一种机载DSP系统主控机的实时计算模型

现代机载数字信号处理（DSP）系统中的主控机是具有严格实时需求的计算环境，负责实时存储，显示和控制等重要功能，针对机载DSP系统的特殊性及其对实时计算的具体需求，提出了一种基于实时Linux技术的实时计算模型，它通过与操作系统层的实时支持相结合，实现了包括多任务并发的实时调度方法，硬实时和软实时任务协同工作机制以及实时事件驱动机制在内的完整运行环境，相对于现有的基于分时操作系统的方案，实时性能更为可靠，计算资源利用率高，相对于使用受严格许可证限制的商业实时操作系统的技术，应用开发灵活易行，软件成本更低。     

可靠通信协议中多定时器的实现方案

在TCP、HDLC等能提供可靠通信服务的通信协议中,需要使用定时器来对数据包的超时重发进行计时。由于在发送窗口的范围内可发送多个数据包,所以需要使用多个独立的定时器。在协议实现时,如果直接利用操作系统或硬件实现多个定时器的功能,不仅受到诸多限制,而且浪费资源。本文介绍了一种用单个定时器模拟实现多个定时器的方案,该方案以数据链路层ARQ协议模型为基础,经过修改可以很容易地应用于各种通信协议。     

基于嵌入式实时操作系统的驱动框架

嵌入式设备随着应用领域的扩展呈现出多样性以及复杂性，而嵌入式实时系统普遍不具有良好的设备驱动体系结构，造成驱动开发困难、可移植性差。该文给出了一种嵌入式实时操作系统下的驱动框架，支持各种设备及总线接口，设计了一种快速的设备中断机制，符合嵌入式实时系统的强实时、高可靠的特点，能够满足开发各种嵌入式系统。     

信息安全风险管理系统的设计与实现

嵌入式设备随着应用领域的扩展呈现出多样性以及复杂性,而嵌入式实时系统普遍不具有良好的设备驱动体系结构,造成驱动开发困难、可移植性差.该文给出了一种嵌入式实时操作系统下的驱动框架,支持各种设备及总线接口,设计了一种快速的设备中断机制,符合嵌入式实时系统的强实时、高可靠的特点,能够满足开发各种嵌入式系统.     

Periodic timers revisited: The real-time embedded system perspective

Common sense dictates that single-shot timer mechanisms are more suitable for real-time applications than periodic ones, specially in what concerns precision and jitter. Nevertheless, real-time embedded systems are inherently periodic, with tasks whose periods are almost always known at design-time. Therefore a carefully designed periodic timer should be able to incorporate much of the advantages of single-shot timers and yet avoid hardware timers reprogramming, an expensive operation for the limited-resource platforms of typical embedded systems.In this paper, we describe and evaluate two timing mechanisms for embedded systems, one periodic and another single-shot, aiming at comparing them and identifying their strengths and weaknesses. Our experiments have shown that a properly designed periodic timer can usually match, and in some cases even outperform, the single-shot counterpart in terms of precision and interference, thus reestablishing periodic timers as a dependable alternative for real-time embedded systems.     

Implementation of Hard Real-Time Embedded Control Systems

Although the domain of hard real-time systems has been thoroughly elaborated in the academic sphere, embedded computer control systems –- being an important component in mechatronic designs –- are seldom dealt with consistently. Often, off-the-shelf computer systems are used, with no guarantee that they will be able to meet the requirements specified. In this paper, a design for embedded control systems is presented. Particularly, the paper deals with the hardware architecture and design details, the operating system, and high-level real-time language support. It is shown how estimates of process run-times necessary for schedulability analysis can be acquired on the basis of deterministic behavior of the hardware platform.     

嵌入式系统平台抽象层设计与接口实现

近年来,随着嵌入式计算机技术飞速发展,各种异构嵌入式硬件不断更新,提高操作系统的可移植性和应用程序的代码重用性成为了一种趋势.本文设计了一种通用性较强的平台抽象层,针对Linux操作系统、“锐华”操作系统与硬件平台的应用程序开发接口重新进行设计,为用户开发各种嵌入式应用程序提供标准化的接口.研究证明,平台抽象层能提高操作系统的可移植性和应用程序的代码重用性,同时具有可靠的实时性.     

VxWorks和RTlinux的性能测试分析

比较并分析了两种操作系统VxWorks和RTlinux的可适用性及可控性;为了使二者之间的差异表现的更加充分,基于统一的硬件平台和相同的测量方法,在两种操作系统稳定运行期间,我们对能反应操作系统性能的四项指标:上下文切换,中断响应能力,同步运行能力和信息传递能力,进行了功能性测试;在优先级反转问题上,对二者的效率进行了检测。测试结果表明,无论VxWorks还是RTlinux都显示出了良好的适用性,但是VxWorks具有更好的可控性和可预知性,因此这使它成为更好发展前景和更严格软硬件的实时操作系统平台。     

SAR数据存储系统中FAT32文件系统开发与实现

针对合成孔径雷达（SAR）技术中高速实时处理、实时存储大容量数据的要求,该文提出SAR数据存储系统中FAT32文件系统实现方案。该方案以SATA硬盘为硬件平台,以嵌入式实时操作系统为软件平台,能够实现实时处理存储功能。     

Analysis of window-constrained execution time systems

Feasibility tests for hard real-time systems provide information about the schedulability of the task set. However, this information is a yes or a no answer, that is, whether the task set achieves the test or not. From the real-time system design point of view, having more information available would be useful. For example, how much the computation time can vary without jeopardising the system feasibility. This work specifically provides methods to determine off-line how much a task can increase its computation time, by maintaining the system feasibility under a dynamic priority scheduling. The extra time can be determined not only in all the task activations, but in n of a window of m invocations. This is what we call a window-constrained execution time system. The results presented in this work can be used in all kinds of real-time systems: fault tolerance management, imprecise computation, overrun handling, control applications, etc. Patricia Balbastre is an assistant professor of Computer Engineering. She graduated in Electronic Engineering at the Technical University of Valencia, Spain, in 1998. And the Ph.D. degree in Computer Science at the same university in 2002. Her main research interests include real-time operating systems, dynamic scheduling algorithms and real-time control. Ismael Ripoll received the B.S. degree from the Polytechnic University of Valencia, Spain, in 1992; the Ph.D. degree in Computer Science at the Polytechnic University of Valencia, Spain, in 1996. Currently he is Professor in the DISCA Department of the same University. His research interests include embedded and real-time operating systems. Alfons Crespo is Professor of the Department of Computer Engineering of the Technical University of Valencia. He received the PhD in Computer Science from the Technical University of Valencia, Spain, in 1984. He held the position of Associate professor in 1986 and full Professor in 1991. He leads the group of Industrial Informatics and has been the responsible of several European and Spanish research projects. His main research interest include different aspects of the real-time systems (scheduling, hardware support, scheduling and control integration, …). He has published more than 60 papers in specialised journals and conferences in the area of real-time systems.