【正文】 摘 要 隨著社會的不斷進步發(fā)展，人們對燃氣熱水器的要求越來越高。而現(xiàn)今大多數(shù)熱水器還是處于手動調(diào)溫階段，熱水溫度不能實時顯示，水量和氣量不能實時顯示和控制，洗浴過程中調(diào)溫困難等等情況。 根據(jù)以上情況， 設計了合理的燃氣熱水器恒溫控制系統(tǒng)結(jié)構(gòu)：采用 8 位單片機 89S51和 DS18B20 溫度傳感器構(gòu)成溫度采集系統(tǒng)的方案，較之采用 16 位的單片機和熱敏電阻加 A/D 轉(zhuǎn)換器的溫度采集系統(tǒng)具有較高的性價比； 單片機根據(jù)溫度傳感器采集到的數(shù)據(jù)， 經(jīng)過程序處理，發(fā)送數(shù)據(jù)指令給 0832， 通過 DAC0832 數(shù)模 轉(zhuǎn)換輸出不同的電流來控制 燃氣比例閥的開度， 達到 控制火力的大小，實現(xiàn)溫度的自動控制；為了提高溫度控制精度，采用數(shù)字 PID 程序控制，可實現(xiàn)溫度的連續(xù)可調(diào)，用液晶顯示器 LCD1602 顯示出水溫度； 為加強系統(tǒng)的安全性能，設計中還加入了看門狗和聲光報警電路；最后，制作出了工程樣板并進行硬件模擬調(diào)試。 實際調(diào)試結(jié)果顯示硬件設計基本達到了要求的技術(shù)指標，對比分析可知此設備具有良好的應用前景。 關鍵詞 ：單片機；溫度轉(zhuǎn)換； DS18B20 ； DAC0832 ABSTRACT With the continuous progress and development, people are increasingly demanding gas water heater. And now most of the water heater thermostat stage or in the manual, hot water temperature can not be realtime display, water and gas can not be realtime display and control the process bath thermostat, etc. difficult situation. According to the above, the design of a reasonable gas water heater temperature control system architecture: 8bit microcontroller 89S51 and temperature sensor DS18B20 programs constitute the temperature acquisition system, pared with 16bit microcontroller and the thermistor plus A / D converter temperature acquisition system has a high price。 Microcontroller according to the temperature sensor to the data, after procedures to send mands to the 0832 data, through the DAC0832 digitalanalog converter output current to control the different gas proportional valve opening, to control the size of firepower to achieve automatic temperature control。 To improve the accuracy of temperature control, digital PID process control, enabling the temperature of the continuously adjustable, LCD1602 display with water temperature。 To enhance the safety performance of the system, the design watchdog also added sound and light alarm circuit。 Finally, the project produced a simulation model and hardware debugging. The results showed that the actual hardware design debug basically reached the requirements of the technical indicators, parative analysis shows that this device has a good prospect. Keywords: microcontroller。 temperature conversion。 DS18B20。 DAC0832 桂林電子科技大學畢業(yè)設計（論文）報告用紙 第 I 頁 目 錄 1 緒論 ................................................................................................................ 1 選題的意義 ...................................................................................................................... 1 燃氣熱水器簡介 ....................................................................................................... 1 燃氣熱水器的發(fā)展趨勢 ........................................................................................... 2 現(xiàn)有燃氣熱水器溫度調(diào)節(jié)方案及不足 ................................................................. 3 2 燃氣熱水器方案設計 ..................................................................................... 4 設計要求及系統(tǒng)設計要點 .............................................................................................. 4 設計要求 ................................................................................................................. 4 系統(tǒng)設計要點 .......................................................................................................... 4 方案設計 .......................................................................................................................... 6 系統(tǒng)性能指標 .................................................................................................................. 7 3 熱水器控制器系統(tǒng)分析 ................................................................................. 8 燃氣熱水器的系統(tǒng)組成與工作原理 .............................................................................. 8 燃氣熱水器的數(shù)字 PID 溫度控制 .................................................................................. 9 PID 算法控制的實現(xiàn) .............................................................................................. 9 PID 控制器的參數(shù)整定 ........................................................................................ 11 4 燃氣熱水器系統(tǒng)的硬件設計 ....................................................................... 13 元器件的選擇 ................................................................................................................ 13 單片機的選擇 ......................................................................................................... 13 顯示器件的選擇 ...................................................................................................... 14 數(shù)字溫度傳感器的選擇 ......................................................................................... 16 D/A 數(shù)模轉(zhuǎn)換的選擇 .............................................................................................. 18 比例閥的選擇 ......................................................................................................... 20 風機的選擇 ............................................................................................................. 22 水汽聯(lián)動裝置的選擇 .............................................................................................. 22 變壓器的選擇 ......................................................................................................... 24 硬件電路的設計 ............................................................................................................ 24 主控制電路的設計 .................................................................................................. 24 鍵盤輸入電路的設計 .............................................................................................. 25 聲光報警電路的設計 .............................................................................................. 25 溫度檢測電路的設計 .............................................................................................. 25 液晶顯示電路的設計 .............................................................................................. 26 電流控制電路的設計 ..................