單片機的問世（The advent of single chip microcomputer）.doc

1、單片機的問世（The advent of single chip microcomputer）Design of greenhouse temperature and humidity control system based on single chip microcomputerWang Baoqin, fan Changsheng, Guo Yanling(School of mechanical and electrical engineering, Northeast Forestry University, Heilongjiang, Harbin 150040)Abstract:

2、 a greenhouse temperature and humidity control system based on single chip microcomputer and SHT11 temperature and humidity sensor is designed. The system is reliable and simple in structure,Can automatically adjust the temperature and humidity in a greenhouse.Keywords: greenhouse; SCM; temperature

3、and humidity sensorCLC number: TP273 document identification code: A article number: 1001-4462 (2008) 03- 0039- 02Design of SCM- based Temper atur E and Humidity ControlSystem for a Gr eenhouseWANG Bao- Qin, FAN Chang- Sheng, GUO Yan- Ling(Mechanical & Electrical Engineering College, Northeast Fores

4、try University, Harbin Heilongjiang 150040, China)Abstr act: Based on SCMand SHT11 temperature and humidity sensor, the temperature and humidity control system used forA greenhouse is designed. With a simple structure and reliable performance, the system allows automatic adjustment of theTemperature

5、 and humidity in a greenhouse.Key words: greenhouse; SCM; temperature and humidity sensorIn recent years, the facility agriculture has developed greatly in ChinaShed planting technology has broken through the traditional crop planting by the regional natural ringThe restriction of environment and ot

6、her factors is of great significance to agricultural production. But nowThe temperature and humidity measurement and equipment operation of greenhouse in our country are mostly made up ofManual work, when the greenhouse is large, the operators labor intensity is veryBig. The temperature and humidity

7、 control system is based on single chip microcomputer control, with SwitzerlandSHT11 monolithic integrated temperature and humidity sensor for temperature and humidity detectionThe automatic management of greenhouse has been realized and greatly reducedLabor intensity of workers.1 basic working prin

8、cipleThe temperature and humidity control system of the greenhouse works first, and the user passes it firstKeyboard input temperature and humidity of the initial value, SCM system set up the userThe initial value is saved in the X25045 chip. SCM into the main program after,Began to query the temper

9、ature and humidity sensor SHT11 temperature and humidityThe corresponding values are displayed through the lcd. When the temperatureWhen the indoor temperature (or humidity) is less than the initial value set, the microcontroller will passThe control output interface makes the heating equipment (or

10、humidification equipment) work;When the temperature (or humidity) in the temperature chamber is greater than or equal to the initial value setThe heating device (or humidifying device) will be controlled by the MCU through controlling the output interface() stop working. The overall structure of the

11、 block diagram is shown in figure 1.2 hardware designThe hardware composition of the system mainly includes temperature and humidity detection circuit and LCDDisplay interface circuit, SCM and X25045 interface circuit, keyboard and controlOutput interface circuit.2.1 temperature and humidity detecti

12、on circuitThe temperature and humidity sensor is made of SHT11 single chip set produced in SwitzerlandIt is a sensor that can measure temperature, humidity and dew point simultaneouslyThe sensor can be output directly without external components, and the phase after calibration has been calibratedTh

13、e digital signals of temperature, humidity and dew point can effectively compensate for the traditionalThe temperature and humidity transfer received: 2007- 12- 25 sensor. Hardware connection between SHT11 and single chip microcomputerThirty-sixth volume third forestry machinery and woodworking equi

14、pment Vo1 36 No.3March 2008 FORESTRY MACHINERY & WOODWORKING EQUIPMENT Mar. 2008SHT11 temperature and humidity sensorX25045 initial value save chipLiquid crystal displayKeyboard entryControl outputsingleslicemachinecontrolsystemsystemTheFig. 1 general structure diagramAs shown in figure 2.40 forestr

15、y machinery and woodworking equipment thirty-sixth volumesC14_1U14_1TenInterface circuit of 2.4 single chip microcomputer with keyboard and control outputThe keyboard is divided into eight independent keys, one end with the P2 port of the microcontroller and the otherThe 50K is connected to the pull

16、-up resistor, and the other end is grounded, when any key is pressed,P2 port read low level effective. After the system is powered on, it enters the keyboard scanning subroutineIn order to complete the initial value of temperature and humidity, the keys are determined by inquiryWhen the system enter

17、s the main program, the key function is invalid. Control output circuitIn the control of heating equipment and humidification equipment, the control end uses single-chip microcomputer P1The two ports P16 and P17, when P16 and P17 are high power, relayWorking in the long open state, when P16 and P17

18、are low, the relay worksIn the closed state. The interface circuit is shown in figure 5.3 software designSoftware design is divided into main program, initial setting subroutine, temperature and humidityDegree reading subroutine, liquid crystal display subroutine and output control subroutine.Initia

19、l value setting subroutine completes the setting of temperature and humidity initial value and data protectionThe temperature and humidity reading subroutine is used to read the temperature and humidity sensor dataData conversion and display of temperature and humidity by liquid crystal display subr

20、outineThe output control subroutine completes the output according to the value of temperature and humidityMouth control.4 ConclusionThe SHT11 temperature and humidity sensor is used, and its internal and 14 bit A/D are usedThe converter and serial interface circuit realize seamless connection, so t

21、he systemIt has the advantages of simple hardware structure, fast response speed, strong anti-interference ability, etc.Point. The design of temperature and humidity are applied in Rice Seed Germination in greenhouse controlIn the system, the circuit is stable and reliable, and the design is complet

22、ely achievedRequirements, with very good practicality.Reference:1, Li Min, et al. Digital temperature and humidity sensor SHT15 and its application J. New device and new technologyOperation, 2003.2, Yi Yunhui, et al.SHT1x/7x temperature / humidity sensor applications J. Modern electronic technology,

23、2003, 159 (16): 105- 107.3 Yan Jun. Smart thermometer J. Instrument technology and sensors, 1994, (1): 23- 26.Fig. 5 interface circuit of single chip microcomputer with keyboard and control outputTwoOneDesign of backlash free harmonic gear drive by displacement correction methodLi Min(Harbin Vocatio

24、nal and Technical College, Heilongjiang, Harbin, 150081)Abstract: by analyzing the working principle and characteristics of harmonic gear drive and the engineering requirements of transmission without backlash, the backlash of harmonic gear drive is studiedThe flexible and rigid wheel deflection coe

25、fficient and the modification of the modification coefficient are adopted to realize the transmission without backlash requirements.Key words: harmonic gear drive; meshing parameter; backlash; modification of positionCLC number: TH132.41 document identification code: A article number: 1001-4462 (200

26、8) 03- 0041- 03The composition, working principle and characteristics of 1 harmonic gear driveThe harmonic gear drive consists of 2 groups: the wave generator H, the flexible wheel 1 and the rigid wheelAs shown in figure 1. Before assembly, the original profile of the flexible wheel is roundIt is a

27、thin cylindrical external gear which is easy to deform; the rigid wheel is a rigid oneThe inner gear of the gear has the same pitch, but the number of teeth of the flexible wheel is more than that of the rigid wheel Z1The number of teeth Z2 is less than 1 or several teeth; the wave generator H can be made by an ellipseThe disk can also be composed of a rotating arm and several disks, and the original characteristic curve is us