基于ARM+FPGA的PLC计数器的设计

计数器是PLC内部重要的软元件之一,在以PLC为核心部件的自动控制系统中,这种软元件通过相应的程序实现系统的实时准确的计数;ARM通过双口RAM发送指令命令给FPGA,FPGA控制计数器进行相关操作,FPGA的晶振工作频率50 MHz作为计数器控制模块的时序约束,设计的计数器具有加减计数功能、断电保持功能、数据回传功能等,以满足PLC控制器的计数需求,并通过使用地址映射存储器使得计数器控制器的指令执行更加高效;设计了计数器与FPGA指令执行控制器的通信协议;通过对设计完成后的仿真与测试,单个计数器的计数频率达到2 MHz,基本实现了PLC计数器的功能,并且达到了稳定计数的设计要求。     

基于FPGA的PLC并行定时器的设计

构建了一种采用ARM与FPGA协同并行工作实现定时功能的PLC控制系统.设计了ARM-FPGA系统的通信方式与协议,实现了删与FPGA之间快速高效的通信.由于PLC内部包含了数量较多的定时器,因此在FPGA中采用串行方式与并行方式相结合的方法实现PLC定时功能,经过分析与测试可知,该设计方法不仅可以保证定时器的计时误差在1ms以内,还能提高系统工作效率与减少硬件资源耗用.通过对FPC-A内部功能模块的仿真测试与ARM-FPGA系统联合测试,验证了ARM-FPGA系统可以初步实现PLC的预期功能,其中FPGA可以稳定精确地实现定时功能.     

高可靠性小型固体动力运载火箭时序控制器设计

阐述了时序控制器电路原理,采用Microsemi公司的A3P250系列FPGA作为控制器,设计了一款高可靠性的时序控制器。围绕可靠性,从结构、硬件及软件设计等方面,介绍了设计方案,该时序控制器在硬件电路设计中采用了安全性设计措施,在时序测试中,能够将火工品点火回路短接,在火工品阻值测试中,能够断开点火回路确保火工品的绝对安全。在软件设计中,采用了FPGA仲裁机制,只有按照预定的测试流程,按照特定的逻辑顺序,才能完成相应的功能。在设计定时器时,采用格雷码计数器,有效地避免了计数器累加时位寄存器翻转产生的亚稳态现象。该时序控制器参加了火箭的多次飞行试验,具有相当的稳定性和可靠性。     

基于SPI总线的飞腾FT2000/4与FPGA通信设计与实现

针对串行通信总线协议(SPI)应用,提出了一种基于飞腾处理器FT2000/4和FPGA之间的通信设计方法,在FPGA中实现了SPI转局部总线模块和寄存器读写模块;在Modelism环境下对所设计的SPI从控制器进行了功能仿真验证,仿真结果表明,该SPI从控制器可与飞腾处理器内的SPI主控制器进行通信;在FT2000/4和FPGA的集成开发板上进行实测,通过扩展的RS422接口与422板卡进行通信,结果表明,在FPGA中设计的SPI从控制器工作正常.     

基于单片机的数字脉宽调制器

针对采用单片机2个定时器/计数器实现PWM存在资源不足的问题,提出了一种采用单片机单个定时器/计数器实现PWM的方法;给出了PWM信号的特点和MCS-51单片机定时器/计数器的特性,以控制液压比例阀的PWM为例,详细介绍了该方法的具体实现,并分析了该PWM的性能。分析结果表明,设计的PWM能够满足一般应用,解决了单片机中定时器/计数器资源不足的问题,但单片机中断响应时间对PWM信号的频率、相位精度与稳定度有一定的影响。     

基于FPGA和EMIFA的SPI控制器系统设计

为了在现有C6000系列DSP芯片上扩展多路SPI外围设备,提出了一种基于FPGA和EMIF接口的多路SPI控制器系统方案。该方案采用C6000系列DSP上的EMIF接口与FPGA进行数据交互,扩展出多路SPI控制器。在FPGA上实现了接口模块、寄存器读写模块以及多路通用SPI模块。在ModelSim环境下对所设计的SPI控制器进行了仿真实验,仿真结果表明SPI控制器可以进行全双工通信。随之,在DSP-FPGA集成计算机上进行了实物测试,扩展的SPI控制器外接具有SPI接口的CAN控制器芯片MCP2515,通过扩展的SPI控制器控制MCP2515的数据收发,测试结果显示DSP可以通过MCP2515与其它CAN设备进行通信,扩展的SPI控制器工作正常。     

基于现场可编程门阵列的新型可编程逻辑控制器在线调试技术

针对基于现场可编程门阵列(FPGA)的新型可编程逻辑控制器(FPGA based PLC)的在线监控问题,提出了泛化的基于FPGA技术对嵌入式片上系统(SoC)进行在线监控的方法。该方法设计了一个FPGA片上通信系统,系统内部固化基于UART的ModBus通信协议栈,通过串口与计算机上位机进行通信;采用双口RAM(DRAM)作为与监控对象间共享的数据缓存区,通过中断机制实现缓存数据的同步交换。性能分析结果表明,该方法将SoC处理监控通信的时间百分比降低至0.002%,确保了监控数据传送的实时性,且使SoC能够获得更佳控制性能。在Altera的cycloneⅡ系列芯片开发板上验证了方案的可行性。     

基于BU-61580总线控制器的接口及容错设计

针对RS-422接口与1553B总线接口无法直接进行高可靠性数据通信,提出了一种基于BU-61580总线控制器的接口及容错设计;设计采用1553B接口芯片BU-61580,通过FPGA控制完成了RS-422与1553B的接口控制及二者之间的数据处理;在硬件接口设计的基础上,设计IP-CORE完成BU-61580的芯片配置,并通过增加容错设计提高了总线控制器数据通信的可靠性;经测试结果显示,计算机通过总线控制器与RT终端通信稳定、可靠,并应用于某测试系统中。     

基于TMS320C32的CAN总线通信系统设计

为实现空间相机控制器与星务计算机之间的可靠数据通讯,设计了基于TMS320C32的CAN总线通信系统;针对TMS320C32和SJA1000的工作时序特点,利用可编程逻辑器件FPGA实现了接口逻辑转换,编写激励文件利用Modelsim软件进行了功能仿真,给出了CAN总线通信系统的软件设计,包括SJA1000的初始化、数据的发送接收及位定时参数的设定;最后通过周立功公司的ZLGCANTest软件对设计的CAN总线通信系统进行了测试;实验结果表明,系统的通信速率达到307.2kbps,通讯无误,满足相机控制器可靠性的要求。     

手把手教你学单片机（九）

MCS-51单片机可提供两个16位的定时器/计数器:定时器/计数器1和定时器/计数器0。它们均可用作定时器或事件计数器,为单片机系统提供计数和定时功能。定时器/计数器的结构及工作原理图1为定时器/计数器的结构框图。由图1可见,定时器/计数器的核心是一个加1计数器,加1计数器的脉冲有两个来源,一个是外部     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.