1、preface
With the development of society and the technological progress, people pay more and more attention to the importance of temperature detection and display. Temperature detection and status display technology and equipment has been widely applied in industries, products on the market emerge in endlessly. Temperature testing and also gradually adopt the automatic control technology to realize the monitor. This topic is a temperature testing and status of the monitoring system.
2、System solutions
This system USES the monolithic integrated circuit AT89S52 as this system. The whole system, the hardware circuit including power supply circuit, sensor, the temperature display circuit circuit, upper alarm circuit such as shown in figure 1. Figure in the alarming circuit can be measured in upper temperature range, screaming voice alarm. The basic principle for the temperature control DSl8B20: when the temperature signal acquisition to after temperature signal sent to handle, AT89S52 temperature to LCD screen, SCM according to initialize the upper temperature setting, namely, if the judgement of temperature than the highest temperature cooling fan is started, If the temperature is less than the lowest temperature setting on alarm device. Temperature controller diagram
3、The system hardware design
（1）AT89S52 SCM are introduced
AT89S52 devices is a low power consumption, high CMOS8 bit micro-controller, 8K programmable Flash memory. Use Atmel company high-density nonvolatile storage technology, and industrial 80C51 product instruction and pin fully compatible. The Flash memory chips allows programs in system programming, also suitable for conventional programming. In a single chip, have clever 8 bits CPU and programmable Flash in the system, for many embedded control AT89S52 application system provides a highly flexible, efficient solutions [5]. AT89S52 has the following functions: the standard 256 bytes, 8k byte Flash RAM, 32 I/O port, the watchdog timer, 2 data, three pointer 16 timer/counter, a 6 vector level 2 interrupt structure, full-duplex serial, timely clock circuit within crystals. In addition, 0Hz AT89S52 can drop to the static logic operation, support two software can choose power saving mode. Idle mode, the CPU to stop working, and allows the RAM, timer/counters, serial, continue to work. Protection mode, RAM by MCU, oscillator is frozen, all the work to stop until the next interruption or hardware reset.
　隨著社會的發(fā)展和技術(shù)的進步，人們越來越注重溫度檢測與顯示的重要性。溫度檢測與狀態(tài)顯示技術(shù)與設備已經(jīng)普遍應用于各行各業(yè)，市場上的產(chǎn)品層出不窮。溫度檢測及顯示也逐漸采用自動化控制技術(shù)來實現(xiàn)監(jiān)控。本課題就是一個溫度檢測及狀態(tài)顯示的監(jiān)控系統(tǒng)。
二、系統(tǒng)方案
　　本系統(tǒng)采用 AT89S52 作為該系統(tǒng)的單片機。系統(tǒng)整體硬件電路包括，電源電路，傳感器電路，溫度顯示電路，上下限報警電路等如圖1 所示。圖中報警電路可以在被測溫度不在上下限范圍內(nèi)時，發(fā)出報警鳴叫聲音。溫度控制的基本原理為:當DSl8B20 采集到溫度信號后，將溫度信號送至AT89S52 中處理，同時將溫度送到LCD 液晶屏顯示，單片機根據(jù)初始化設置的溫度上下限進行判斷處理，即如果溫度大于所設的最高溫度就啟動風扇降溫;如果溫度小于所設定的最低溫度就啟動報警裝置。溫度控制器的原理圖
三、系統(tǒng)硬件設計
1.單片機AT89S52 的介紹
　　AT89S52 是一種低功耗、高性能CMOS8 位微控制器,具有8K 可編Flash 存儲器。使用Atmel 公司高密度非易失性