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数据库函数,用于将字符串类型值的大写字母全部转换成小写字母。
  • FPGA设计重利用方法(Design Reuse Methodology)

      FPGAs have changed dramatically since Xilinx first introduced them just 15 years ago. In thepast, FPGA were primarily used for prototyping and lower volume applications; custom ASICswere used for high volume, cost sensitive designs. FPGAs had also been too expensive and tooslow for many applications, let alone for System Level Integration (SLI). Plus, the development

    标签: Methodology Design Reuse FPGA

    上传时间: 2013-10-23

    上传用户:旗鱼旗鱼

  • 基于以太网分布式的数据采集控制系统

    针对飞行模拟器座舱数据采集的复杂性,设计了一种基于以太网分布式的数据采集控制系统,该系统是RCM5700微处理器模块上的以太网应用。在系统的基础上具体讨论了PoE技术的应用,在传输数据的网线上同时提供电流,提出并实现了一种包括辅助电源在内的完整可靠的PoE供电方案。设计采用美国国家半导体的LM5073和LM5576并根据不同的负载情况,进行稳定可靠的电压转换,以满足数据采集电路的要求。实验结果表明:该设计稳定可靠,满足低于13 W的采集节点供电要求,提高了模拟器信号采集系统的通用性和标准化程度,避免了以往数据采集节点单独繁琐的电源设计。 Abstract:  Aiming at the complexity of large avion simulation and controlling,the simulator cabin distribute data collecting and control system was designed. This system is the application of RCM5700 on Ethernet. Based on this system,PoE technique that makes Ethernet can also provide power were expounded with emphasis and included FAUX design the PoE resolution was realized. To achieve the requirement of this system,LM5073 and LM5576 were used to DC-DC switch. From the data of experiment,the design filled the requirement of power-need of node whose power was lower than 13W. The application of the technique can advance the degree of simulation data collections currency and standardization and avoid designing additional power system.

    标签: 以太网 分布式 数据采集 控制系统

    上传时间: 2013-11-09

    上传用户:xyipie

  • NCV7356单线CANBUS收发器数据手册

    The NCV7356 is a physical layer device for a single wire data linkcapable of operating with various Carrier Sense Multiple Accesswith Collision Resolution (CSMA/CR) protocols such as the BoschController Area Network (CAN) version 2.0. This serial data linknetwork is intended for use in applications where high data rate is notrequired and a lower data rate can achieve cost reductions in both thephysical media components and in the microprocessor and/ordedicated logic devices which use the network.The network shall be able to operate in either the normal data ratemode or a high-speed data download mode for assembly line andservice data transfer operations. The high-speed mode is onlyintended to be operational when the bus is attached to an off-boardservice node. This node shall provide temporary bus electrical loadswhich facilitate higher speed operation. Such temporary loads shouldbe removed when not performing download operations.The bit rate for normal communications is typically 33 kbit/s, forhigh-speed transmissions like described above a typical bit rate of83 kbit/s is recommended. The NCV7356 features undervoltagelockout, timeout for faulty blocked input signals, output blankingtime in case of bus ringing and a very low sleep mode current.

    标签: CANBUS 7356 NCV 单线

    上传时间: 2013-10-24

    上传用户:s蓝莓汁

  • 快速跳频通信系统同步技术研究

    同步技术是跳频通信系统的关键技术之一,尤其是在快速跳频通信系统中,常规跳频通信通过同步字头携带相关码的方法来实现同步,但对于快跳频来说,由于是一跳或者多跳传输一个调制符号,难以携带相关码。对此引入双跳频图案方法,提出了一种适用于快速跳频通信系统的同步方案。采用短码携带同步信息,克服了快速跳频难以携带相关码的困难。分析了同步性能,仿真结果表明该方案同步时间短、虚警概率低、捕获概率高,同步性能可靠。 Abstract:  Synchronization is one of the key techniques to frequency-hopping communication system, especially in the fast frequency hopping communication system. In conventional frequency hopping communication systems, synchronization can be achieved by synchronization-head which can be used to carry the synchronization information, but for the fast frequency hopping, Because modulation symbol is transmitted by per hop or multi-hop, it is difficult to carry the correlation code. For the limitation of fast frequency hopping in carrying correlation code, a fast frequency-hopping synchronization scheme with two hopping patterns is proposed. The synchronization information is carried by short code, which overcomes the difficulty of correlation code transmission in fast frequency-hopping. The performance of the scheme is analyzed, and simulation results show that the scheme has the advantages of shorter synchronization time, lower probability of false alarm, higher probability of capture and more reliable of synchronization.

    标签: 快速跳频 同步技术 通信系统

    上传时间: 2013-11-23

    上传用户:mpquest

  • MAX338/MAX339的英文数据手册

      本软件是关于MAX338, MAX339的英文数据手册:MAX338, MAX339   8通道/双4通道、低泄漏、CMOS模拟多路复用器   The MAX338/MAX339 are monolithic, CMOS analog multiplexers (muxes). The 8-channel MAX338 is designed to connect one of eight inputs to a common output by control of a 3-bit binary address. The dual, 4-channel MAX339 is designed to connect one of four inputs to a common output by control of a 2-bit binary address. Both devices can be used as either a mux or a demux. On-resistance is 400Ω max, and the devices conduct current equally well in both directions.   These muxes feature extremely low off leakages (less than 20pA at +25°C), and extremely low on-channel leakages (less than 50pA at +25°C). The new design offers guaranteed low charge injection (1.5pC typ) and electrostatic discharge (ESD) protection greater than 2000V, per method 3015.7. These improved muxes are pin-compatible upgrades for the industry-standard DG508A and DG509A. For similar Maxim devices with lower leakage and charge injection but higher on-resistance, see the MAX328 and MAX329.

    标签: MAX 338 339 英文

    上传时间: 2013-11-12

    上传用户:18711024007

  • 半导体器件物理与设计

    It would not be an exaggeration to say that semiconductor devices have transformed humanlife. From computers to communications to internet and video games these devices and the technologies they have enabled have expanded human experience in a way that is unique in history. Semiconductor devices have exploited materials, physics and imaginative applications to spawn new lifestyles. Of course for the device engineer, in spite of the advances, the challenges of reaching higher frequency, lower power consumption, higher power generation etc.

    标签: 半导体器件 物理

    上传时间: 2013-10-28

    上传用户:songnanhua

  • 场效应管产品指南

    The super-junction structure, which has P-type pillar layers as shown left, realizes high withstand voltage and ON-resistance lower than the conventional theoretical limit of silicon.

    标签: 场效应管 产品指南

    上传时间: 2014-12-31

    上传用户:qwer0574

  • WP312-Xilinx新一代28nm FPGA技术简介

    Xilinx Next Generation 28 nm FPGA Technology Overview Xilinx has chosen 28 nm high-κ metal gate (HKMG) highperformance,low-power process technology and combined it with a new unified ASMBL™ architecture to create a new generation of FPGAs that offer lower power and higher performance. These devices enable unprecedented levels of integration and bandwidth and provide system architects and designers a fully programmable alternative to ASSPs and ASICs.

    标签: Xilinx FPGA 312 WP

    上传时间: 2013-12-07

    上传用户:bruce

  • FPGA设计重利用方法(Design Reuse Methodology)

      FPGAs have changed dramatically since Xilinx first introduced them just 15 years ago. In thepast, FPGA were primarily used for prototyping and lower volume applications; custom ASICswere used for high volume, cost sensitive designs. FPGAs had also been too expensive and tooslow for many applications, let alone for System Level Integration (SLI). Plus, the development

    标签: Methodology Design Reuse FPGA

    上传时间: 2013-11-01

    上传用户:shawvi

  • 赛灵思电机控制开发套件简介(英文版)

      The power of programmability gives industrial automation designers a highly efficient, cost-effective alternative to traditional motor control units (MCUs)。 The parallel-processing power, fast computational speeds, and connectivity versatility of Xilinx® FPGAs can accelerate the implementation of advanced motor control algorithms such as Field Oriented Control (FOC)。   Additionally, Xilinx devices lower costs with greater on-chip integration of system components and shorten latencies with high-performance digital signal processing (DSP) that can tackle compute-intensive functions such as PID Controller, Clark/Park transforms, and Space Vector PWM.   The Xilinx Spartan®-6 FPGA Motor Control Development Kit gives designers an ideal starting point for evaluating time-saving, proven, motor-control reference designs. The kit also shortens the process of developing custom control capabilities, with integrated peripheral functions (Ethernet, PowerLink, and PCI® Express), a motor-control FPGA mezzanine card (FMC) with built-in Texas Instruments motor drivers and high-precision Delta-Sigma modulators, and prototyping support for evaluating alternative front-end circuitry.

    标签: 赛灵思 电机控制 开发套件 英文

    上传时间: 2013-10-28

    上传用户:wujijunshi