【正文】 畢業(yè)論文 I 多通道數(shù)據(jù)采集系統(tǒng)的開發(fā) 目 錄 摘 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 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 單片機與 PC 機通信的接口電路 ............................................................ 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 單片機控制的數(shù)據(jù)采集系統(tǒng)的硬件電路的設(shè)計。 本系統(tǒng)的硬件設(shè)計主要包括：多路轉(zhuǎn)換開關(guān)及前置放大電路的設(shè)計，采樣保持電路的設(shè)計，模數(shù)轉(zhuǎn)換電路的設(shè)計， PC 機通信的技術(shù)，鍵盤和顯示的設(shè)計，系統(tǒng)電源的設(shè)計。多路轉(zhuǎn)換開關(guān)及前置放大電路的設(shè)計中重點介紹了多路開關(guān)的選擇、 AD521 放大倍數(shù)的計算以及多路開關(guān) CD4051 和放大器 AD521 硬件連接電路。采樣保持電路的設(shè)計中重點介紹了采樣保持電路的原理和主要參數(shù)以及采樣保持器的選擇和連接電路。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。單片機與 pc機通信主要是利用 MAX232 單芯片 RC232 標(biāo)準(zhǔn)的接口通信電路。鍵盤和顯示的設(shè)計采用八個獨立鍵盤并通過串行通信的方式傳輸?shù)?12864 中并顯示。電源部分的設(shè)計通過采用 2*6V 的變壓器對 220V 的輸入交流電進行降壓，經(jīng)二極管全波整流，通過三端穩(wěn)壓器的穩(wěn)壓，輸出 5V直流電壓，利用 555 時基電路輸出 ? 15V 的雙電源電壓。 關(guān)鍵詞： 數(shù)據(jù)采集； AT89S51 單片機； 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