一种改进的SPI接口设计与实现

串行外设接口(SPI)总线系统是一种应用广泛的同步串行通信的外设接口。为满足微处理器之间频繁快速的数据交换,设计了一种改进的SPI。该SPI采用一个16 bit复用移位寄存器,且内置2个32 bit先入先出存储器(FIFO)以实现SPI高速有效的数据通信,提高了总线整体效率。采用硬件描述语言Verilog HDL设计并实现了SPI模块。仿真结果表明,该SPI接口能够支持多种工作模式和通信方式,提高总线效率,加快数据传输。     

TMS320F240型DSP的SPI口的扩展

以DSP之间的相互扩展和扩展串行EEPROM为例，讨论了TI公司的TMS320F240型DSP的串行外设接口（SPI）模块的功能扩展。     

AVR单片机的SPI串行通信的应用

SPI(Serial Peripheral Interface——串行外设接口)串行通信简单实用,控制方便,通信速率快。作为主机传输,它的传输速率最高可达单片机工作频率的二分之一,作为从机则最高可达单片机工作频率的四分之一。文章分析了基于AVR单片机的SPI串行通信原理,并给出SPI串行通信程序实例。     

数字信号处理器与串行EEPROM的接口设计

介绍了串行电擦除可编程只读存储器93LC56A的性能、接口时序及DSP芯片TMS320F240串行外设接口(SPI)模块的主要特点。针对这两种接口的时序配合问题，给出了从接口电路到软件设计的解决方案，并在程序实例的基础上进行了深入的分析。     

SPI串行总线接口的Verilog实现

集成电路设计越来越向系统级的方向发展，并且越来越强调模块化的设计。SPI（Serial Peripheral Bus）总线是Motorola公司提出的一个同步串行外设接口，容许CPU与各种外围接口器件以串行方式进行通信、交换信息。本文简述了SPI总线的特点，介绍了其4务信号线，SPI串行总线接口的典型应用。重点描述了SPI串行总线接口在一款802．11b芯片中的位置，及该接口作为基带和射频的通讯接口所完成的功能，并给出了用硬件描述语言Verilog HDL实现该接口的部分程序。该实现已经在Modelsim中完成了仿真，并经过了FPGA验证，最后给出了仿真和验证的结果。     

利用SPI为C805IF单片机扩展数据存储

本文介绍了一种利用串行外设接口(SPI)为SOC单片机C8051F扩展大容量数据存储器的设计方案，并给出软件流程图和示例。该方案充分利用了SPI的功能，在极少地占用单片机引脚的情况下，实现了数据存储器的扩展。     

利用SPI为C8051F单片机扩展数据存储

本文介绍了一种利用串行外设接口(SPI)为SOC单片机C8051F扩展大容量数据存储器的设计方案,并给出软件流程图和示例.该方案充分利用了SPI的功能,在极少地占用单片机引脚的情况下,实现了数据存储器的扩展.     

利用SPI为C8051F单片机扩展数据存储

本文介绍了一种利用串行外设接口(SPI)为SOC单片机C8051F扩展大容量数据存储器的设计方案,并给出软件流程图和示例。该方案充分利用了SPI的功能,在极少地占用单片机引脚的情况下,实现了数据存储器的扩展。     

基于S3C6410与FPGA通讯的SPI接口驱动设计

SPI总线系统是一种同步串行外设接口,能与外设以串行方式进行通信。介绍Windows CE6.0的SPI驱动程序结构及SPI中断处理过程,实现与FPGA通讯的SPI接口驱动设计。     

单线网络控制远程SPI外设

有许多兼容单线的外设可供利用．但对于缺乏单线能力的外设而言,图1中的电路描绘了一种实现方式。该例子通过单线网络和兼容SPI（串行外设接口）的显示器控制器来控制远程LED显示器。     

Improved LUT Technique for HPA Nonlinear Pre-Distortion in OFDM Systems

In this paper, we focus on the Look-up Table (LUT) technique for the compensation of HPA nonlinear distortion. An improved LUT method is proposed with better performance compared with conventional LUT technique in terms of convergence speeds, BER and total degradation (TD). It can get over 8 dB gain in out-of-band spectrum re-growth suppression and about 0.3 dB BER performance gain than conventional LUT technique with the same iteration times. Also, we propose an actual application of HPA with pre-distorter in OFDM transmitter. Ai Bo was born in Shannxi Province in China on February 7, 1974. He received a BSc. Degree from Engineering Institute of Armed Police Force in 1997, a Master and Dr. degree from Xidian University in 2002 and 2004 in China respectively, and now working as a post dr. in Dept. of E&E, state of key lab. on microwave and digital communications in Tsinghua University in China. He has once participated in the key research project on HDTV in TEEG (Team of Engineering Expert Group) of China. He is an editorial committee member of journal of “Computer Simulations”, “Information and Electronic Engineering”, an IEEE member and a senior member of Electronics Institute of China (CIE). He has published over 60 scientific papers in his research area till now. His current interests are the research and applications of OFDM techniques with emphasis on synchronization and HPA linearization techniques. Yang Zhi-Xing graduated from Tsinghua University, P.R. China in 1970. He is now a Professor and Deputy Director of State Key Lab. on Microwave and Digital Communication at the Department of Electronic Engineering and the Director of the DTV R&D Center in Tsinghua University. As a DTV technical expert for the Chinese government, Professor Yang has also been a member of the DTV standardization Committee of China and a leader of the DTV Standardization Harmonizing Group in Ministry of Information Industry of China. His major research interests include broadband information transmission technologies and DTV broadcasting systems. Pan Chang-Yong received the B.S. and M.S. degrees from the Department of Electronic Engineering in Tsinghua University, P.R. China, in 1996 and 1999, respectively. He is now an associate professor in the Department of Electronic Engineering and a member of the DTV R&D Center in Tsinghua University. His research interests are in the areas of broadband wireless transmission systems and satellite communications. Zhang Tao-Tao was born in Shandong Province in China in 1982, he received BSc. degree from Tsinghua University in 2004 and now pursing his Master degree in Dept. of E&E, state of key lab. on microwave and digital communications in Tsinghua University in China. His research interests is the power amplifier linearization techniques. Wang Yong was born in Shannxi Province in China in 1976. He received a BSc., a Master and a Dr. Degree from Xidian University in China in 1997, 2002 and 2005, respectively, and now is an associate professor in Xidian University. He has once participated in the key research project on HDTV in TEEG (Team of Engineering Expert Group) in China and is an IEEE Member. His interests are broadband multimedia communications. Ge Jian-Hua was born in September, 1961 in JiangSu Province in China. He received the B.Sc., Master and Ph.D. degree from Xidian University in 1982, 1985 and 1989, respectively. He is now the professor in both Xidian University in Xi’an and Shanghai Jiaotong University in Shanghai. He is the senior member of Chinese Electronics Institute. He has won lots of scientific and technical prizes in China and published many papers. His interests are transmission communications and web security.     

UMTS及EPC网络QoS机制的研究

随着社会的发展,用户对业务质量的需求也日益提高,为此3GPP组织加强了对QoS的研究,在UMTS阶段引入了端到端QoS机制,并在LTE阶段对QoS机制进行了扩展和增强,目前QoS的研究是3GPP研究的一个热点。本文对3GPP移动通信网QoS演进进行了介绍,分析了UMTS和EPC网络的QoS实现机制,并对两种QoS实现机制进行了分析。     

中国地区云量和云光学厚度的分布与变化趋势

利用最新的1983~2009年国际卫星云气候计划（ISCCP） D2月平均资料集,得到了中国地区总云量、低云量、中云量、高云量与云光学厚度的分布与变化趋势,结果表明：中国总云量和中云量呈现南多北少的分布,青藏高原地区高云量较大而低云量很小;总云量和中云量在东部呈增加趋势,西部呈减小趋势,低云量和高云量在大部分地区呈减小趋势。从不同季节来看,春季和秋季北方总云量增加,西部总云量减小;夏季大部分地区总云量增加,冬季大部分地区总云量减少。云的光学厚度呈现南多北少的分布,且在大部分地区呈增加趋势。同时利用中分辨率成像光谱仪（MODIS）资料分析了2001~2013年间中国不同污染地区总云量与云光学厚度的分布及变化趋势的异同,结果表明：中国不同污染地区云量与云光学厚度呈现不同的分布和变化规律。     

高校固定资产管理中云计算技术的应用探讨

随着时代的发展,国家对人才的需求量不断增加,并且对人才培养的要求越来越高。高校作为人才输出的重要基地,人们对高等教育的重视程度不断加深,尤其是近年来高校在发展的过程中其规模也在不断的扩展,导致固定资产管理中的一些问题逐渐凸显出来。本文就固定资产管理中存在的问题进行分析,进一步探讨云计算技术在高校固定资产管理中的应用。     

Performance of a burst-frame-based CSMA/CA protocol: Analysis and enhancement

In this paper, we develop an analytical model to evaluate the delay performance of the burst-frame-based CSMA/CA protocol under unsaturated conditions, which has not been fully addressed in the literature. Our delay analysis is unique in that we consider the end-to-end packet delay, which is the duration from the epoch that a packet enters the queue at the MAC layer of the transmitter side to the epoch that the packet is successfully received at the receiver side. The analytical results give excellent agreement with the simulation results, which represents the accuracy of our analytical model. The results also provide important guideline on how to set the parameters of the burst assembly policy. Based on these results, we further develop an efficient adaptive burst assembly policy so as to optimize the throughput and delay performance of the burst-frame-based CSMA/CA protocol. Kejie Lu received the B.E. and M.E. degrees in Telecommunications Engineering from Beijing University of Posts and Telecommunications, Beijing, China, in 1994 and 1997, respectively. He received the Ph.D. degree in Electrical Engineering from the University of Texas at Dallas in 2003. In 2004 and 2005, he was a postdoctoral research associate in the Department of Electrical and Computer Engineering, University of Florida. Currently, he is an assistant professor in the Department of Electrical and Computer Engineering, University of Puerto Rico at Mayagüez. His research interests include architecture and protocols design for computer and communication networks, performance analysis, network security, and wireless communications. Jianfeng Wang received the B.E. and M.E. degrees in electrical engineering from Huazhong University of Science and Technology, China, in 1999 and 2002, respectively, and the Ph.D. degree in electrical engineering from University of Florida in 2006. From January 2006 to July 2006, he was a research intern in wireless standards and technology group, Intel Corporation. In October 2006, he joined Philips Research North America as a senior member research staff in wireless communications and networking department. He is engaged in research and standardization on wireless networks with emphasis on medium access control (MAC). Dapeng Wu received B.E. in Electrical Engineering from Huazhong University of Science and Technology, Wuhan, China, in 1990, M.E. in Electrical Engineering from Beijing University of Posts and Telecommunications, Beijing, China, in 1997, and Ph.D. in Electrical and Computer Engineering from Carnegie Mellon University, Pittsburgh, PA, in 2003. Since August 2003, he has been with Electrical and Computer Engineering Department at University of Florida, Gainesville, FL, as an Assistant Professor. His research interests are in the areas of networking, communications, multimedia, signal processing, and information and network security. He received the IEEE Circuits and Systems for Video Technology (CSVT) Transactions Best Paper Award for Year 2001, and the Best Paper Award in International Conference on Quality of Service in Heterogeneous Wired/Wireless Networks (QShine) 2006. Currently, he serves as the Editor-in-Chief of Journal of Advances in Multimedia, and an Associate Editor for IEEE Transactions on Wireless Communications, IEEE Transactions on Circuits and Systems for Video Technology, IEEE Transactions on Vehicular Technology, and International Journal of Ad Hoc and Ubiquitous Computing. He is also a guest-editor for IEEE Journal on Selected Areas in Communications (JSAC), Special Issue on Cross-layer Optimized Wireless Multimedia Communications. He served as Program Chair for IEEE/ACM First International Workshop on Broadband Wireless Services and Applications (BroadWISE 2004); and as a technical program committee member of over 30 conferences. He is Vice Chair of Mobile and wireless multimedia Interest Group (MobIG), Technical Committee on Multimedia Communications, IEEE Communications Society. He is a member of the Best Paper Award Committee, Technical Committee on Multimedia Communications, IEEE Communications Society. Yuguang Fang received a Ph.D. degree in Systems Engineering from Case Western Reserve University in January 1994 and a Ph.D. degree in Electrical Engineering from Boston University in May 1997. He was an assistant professor in the Department of Electrical and Computer Engineering at New Jersey Institute of Technology from July 1998 to May 2000. He then joined the Department of Electrical and Computer Engineering at University of Florida in May 2000 as an assistant professor and got an early promotion to an associate professor with tenure in August 2003 and to a full professor in August 2005. He has published over 200 papers in refereed professional journals and conferences. He received the National Science Foundation Faculty Early Career Award in 2001 and the Office of Naval Research Young Investigator Award in 2002. He has served on several editorial boards of technical journals including IEEE Transactions on Communications, IEEE Transactions on Wireless Communications, IEEE Transactions on Mobile Computing and ACM Wireless Networks. He have also been actively participating in professional conference organizations such as serving as The Steering Committee Co-Chair for QShine, the Technical Program Vice-Chair for IEEE INFOCOM’2005, Technical Program Symposium Co-Chair for IEEE Globecom’2004, and a member of Technical Program Committee for IEEE INFOCOM (1998, 2000, 2003–2007). He is a senior member of the IEEE.     

Explaining caste-based digital divide in India

With the increasing importance of information and communication technologies in access to basic services like education and health, the question of digital divide based on caste assumes importance in India where large socioeconomic disparities persist between different caste groups. Studies on caste-based digital inequality are still scanty in India. Using nationally representative survey data, this paper analyzes the first-level digital divide (ownership of computer and access to the Internet) and the second-level digital divide (individuals skills to use computer and the Internet) between the disadvantaged caste groups and Others. Further, this paper identifies the caste-based differences in socioeconomic factors that contribute to the digital divide between these groups using a non-linear decomposition method. The results show that there exists large first-level and second-level digital divide between the disadvantaged caste groups and Others in India. The non-linear decomposition results indicate that caste-based digital divide in India is rooted in historical socioeconomic deprivation of disadvantaged caste groups. More than half of the caste-based digital gap is attributable to differences in educational attainment and income between the disadvantaged caste groups and Others. Findings of this study highlight the urgent need for addressing educational and income inequality between the different caste groups in India in order to bridge the digital divide.     

欧洲科学商店及其启示

科学商店是荷兰在20世纪70年代创造的,现在已扩展到欧洲许多国家。科学商店不是传统意义上的商店,而是一种科学传播的理念和服务。它运用双向互动的科学传播创新机制,支持科研人员深入社区、拓宽研究范围;为社区居民提供科学和研究服务;为大学学生创造实践和了解社会的机会。参与科学商店研究项目的工作人员、科研人员、市民和其他专业人员都可以从中受益。我国的科普工作可以借鉴欧洲科学商店的运作机制和成功经验,在建立全社会支持科普工作的机制和网络、创新社区科学传播活动和提高公众的科学素质和参与度等方面进行思考和探索。     

Alternative Schemes for Dynamic Secure VPN Deployment in UMTS

Three alternative schemes for secure Virtual Private Network (VPN) deployment over the Universal Mobile Telecommunication System (UMTS) are proposed and analyzed. The proposed schemes enable a mobile node to voluntarily establish an IPsec-based secure channel to a private network. The alternative schemes differ in the location where the IPsec functionality is placed within the UMTS network architecture (mobile node, access network, and UMTS network border), depending on the employed security model, and whether data in transit are ever in clear-text, or available to be tapped by outsiders. The provided levels of privacy in the deployed VPN schemes, as well as the employed authentication models are examined. An analysis in terms of cost, complexity, and performance overhead that each method imposes to the underlying network architecture, as well as to the mobile devices is presented. The level of system reliability and scalability in granting security services is presented. The VPN management, usability, and trusted relations, as well as their behavior when a mobile user moves are analyzed. The use of special applications that require access to encapsulated data traffic is explored. Finally, an overall comparison of the proposed schemes from the security and operation point of view summarizes their relative performance. Christos Xenakis received his B.Sc. degree in computer science in 1993 and his M.Sc. degree in telecommunication and computer networks in 1996, both from the Department of Informatics and Telecommunications, University of Athens, Greece. In 2004 he received his Ph.D. from the University of Athens (Department of Informatics and Telecommunications). From 1998–2000 was with the Greek telecoms system development firm Teletel S.A., where was involved in the design and development of advanced telecommunications subsystems for ISDN, ATM, GSM, and GPRS. Since 1996 he has been a member of the Communication Networks Laboratory of the University of Athens. He has participated in numerous projects realized in the context of EU Programs (ACTS, ESPRIT, IST). His research interests are in the field of mobile/wireless networks, security and distributed network management. He is the author of over 15 papers in the above areas. Lazaros Merakos received the Diploma in electrical and mechanical engineering from the National Technical University of Athens, Greece, in 1978, and the M.S. and Ph.D. degrees in electrical engineering from the State University of New York, Buffalo, in 1981 and 1984, respectively. From 1983 to 1986, he was on the faculty of Electrical Engineering and Computer Science at the University of Connecticut, Storrs. From 1986 to 1994 he was on the faculty of the Electrical and Computer Engineering Department at Northeastern University, Boston, MA. During the period 1993–1994 he served as Director of the Communications and Digital Processing Research Center at Northeastern University. During the summers of 1990 and 1991, he was a Visiting Scientist at the IBM T. J. Watson Research Center, Yorktown Heights, NY. In 1994, he joined the faculty of the University of Athens, Athens, Greece, where he is presently a Professor in the Department of Informatics and Telecommunications, and Director of the Communication Networks Laboratory (UoA-CNL) and the Networks Operations and Management Center. His research interests are in the design and performance analysis of broadband networks, and wireless/mobile communication systems and services. He has authored more than 150 papers in the above areas. Since 1995, he is leading the research activities of UoA-CNL in the area of mobile communications, in the framework of the Advanced Communication Technologies & Services (ACTS) and Information Society Technologies (IST) programmes funded by the European Union (projects RAINBOW, Magic WAND, WINE, MOBIVAS, POLOS, ANWIRE). He is chairman of the board of the Greek Universities Network, the Greek Schools Network, and member of the board of the Greek Research Network. In 1994, he received the Guanella Award for the Best Paper presented at the International Zurich Seminar on Mobile Communications.     

刺五加雌、雄花的花柱引导组织结构观察

利用光学显微镜、透射电子显微镜观察了刺五加(Eleutherococcus senticosus)雌、雄花的花柱及其引导组织的结构.结果表明:1.刺五加花柱处合生心皮内表面未完全融合,形成由中心向四周分支的裂缝；2.雌性花柱较雄性花柱,引导组织更为发达；3.发育过程中引导组织细胞内不断有储存为脂体的营养物质分解,并分泌...     

New layout strategies with improved matching performance

In this paper, the systematic mismatch error in integrated circuits due to gradient effects is modeled and analyzed. Three layout strategies with improved matching performance are reviewed and summarized. The hexagonal tessellation pattern can cancel quadratic gradient errors with only 3 units for each device and has high area-efficiency when extended. Both the Nth-order circular symmetry patterns and Nth-order central symmetry patterns can cancel up to Nth-order gradient effects between two devices using 2^N unit cells for each one. Among these three techniques, the central symmetry patterns have the best-reported matching performance for Manhattan structures; the circular-symmetry patterns have the best theoretical matching performance; and the hexagonal tessellation pattern has high density and high structural stability. The Nth-order central symmetry technique is compatible to all IC fabrication processes requiring no special design rules. Simulation results of these proposed techniques show better matching characteristics than other existing layout techniques under nonlinear gradient effects. Specifically, two pairs of P-poly resistors using 2nd and 3rd-order central symmetry patterns were fabricated and tested. Less than 0.04% mismatch and less than 0.002% mismatch were achieved for the 2nd and the 3rd-order structures, respectively. Chengming He was born in YiWu, China in 1976. He received his B.S. in 1999 in Electronic Engineering department and his M.S. degree in the institute of Microelectronics in 2001 at Tsinghua University, Beijing. He started to work toward his PhD in Iowa State University since August 2001. Since June 2004 he started to work as a design engineer in Silicon Laboratories, Inc., Austin, TX. He studied and designed LNA, band-pass filter and on-chip power management blocks as well as matching-enhanced layout patterns. He is interested in designing high gain low voltage amplifier, high speed power-efficient ADC and high speed high linear DAC as well as other mixed-signal circuits. He is also interested in the application of nonlinear system dynamical theory in mixed-signal design and yield-enhancement by improving layout matching. He has published more than 10 technical papers. He was a student member of IEEE from 01--04 and now is a member. He is a member of Tau Beta Pi. Xin Dai was born in Shanghai, China on March 11, 1981. She received the B.Eng. in 2003 from Shanghai Jiao Tong University, Shanghai, China. She is currently a graduate student in Department of Electrical and Computer Engineering at Iowa State University, Ames, IA. Her research has been connected to data converter design and calibrations, layout techniques and build-in-self-test. Xin Dai is now taking a summer-intern in Broadcom Corp., CA. Hanqing Xing was born in Dalian, China, in 1978. He received the B.S. and M.S. degrees with honors in Electronic Engineering from Tsinghua University, Beijing, China, in 2000 and 2003, respectively. He is currently a PhD student at Iowa State University working in analog and mixed signal design group. His research interests include analog, mixed-signal, and data-conversion integrated circuits design and test. Degang Chen received his B.S. degree in 1984 in Instrumentation and Automation from Tsinghua University, Beijing, China and his M.S. and Ph.D. degrees in 1988 and 1992, respectively, both in Electrical and Computer Engineering, from the University of California, Santa Barbara. From 1984 to 1986, he was with the Beijing Institute of Control Engineering, a space industry R/D institute. From March 1992 to August 1992, he was the John R. Pierce Instructor of Electrical Engineering at California Institute of Technology. After that, he joined Iowa State University where he is currently an Associate Professor. He was with the Boeing Company in summer of 1999 and was with Dallas Semiconductor-Maxim in summer of 2001. His research experience include particulate contamination in microelectronic processing systems, vacuum robotics in microelectronics, adaptive and nonlinear control of electromechanical systems, and dynamics and control of atomic force microscopes. His current teaching and research interests are in the area of analog and mixed-signal VLSI integrated circuit design and testing. In particular, he is interested in low-cost high-accuracy testing and built-in-self-test of analog and mixed-signal and RF circuits, and in self-calibration and adaptive reconfiguration/repair strategies for performance and yield enhancement. Dr. Chen is the recipient of the Best Paper Award at the 1990 IEEE Conference on Decision and Control and the Best Transaction Paper Award from the ASME Journal of Dynamic Systems, Measurement, and Control in 1995. He was selected an A.D. Welliver Faculty Fellow with the Boeing Company in 1999.