陕西理工学院毕业设计
致谢
通过几个月的努力，本次设计圆满完成，首先感谢指导教师刘亚锋老师。经过刘老师的耐心讲解、悉心教诲，我慢慢学会了各种元器件的工作原理，比如蜂鸣器，数码管，LED灯等。并能自主的设计电路，完成本次设计。在做毕业设计的过程中，也是刘老师给予认真的指导，包括硬件采购，电路连接以及软件程序设计等给我提供了很大的帮助。其次感谢大学四年来授课的全部老师，是你们认真负责的教导，才奠定了现在顺利完成课程设计的基础。最后我要感谢一直陪我完成毕业设计和一起讨论问题的同学，是他们在我困惑时给予我精神上的鼓励，谢谢他们在平时对我的帮助和关心。我很高兴能生活在一个互助友爱和充满活力团结的集体中，在他们的身上有很多需要我学习的地方。再次，感谢老师、同学、朋友们的帮助。
2016
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陕西理工学院毕业设计
参考文献
[1]万隆.单片机原理及应用技术[M].北京:清华大学出版社,2010.
[2]姚有峰,赵江东,郝诗平.基于单片机技术的环境状态监测系统的设计[J].测控技术,2012,01:15-18. [3]薛营,孙徽.基于单片机的大棚温湿度的检测系统的设计[J].读与写(教育教学刊),2014,04:93-94. [4]龚宗辉,朱鹏,李盼盼.AT89S52单片机在温室大棚温湿度监控系统的应用[J].才智,2013,36:37-38. [5]王金环.基于单片机的温室环境监控系统的设计[J].硅谷,2014,24:12-13. [6]吴卓葵.基于单片机和光照检测的开关控制装置设计[J].电子技术,2014,07:52-54.
[7]韩力英,杨宜菩,王杨,唐红梅,牛新环.基于单片机的温室大棚智能监控系统设计[J].中国农机化学报,2016,01:65-72.
[8]杨丽文,陈如清.基于单片机的温室大棚环境参数监测系统设计[J].科技视界,2015,25:170-210 [9]林宏.智能化温室大棚环境监控系统研究[J].河北农业大学学报,2014,05:130-134. [10]李红军,姜庆昌.大棚环境的检测调节系统设计[J].科技创新与生产力,2015,04:113-115.
[11]张铁山,任众.基于AT89C51的温室大棚环境参数自动控制系统的设计[J].机械工程师,2016,04:34-36. [12]何希才,薛永毅.传感器及其应用实例[M].北京：机械工业出版社,2014.
[13]王丽雅.大棚温湿度和光照度自动控制系统设计与实现[J].农业工程,2013,04:48-51. [14]邵婷婷,任瑞瑞,李平.基于单片机的环境监测系统设计[J].电子测试,2014,05:67-68.
[15]Meilan Jiang,Jonghyun Lee,Karpjoo Jeong,Zhenguo Cui,Bomchul Kim,Suntae Hwang,Young Jean Choi,Zhenhong Li.A Data Stream-Based, Integrative Approach to Reliable and Easily Manageable Real Time Environmental Monitoring[J].International Journal of Distributed Sensor Networks,2015.
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陕西理工学院毕业设计
附录A 英文文献原文
An embedded design for monitoring and controlling
temperature
A Goswami, T Bezboruah and K C Sarma
1
1*2
1
2
Department of Instrumentation and USIC, Gauhati University, Guwahati-781 014, Assam, India Department of Electronics and Communication Technology, Gauhati University, Guwahati-781 014, Assam, India
E-mail : amarjyoti27@gmail.com
Received 26 June 2008, accepted 11 September 2009
Abstract:Each and every part of human life is somehow linked with the embedded products. Embedded systems are
product of hardware and software co design. It is becoming an integral part of engineering design process for efficient analysis of data acquisition. Data acquisition implies the gathering of information about a system or process. It is the process of collecting data in an automated way from analog and digital sources of measurement, such as sensors and devices under test. The present paper describes the design of an embedded system for the control of temperature and light intensity in a single system using sensors, microcontroller and Liquid Crystal Display (LCD). It describes the controlling action incorporated in the hardware to control any device connected when specific conditions are met.
Keywords:Embedded system, analog to digital converter, ,data logger, offline analysis.
PACS No:07.05.Hd.
1. Introduction
It is very much essential in industrial as well as experimental setup to monitor and control temperature continuously. The efficient solution for this problem is to develop a data logger. Earlier development of data logger had been done through manual measurements from analog instruments, such as thermometers and manometers. Unfortunately data logger of this type can’t fulfill the current requirements in terms of timing and accuracy. Since 1990, further development in data logging took place as people begin to create PC-based data logging systems [1,2]. In later stages of development it has been found that microcontrollers (integration of microprocessors and certain peripherals including memory) are more reliable as well as efficient [3]. Use ofmicrocontrollers in embedded design has not only been increased but brought a revolutionary change. At the same time competitive pressures require manufacturers to expand their product functionality and provide differentiation while maintaining or reducing the cost.
Monitoring and controlling physical parameters like temperature, pressure, humidity etc. using
microcontrollers are very much effective in industrial and research oriented requirements. As a parameter, nature of temperature is ever-changing. It is exposed to huge array of stimuli from its environment. Though temperature can be monitored through variety of sensors, one should adhere maximum cares in selecting sensors due to different levels of complexity associated with the calibration process. If calibration is not implemented properly output of the embedded system may vary from actual temperature measured through standard instruments.
The purpose of the present work is to explore the possibility of continuously monitoring temperature. The system is also equipped with necessary hardware to initiate control action for temperature as soon as temperature reaches higher than set value. The system developed enables it’s user to set the value of temperature as required and set transfer rate of data through RS-232. Necessary Keypad in the form of push-buttons is provided for setting desired temperature and transfer time. For the purpose of storing and some intelligent analysis of data, the system is connected to PC through RS-232. This setup can be effectively used in industries for single control end.
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陕西理工学院毕业设计
2. Motivation
The purpose of the proposed work is its low cost and industrial demand. Such a design can effectively decrease the number of computers used in an industry, such as food processing, green house or a packing industry and thus in turn can save power which is the main feature of this work.
3. Experimental setup
The block diagram of the experiment is shown in Figure 1. The hardware and software description of the embedded system for monitoring and controlling temperature are described below :
3.1. Hardware description:
The whole circuit of the experiment can be divided into following sections :
(i) Power supply section : The regulated power supply section is design and fabricated with full wave rectifier using voltage regulator 7805 which provides a constant voltage of 5 V to the circuit.
(ii) Analog to digital conversion section : Since we have to sense analog parameters i.e. temperature and light, hence we have to use any analog to digital converter (ADC).
Figure 1. Block diagram of the experimetal setup.
We have opted for ADC 0809 as it has 8 channels and is microprocessor compatible ADC which is easily available [4]. It will convert the analog signal of the transducer to digital value with respect to the reference voltage which in our case is 2.5 V. This reference voltage is obtained using TL431, which is a programmable shunt voltage reference with output voltage range of 2.5 V to 36 V and works like zener diode [5]. For the conversion, ADC requires a reference frequency which is supplied from IC555 in the form of astable oscillator. Sensor used for temperature measurement is LM 35 which is calibrated in °C and is linear in +10 mV/°C scale factor with 0.5°C accuracy [6]. The calibration curve of the sensor is shown in Figure 2.
Figure 2. Voltage vs. temperature calibration curve.
(i) Controller section : The analog value is converted to digital value by ADC and is picked up by the microcontroller AT89S52 which is a low-power, high-performance Complementary Metal Oxide
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陕西理工学院毕业设计
Silicon (CMOS) 8-bit microcomputer with 8 KB of Flash programmable and erasable read only memory (EPROM) [7].
(ii) Display section : Since it is essential to display the data received from the microcontroller, a liquid crystal display 44780 LCD is used which is a 2×16 line display [8,9].
(iii) Temperature control section : This section consists of a relay to control hardware to start cooling for maintaining temperature as set by the user and a buzzer to notify the change [10,11].
(iv) Hardware controlling : Simple push buttons are used to set temperature and give the time of data transfer to the PC. A 12 V relay is used to control an LED at the set temperature. The schematic diagram of the system is shown in Figure 3. The whole system that we are fabricating for the experiment on a single board is shown in Figure 4.
Figure 3. Embdeded control hardware circuit – schematic diagram.
3.2. Software description :
Software development for the present work consists of two main modules. One being the online monitoring and controlling, and the other being offline analysis based on data stored in computer. Present article limits its work on first module keeping second module for future development. Software is developed in both C and Assembly language.
Algorithm for online monitoring and controlling of temperature is given below :
(i) First step is to initialize keys, Interrupt vectors panel and LCD Define port P3 of microcontroller ATMEL 89S52 as output port
(ii) Get data through ADC0809 from two different channels of Temperature and Light Intensity continuously after a fixed interval
(iii) Value obtained from different channels converted to appropriate form of display
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