基于單片機的溫度測控系統設計

測控論文編號:CK133   論文字數:25122,頁數:71

目 錄
摘 要 i
Abstract ii
第一章  緒論 1
1.1選題的背景 1
1.2選題的現實意義 2
第二章 設計任務 3
2.1設計題目 3
2.2設計目標與要求 3
2.3設計方案 3
2.3.1方案一 3
2.3.2方案二 4
2.3.3方案比較 4
第三章  系統硬件電路的設計 5
3.1系統硬件電路構成 5
3.2溫度傳感器 6
3.2.1 DS18B20簡介 7
3.2.2 DS18B20的性能特點 8
3.2.3 DS18B20的管腳排列 9
3.2.4 DS18B20的內部結構 9
3.2.5 DS18B20的控制方法 13
3.2.6 DS18B20的測溫原理 14
3.2.7 DS18B20的時序 14
3.2.8 DS18B20的注意事項 16
3.3 單片機的選擇 17
3.3.1 單片機的概述 17

3.3.2 單片機的歷史與發展 17
3.3.3 單片機的組成 19
3.3.4 單片機的特點 21
3.3.5 單片機的應用領域 22
3.3.6 AT89C2051芯片的主要性能 23
3.3.7 AT89C2051芯片的內部結構框圖 23
3.3.8 AT89C2051芯片的引腳說明 25
3.3.9 使用AT89C2051芯片編程時的注意事項 27
3.4 74LS164簡介 28
3.4.1 74LS164的概述 28
3.4.2 74LS164的特性 28
3.4.3 74LS164的功能圖 29
3.5 顯示電路的設計 32
3.5.1 LED數碼管簡介 32
3.5.2 LED數碼管的分類 33
3.5.3 LED數碼管的驅動方式 33
3.5.4 LED數碼管的顯示電路 34
3.6本章小結 35
第四章  系統軟件的設計 37
4.1 系統軟件總述 37
4.2 系統部分子程序 39
4.2.1 DS18B20的初始化 39
4.2.2 DS18B20的讀子程序 41
4.2.3 DS18B20的寫子程序 44
第五章  總結 46
參考文獻 47
致謝 49

附錄一  電路原理圖 50
附錄二  電路仿真圖 51
附錄三  硬件電路實物圖 54
附錄四  系統總程序 57

 摘 要
 
 隨著大棚技術的普及，溫室大棚數量不斷增多，溫室大棚的溫度控制成為一個難題。目前應用于溫室大棚的溫度檢測系統大多采用由模擬溫度傳感器、多路模擬開關、A/D轉換器及單片機等組成的傳輸系統。這種溫度采集系統需要在溫室大棚內布置大量的測溫電纜，才能把現場傳感器的信號送到采集卡上，安裝和拆卸繁雜，成本也高。同時線路上傳送的是模擬信號，易受干擾和損耗，測量誤差也比較大，不利于控制者根據溫度變化及時做出決定。在這樣的形式下，開發一種實時性高、精度高，能夠綜合處理多點溫度信息的測控系統就很有必要。
  本課題提出一種基于單片機的溫度測控系統應用于溫室大棚的設計方案，該方案是利用溫度傳感器將溫室大棚內溫度的變化，變換成電流的變化，再轉換為電壓變化輸入模數轉換器，其值由單片機處理，最后由單片機去控制數字顯示器，顯示溫室大棚內的實際溫度。一旦該溫度值超過我們預先設定的上、下限，單片機便啟動報警系統進行報警，進而對大棚內溫度進行控制。而且這種設計方案能對多點的溫度進行實時巡檢，各檢測單元能獨立完成各自功能，同時能夠根據主控機的指令對溫度進行定時采集。該測控系統不需要任何固定網絡的支持，安裝簡單方便，系統穩定可靠、可維護性好。

關鍵詞  單片機；溫度傳感器；溫室大棚；測控系統

Abstract
 
 With the popularization of greenhouse technology，the amount of the greenhouse is larger and larger. However, the temperature control of the greenhouse is becoming a difficult problem. Currently, the temperature control system of greenhouse is mostly using a transfers system which consists of analog temperature sensors，multiplexing analog switches, A/D conversion units and SCM. This kind of temperature collection system needs a lot of cables which is laid to make the signal of the sensor be sent to the collection card in the greenhouse. Thus the work of fixing and take-down is miscellaneous，and the cost is high. What’s more, what is transferred in the system is analog signals which are easily interfered and have more wastage. It is hard for the controller to make a decision in time according to the change of temperature because the measure error is bigger. So under this circumstance，it is necessary to develop a real time and precise temperature control system which is in a position to deal with temperature information of many nods.
 This paper gives a greenhouse temperature control project which is based upon the SCM technology. In this project, the change of temperature in the greenhouse is transformed into the change of electric current and then into the change of voltage by using the temperature sensors. The change of voltage is input into the A/D conversion units .At last the real time temperature in the greenhouse is displayed on the monitor under the control of SCM. Once the value of the temperature in the greenhouse exceeds the minimum and maximum which is preestablished, the SCM will give an alarm and autocontrol the temperature in the greenhouse. This project can make real time patrol checking to the different nod’s temperature in the greenhouse, and every separate checking unit can finish its task independently. This temperature control system whose stabilization and maintainability is good doesn’t need any fixed network to support and is easily fixed.
Keywords   SCM；temperature sensor；greenhouse；measuring &controlling system