基于单片机的LED汉字显示屏的设计

文中详细介绍了由STC89C52RC单片机、74HC154芯片、晶振电路、复位电路、驱动电路、16×16 LED点阵构成的LED汉字显示屏系统。设计采用STC89C52RC单片机为微控制器,74HC154为译码器、PNP型三极管8550构成行驱动电路,NPN型三极管8050构成列驱动电路,采用4个8x8LED显示器级联构成16×16的点阵汉字显示屏。软、硬件设计结果表明所设计的LED汉字显示屏可以实现汉字的滚动显示,且汉字清晰,无串扰,无重影     

串行显示驱动器MC14499的应用

MC14499是MOTOROLA公司的高集成度LED显示驱动器,采用动态扫描方式显示驱动4个LED数码管。它集锁存、译码、驱动、扫描、时钟于一体。所需的辅助电路简单,MC14499与单片机的数据传送采用串行同步方式。因此,用MC14499组成单片机的显示电路,具有占用单片机软件资源小,不需再外加电路即可与单片机协调工作使用灵活方便,电路简单可靠等特点。电路工作原理MC14499能接受20位数据的串行输入,16位用作四位LED显示,4位用作小数点显示。输入时序是先发送四位小数点码,具体如图王所示。当ENB由高变低时,MC14499的寄存器开始接…     

基于Proteus的单片机汉字点阵显示电路设计

在嵌入式系统软硬件设计仿真平台Proteus的基础上设计了16×16 LED汉字点阵显示电路.硬件电路由AT89C51单片机控制器、LED显示屏行列驱动电路以及LED点阵显示屏3部分组成.通过汉字字模点阵数据批量生成软件来实现汉字点阵,采用汇编语言对单片机进行控制操作.完成了实物电路并在 Proteus软件的基础上对结果进行了仿真,得到了汉字点阵效果图.实验结果表明,在单片机显示领域的设计开发中Proteus软件具有重要的实用价值,可以大幅缩短开发周期,节约开发成本.     

基于单片机的LED点阵显示控制的设计

LED点阵显示屏具有运行可靠、安全、节能、成本低、使用方便等特点.本文讨论了基于单片机的LED点阵显示控制系统设计所用的各种方法,制作出一个以单片机作为控制单元的点阵显示屏.设计采用动态扫描的显示方法,选取74LS154和74LS595芯片分别构成行、列驱动电路,单片机通过行、列驱动电路,可对点阵显示模块单元进行行列信号控制,达到控制点阵显示屏正常显示汉字、图片信息的设计要求.     

大屏幕LED显示屏控制系统设计

设计一种基于单片机的大屏幕LED显示屏控制系统,由单片机、串行通信电路、存储器电路、显示屏及行列驱动电路组成。广泛应用于商场、学校、银行、邮局、机场、车站、码头、金融证券市场、文化中心等公共场所进行广告、新闻和信息发布,可显示M行N列汉字、字符、数字和图片,可实现上下、左右移动等显示方式。采用模块化结构设计,扩展容易,操作方便、使用灵活。详细介绍了控制系统设计方法,并给出了系统仿真运行结果。经实际应用表明,稳定可靠,效果良好。     

基于单片机的LED汉字条屏显示技术

文中设计了一种基于单片机动态扫描控制的16×16LED汉字显示条屏,简单分析了汉字显示的原理,并对LED显示模块单元如何进行行列信号控制及信号传输中的驱动问题进行了研究。结果表明采用并行数据输入、串行数据输出的专用电路可大大减少CPU的辅助时间,提高数据的发送速度。     

基于FPGA的LED显示屏控制系统设计

介绍了一种基于FPGA的LED显示屏控制系统的设计方法,系统由一片FPGA芯片、LED显示及接口驱动电路模块组成。采用Altera公司的EP2C35F672C8FPGA芯片并使用NiosⅡ软核微处理器。PC上位机与FPGA核心板采用RS232串口通信和JTAG下载线。FPGA核心板的输出通过显示驱动模块点亮LED点阵。串口通信电路接口电路采用MAX232芯片。驱动电路使用4片74HC595移位寄存器。与传统的单片机控制LED显示系统相比,本系统具有外围电路简单、升级容易、稳定性好的优点。     

MAX7219原理及其应用

在单片机应用系统中,单片机与LED的连接有并行和串行方式。由于串行方式占用单片机口线少,因而得到广泛应用。MAX7219芯片是一个专用的八位LED显示驱动串行接口,文章介绍了其组成原理、应用电路、程序设计及应用中应注意的问题。     

地铁列车LED显示屏的设计

根据地铁车辆CAN智能总线通讯的要求设计了一种先进的多功能LED屏,其特点是采用多模块化设计,可根据需要对系统的总线通讯模块和测温模块进行更换,实现了对多种动态文字和静态图形的显示和车内外的温度和湿度的监测。该显示屏的刷新频率可以达到61.6Hz,动态显示的换帧频率达到26.2Hz。文章从组成框图、硬件设计以及逻辑控制流程等几方面介绍了该LED的驱动电路,给出了硬件接口电路图。驱动电路的核心部分采用单片机77E58来控制LED的显示,大大降低了LED显示屏的成本,优化了LED显示器件的驱动电路。     

一种应用于大尺寸LED屏的背光驱动设计

近年,电视机显示屏已经逐步从CCFL时代过渡到LED时代。显示屏日益大型化,LED背光驱动技术也是不断发展。传统升压型LED驱动传统的LED驱动采用升压型Boost电路,简化电路形式如图1所示。     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

中国建立EB级存储实验室,致力云计算应用(英文)

正With the support of 863 programs,Sugon Information Industry Co.,Ltd.,set up a dawning EB-class storage laboratory to address massive data storage requirements and largescale cloud computing demonstration applications.The Dawning EB-class cloud storage system adopts advanced fault-tolerant architecture,efficient data fault-tolerant algorithms with user authentication and data encryption policies to deal with the"lost""wrong"and"stolen"problems of data for ensuring the reliability and safety of the EB-class storage system in the public network application environments.The Dawning EB-class Storage Laboratory taking advan-