Control systems are becoming increasingly dependent on digital processing and so require sensors able to provide direct digital inputs. Sensors based on time measurement, having outputs based on a frequency or phase, have an advantage over conventional analogue sensors in that their outputs can be measured directly in digital systems by pulse counting.
上传时间： 2013-10-08
上传用户：wuyuying
生活中许多目标的高度和水平距离需要进行测量。目前主要的测量方法，仍以传统的皮尺丈量为主，测量效率不高，有时还很不方便，没有技术成熟的数字式测高测距产品。以基本的数学方法为理论依据，利用遥控小车做为载体，采用角度传感器测量角度、霍尔传感器测量水平距离等，通过单片机LM3S615进行数据计算，实现了对待测目标物体的高度、水平距离等数据的快速、精确和数字式的测量，高度测量精度可达99.06%，水平测量精度则可达98.06%。 Abstract: In our lives， the height and horizontal distance of some goals are needed to be measured. Because the currently used methods are still traditional tape-based measuring methods， and the measuring efficiency is low and inconvenient so some kinds of digital and portable measuring methods or instruments are needed. Based on the basic math theory， this paper designed and manufactured a portable， digital and remote controlled measuring mobile small vehicle， which assembled with angle measuring sensor for angle measurement and Hall sensor for horizontal distance measuring. MCU LM3S615 calculated the height and horizontal distance data gotten from these sensors. The measuring process is simple， the measuring results are more accurate and the measuring efficiency is higher than traditional measure instruments. The accuracy of height and distance measurement can reach 99.06% and 98.06%.
上传时间： 2013-10-30
上传用户：jackandlee
为提高温度测量效率，降低系统的成本，扩展传输距离，设计出一种新型温度采集系统。单片机通过控制具有单总线方式的温度传感器DS18B20实现对温度的测量，同时单片机通过控制具有单总线方式300～450MHz频率范围内的MAX7044与MAX7033无线发射与接收芯片实现温度数据的无线传输。与传统温度采集系统相比，该系统利用单总线方式连接，采用无线传输方式实现远距离通信，易于系统的集成与扩展。实验结果表明，该系统结构简单、方便移植，能够同时实现多达上百点温度的测量与500m范围的传输。 Abstract: To improve the temperature measurement efficiency and reduce system cost,expansion of transmission distance,a new type of temperature acquisition system is designed.Microcontroller controlled temperature sensor DS18B20which has a single-bus achieves temperature measurement,while microcontroller by controlled the MAX7044and MAX7033chip with a single-bus and having300~450MHz radiofrequency to achieve the wireless transmission of temperature data.Compared with conventional temperature acquisition system,the system uses single-bus connected,and uses wireless transmission means to achieve long-distance communications,easy-to-system integration and expansion.The experimental results show that the system is simple,convenient transplantation,and can be implemented in as many as a hundred-point temperature measure-ment and the transmission range of500meters.
上传时间： 2013-10-29
上传用户：515414293
阐述了一个由上位PC机和AT89C52下位单片机组成的主从分布式温度巡回检测系统。主从机采用RS-485 串行通讯标准进行通信，可在下位单片机实现基本的温度数据巡回检测基础上，由上位PC机实现综合处理功能或扩展为远程操作。整个系统具有巡检速度快，扩展性好的特点。 Abstract: In this paper,a top PC and AT89C52 under-bit microcontrollers from the main component of the tour distributed temperature detection system is presented. Master and slave can use RS-485 serial communication standards for communications.Based on next-bit machine for basic goods temperature detected data Tour, the top can achieve the integrated treatment of PC functions or for the expansion of long-distance operation. The entire inspection system is fast, expansion.
上传时间： 2013-10-13
上传用户：zhoujunzhen
介绍了电力操作电源与智能电池巡检系统的特点，给出了一种基于超低功耗单片机MSP430 F149针对中小型变电站自动化运行的专用设备的基本设计原理及实现方法，最后给出了详细硬件构成和软件实现。该系统能满足中小型变电站安全、可靠、自动运行的要求，并通过与上位机的串行通信实现变电站的远程管理和控制。 Abstract: The characters of the intelligent battery data logging system of the electric operation power are introduced.The basic design principle and the implemented methods of the special equipment which only designed for the middle or small transformer substation based on MSP430F149 are prescribed. Finally, the hardware block diagram and the software flow chart are also given. The function that the system finally needs to realize can basically meet with the middle or small transformer substation’s satisfy, reliably,and automatic running.And it can also realize the transformer substation long-distance management and control by serial communicating with the host computer.
上传时间： 2013-11-25
上传用户：黄华强
基于幅移键控技术ASK（Amplitude-Shift Keying），以C8051F340单片机作为监测终端控制器，C8051F330D单片机作为探测节点控制器，采用半双工的通信方式，通过监控终端和探测节点的无线收发电路，实现数据的双向无线传输。收发电路采用直径为0.8 mm的漆包线自行绕制成圆形空心线圈天线，天线直径为（3.4±0.3）cm。试验表明，探测节点与监测终端的通信距离为24 cm，通过桥接方式，节点收发功率为102 mW时，节点间的通信距离可达20 cm。与传统无线收发模块相比，该无线收发电路在受体积、功耗、成本限制的场合有广阔的应用前景。 Abstract: Based on ASK technology and with the C8051F340 and C8051F330D MCU as the controller， using half-duplex communication mode， this paper achieves bi-directional data transfer. Transceiver circuit constituted by enameled wire which diameter is 0.8mm and wound into a diameter （3.4±0.3） cm circular hollow coil antenna. Tests show that the communication distance between detection and monitoring of the terminal is 24cm，the distance is up to 20cm between two nodes when using the manner of bridging and the node transceiver power is 102mW. Compared with the conventional wireless transceiver modules， the circuit has wide application prospect in small size， low cost and low power consumption and other characteristics.
上传时间： 2013-10-19
上传用户：xz85592677
All inputs of the C16x family have Schmitt-Trigger input characteristics. These Schmitt-Triggers are intended to always provide proper internal low and high levels, even if anundefined voltage level (between TTL-VIL and TTL-VIH) is externally applied to the pin.The hysteresis of these inputs, however, is very small, and can not be properly used in anapplication to suppress signal noise, and to shape slow rising/falling input transitions.Thus, it must be taken care that rising/falling input signals pass the undefined area of theTTL-specification between VIL and VIH with a sufficient rise/fall time, as generally usualand specified for TTL components (e.g. 74LS series: gates 1V/us, clock inputs 20V/us).The effect of the implemented Schmitt-Trigger is that even if the input signal remains inthe undefined area, well defined low/high levels are generated internally. Note that allinput signals are evaluated at specific sample points (depending on the input and theperipheral function connected to it), at that signal transitions are detected if twoconsecutive samples show different levels. Thus, only the current level of an input signalat these sample points is relevant, that means, the necessary rise/fall times of the inputsignal is only dependant on the sample rate, that is the distance in time between twoconsecutive evaluation time points. If an input signal, for instance, is sampled throughsoftware every 10us, it is irrelevant, which input level would be seen between thesamples. Thus, it would be allowable for the signal to take 10us to pass through theundefined area. Due to the sample rate of 10us, it is assured that only one sample canoccur while the signal is within the undefined area, and no incorrect transition will bedetected. For inputs which are connected to a peripheral function, e.g. capture inputs, thesample rate is determined by the clock cycle of the peripheral unit. In the case of theCAPCOM unit this means a sample rate of 400ns @ 20MHz CPU clock. This requiresinput signals to pass through the undefined area within these 400ns in order to avoidmultiple capture events.For input signals, which do not provide the required rise/fall times, external circuitry mustbe used to shape the signal transitions.In the attached diagram, the effect of the sample rate is shown. The numbers 1 to 5 in thediagram represent possible sample points. Waveform a) shows the result if the inputsignal transition time through the undefined TTL-level area is less than the time distancebetween the sample points (sampling at 1, 2, 3, and 4). Waveform b) can be the result ifthe sampling is performed more than once within the undefined area (sampling at 1, 2, 5,3, and 4).Sample points:1. Evaluation of the signal clearly results in a low level2. Either a low or a high level can be sampled here. If low is sampled, no transition willbe detected. If the sample results in a high level, a transition is detected, and anappropriate action (e.g. capture) might take place.3. Evaluation here clearly results in a high level. If the previous sample 2) had alreadydetected a high, there is no change. If the previous sample 2) showed a low, atransition from low to high is detected now.
上传时间： 2013-10-23
上传用户：copu
All inputs of the C16x family have Schmitt-Trigger input characteristics. These Schmitt-Triggers are intended to always provide proper internal low and high levels, even if anundefined voltage level (between TTL-VIL and TTL-VIH) is externally applied to the pin.The hysteresis of these inputs, however, is very small, and can not be properly used in anapplication to suppress signal noise, and to shape slow rising/falling input transitions.Thus, it must be taken care that rising/falling input signals pass the undefined area of theTTL-specification between VIL and VIH with a sufficient rise/fall time, as generally usualand specified for TTL components (e.g. 74LS series: gates 1V/us, clock inputs 20V/us).The effect of the implemented Schmitt-Trigger is that even if the input signal remains inthe undefined area, well defined low/high levels are generated internally. Note that allinput signals are evaluated at specific sample points (depending on the input and theperipheral function connected to it), at that signal transitions are detected if twoconsecutive samples show different levels. Thus, only the current level of an input signalat these sample points is relevant, that means, the necessary rise/fall times of the inputsignal is only dependant on the sample rate, that is the distance in time between twoconsecutive evaluation time points. If an input signal, for instance, is sampled throughsoftware every 10us, it is irrelevant, which input level would be seen between thesamples. Thus, it would be allowable for the signal to take 10us to pass through theundefined area. Due to the sample rate of 10us, it is assured that only one sample canoccur while the signal is within the undefined area, and no incorrect transition will bedetected. For inputs which are connected to a peripheral function, e.g. capture inputs, thesample rate is determined by the clock cycle of the peripheral unit. In the case of theCAPCOM unit this means a sample rate of 400ns @ 20MHz CPU clock. This requiresinput signals to pass through the undefined area within these 400ns in order to avoidmultiple capture events.
上传时间： 2014-04-02
上传用户：han_zh
很多不同的厂家生产各种型号的计算机，它们运行完全不同的操作系统，但TCP.IP协议族允许它们互相进行通信。这一点很让人感到吃惊，因为它的作用已远远超出了起初的设想。T C P / I P起源于6 0年代末美国政府资助的一个分组交换网络研究项目，到9 0年代已发展成为计算机之间最常应用的组网形式。它是一个真正的开放系统，因为协议族的定义及其多种实现可以不用花钱或花很少的钱就可以公开地得到。它成为被称作“全球互联网”或“因特网(Internet)”的基础，该广域网（WA N）已包含超过1 0 0万台遍布世界各地的计算机。本章主要对T C P / I P协议族进行概述，其目的是为本书其余章节提供充分的背景知识。 TCP.IP协议 缩略语 ACK (ACKnowledgment) TCP首部中的确认标志 API (Application Programming Interface) 应用编程接口 ARP (Address Resolution Protocol) 地址解析协议 ARPANET(Defense Advanced Research Project Agency NETwork) (美国)国防部远景研究规划局 AS (Autonomous System) 自治系统 ASCII (American Standard Code for Information Interchange) 美国信息交换标准码 ASN.1 (Abstract Syntax Notation One) 抽象语法记法1 BER (Basic Encoding Rule) 基本编码规则 BGP (Border Gateway Protocol) 边界网关协议 BIND (Berkeley Internet Name Domain) 伯克利I n t e r n e t域名 BOOTP (BOOTstrap Protocol) 引导程序协议 BPF (BSD Packet Filter) BSD 分组过滤器 CIDR (Classless InterDomain Routing) 无类型域间选路 CIX (Commercial Internet Exchange) 商业互联网交换 CLNP (ConnectionLess Network Protocol) 无连接网络协议 CRC (Cyclic Redundancy Check) 循环冗余检验 CSLIP (Compressed SLIP) 压缩的S L I P CSMA (Carrier Sense Multiple Access) 载波侦听多路存取 DCE (Data Circuit-terminating Equipment) 数据电路端接设备 DDN (Defense Data Network) 国防数据网 DF (Don’t Fragment) IP首部中的不分片标志 DHCP (Dynamic Host Configuration Protocol) 动态主机配置协议 DLPI (Data Link Provider Interface) 数据链路提供者接口 DNS (Domain Name System) 域名系统 DSAP (Destination Service Access Point) 目的服务访问点 DSLAM (DSL Access Multiplexer) 数字用户线接入复用器 DSSS (Direct Sequence Spread Spectrum) 直接序列扩频 DTS (Distributed Time Service) 分布式时间服务 DVMRP (Distance Vector Multicast Routing Protocol) 距离向量多播选路协议 EBONE (European IP BackbONE) 欧洲I P主干网 EOL (End of Option List) 选项清单结束 EGP (External Gateway Protocol) 外部网关协议 EIA (Electronic Industries Association) 美国电子工业协会 FCS (Frame Check Sequence) 帧检验序列 FDDI (Fiber Distributed Data Interface) 光纤分布式数据接口 FIFO (First In, First Out) 先进先出 FIN (FINish) TCP首部中的结束标志 FQDN (Full Qualified Domain Name) 完全合格的域名 FTP (File Transfer Protocol) 文件传送协议 HDLC (High-level Data Link Control) 高级数据链路控制 HELLO 选路协议 IAB (Internet Architecture Board) Internet体系结构委员会 IANA (Internet Assigned Numbers Authority) Internet号分配机构 ICMP (Internet Control Message Protocol) Internet控制报文协议 IDRP (InterDomain Routing Protocol) 域间选路协议 IEEE (Institute of Electrical and Electronics Engineering) （美国）电气与电子工程师协会 IEN (Internet Experiment Notes) 互联网试验注释 IESG (Internet Engineering Steering Group) Internet工程指导小组 IETF (Internet Engineering Task Force) Internet工程专门小组 IGMP (Internet Group Management Protocol) Internet组管理协议 IGP (Interior Gateway Protocol) 内部网关协议 IMAP (Internet Message Access Protocol) Internet报文存取协议 IP (Internet Protocol) 网际协议 I RTF (Internet Research Task Force) Internet研究专门小组 IS-IS (Intermediate System to Intermediate System Protocol) 中间系统到中间系统协议 ISN (Initial Sequence Number) 初始序号 ISO (International Organization for Standardization) 国际标准化组织 ISOC (Internet SOCiety) Internet协会 LAN (Local Area Network) 局域网 LBX (Low Bandwidth X) 低带宽X LCP (Link Control Protocol) 链路控制协议 LFN (Long Fat Net) 长肥网络 LIFO (Last In, First Out) 后进先出 LLC (Logical Link Control) 逻辑链路控制 LSRR (Loose Source and Record Route) 宽松的源站及记录路由 MBONE (Multicast Backbone On the InterNEt) Internet上的多播主干网 MIB (Management Information Base) 管理信息库 MILNET (MILitary NETwork) 军用网 MIME (Multipurpose Internet Mail Extensions) 通用I n t e r n e t邮件扩充 MSL (Maximum Segment Lifetime) 报文段最大生存时间 MSS (Maximum Segment Size) 最大报文段长度 M TA (Message Transfer Agent) 报文传送代理 MTU (Maximum Transmission Unit) 最大传输单元 NCP (Network Control Protocol) 网络控制协议 NFS (Network File System) 网络文件系统 NIC (Network Information Center) 网络信息中心 NIT (Network Interface Tap) 网络接口栓（S u n公司的一个程序） NNTP (Network News Transfer Protocol) 网络新闻传送协议 NOAO (National Optical Astronomy Observatories) 国家光学天文台 NOP (No Operation) 无操作 NSFNET (National Science Foundation NETwork) 国家科学基金网络 NSI (NASA Science Internet) （美国）国家宇航局I n t e r n e t NTP (Network Time Protocol) 网络时间协议 NVT (Network Virtual Terminal) 网络虚拟终端 OSF (Open Software Foudation) 开放软件基金 OSI (Open Systems Interconnection) 开放系统互连 OSPF (Open Shortest Path First) 开放最短通路优先 PAWS (Protection Against Wrapped Sequence number) 防止回绕的序号 PDU (Protocol Data Unit) 协议数据单元 POSIX (Portable Operating System Interface) 可移植操作系统接口 PPP (Point-to-Point Protocol) 点对点协议 PSH (PuSH) TCP首部中的急迫标志 RARP (Reverse Address Resolution Protocol) 逆地址解析协议 RFC (Request For Comments) Internet的文档，其中的少部分成为标准文档 RIP (Routing Information Protocol) 路由信息协议 RPC (Remote Procedure Call) 远程过程调用 RR (Resource Record) 资源记录 RST (ReSeT) TCP首部中的复位标志 RTO (Retransmission Time Out) 重传超时 RTT (Round-Trip Time) 往返时间 SACK (Selective ACKnowledgment) 有选择的确认 SLIP (Serial Line Internet Protocol) 串行线路I n t e r n e t协议 SMI (Structure of Management Information) 管理信息结构 SMTP (Simple Mail Transfer Protocol) 简单邮件传送协议 SNMP (Simple Network Management Protocol) 简单网络管理协议 SSAP (Source Service Access Point) 源服务访问点 SSRR (Strict Source and Record Route) 严格的源站及记录路由 SWS (Silly Window Syndrome) 糊涂窗口综合症 SYN (SYNchronous) TCP首部中的同步序号标志 TCP (Transmission Control Protocol) 传输控制协议 TFTP (Trivial File Transfer Protocol) 简单文件传送协议 TLI (Transport Layer Interface) 运输层接口 TTL (Ti m e - To-Live) 生存时间或寿命 TUBA (TCP and UDP with Bigger Addresses) 具有更长地址的T C P和U D P Telnet 远程终端协议 UA (User Agent) 用户代理 UDP (User Datagram Protocol) 用户数据报协议 URG (URGent) TCP首部中的紧急指针标志 UTC (Coordinated Universal Time) 协调的统一时间 UUCP (Unix-to-Unix CoPy) Unix到U n i x的复制 WAN (Wide Area Network) 广域网 WWW (World Wide Web) 万维网 XDR (eXternal Data Representation) 外部数据表示 XID (transaction ID) 事务标识符 XTI (X/Open Transport Layer Interface) X/ O p e n运输层接口
上传时间： 2013-11-13
上传用户：tdyoung
在研究传统家用燃气报警器的基础上，以ZigBee协议为平台，构建mesh网状网络实现网络化的智能语音报警系统。由于传感器本身的温度和实际环境温度的影响，传感器标定后采用软件补偿方法。为了减少系统费用，前端节点采用半功能节点设备，路由器和协调器采用全功能节点设备，构建mesh网络所形成的家庭内部报警系统，通过通用的电话接口连接到外部的公用电话网络，启动语音模块进行报警。实验结果表明，在2.4 GHz频率下传输，有墙等障碍物的情况下，节点的传输距离大约为35 m，能够满足家庭需要，且系统工作稳定，但在功耗方面仍需进一步改善。 Abstract: On the basis of studying traditional household gas alarm system, this paper proposed the platform for the ZigBee protocol，and constructed mesh network to achieve network-based intelligent voice alarm system. Because of the sensor temperature and the actual environment temperature, this system design used software compensation after calibrating sensor. In order to reduce system cost, semi-functional node devices were used as front-end node, however, full-function devices were used as routers and coordinator，constructed alarm system within the family by building mesh network，connected to the external public telephone network through the common telephone interface, started the voice alarm module. The results indicate that nodes transmit about 35m in the distance in case of walls and other obstacles by 2.4GHz frequency transmission, this is able to meet family needs and work steadily, but still needs further improvement in power consumption.
上传时间： 2013-10-30
上传用户：swaylong
