一种USB从设备访问主设备的方法

介绍了一种USB从设备访问主设备的方法。该方法利用USB从设备端存储器中建立的交换缓存区,无须拔插flash存储卡即可实现USB从设备端对主设备端文件的直接访问,从而使USB从设备可访问远大于自身存储空间的文件。通过该方法可实现手持播放器以低成本和省电的方式扩展外接硬盘。     

USB设备的开发

USB接口具有使用方便，数据传输速率高等特点，但由于USB接口协议复杂，涉及的方面，特别是软件比较多，使得USB设备的开发非常困难，本着抛砖引玉的目的，首先简要介绍USB接口的特点，然后具体介绍了USB设备的开发过程，最后Philips公司的USB接口芯片PDIUSBD12为例，给出了一个具体的应用实例。     

USB设备安装指南

USB需要主机硬件、操作系统和外设三个方面的支持才能正常工作,主机硬件的支持就不说了,现在市面上的主板都内置了USB接口,甚至一些比较老的主板上都预留了USB的升级针脚接口,下面就来详细谈谈操作系统和外设的USB驱动的安装。     

USB设备常见故障排除

尽管USB设备的推出已经有些时日,而且现在的软硬件对USB设备的支持也比较好,但是还是经常会出现无法使用USB设备的现象。下面就针对一些典型的USB“病症”来谈谈常见USB设备故障的排除方法。 1.USB设备接到USB口后,系统没有反应,并没有发现什么新的设备? 对于这种情况,使用者应该先参照《USB设备安装指南》一文中“主板USB控制器的安装”部分的内容,仔细地看一下系统是否已经成功地安装了USB,具体从控制面板的“系统属性”中查看,如果没有,则可以参照上文中的内容进行相应的设置和安装工作。另外,对于带电源开关的USB设备     

一种FPGA高速访问USB设备的设计方案

针对FPGA访问USB设备存在传输速率低、资源消耗大、开发复杂的缺点,提出了一种将ARM处理器与FPGA相结合实现高速访问USB设备的方案。该方案利用ARM处理器的USB Host读取USB设备数据并缓存于高速内存,采用乒乓机制通过SRAM接口将数据传给FPGA。经测试,数据传输速率可以达到48Mbps。该方案具有开发难度小,资源占用率低和传输速率高的特点,适合于FPGA高速读取大量外部数据。     

非USB设备也热插拔

记得曾经有人提出非USB设备也可以热插拔的观点。首先表示同意,而且可以进一步丰富这一理论。首先,笔者要阐述这一理论并非要读者经常进行非USB设备的热插拔操作,而是让大家知道什么设备热插拔出故障的概率更小,而在关键的场合可以利用热插拔进行有意义的工作。 小知识:了解USB设备的插拔过程     

安装正版Windows XP后，USB设备不支持即插即用

画地为牢：我装了正版Windows XP了，可是有些USB设备不能支持即插即用。     

USB设备电力随意看

电脑同时接人多个USB接口的设备时，主板就可能无法为每一个USB端口部提供足够的电力，USB设备会出现各种莫名其妙的故障。怎样才能知道USB设备是否有足够的“动力”呢？     

VRMosaic: Web access from within a virtual environment

For the foreseeable future, users of virtual reality systems will likely spend more time in the “real” environment than in a virtual environment. In the “real” environment, users access much of their data using flat screen applications, which include tools such as authoring and analysis programs and even hyperlinked browsers. We believe that users will find VEs more appealing if they can import their flat screen applications. We also believe that the World Wide Web infrastructure, and supporting tools such as NCSA Mosaic, Netscape's Navigator, and Sun's HotJava, have become a de facto standard both for making data available and allowing limited interaction with that data. These beliefs motivated us to develop a technology for porting flat screen applications based on the 3.1 version of the InterViews toolkit into VR. NCSA Mosaic provided us with a real application that would: (1) test our infrastructure effectively; and (2) provide a compelling application example. We used our “2D interface in VR” infrastructure to port Mosaic into RealEyes, our VR system. Dubbed “VRMosaic”, this application lets users familiar with Mosaic access the Web from within an immersive VE. But VRMosaic is not just an embedded version of NCSA Mosaic-it also allows for VR specific features such as navigation within the VE     

第三代移动通信中的多用户检测技术

研究了应用于CDMA移动通信系统中的各种多用户检测技术的原理和优缺点,指出目前多用户检测技术主要分为线性多用户检测和干扰消除多用户检测两种。并对各种多用户检测的特点进行了分析比较。     

Standardization of the virtual device metafile and the virtual device interface

The American National Standards Institute (ANSI) is developing several graphics standards. Two of these standards, the Virtual Device Metafile and the Virtual Device Interface, are reviewed. The purpose, basic concepts and philosophy of these standards are discussed and contrasted with current practice and the Graphical Kernel System standard. The virtual device metafile is in the final stages of standardization within ANSI and is being reviewed within the International Standards Organization (ISO) for adoption as an international standard. The virtual device interface standard is currently under development within ANSI.     

多级环境下基于角色和本体的访问控制方法

为了解决多级环境中敏感资源的安全性问题,提出了多级环境下基于角色和本体的访问控制方法.通过使用本体等语义技术,构造了一个结合基于角色的访问控制和Bell-LaPadula (BLP)模型的访问控制模型.根据角色的继承关系推导用户及资源之间安全级别的高低关系,在为角色指派权限时按照BLP模型进行授权的限制.实验表明,该方法在保证多级安全特性的前提下实现了用户权限的自动分配,消除了角色权限继承带来的安全隐患,为多级环境下的访问控制提供了一种新的思路.     

虚拟人环境感知的仿真方法研究

针对目标驱动的追击问题,将视线升维为柱体的视线筒,提出了一种虚拟人环境感知的筒视线方法.根据虚拟人所处的环境和行进速度,以变频方式、周期性地向目标发射筒视线,根据该筒视线与环境中障碍物的各碰撞点的信息和预先设置的行动推理知识库,确定虚拟人的追逐行动;为不完全可知的、动态虚拟环境中的目标追击问题提供了一种新的解决方案.该方案抛开了基于传统视野范围的拟人方式,以通过性的感知为中心,形成虚拟世界的互动性感知标准,建立虚拟人自身的感知功能,取得了更加逼真的仿真效果.原型系统验证了该方法的可行性和有效性.     

Deception in avatar-mediated virtual environment

This study explored the effects of avatars on deception – how perceived avatar likeness to self can affect the truthfulness and accuracy of interactions online. More specifically, this study examined the extent to which perceived avatar similarity influences self-awareness and users’ degree of attraction to them, and how these psychological states affect deception in the context of Second Life. The results, based on web-based survey data of 159 Second Life users, revealed that avatar similarity in attitude and behavior to the owner heightened self-awareness, which, in turn, reduced deception. Perceived avatar similarity in terms of appearance was found to have a direct negative impact on deception so that those who perceived their avatars to look similar to themselves were less likely to engage in deceptive behavior. Implications of the findings are discussed.     

一种抗窃听USB设备控制器

针对USB总线窃听问题,通过深入分析USB传输特性设计实现了一种抗窃听设备控制器。该设备控制器于接口电路与端点缓冲区之间嵌入分组密码模块与端点独立的序列密码模块,使得加解密能够在数据存取过程中透明进行且支持USB的全部传输方式与多管道应用。接口电路与密码模块设计支持流水传输,基本消除了加解密对端点缓冲区存取速度的影响。基于FPGA平台对其进行了实现,并结合Nios II片上系统与主机端软件进行了测试。测试结果表明该设备控制器能够正确地对总线数据进行加解密,可为各类外设提供抗窃听的USB通信能力。     

E-commerce transactions in a virtual environment: virtual transactions

E-commerce is a fundamental method of doing business, such that for a firm to say it is trading at all in the modern market-place it must have some element of on-line presence. Coupled with this is the explosion of the “population” of Massively Multiplayer On-line Role Playing Games and other shared virtual environments. Many suggest this will lead to a further dimension of commerce: virtual commerce. We discuss here the issues, current roadblocks and present state of an e-commerce transaction carried out completely within a virtual environment; a virtual transaction. Although technically such transactions are in a sense trivial, they raise many other issues in complex ways thus making V-transactions a highly interesting cross-disciplinary issue. We also discuss the social, ethical and regulatory implications for the virtual communities in these environments of such v-transactions, how their implementation affects the nature and management of a virtual environment, and how they represent a fundamental merging of the real and virtual worlds for the purpose of commerce. We highlight the minimal set of features a v-transaction capable virtual environment requires and suggest a model of how in the medium term they could be carried out via a methodology we call click-through, and that the developers of such environments will need to take on the multi-modal behavior of their users, as well as elements of the economic and political sciences in order to fully realize the commercial potential of the v-transaction.     

Linux下有中断端点的USB设备驱动的实现

手写板是有中断端点的USB设备,为了在Linux下实现此类设备的驱动,分析了USB设备的基本概念和Linux设备驱动原理,对Linux下设备驱动程序的内部机制和框架构成进行了研究.在此基础上,提出了引入信号量机制控制内核线程同步的方法来实现read函数,进而设计出Linux下有中断端点的USB设备的驱动程序.通过编写应用程序和设计对比实验,证明了此驱动可以准确、高效地读写设备.与针对中断端点普遍采用的输入子系统方式相比,简化了程序设计,提高了系统效率.     

USB技术在飞机外场设备测试中的应用

通用串行总线（USB）是近年来流行的一种新的微机总线接口标准，它可以实现较传统方式更有效、更经济、更多点的数据采集，详细介绍了利用USB技术实现飞机外场快速测试的方法。