【正文】 I單片機的瓦斯報警系統(tǒng)的設計摘要 本文設計的用單片微機控制的瓦斯?jié)舛缺O(jiān)控報警系統(tǒng)，是采用熱催化原理(俗稱黑白元件)探頭制成的甲烷濃度測量儀，適用于煤礦井下各作業(yè)場所中測量空氣中的瓦斯?jié)舛?。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。 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。其中 CPU是監(jiān)控儀的核心，完成數據采集、處理、輸出、顯示等功能。敏感元件是準確檢測瓦斯氣體含量的主要元件之一，其輸出是與瓦斯?jié)舛认鄬碾妷盒盘?。小信號放大電路則是用來放大敏感元件輸出的電壓信號。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。顯示電路則顯示實時瓦斯?jié)舛?。報警電路對超限瓦斯?jié)舛冗M行報警。 該系統(tǒng)的特點是測量范圍寬，精度高。結構簡單，成本低?？煽啃院头€(wěn)定性好，是一種電路設計新穎、參數測量準確、操作方便的礦用瓦斯?jié)舛缺O(jiān)控報警系統(tǒng)。關鍵詞: AT89C51，A/D 轉換電路，敏感元件IIAbstractThe concentration of methane monitor controlled by chip microprocessors15 able to sound the alarm bell based on the limit of methane concentration，and start device to drain the gas at the same time. The instrument include CPU，sensitive element，Canmengou monitoring circuit，little signal amplify circuit，A/D transform circuit，munication circuit，display circuit，monitoring circuit，CPU is the core in the instrument，plete data gather，Process，export，display and so on. Sensitive element is one of the important to measure the concentration of methane，and it’s export is a little voltage signal，little signal amplify circuit is to transform the analogue signal to digital signal，display circuit is to display the concentration of methane，monitoring circuit is to monitor the overstep limit of methane concentration 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 .........................................................