基于can的糧倉溫濕度監控系統的設計-文庫吧在線文庫

　　

【正文】 種物質，即所謂測溫介質的物理特性變化的方法來確定。隨著溫度的增高空氣中可以含的水就越多，也就是說，在同樣多的水蒸氣的情況下溫度升高相對濕度就會降低。絕對濕度是一定體積的空氣中含有的水蒸氣的質量，一般其單位是克/立方米， 其計算見公式（）。它規定了溫度的讀數起點（零點）和測量溫度的基本單位。 (3) 設計現場控制單元，使之能快速、準確、穩定地控制溫濕度。本文只闡述了對溫濕度的檢測和控制，以下所說糧情僅指溫度和濕度，但涉及到的 一些方法也適合其他糧情檢測情況。（3）系統結構已經普遍采用網絡連接的現場總線技術(FCS)，有些需要的場合，則 連接到Internet上，實現遠程控制、遠程診斷。初期，以熱敏電阻，濕敏電阻作為傳感器件，通過檢測電阻的變化來反映糧食溫濕 度的變化，為糧食保管提供參考依據。（3）因為霉菌等微生物喜溫，所以低溫儲糧使霉菌的活動基本停止，可有效地防 止糧食發生霉變。為了保證存放在糧倉中的糧食不致腐 爛變質，就必須使糧倉內的溫度和濕度保持在一定的范圍以內。關鍵詞：糧倉，溫濕度控制，CAN 總線東北大學秦皇島分校畢業設計（論文）第 5 頁The Design of Barn?s Temperature and Humidity MonitorSystem based on SCMAuthor：Wei Yi HengTutor：Liu YunJingAbstractIn the process of grain storage, grain deteriorates due to the abnormal of the barn?s temperature and humidity, and the economic losses which brought about are amazing. At present many grain storage units in our country use the traditional methods which is bined of thermometer device, artificial transcription and artificial management, consuming a lot of manpower and financial resources, and the results are poor, the phenomena of mildewing and metamorphism exists in large quantities. Therefore, designing the temperature and humidity monitor system on barn, improving efficiency and achieving realtime monitoring of barn?s temperature and humidity, is an important problem demanding prompt solution by storage units.In the actual production process, the monitoring of temperature and humidity?s is a very plex issue. In this paper, a method of designing the barn?s temperature and humidity monitor system after fully analysis the characteristics of temperature and humidity monitor issues and domestic and the research and development status both at home and abroad. The system uses microputer to detect the temperature and humidity information automatic, municate with the host puter by the CAN bus and solve the problem of temperature and humidity?s realtime detection and reliable control in the barn. Then according to the specificity of problem, an improvement is made on detection, storage and control?s realizing, which solves the problem reasonably in relatively short time. In the simulation, the feasibility of the system is verified, the shortage of this system when processing actual problem is also analyzed and the new improvement is raised.Each barn has an intelligent node, which is based on STC89C52 microcontroller mainly plete the collection and processing of temperature and humidity inside the barn, anddisplay and make judgments on the overlimit alarm and No difference control. It also deliver the relevant information to PC by the CAN bus. Host puter find out each barn? s temperatures and humidity through the information ing from intelligent nodes, and set temperature and humidity alarm threshold in every ban based due to every intelligent node?s address, and therefore the problem on Multiple barn?s temperature and humidity monitor has been solved.In the end, the work in this paper is summarized and the further step of this research is clarified.Key Words: barn, temperature and humidity control, CANbus目 錄1 緒論 ............................................................................................................................ 1 背景....................................................................................................................... 1 國內外研究現狀與發展趨勢............................................................................... 3 設計的目的及意義............................................................................................... 4 設計的主要工作................................................................................................... 5 本文的研究內容................................................................................................... 52 方案選擇與總體設計 ................................................................................................ 6 溫濕度的相關概念............................................................................................... 6 溫濕度的測量方法............................................................................................... 8 溫濕度傳感器的選取........................................................................................... 9 系統總體設計..................................................................................................... 103 系統硬件設計 .......................................................................................................... 15 STC89C52 簡介.................................................................................................. 15 數據采集電路..................................................................................................... 16 DHT21 性能說明......................................................................................... 17 DHT21 引腳介紹......................................................................................... 18 DHT21 數據格式......................................................................................... 18 DHT21 時序................................................................................................. 18 鍵盤輸入電路..................................................................................................... 20 LCD 顯示電路 .................................................................................................... 21 電路概述 ...................................................................................................... 21 LCD1602 引腳 ............................................................................................. 21 LCD1602 控制器 ......................................................................................... 21 LCD1602 基本操作 ..................................................................................... 22 實時時鐘電路..................................................................................................... 23 電路及芯片概述 ......................................................