【正文】 要 ........................................................................................................................ III ABSTRACT .............................................................................................................IV 1 前 言 ................................................................................................................. 1 多路數(shù)據(jù)采集系統(tǒng)簡介 .................................................................................. 2 本設(shè)計的主要任務(wù) .......................................................................................... 3 2 系統(tǒng)硬件設(shè)計 .................................................................................................. 4 硬件設(shè)計思想 .................................................................................................. 5 多路數(shù)據(jù)輸入部分 ..................................................................................... 5 采樣保持部分 ............................................................................................. 5 A/D 轉(zhuǎn)換部分 .............................................................................................. 6 . 4 PC 和單片機(jī)的通信部分 ........................................................................... 6 獨立鍵盤和顯示部分 ................................................................................. 6 電源部分 ..................................................................................................... 6 硬件電路設(shè)計 .................................................................................................. 7 單片機(jī) AT89S51......................................................................................... 7 多路轉(zhuǎn)換開關(guān) ........................................................................................... 10 前置放大電路 ........................................................................................... 13 采樣 /保持電路 .......................................................................................... 15 模 /數(shù)轉(zhuǎn)換電路 .......................................................................................... 19 單片機(jī)與 PC 機(jī)通信的接口電路 ............................................................ 24 鍵盤結(jié)構(gòu) ................................................................................................... 25 液晶顯示 ................................................................................................... 26 系統(tǒng)電源 ................................................................................................... 32 系統(tǒng)總圖 ................................................................................................. 38 畢業(yè)論文 II 3 程序流程圖 ..................................................................................................... 39 主程序流程圖 ................................................................................................. 40 A/D 轉(zhuǎn)換程序的流程圖 ................................................................................. 41 鍵盤和顯示程序的流程圖 ............................................................................ 42 4 系統(tǒng)性能及誤差分析 .................................................................................. 43 系統(tǒng)可靠性措施 ............................................................................................. 44 低功耗措施 ................................................................................................ 44 抗干擾措施 ................................................................................................ 44 5 結(jié) 論 .............................................................................................................. 44 謝 辭 ................................................................................................................... 45 參考文獻(xiàn) .............................................................................................................. 46 附 錄 ................................................................................................................... 47 畢業(yè)論文 III 摘 要 本設(shè)計主要完成了基于 AT89S51 單片機(jī)控制的數(shù)據(jù)采集系統(tǒng)的硬件電路的設(shè)計。模數(shù)轉(zhuǎn)換電路的設(shè)計中重點介紹了系統(tǒng) A/D 通道的選擇和 A/D 轉(zhuǎn)換器的各項誤差分析以及 A/D 轉(zhuǎn)換器 AD574 的介紹、輸入方式和連接電路。 關(guān)鍵詞： 數(shù)據(jù)采集； AT89S51 單片機(jī)； CD4051； MAX232 畢業(yè)論文 IV Multichannel data acquisition system development ABSTRACT The design pletes the hardware design of data acquisition system that it bases on the control of AT89S51 microcontroller. This system hardware design includes: multiplexer switch and preamplifier circuit design, sampling keep circuit design, the design of the circuit module conversion, the PC munication technology, the keyboard and display design, the design of the power system. The multiplexer switch and preamplifier circuit design focuses on introducing the multiple switch choice, AD521 magnification calculation and multiple switch CD4051 and amplifier AD521 hardware connection circuit. Sampling keep circuit design of mainly introduced in sampling keeping circuit principle and main parameters and implement the choice and sampling keep connection circuit. The design of the circuit module conversion introduced the system A/D channel selection and A/D converter and the error analysis of the A/D converter AD574 introduction, input methods and connection circuit. SCM and PC munication is use of a MAX232 singlechip posed of RC232 standard interface munication circuit. Keyboard and display design with eight separate keyboard and through serial munication mode to 12864 and display. The power of design by the use of the 2*6V transformer to stepdown the input AC output 5V DC voltage by the diode fullwave rectifier, threeterminal voltage stabilizer voltage stabilizing.， The use of the 555 output 15V dualsupply voltage. Keywords: data acquisition。例如：在生產(chǎn)過程中，應(yīng)用這一系統(tǒng)可對生產(chǎn)現(xiàn)場的工藝參數(shù)進(jìn)行采集、監(jiān)視和記錄，