粮库温度检测报警系统本科毕业生外文文献翻译.docx

1、粮库温度检测报警系统本科毕业生外文文献翻译本科毕业生外文文献翻译学生姓名： 指导教师： 所在学院：信息技术学院专 业：电气工程及其自动化中国2012 年 5 月Based on SCM multi-functional temperature testing system designIntroductionWith the development of society and the technological progress, people pay more and more attention to the importance of temperature detection and

2、 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

3、 status of the monitoring system.1 System solutionsThis 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 . The alarming circuit can be meas

4、ured 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, i

5、f 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. 2 The system hardware design2.1AT89C51 SCM are introducedThe AT89S52 is a low-power, high-performance CMOS 8-bit microcomputer with 4K b

6、ytes of Flash Programmable and Erasable Read Only Memory (PEROM) and 128 bytes RAM. The device is manufactured using Atmels high density nonvolatile memory technology and is compatible with the industry standard MCS-51 instruction set and pinout. The chip combines a versatile 8-bit CPU with Flash on

7、 a monolithic chip, the Atmel at89s52 is a powerful microcomputer which provides a highly flexible and cost effective solution to many embedded control applications.Pin Description:VCC Supply voltage.GND Ground.Port 0Port 0 is an 8-bit open drain bidirectional I/O port. As an output port each pin ca

8、n sink eight TTL inputs. When is are written to port 0 pins, the pins can be used as high impedance inputs. Port 0 may also be configured to be the multiplexed loworder address/data bus during accesses to external program and data memory. In this mode P0 has internal pullups. Port 0 also receives th

9、e code bytes during Flash programming, and outputs the code bytes during program verification. External pullups are required during program verification.Port 1Port 1 is an 8-bit bidirectional I/O port with internal pullups. The Port 1 output buffers can sink/source four TTL inputs. When 1s are writt

10、en to Port 1 pins they are pulled high by the internal pullups and can be used as inputs. As inputs, Port 1 pins that are externally being pulled low will source current because of the internal pullups. Port 1 also receives the low-order address bytes during Flash programming and verification.Port 2

11、Port 2 is an 8-bit bidirectional I/O port with internal pullups. The Port 2 output buffers can sink/source four TTL inputs. When 1s are written to Port 2 pins they are pulled high by the internal pullups and can be used as inputs. As inputs, Port 2 pins that are externally being pulled low will sour

12、ce current because of the internal pullups. Port 2 emits the high-order address byte during fetches from external program memory and during accesses to external data memory that use 16-bit addresses (MOVX DPTR). In this application it uses strong internal pull-ups when emitting 1s. During accesses t

13、o external data memory that use 8-bit addresses (MOVX RI), Port 2 emits the contents of the P2 Special Function Register. Port 2 also receives the high-order address bits and some control signals during Flash programming and verification.Port 3Port 3 is an 8-bit bidirectional I/O port with internal

14、pullups. The Port 3 output buffers can sink/source four TTL inputs. When 1s are written to Port 3 pins they are pulled high by the internal pullups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current because of the pullups. Port 3 also serves th

15、e functions of various special features of the at89s52 as listed below:Port pinalternate functionsP3.0rxd (serial input port)P3.1txd (serial output port)P3.2int0 (external interrupt0)P3.3int1 (external interrupt1)P3.4t0 (timer0 external input)P3.5t1 (timer1 external input)P3.6 WR (external data memo

16、ry write strobe)P3.7rd (external data memory read strobe)Port 3 also receives some control signals for Flash programming and verification.RSTReset input. A high on this pin for two machine cycles while the oscillator is running resets the device.ALE/PROGAddress Latch Enable output pulse for latching

17、 the low byte of the address during accesses to external memory. This pin is also the program pulse input (PROG) during Flash programming.In normal operation ALE is emitted at a constant rate of 1/6 the oscillator frequency, and may be used for external timing or clocking purposes. Note, however, th

18、at one ALE pulse is skipped during each access to external Data Memory. If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has no

19、 effect if the microcontroller is in external execution mode.PSENProgram Store Enable is the read strobe to external program memory. When the at89s52 is executing code from external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped during each a

20、ccess to external data memory.EA/VPPExternal Access Enable. EA must be strapped to GND in order to enable the device to fetch code from external program memory locations starting at 0000H up to FFFFH. Note, however, that if lock bit 1 is programmed, EA will be internally latched on reset. EA should

21、be strapped to VCC for internal program executions. This pin also receives the 12-volt programming enable voltage(VPP) during Flash programming, for parts that require 12-volt VPP.XTAL1Input to the inverting oscillator amplifier and input to the internal clock operating circuit.XTAL2Output from the

22、inverting oscillator amplifier.2.2 DS18B20 sensor2.2.1The introduction of DS18B20The DS18B20 Digital Thermometer provides 9 to 12-bit (configurable) temperature readings which indicate the temperature of the device. Information is sent to/from the DS18B20 over a 1-Wire interface, so that only one wi

23、re (and ground) needs to be connected from a central microprocessor to a DS18B20. Power for reading, writing, and performing temperature conversions can be derived from the data line itself with no need for an external power source. Because each DS18B20 contains a unique silicon serial number, multi

24、ple DS18B20s can exist on the same 1-Wire bus. This allows for placing temperature sensors in many different places. Applications where this feature is useful include HVAC environmental controls, sensing temperatures inside buildings, equipment or machinery, and process monitoring and control.The DS

25、18B20 has four main data components: 1) 64-bit laser ROM, 2) temperature sensor, 3) nonvolatile temperature alarm triggers TH and TL, and 4) a configuration register. The device derives its power from the 1-Wire communication line by storing energy on an internal capacitor during periods of time whe

26、n the signal line is high and continues to operate off this power source during the low times of the 1-Wire line until it returns high to replenish the parasite (capacitor) supply. As an alternative, the DS18B20 may also be powered from an external 3V - 5.5V supply.Communication to the DS18B20 is vi

27、a a 1-Wire port. With the 1-Wire port, the memory and control functions will not be available before the ROM function protocol has been established. The master must first provide one of five ROM function commands: 1) Read ROM, 2) Match ROM, 3) Search ROM, 4) Skip ROM, or 5) Alarm Search. These comma

28、nds operate on the 64-bit laser ROM portion of each device and can single out a specific device if many are present on the 1-Wire line as well as indicate to the bus master how many and what types of devices are present. After a ROM function sequence has been successfully executed, the memory and co

29、ntrol functions are accessible and the master may then provide any one of the six memory and control function commands. Temperature sensor DS1820memory by a high speed buffer pad type RAM and a nonvolatile electrically erasable E2RAM composition, the latter is stored at high temperature and low temp

30、erature and the trigger of TH and TL. Scratchpad memory helps in one-way communication to ensure data integrity, data is first written to a buffer memory, where it can be read back. When data is checked, copy scratchpad memory command to send the data to the non-volatile E2RAM. This process ensures

31、that the change of memory while maintaining data integrity.2.2.2The characteristics of DSl820The unique single interface mode: DS18B20is connected with the microprocessor only needs an export line can realize microprocessor with DS18B20bidirectional communication.Available data line power supply, vo

32、ltage range: + 3and + 5.5 V.Temperature range: -55 to + 125degrees c. Intrinsic temperature measurement resolution of 0.5DEG c.Support point network function, multiple DS18B20 can be connected in parallel in only three online, realize the multipoint temperature measurementNegative pressure characteristics, power polarity reverse connection, the thermometer is not due to heat and burning, but not normalWork.2.3LCD1602 LCD1602 LCD module can and monolithic integrated circuit AT89C51 directly interface.