溫度控制系統(tǒng)的設(shè)計(jì)外文翻譯（英文）

1、Design of the Temperature Control System Based on AT89S51 Dr. Leon Gaillard Head of Research, Lao Institute for Renewable Energy (LIRE), Sokpaluang Road, Sokpaluang Village, Vientiane, Lao PDR, P.O. Box 8010ABSTRACT: The

2、 principle and functions of the temperature control system based on microcontroller AT89S51 are studied, and the temperature measurement unit consists of the 1-Wire bus digital temperature sensor DS18B20. The system c

3、an be expected to detect the preset temperature, display time and save monitoring data. An alarm will be given by system if the temperature exceeds the upper and lower limit value of the temperature which can be set

4、discretionarily and then automatic control is achieved, thus the temperature is achieved monitoring intelligently within a certain range. Basing on principle of the system, it is easy to make a variety of other non-li

5、near control systems so long as the software design is reasonably changed. The system has been proved to be accurate, reliable and satisfied through field practice. KEYWORDS: AT89S511; microcontroller2; DS18B203;

6、temperature4I. INTRODUCTION Temperature is a very important parameter in human life. In the modern society, temperature control (TC) is not only used in industrial production, but also widely used in other fields. Wit

7、h the improvement of the life quality, we can find the TC appliance in hotels, factories and home as well. And the trend that TC will better serve the whole society, so it is of great significance to measure and contr

8、ol the temperature. Based on the AT89S51 and temperature sensor DS18B20, this system controls the condition temperature intelligently. The temperature can be set discretionarily within a certain range. The system can

9、 show the time on LCD, and save monitoring data; and automatically control the temperature when the condition temperature exceeds the upper and lower limit value. By doing so it is to keep the temperature unchanged.

10、The system is of high anti-jamming, high control precision and flexible design; it also fits the rugged environment. It is mainly used in people's life to improve the quality of the work and life. It is also versa

11、tile, so that it can be convenient to extend the use of the system. So the design is of profound importance. The general design, hardware design and software design of the system are covered. II. SYSTEM GENERAL DESIGN

12、The hardware block diagram of the TC is shown in Fig. 1. The system hardware includes the microcontroller, temperature detection circuit, keyboard control circuit, clock circuit, Display, alarm, drive circuit and

13、 external RAM. Based on the AT89S51, the DS18B20 will transfer the temperature signal detected to digital signal. And the signal is sent to the microcontroller for processing. At last the temperature value is showed

14、on the LCD 12232F. These steps are used to achieve the temperature detection. Using the keyboard interface chip HD7279 to set the temperature value, using the microcontroller to keep a certain temperature, and using t

15、he LCD to show the preset value for controlling the temperature. In addition, the clock chip DS1302 is used to show time and the external RAM 6264 is used to save the monitoring data. An alarm will be given by buzzer

16、 in time if the temperature exceeds the upper and lower limit value of the temperature. AT89S51 DS18B20Keyboard control circuitFigure 1. Hardware block diagram III. HARDWARE DESIGNA. Microcontroller The AT89S51 is a l

17、ow-power, high-performance CMOS 8-bit microcontroller with 4K bytes of in-system programmable Flash memory. The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible

18、with the industry-standard 80C51 instruction set and pinout. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile

19、 8-bit CPU with in-system programmable Flash on a monolithic chip, the Atmel AT89S51 is a powerful microcontroller which provides a highly-flexible and cost-effective solution to many embedded control applic

20、ations. Minimum system of the microcontroller is shown in Fig. 2. In order to save monitoring data, the 6264 is used as an external RAM. It is a static RAM chip, low-power with 8K bytes memory. B. Temperature Detecti

21、on Circuit The temperature sensor is the key part in the system. The Dallas DS18B20 is used, which supports the 1-Wire bus interface, and the ON-BOARD Patented is used internally. All the sensor parts and the converti

22、ng circuit are integrated in integrated circuit like a transistor [1]. Its measure range is -55 ~125 , and the precision between ℃ ℃ -10 ~85is ℃ ℃Drive circuitAlarm circuitLCD circuitClock circuitExternal RAM2010 Int

23、ernational Forum on Information Technology and Applications978-0-7695-4115-0/10 $26.00 © 2010 IEEE DOI 10.1109/IFITA.2010.209 632010 International Forum on Information Technology and Applications978-0-7695-4115-0/10

24、 $26.00 © 2010 IEEE DOI 10.1109/IFITA.2010.209 63is connected to the keyboard and display without using any active-device. According to the basic requirements and functions of the system, only 6 buttons are needed

25、. The system's functions are set by the AT89S51 receiving the entered data. In order to save the external resistor, the 1×6 keyboard is used, and the keyboard codes are defined as: 07H, 0FH, 17H, 1FH, 27H, 2

26、FH. The order can be read out by reading the code instruction. HD7279A is connected to the AT89S51 in serial mode and only 4 ports are need. As shown in Fig. 6, DIG0~DIG5 and DP are respectively the column lines and

27、row line ports of the six keys which achieve keyboard monitoring, decoding and key codes identification. Figure 6. Keyboard control circuit F. Alarm Circuit In order to simplify the circuit and convenient debugging,

28、a 5V automatic buzzer is used in the alarm circuit [8]. And this make the software programming simplified. As shown in Fig. 7, it is controlled by the PNP transistor 9012 whose base is connected to the pin P2.5 of the

29、 AT89S51. When the temperature exceeds the upper and lower limit value, the P2.5 output low level which makes the transistor be on and then an alarm is given by the buzzer. Figure 7. Alarm circuit G. Drive Circuit A

30、step motor is used as the drive device to control the temperature. The four-phase and eight-beat pulse distribution mode is used to drive motor and the simple delay program is used to handle the time interval between

31、the pulses to obtain different rotational speed. There are two output states for the step motor. One: when the temperature is over the upper value, the motor rotates reversely (to low the temperature), while when low

32、er than the lower limit value, the motor rotates normally (to raise the temperature); besides not equals the preset value. Two: when the temperature is at somewhere between the two ends and equals the preset value, th

33、e motor stops. These steps are used to achieve the temperature control. In addition, the motor speed can also be adjusted by relative buttons. As shown in Fig. 8, the code data is input through ports A11~A8 (be P2.3~P

34、2.0) of the AT89S51 and inverted output by the inverter 74LS04. Finally it is amplified by the power amplifier 2803A to power the motor. Figure 8. Drive circuit IV. SOFTWARE DESIGN According to the general design re

35、quirement and hardware circuit principle of the system, as well as the improvement of the program readability, transferability and the convenient debugging, the software design is modularized. The system flow m

36、ainly includes the following 8 steps: POST (Power-on self-test), system initiation, temperature detection, alarm handling, temperature control, clock chip DS1302 operation, LCD and keyboard operation. The main progra

37、m flow is shown in Fig. 9. Give a little analysis to the above 8 tasks, it is easy to find out that the last five tasks require the real time operation. But to the temperature detection it can be achieved with timer0

38、 timing 1 second, that is to say temperature detection occurs per second. The system initiation includes global variable definition, RAM initiation, special function register initiation and peripheral equipment initi

39、ation. Global variable definition mainly finishes the interface definition of external interface chip connected to the AT89S51, and special definition of some memory units. RAM initiation mainly refers to RAM process

40、ing. For example when the system is electrified the time code will be stored in the internal unit address or the scintillation flag will be cleared. The special function register initiation includes loading the initia

41、l value of timer and opening the interrupt. For example, when the system is electrified the timer is initialized. The peripheral equipment initiation refers to set the initial value of peripheral equipment. For examp

42、le, when the system is electrified, the LCD should be initialized, the start-up display should be called, the temperature conversion command should be issued firstly and the clock chip DS1302 should also be initializ

43、ed. The alarm handling is mainly the lowering and the raising of temperature to make the temperature remain with the preset range. When the temperature is between the upper and the lower limit value, it goes to tempe