(The contents of the report include research significance, development at home and abroad, research contents, research methods, research means, research steps and references, etc. ).)
The research significance of 1) project.
With the rapid development of modern information technology and the gradual realization of traditional industrial transformation, temperature detection and display systems that can work independently have been applied in many fields, making temperature control widely used in production and life.
Temperature is the most commonly used physical quantity in daily life, industry, medicine, environmental protection, chemical industry, petroleum and other fields. The basic method of measuring temperature is to read the temperature directly with a thermometer. The most commonly used tools for measuring temperature are various thermometers, such as mercury glass thermometer and alcohol thermometer. They often indicate the temperature in the form of scales, and people must measure the temperature by reading the scale values. The electronic intelligent thermometer composed of single chip microcomputer and temperature sensor can directly measure the temperature and get the digital value of the temperature, which is simple, convenient, intuitive and accurate. Compared with the traditional thermometer, the digital thermometer introduced in this design has the advantages of convenient reading, wide temperature measurement range and accurate temperature measurement, and its output temperature is displayed in digital form, which is mainly used in places or scientific research laboratories with accurate temperature measurement. The design controller adopts single chip microcomputer AT89S5 1, the temperature sensor adopts DS 18B20, and the LCD 1602 liquid crystal display can accurately meet the above requirements.
2) Development at home and abroad
At present, the development of thermometers is very fast, from the initial glass thermometer tube thermometer to the current thermal resistance thermometer, thermocouple thermometer, digital thermometer, electronic thermometer and so on. The main temperature instruments, such as thermocouple, thermal resistance and radiation thermometer, are technically mature, but they can only be used in traditional occasions and cannot meet the requirements of simple, rapid and accurate temperature measurement, especially in the high-tech field. Therefore, experts from all over the world are competing to develop various new temperature sensors and special practical temperature measurement technologies, such as new thermometers using optical fiber, laser and remote sensing or storage technology, which have been put into practice.
Since 2008, China's digital thermometer and thermostat market has developed rapidly, and the product output has continued to expand. The national industrial policy encourages the electronic thermometer and thermostat industry to develop in the direction of high-tech products, and the investment in new investment projects of domestic enterprises is gradually increasing. Investors pay more and more attention to the electronic thermometer and thermostat industry, which makes the development demand of the electronic thermometer and thermostat industry increase. In order to overcome the shortcomings of traditional methods, this paper studies a temperature control system based on single chip microcomputer.
3) Research contents and methods.
Using digital temperature sensor as detection device, single-point temperature detection is carried out. The temperature value is directly displayed by LCD 1602 liquid crystal, and the single chip microcomputer system is used as the control and display system of the electronic thermometer.
The system is considered from the following three aspects:
(1) The detection temperature range is 0℃ ~ 100℃, and the detection resolution is 0.5℃.
(2) Use LCD 1602 to display the temperature value.
(3) When the alarm value (user-defined) is exceeded, an alarm prompt shall be given.
The temperature sensing function of DS 18B20 is mainly used to detect the current temperature value, which is displayed by LCD. When the detected temperature value exceeds the set temperature range, it will send an alarm reminder to achieve the purpose of accurate detection.
The system mainly consists of four parts:
1) temperature detection module, that is, the sensor data acquisition part, can meet the measurement range of 40℃ to 90℃ if thermistor is used, but the thermistor has poor accuracy, repeatability and reliability, and is not suitable for detecting the signal of 1℃, so the intelligent integrated digital temperature sensor DS 18B20 can be used. DS 18B20 is a single-wire digital temperature sensor produced by DALLAS Company, which has a 3-pin TO-92 small package. The temperature measuring range is -55℃ ~+ 125℃, and the 9-bit ~ 12-bit A/D conversion accuracy can be programmed, and the temperature measuring resolution can reach 0.0625℃. The measured temperature is serially output in a sign-extended 16-bit digital quantity mode. Its working power supply can be introduced at the far end or generated in parasitic power mode; Multiple DS 18B20 can be connected to one line, and the CPU can communicate with multiple DS 18B20 with only one port line, which occupies fewer ports of the microprocessor and saves a lot of leads and logic circuits.
2) The temperature display part can adopt LED digital tube or LCD liquid crystal display. The module adopts LCD 1602.
3) The upper and lower alarm adjustment modules set the alarm temperature through buttons and alarm with buzzer.
4) The intelligent module of the single-chip microcomputer motherboard mainly refers to the single-chip microcomputer, which mainly completes the receiving and processing of sensor signals. In the design of this module, we should first choose single chip microcomputer, and consider the performance and cost, choose AT89S52.
The whole system works under the control of AT89S52. The working process is as follows: first, the temperature button sets the upper and lower temperature ranges, then the temperature sensor DS 18B20 collects the current temperature signal, which is received by the single chip microcomputer and displayed on the LCD 1602 after processing. If the measured temperature exceeds the set range, the buzzer will send out an alarm signal.
In view of this, the objectives of this graduation project are:
(1) Design the signal detection part of electronic thermometer.
(2) Design of signal processing part of electronic thermometer.
(3) The design of main controller of electronic thermometer.
(4) Design the display part and alarm part of the electronic thermometer.
(5) Write and debug related software design.
(6) Construction of experimental platform
(7) Debugging of the whole machine
4) Future development trend and four important fields of global sensors (turn)
In recent years, the research on new principles, new materials and new technologies of sensor technology is more in-depth and extensive, and new varieties, new structures and new applications are constantly emerging. Among them,? Five transformations? It has become an important trend of its development.
One is intelligence, and the two development tracks go hand in hand. One direction is the integration of various sensing functions with data processing, storage and two-way communication. , which can fully or partially realize signal detection, transformation processing, logic judgment, function calculation, two-way communication, internal self-inspection, self-calibration, self-compensation and self-diagnosis. It has the characteristics of low cost, high precision information collection, data storage and communication, programming automation and diversified functions. For example, the smart sensor of LinearTechnology in the United States has a 32-bit processor based on ARM architecture. The other direction is soft sensing technology, that is, the combination of intelligent sensors and artificial intelligence. At present, all kinds of intelligent sensors based on fuzzy reasoning, artificial neural network, expert system and other artificial intelligence technologies have appeared, and they have been applied in smart homes and other aspects. For example, NEC has developed a new method to simplify the monitoring of a large number of sensors? Invariant analysis technology? , has been put into use in infrastructure system this year.
The second is mobility, and the application of wireless sensor network technology is accelerating. The key of wireless sensor network technology is to overcome the resource constraints of nodes (energy supply, computing and communication capabilities, storage space and so on). ) and meet the requirements of scalability and fault tolerance of sensor networks. This technology was rated as the top ten emerging technologies that will have a far-reaching impact on human life in the future by the Technology Review magazine of Massachusetts Institute of Technology (MIT). At present, the research and development focuses on routing protocol design, positioning technology, time synchronization technology, data fusion technology, embedded operating system technology, network security technology, energy collection technology and so on. So far, some developed countries and cities have applied technology in smart home, precision agriculture, forestry monitoring, military, intelligent building, intelligent transportation and other fields. For example, VoltreePowerLLC, an independent company from Massachusetts Institute of Technology, was commissioned by the US Department of Agriculture to set up temperature sensors in mountainous areas of California and build a sensor network to detect forest fires and reduce fire losses.
The third is miniaturization, and the research and development of MEMS sensors has sprung up. With the maturity of integrated MEMS technology, MEMS sensors introduce semiconductor processing technology (such as oxidation, lithography, diffusion, deposition and etching) into the manufacturing of sensors, realizing large-scale production and providing important technical support for the miniaturization development of sensors. In recent years, Japan, the United States, the European Union and other countries have made important progress in the technical fields of semiconductor devices, micro-systems and microstructures, speed measurement, micro-system processing methods/equipment, microphones/speakers, horizontal/ranging/gyroscopes, lithography plate-making technology and measurement/analysis of material properties. At present, the research and development of MEMS sensor technology is mainly in the following directions: (1) miniaturization while reducing power consumption; (2) improve the accuracy; (3) Realizing the integration and intelligence of MEMS sensor; (4) Develop new sensors that cross and fuse with optical and biological fields, such as MOMES sensors (combined with micro-optics), biochemical sensors (combined with biotechnology and electrochemistry) and nano sensors (combined with nanotechnology).
Fourthly, integrated and multifunctional integrated sensors are widely concerned. Sensor integration includes two types: one is the integration of multiple sensors of the same type, that is, multiple sensor elements with the same function are arranged on the same plane through integration technology to form a linear sensor (such as CCD image sensor). The other is multifunctional integration, for example, making several different sensitive elements on the same silicon chip to make an integrated multifunctional sensor, which has high integration, small volume and easy compensation and correction, and is the main direction of sensor integration development at present. Ruyifa Semiconductor proposes to use a module composed of multiple sensors as the sensor hub to improve product functions. Toshiba has developed a wafer-level combination sensor, and in March this year, it released a sensor module that can simultaneously detect four vital signs, such as pulse, ECG, body temperature and physical activity, and wirelessly send the data to a smartphone or tablet computer? Silmi? .
Fifth, diversification and the breakthrough of new material technology have accelerated the emergence of various new sensors. New sensitive materials are the technical basis of sensors, and material technology research and development is an important means to improve performance, reduce cost and upgrade technology. In addition to traditional semiconductor materials, optical fibers, etc. Organic sensitive materials, ceramic materials, superconductivity, nano-materials and biomaterials have become research and development hotspots, and new sensors such as biosensors, optical fiber sensors, gas sensors and digital sensors have emerged at an accelerated pace. For example, optical fiber sensor is a sensor that uses the sensitive function of optical fiber itself or transmits light waves through optical fiber. It has the characteristics of high sensitivity, strong anti-electromagnetic interference ability, corrosion resistance, good insulation, small volume and low power consumption. At present, the optical fiber sensor can measure more than 70 kinds of physical quantities, which has broad development prospects. The gas sensor can convert the measured gas concentration into an electric quantity output related to it. It has the characteristics of good stability, good repeatability, good dynamic characteristics, fast response and convenient use and maintenance. , and is widely used. According to BCCResearch, biosensors and chemical sensors are expected to become the fastest growing sensor fields. It is estimated that the compound annual growth rate from 20 14 to 20 19 will reach 9.7%.
Four areas worthy of attention in the future
With the breakthrough of cutting-edge technologies in the fields of materials science, nanotechnology and microelectronics and the demand of economic and social development, these four fields may become the focus of the future development of sensor technology.
The first is wearable applications. According to the prediction of American ABI survey company, the number of wearable sensors will reach 65.438+0.6 billion in 2065.438+07. Wearable devices represented by Google Glass are the most concerned hardware innovation. Google Glass has more than 10 kinds of sensors, including gyro sensors, acceleration sensors, magnetic sensors, linear acceleration sensors and so on. , which realizes some functions that traditional terminals can't, such as users can take pictures just by blinking. At present, the application field of wearable devices is expanding from external watches, glasses and shoes to broader fields, such as electronic skin. A few days ago, the University of Tokyo developed a flexible wearable sensor that can be attached to the skin. The sensor is film-shaped, its weight per unit area is only 3g/m2, which is about 1/27 of that of ordinary paper, and its thickness is only 2 microns.
The second is unmanned driving. IHS pointed out that the application of sensor technology to promote the development of driverless driving is accelerating the breakthrough. In this field, the development of Google's driverless car project has achieved important results. Through the camera, radar sensor and laser range finder installed in the car, real-time road information around the car is generated at intervals of 20 times per second, and the future trend of related road conditions is analyzed and predicted by using artificial intelligence software, and road navigation is carried out by combining Google Maps. Google driverless cars have been granted the right to drive on the roads in Nevada, Florida and California. Global auto giants such as Audi, Mercedes-Benz, BMW and Ford have begun to develop driverless technology, and some models are close to mass production.
The third is medical and health monitoring. Many medical research institutions at home and abroad, including internationally renowned medical giants, have made important progress in the application of sensor technology in the medical field. For example, Roma is currently developing an image sensor using near infrared light (NIR). The principle is that after the near-infrared LED is irradiated, the reflected light is photographed by a special camera element, an image is obtained by changing the wavelength of the near-infrared light, and then blood vessels and the like are presented more vividly through image processing. Some research institutions have made progress in manufacturing sensors with materials that can be embedded or swallowed in the body. For example, Georgia Institute of Technology is developing an embedded sensor with pressure sensor and wireless communication circuit. The device is composed of conductive metal and insulating film, which can detect the pressure change according to the frequency change of the constituted * * * vibration circuit, and will dissolve in body fluid after it plays a role.
The fourth is industrial control. In 20 12, GE company put forward in the report "industrial internet: breaking the boundary between wisdom and machine" that connecting man and machine through intelligent sensors, combined with software and big data analysis, can break through the limitations of physics and materials science and will change the way the world operates. The report also pointed out that by deploying industrial internet in the United States, all industries can achieve 1% efficiency improvement, and the energy industry will save 1% fuel (about 66 billion US dollars) in 15. 20 13 In June, GE installed more than 10000 sensors in a battery manufacturer in new york * * to monitor data such as temperature, energy consumption, air pressure, etc. in the production process. Factory managers can obtain these data through iPad, so as to supervise production.
In addition, multinational companies such as Dutch Shell and Fuji Electric have also made some moves in this field.
Important trend of sensor industrialization development
In recent years, with the deepening of technology research and development, the decline of cost, the improvement of performance and reliability, and the rapid development of Internet of Things, mobile Internet and high-end equipment manufacturing, the typical application market of sensors has developed rapidly. According to the analysis of BCCResearch, the global sensor market is expected to reach $79.5 billion in 20 14 years, $20161100 million, with a compound annual growth rate of 7.9%.
The Asia-Pacific region will become the most potential market. At present, the United States, Japan and European countries have advanced sensor technology and mature upstream and downstream industries, and are the main manufacturers and the largest application markets of high-end sensor products. At the same time, the Asia-Pacific region has become the most potential market in the future. Intel Consulting pointed out that the market share of Asia-Pacific region will continue to grow in the next few years, and it is expected to increase to 38. 1% in 20 16, while the market share of North America and Western Europe will decrease slightly.
Transportation, information and communication have become the fastest growing areas of the market. According to the forecast of Inteno Consulting Company, the global automobile sensor scale will reach 4197 million euros in 20 16 years, accounting for 22.8% of the global market. By 20 16, the information and communication industry will reach 421600 million euros, accounting for 22.9% of the global market, and may become the largest single application market. Innovative applications in medical care, environmental monitoring, oil and gas pipelines, smart grid and other fields will become new hot spots, and it is expected to create more market demand in the future.
Mergers and acquisitions are becoming more and more active. Large sensor enterprises in the United States, Germany, Japan and other countries have a solid foundation for technology research and development, and each enterprise has formed its own technological advantages, and the overall market competition pattern has been initially established (attached table). It should be pointed out that large companies control technical standards and patents through mergers and acquisitions. Tall, elegant and sharp? Sensors and new sensors have gradually formed a monopoly position in the market. Under the competitive pressure of large enterprises, small and medium-sized enterprises are turning? Small (medium) but fine, small but specialized? Development direction, development of proprietary technology, product positioning specific market segments. According to statistics, from July, 20 10 to September, 2010, there were more than 20 large M&A transactions in the sensor industry. For example, American private equity firm VeritasCapitalIII acquired Perkin Elmer's lighting and detection solutions (IDS) business for $500 million in cash; British Spike Company acquired the manufacturing business of temperature and measuring equipment of American Omega Engineering Company for $475 million. At present, more and more M&A transactions appear in emerging market countries.
5) References
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[2] Qiang Fu. Sensor [M]. Beijing Machinery Industry Press 2004
[3] Kang. Basic simulation of electronic technology. Beijing: Higher Education Press, 1998.
[4] Kang. The basic digital part of electronic technology. Beijing: Higher Education Press, 1998.
[5] Liu Shouyi. Single chip microcomputer application technology [M]. Xi An: xidian university Publishing House, 2002.
[6] Li Guangdi. Fundamentals of single chip microcomputer. Beihang University Press, 1994
[7] Sun Huanming. 5 1 A detailed explanation of the application example of single-chip computer C language program. Beijing: Beihang University Press, 20 1 1
design motif
Abstract: (The content is Song Zi No.4)
With the rapid development of modern information technology and the gradual realization of traditional industrial transformation, automatic temperature detection and display systems have been widely used in many fields. People have higher and higher requirements for the accuracy, convenience and rapidity of temperature detection. However, the traditional temperature sensor can no longer meet people's needs, and it is gradually replaced by a new type of temperature sensor.
In this paper, a simple thermometer is designed and manufactured. This design adopts AT89S52 single chip microcomputer and DS 18B20 temperature sensor to form an automatic temperature measurement and control system, which can set the temperature value at will according to actual needs and carry out automatic control. In this design, AT89S52 single chip microcomputer is used as the main control device, DS 18B20 is used as the temperature sensor, and data is transmitted through the serial port of LCD digital tube to realize temperature display. Through DS 18B20, the measured temperature value can be directly read and converted, and the upper and lower temperature limits can be set to set the alarm temperature. And after reaching the alarm temperature, the system will automatically alarm.
This paper analyzes and explains the design from several aspects: temperature measuring circuit, main control circuit and alarm circuit. The device can directly transmit digital signals to the single chip microcomputer, which is convenient for the single chip microcomputer to process and control. In addition, the thermometer can also directly measure the temperature with a temperature measuring device. Thereby simplifying the data transmission and processing process. The advantages of this design are mainly embodied in strong operability, simple structural foundation and large expansion space.
Keywords: single chip microcomputer; Temperature sensor; Thermometer; report to the police
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