包括SD卡与LPC2292的硬件接口电路设计及相应的软件程序设计。     

Improving the Reliability of MLC NAND Flash Memories Through Adaptive Data Refresh and Error Control Coding

NAND Flash memory has become the most widely used non-volatile memory technology. We focus on multi-level cell (MLC) NAND Flash memories because they have high storage density. Unfortunately MLC NAND Flash memory also has reliability problems due to narrower threshold voltage gap between logical states. Errors in these memories can be classified into data retention (DR) errors and program interference (PI) errors. DR errors are dominant if the data storage time is longer than 1 day and these errors can be reduced by refreshing the data. PI errors are dominant if the data storage time is less than 1 day and these errors can be handled by error control coding (ECC). In this paper we propose a combination of data refresh policies and low cost ECC schemes that are cognizant of application characteristics to address the errors in MLC NAND Flash memories. First, we use Gray code based encoding to reduce the error rates in the four subpages (MSB-even, LSB-even, MSB-odd, LSB-odd) of a 2-bit MLC NAND Flash memory. Next, we apply data refresh techniques where the refresh interval is a function of the program/erase (P/E) frequency of the application. We show that an appropriate choice of refresh interval and BCH based ECC scheme can minimize memory energy while satisfying the reliability constraint.     

用于视频监控的便携式数字录像机设计

针对各类视频监控和记录的应用特点和要求,设计并研制了一个基于嵌入式微处理器、专用视频压缩芯片及大容量IDE硬盘或电子盘的便携式数字录像机.讨论了系统结构设计及各功能模块的电路选择,介绍了关键接口电路设计和系统软件设计.系统采用单一直流电源供电,为了方便视频压缩数据的存取,设计了专用的文件系统.测试结果表明,系统性能良好、功能灵活,功耗低、集成度高、独立、便携,非常适合各类视频监控和记录应用.