随着网络技术的飞速发展,分布式应用系统的规模越来越大,网络中各远距离节点间的时间同步性要求越来越高;这种高同步性要求在诸如分布式数据采集和测试测量系统中尤为重要.IEEE 1588——精确时间协议(PTP,Precision Time Protocol)为此提供了一个很好的解决方案,它是一种主要基于以太网的精确时钟同步技术,其同步成本低、精度高、协议开放,广泛应用于各种通信、测试测量设备;文章着重介绍了如何在分布式数据采集系统中实现IEEE 1588 PTP协议,其实现原理可应用到其它类似基于IEEE 1588 PTP协议的分布式应用中;采用此方法构建的分布式数据采集系统同步精度达到了纳秒级.

介绍了一种实用化的无线车辆检测传感器,用于智能交通领域基础数据的采集,实现城市道路的车辆流量、平均车流速度2大统计功能,利用该传感器结合城市智能交通管控平台可有效缓解城市交通拥堵问题.该传感器基于各向异性磁阻(AMR)传感器和ZigBee无线通信协议实现,使用了大容量工业级电池供电,采用超低功耗设计、状态机检测算法、精确授时等关键技术.经过现场一年多的试验与验证,该传感器完全能满足现场复杂的使用环境要求,车辆流量检测精度可达95％以上,速度检测精度可达90％以上.

本文提出了一种以新型的32位高性能低功耗微控制器PPC440EPx为核心的CPCI单板计算机的实现方案.文章介绍了该系统的整体硬件结构及相关硬件模块,对硬件设计的相关细节进行了描述,并对操作系统VxWorks的BSP进行开发和调试.

Aiming at the difficult problem of BSP(Board Support Package)design and debugging,in the process of developing embedded system based on VxWorks,a new method of bootrom implementation is introduced after several methods are compared.And then,the function,hardware design and programming of the Flash chip which is used in the new method are described in detail.This method reduces the difficulty of BSP development,and improves the development efficiency.

This paper introduces a power supply design plan of an embedded system which is based on CPCI.After analyzing the system’s power demand,three novel power supply chips are introduced.Subsequently,a new LDO chip LT3501 is discussed as the emphasis.And how to configure the important parameters of this power supply circuit is explained in detail.This power supply system has been successfully used in an embedded system.Its universality makes it can be applied to similar embedded system.