【正文】 低。A/D 轉換電路把放大了的電壓信號由模擬信號變?yōu)閿底中盘査腿雴纹瑱C。 系統(tǒng)由 AT89C51單片機、敏感元件、看門狗監(jiān)控電路、小信號放大電路、A/D轉換電路、通信電路、顯示電路、報警電路等組成。儀器能夠根據瓦斯?jié)舛葓缶?%)進行聲、光報警，并啟動排風設備，同時具有通信功能。小信號放大電路則是用來放大敏感元件輸出的電壓信號。 該系統(tǒng)的特點是測量范圍寬，精度高。 The feature is new design，accurately measure parameter，convenient to operate and so on. Keywords: AT89C51，sensitive element，A/D transformation Circuit.III目錄摘要 ..............................................................................................................................IABSTRACT................................................................................................................II目錄 ...........................................................................................................................III第 1 章 緒論 ...............................................................................................................1 瓦斯的介紹 ......................................................................................................1 煤礦安全系統(tǒng)概況 ..........................................................................................3 測量儀器的基本性能 ......................................................................................4 測量儀器的概念 ......................................................................................4 測量儀器的基本性能 ..............................................................................5第 2 章 研究內容方法和原則 ...................................................................................8 研究內容方法 ..................................................................................................8 設備和功能 ..............................................................................................8 計時 ..........................................................................................................9 主要實現方法 ..........................................................................................9 設計原則 ..........................................................................................................9 總體設計的原則 ....................................................................................10 課題研究的總體思路 ....................................................................................11第 3 章 監(jiān)控系統(tǒng)工作原理 .....................................................................................12 瓦斯?jié)舛葯z測系統(tǒng)原理分析 ........................................................................12 分類 ........................................................................................................12 熱催化元件的結構及工作原理 ....................................................................13 熱催化元件的結構 ................................................................................13 敏感元件工作原理 ................................................................................14 整機工作原理 ........................................................................................14第 4 章 硬件電路設計 .............................................................................................16 微控制器 CPU .................................................................................................16IV AT89C51 ..................................................................................................16 敏感元件 ........................................................................................................19 .....................................................................................19 敏感元件的組成及作用 ........................................................................21 小信號放大電路 ............................................................................................22 A/D轉換電路 .................................................................................................22 ADC0809的內部結構 .............................................................................22 通信電路 ........................................................................................................27 串行通訊 ................................................................................................27 信號的調制和解調 ................................................................................29 芯片的選擇 ............................................................................................29 串行通信的軟件 ....................................................................................30 可編程看門狗電壓監(jiān)控電路 ........................................................................33 顯示電路 ........................................................................................................37 聲光報警電路 ................................................................................................38 光報警電路 ............................................................................................38 聲報警電路 ............................................................................................38 排風電路 ........................................................................................................39 .......................................................................................................41第 5 章 軟件設計 .....................................................................................................46 系統(tǒng)軟件設計原則 ........................................................................................46 軟件實現功能 ................................................................................................46 主程序流程圖 ........................................................................................46 定時器中斷服務程序 ............................................................................48 串行口中斷服務程序 ............................................................................48第 6 章 儀器標定及主要技術指標 .........................................................................51 儀器的標定 ....................................................................................................51 儀器的主要技術指標 .................................................