为解决传统可视倒车雷达视频字符叠加器结构复杂，可靠性差，成本高昂等问题，在可视倒车雷达设计中采用视频字符发生器芯片MAX7456。该芯片集成了所有用于产生用户定义OSD，并将其插入视频信号中所需的全部功能，仅需少量的外围阻容元件即可正常工作。给出了以MAX7456为核心的可视倒车雷达的软、硬件实现方案及设计实例。该方案具有电路结构简单、价格低廉、符合人体视觉习惯的特点。经实际装车测试，按该方案设计的可视倒车雷达视场清晰、提示字符醒目、工作可靠，可有效降低驾驶员倒车时的工作强度、减少倒车事故的发生。 Abstract: A new video and text generation chip，MAX7456，was used in the design of video parking sensor in order to simplify system structure，improve reliability and reduce cost. This chip included all the necessary functions to generate user-defined OSDs and to add them into the video signals. It could be put into work with addition of just a small number of resistances and capacitors. This paper provided software and hardware implementation solutions and design example based on the chip. The system had the characteristics of simplicity in circuit structure，lower cost，and comfort for the nature of human vision. Loading road test demonstrates high video and text display quality and reliable performance，which makes the driver easy to see backward and reduces chance of accidents.
上传时间： 2013-12-10
上传用户：qiaoyue
提出一种基于单片机AT89C51SND1C的MP3播放系统的设计方案。单片机集成了专用的解码器，使用K9F1208闪存作为外存储器，放音电路采用CS4330，存储文件通过播放器上的USB接口设备从PC机上直接下载，液晶显示采用LCD1602。方案设计简单，性价比高，低功耗，易扩展。由于采用的是通用单片机实现的，可以很容易地移植到其他微控制器系统中，有很强的市场竞争能力和实用价值。 Abstract: A MP3 player design based on microchip AT89C51SND1C was presented, which used K9F1208 Flash chip as the memory circuit and used CS4330 as play chip. Storage files were download from PC through USB interfaces player on the device，and the LCD/602 was used as display screen. This system had characteristics of simple design,low power,easy expand，low cost and high recognition. Using of universual microchip make it easy to transplant to other microcontrol system，and have strong market competitiom and practical value.
上传时间： 2014-12-26
上传用户：佳期如梦
为了在工业生产及过程控制中准确测量温度，设计了一种基于低功耗MSP430单片机的数字温度计。整个系统通过单片机MSP430F1121A控制DS18B20读取温度，采用数码管显示，温度传感器DS18B20与单片机之间通过串口进行数据传输。MSP430系列单片机具有超低功耗，且外围的整合性高，DS18B20只需一个端口即可实现数据通信，连接方便。通过多次实验证明，该系统的测试结果与实际环境温度一致，除了具有接口电路简单、测量精度高、误差小、可靠性高等特点外，其低成本、低功耗的特点使其拥有更广阔的应用前景。 Abstract: In order to obtain accurate measuring temperature in industrial production and process control， a digital thermometer based on MSP430 MCU is designed. The system uses MSP430F1121A MCU to control DS18B20， and gets the temperature data， which is displayed on the LED. The temperature sensor DS18B20 and MCU transmit data through serial communication. MSP430 series has ultra-low power and high integration， DS18B20 only needs one port to achieve data communication. Through many experimental results prove， this system is consistent with actual environment temperature. The system has characteristics of interface circuit simple， high measuring accuracy， minor error， high reliability， besides， the characteristics of low cost and low power make it having vaster application prospect.
上传时间： 2013-10-16
上传用户：wettetw
摘要：本水位监测报警器使用5V低压直流电源（也可以用3节5号电池代替）就可以对5~15厘米的水位进行监测，用LED显示和数码管显示水位，并可以对不再此范围内的水位发出报警。主要采用CD4066、74LS86、74LS32、CD4511芯片，再加上数码管、蜂鸣器、发光二极管、电阻这些器件组成一个简单而灵敏的监测报警电路，操作简单，接通电源即可工作。因为大部分电路采用数字电路，所以本水位监测报警器还具有耗能低、准确性高的特点。关键字：译码电路 报警电路 监测电路 Abstract: The water level alarm monitoring the use of 5 V low-voltage DC power (can also use three batteries replaced on the 5th) will be able to 5 to 15 centimeters of water level monitoring, with LED display and digital display of water level, and this can no longer Within the scope of a water level alarm. Mainly CD4066, 74LS86, 74LS32, CD4511 chips, coupled with digital control, buzzer, light-emitting diode, the resistance of these devices composed of a simple and sensitive monitoring alarm circuits. Because the majority of circuits using digital circuitry, so the water level monitored alarm system also has low energy consumption, high accuracy of the characteristics. Keyword: Decoding circuit alarm circuit monitoring circuit
上传时间： 2013-11-04
上传用户：王庆才
The Motorola MPC106 PCI bridge/memory controller provides a PowerPCªmicroprocessor common hardware reference platform (CHRPª) compliant bridgebetween the PowerPC microprocessor family and the Peripheral Component Interconnect(PCI) bus. In this document, the term Ô106Õ is used as an abbreviation for the phraseÔMPC106 PCI bridge/memory controllerÕ. This document contains pertinent physicalcharacteristics of the 106. For functional characteristics refer to theMPC106 PCI Bridge/Memory Controller UserÕs Manual.This document contains the following topics:Topic PageSection 1.1, ÒOverviewÓ 2Section 1.2, ÒFeaturesÓ 3Section 1.3, ÒGeneral ParametersÓ 5Section 1.4, ÒElectrical and Thermal characteristicsÓ 5Section 1.5, ÒPin AssignmentsÓ 17Section 1.6, ÒPinout Listings 18Section 1.7, ÒPackage DescriptionÓ 22Section 1.8, ÒSystem Design InformationÓ 24Section 1.9, ÒDocument Revision HistoryÓ 29Section 1.10, ÒOrdering InformationÓ 29
上传时间： 2013-11-03
上传用户：as275944189
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
在综合分析谐波励磁无刷同步发电机励磁控制系统的基础上,对其励磁控制策略进行了研究,开发了一套基于DSP( TMS320F2812) 控制的新型柴油发电机励磁控制系统,该系统采用参数自适应模糊PID 控制励磁,选用交流采样方式实时检测各信号的瞬时特性,系统仿真结果以及在1 台25 kW 工频柴油发电机上的试验结果证明了该控制器具有较好的电压调节特性,系统稳态和暂态性能完全满足发电机对励磁系统的要求。关键词:励磁调节;模糊PID 控制;数字信号处理器;交流采样 Abstract :According to the general analysis of the excitation cont rol system of the harmonious wave excitation brushless synchronous generator and it s characteristics ,a new type of diesel generator excitation cont rol system based on DSP( TMS320F2812) was designed. An adaptive fuzzy PID cont rol of excitation is used in this system. To detect the t ransient characteristics of the signals in a timely manner ,AC sampling was applied.The system simulation result s and the testing result s f rom a 25 kW diesel generator (50 Hz) can prove that the voltage regulation characteristics of the excitation cont rol system are very well ,and both the steadyOstate performance and the t ransient performance of the generator are also good.Key words :excitation cont rol ;fuzzy PID cont rol ;digital signal processor (DSP) ;AC sampling
上传时间： 2013-10-29
上传用户：fxf126@126.com
Abstract: The process of designing a radio system can be complex and often involves many project tradeoffs. Witha little insight, balancing these various characteristics can make the job of designing a radio system easier. Thistutorial explores these tradeoffs and provides details to consider for various radio applications. With a focus on theindustrial, scientific, medical (ISM) bands, the subjects of frequency selection, one-way versus two-way systems,modulation techniques, cost, antenna options, power-supply influences, effects on range, and protocol selectionare explored.
标签： 无线
上传时间： 2013-12-12
上传用户：eastgan
通过比较各种隔离数字通信的特点和应用范围，指出塑料光纤在隔离数字通信中的优势。使用已经标准化的TOSLINK接口，有利于节省硬件开发成本和简化设计难度。给出了塑料光纤的硬件驱动电路，说明设计过程中的注意事项，对光收发模块的电压特性和频率特性进行全面试验，并给出SPI口使用塑料光纤隔离通信的典型应用电路图。试验结果表明，该设计可为电力现场、电力电子及仪器仪表的设计提供参考。 Abstract: y comparing characteristics and applications area of various isolated digital communications， this article indicates advantages of plastic optical fiber in isolated digital communications. Using the standardized TOSLINK interface， it helps to control costs and difficulty in hardware development and design. Then it gives the hardware driver circuit of plastic optical fiber module， explains the noticed details in design process， gives results on the basis of the optical transceiver module voltage characteristics and frequency characteristics tests. Finally，it gives typical application circuit of the SPI communication port by using plastic optical fiber isolation .The results show that this design can be referenced for the power field， power electronics and instrumentation design.
上传时间： 2014-01-10
上传用户：gundan
