為解決當前計算機串行通訊接口只有USB，難以滿足舊型號設備或某些單片機要求RS232通訊的問題，設計出兩款RS232/USB電路。采用CH341A與MAX223集成電路芯片構建標準9線RS232/USB通用接口轉換器，無需編程。采用CH341A與PIC16F877A構建單片機與計算機之間的USB通訊電路，軟件遵循RS232通訊協議，硬件進行電平轉換。實際使用表明，這兩款產品與計算機端Windows 操作系統下的串口應用程序完全兼容，且通訊過程中無握手失敗現象。 Abstract: To solve the problem that current computer serial communication only with USB interface can not satisfy with the old type equipments or MCU to communicate with RS232， two kinds of RS232/USB circuit were designed.CH341A and MAX223 integrated circuit chips were used to create a standard 9-line RS232/USB universal interface convertor without programme. CH341A and PIC16F877A chips were adopted to build the USB communication circuit between computers and MCU. The software follows RS232 communication protocol， and the hardware converts electrical levels. Actual practices indicate that the two manufactures are compatible with serial application program of Windows operation system completely，and get avoid of handshake lost.
上傳時間： 2013-11-03
上傳用戶：siying
摘要 本研究計劃之目的，在整合應用以ARM為基礎的嵌入式多媒體實時操作系統于H.264/MPEG-4多媒體上。由于H.264是一種因應實時系統(RTOS)所設計的可擴展性串流傳輸(scalability stream media communication)的編碼技術。H.264主要架構于細細?？蓴U展(Fine Granula Scalability,FGS)的壓縮編碼機制。細粒度可擴展壓縮編碼技術是最新MPEG-4串流式傳輸標準，能依頻寛的差異來調整傳輸的方式。細粒度擴展縮編碼技術以編入可選擇性的增強層(enhanced layers)于碼中，來提高影像傳輸的質量。本計劃主要在于設計一種簡單有效的實時階層可擴展的影像傳輸系統。在增強層編碼及H.264的基本層(base layer)編碼上使用漸進的細粒度可擴展編碼(Progressive Fine Granularity Scalable,PFGS)能直接使用H.264的格式特色來實現FGS。同時加入了LB-LLF(Layer-Based Least-Laxity-Fir stscheduling algorithm)的排程算法，來增 進網路傳輸影像的質量。由實驗結果顯示本系統在串流影像質量PSNR值上確有較佳的效能。
上傳時間： 2014-12-26
上傳用戶：mpquest
以太網和CAN總線應用廣泛，但由于其通信協議不同，兩種總線器件間無法進行數據通信，因此，設計了基于CP2200與C8051F040的以太網總線與CAN總線接口轉換電路，并給出部分相關硬件電路與軟件設計分析。在保證數據完整和協議可靠的前提下，通過握手協議和簡化的以太網協議，不僅實現了以太網數據與CAN數據的轉發，同時還順利的解決了以太網的高速性與CAN的低速率沖突，以及兩者數據包之間的大小不同的矛盾。 Abstract: In the development of actual application， Ethernet and CAN bus are used very extensively. Owing to its various communication protocols， the communicating between two kinds of bus device can’t be carried out. Therefore， in order to solve this problem， the Ethernet-CAN bus interface circuit based on CP2200 and C8051F040 was designed in this paper， and part of the related hardware circuit and software design analysis were given. On the condition of data’s integrity and protocols’reliability， through the handshaking protocols and the simplified the Ethernet protocol， not only the data switching between CAN and Ethernet was realized， but also the differ in velocity and packet size was solved.
上傳時間： 2013-10-15
上傳用戶：Ants
提出一種基于凌陽單片機的步進電機加減速的控制方法。采用凌陽科技推出的16位結構工控單片機SPMC75F2413A為控制器，由Allegro公司生產的兩相步進電機專用驅動器件SLA7042M構成步進電機的驅動電路，在傳統的3段直線加減速控制算法基礎上增加至7段S形曲線加減速過程，控制步進電機的啟動和停止。實驗結果表明，該控制方法克服了直線加減速中不連續、易造成系統沖擊的問題，整個系統實現柔性控制，電機啟動、停止連續性能提高30%。 Abstract: The method of controlled stepping motor is referred based on SPMC75F2413A MCU， which adopts the 16 knots SPMC75F2413A MCU as the controller. The special-purpose actuation chip SLA7042M of two stepping motor produced by Allegro Corporation constituted to actuation electric circuit. The purpose of increasing to seven section of S shape curve based on the traditional three sections of straight line is to control the start and stop process of stepping motor. The experimental results show that the control method solves easy to pull-out and overshot problems. The overall system realizes flexible control， and the performance of motor start or stop continuity is increased 30%
上傳時間： 2013-12-08
上傳用戶：jiangfire
首先研究CAN總線和SAE J1939協議，提出一種基于MC9S12HZ256微控制器的總線式汽車數字儀表解決方案。詳細介紹SAE J1939協議的報文幀格式及應用層協議中發動機相關參數的定義，以及步進電機及其驅動和車速信號的處理方法。該數字儀表系統硬件平臺由微處理器和信號采集和信息處理及顯示等模塊組成。軟件設計部分編程實現了對CAN總線和各傳感器數據的讀取、處理。該系統能夠實時反映車輛工況。 Abstract: In this paper，CAN bus and SAE J1939protocol are researched，and a vehicle digital instrument solution based on MC9S12HZ256MCU is proposed.The message frame format and some engine-related parameters’definition in SAE J1939application layer protocol are introduced in detail.Stepper motor and its driver，the methods of speed signal process-ing are also introduced.The hardware platform of vehicle digital instrument is composed by MCU，signal acquisition mod-ule，and signal processing and displaying module.Data receiving and processing from CAN bus and sensors are accom-plished by programming，and vehicle condition can be reflected in real-time.
上傳時間： 2013-10-20
上傳用戶：huannan88
介紹一種基于C8051單片機的動態心電監護系統。該系統由兩部分組成：以C8051F320單片機為核心的數據采集裝置和以PC機為平臺的分析處理系統。硬件電路功耗低，由單片機自帶的USB接口將數據傳送給PC機。軟件平臺采用LabVIEW可視化虛擬儀器系統開發平臺，將傳統儀器的功能模塊集成到計算機中，用戶可通過修改虛擬儀器的程序改變其功能。采用USB接口實時傳輸心電數據，并將數據采集模塊設計為計算機外設，使該系統高速快捷、小巧便攜。 Abstract: In this design，a low-cost ECG electrocardiogram monitoring system is introduced，which consists of two parts:data acquisition device based on C8051F320and PC terminal as the analysis and processing system.The system is low-power consumption，the data is transmitted to the PC terminal by USB interface of the C8051F320.By using the visible virtual instrument system developing platform LabVIEW，the traditional instruments function modules are integrated into the computer，so the user can modify virtual instrument software to change its function to meet their needs.Using USB in-terface to realize real-time ECG data transmission，in addition，ECG data acquisition module is designed as the computer peripheral，which makes the syetem high-speed and portable.
上傳時間： 2013-11-13
上傳用戶：zhangzhenyu
介紹一種基于CAN總線的牽引變電站自動化系統通訊規約的設計，CAN通訊規約采用標準幀，報文采用主動發送和發送查詢兩種處理形式。該設計在城市輕軌與地鐵牽引變電站中的應用表明：可實現間隔層和通訊處理層的數據快速、可靠的交換，提高牽引變電站的安全性和穩定性 。 Abstract: This paper firstly presents a kind of design dealing with communicational protocol to the traction substation automation system based on CAN bus,and then comes up with the ideas that all frames of CAN communicational protocol should adopt the standard frame,and that messages be processed by two ways:sending initiatively and sending quiries.Subway and light rail application shows that the use of the CAN bus is possible to exchange data quickly and reliably between the layers of the middle and the communicational processing,hence to improve the safety and stability of traction substations.
上傳時間： 2013-11-07
上傳用戶：bs2005
介紹一種多功能音樂播放器，它是以AT89S52單片機為核心，并輔有一些外圍器件，采用匯編語言編寫程序，實現多功能音樂播放，歌曲自動循環播放和使用琴鍵自編曲目功能。此外，彩燈顯示歌曲節奏，按鍵跳轉到喜愛曲目，液晶顯示當前播英文曲目。并給出了系統軟硬件設計。 Abstract: It introduces a multifunctional music player,taking AT89S52 single-chip microcomputer as hardware control core and using some peripheral elements.Programmes are compiled in assembly language to act as expected.There are two functional modes in this system.One is to make the music play automatically and consecutively,the other is to compose new songs through keys.In addition,lights show the pace of music and the English names can be displayed in the liquid crystal screen.With perfect combination of hardware and software,the music player can meet many music lovers’needs for multifunctional music player.And the hardware and software of the system are given.
上傳時間： 2013-11-18
上傳用戶：xiaodu1124
對于傳統的跑步機無法聯機組網，保存歷史數據，實時調試等問題，介紹了一個由多臺跑步機通過RS-232串行總線與上位機相連組成的跑步機聯網系統。系統采用W77E58作為下位機核心控制器件，它具有雙串行通訊端口，其中一個串口用于與變頻器通訊，另一個串口則與上位機相連，構成跑步機網絡。 Abstract: The traditional running machine can not be connected to a network, saving historical data, real time debug etc.In this paper,a new network system which is composed of running machines connected by a RS-232 communication bus is introduced.In the system,W77E58 is used as a core control unit.W77E58 has two serial ports,one is connected to the inverter and the other is connected to the PC. Thus a network appears.
上傳時間： 2014-12-27
上傳用戶：哇哇哇哇哇
為深入了解基于UC3854A控制的PFC變換器中的動力學特性，研究系統參數變化對變換器中分岔現象的影響，在建立Boost PFC變換器雙閉環數學模型的基礎上，用Matlab軟件對變換器中慢時標分岔及混沌等不穩定現象進行了仿真。在對PFC變換器中慢時標分岔現象仿真的基礎上，分析了系統參數變化對分岔點的影響，并進行了仿真驗證。仿真結果清晰地顯示了輸入整流電壓的幅值變化對系統分岔點的影響。 Abstract: In order to better understand the dynamics characteristic of power factor correction converter based on UC3854A， and make the way that parameters change influences the bifurcation phenomena of the system clearly. The math model of the two closed loop circuits to the Boost PFC （Power Factor Correction） converter controller was built. Then， with the help of Matlab， the simulation for nonlinear phenomena such as chaos and slow-scale bifurcation in the PFC converter was made. Finally the factors that have influence to the phenomenon of bifurcation under slow-scale in PFC converter were analyzed. The simulation results clearly show the parameters change influences the bifurcation point of the system.
上傳時間： 2013-10-17
上傳用戶：杜瑩12345
