Abstract
The development of single-chip microcomputer has undergone earth-shaking changes under the condition that integrated circuit technology is becoming more and more mature. In the initial stage of single-chip microcomputer manufacturing, the cost required is very high, and the manufacturing process is quite complicated. However, with the passage of time, the continuous innovation of electronic technology has made today's single-chip microcomputer more cost-effective and more powerful. If this system also has a timing function, it can solve some problems in practical applications. This makes the response speed faster and timely while ensuring the temperature is accurate. Temperature control is a very important link in the production process and has a vital impact on the quality of the produced products.
The timing temperature control system has the following characteristics: simple operation, high flexibility in practical application, and more stable operation. Although there are many types of single-chip microcomputers on the market, each of which has its own characteristics, the single-chip microcomputer with AT89C51 as the core is the most widely used in recent years. The main application of this system is the AT89C51 single-chip microcomputer. The temperature sensor DS18B20 is responsible for collecting the temperature signal. DS18B20 temperature sensor can change the temperature of the controlled object into digital quantity and feed it back to AT89C51 microcontroller. The hardware part is divided into real-time temperature measurement circuit, temperature intelligent control circuit and multiple interface circuits by us. After the single-chip microcomputer processes the corresponding signal, the purpose of controlling the signal can be realized. In order to be more organized, the software part adopts a modular approach to realize the design. The modules are digital tube display module, main scanning and main processing module, temperature signal processing module, relay control and high temperature alarm modules.
Single-chip microcomputers can be seen everywhere in daily life, ranging from small fans and water heaters to large air conditioners and washing machines. Our lives are changing invisibly, and our way of life is also changing quietly. And our dependence on it is becoming more and more serious. The single-chip microcomputer has high integration and good performance, and the functions we want can be realized by expanding some simple circuits in the periphery. We should continue to develop and develop a single-chip microcomputer that is more powerful than the existing ones in terms of performance and other aspects. We can only make progress if we keep exploring.
Keywords: AT89C51 microcontroller DS18B20 temperature sensor DS12887 clock chip
Abstract
As the integrated circuit technology becomes more and more mature, the development of the SCM has also undergone tremendous changes. In the early days of the manufacture of SCMs, the cost required was very high, and the production process was quite complicated. However, with the passage of time, electronic technology through continuous innovation, it makes today's SCM cost-effective and more powerful. If the system also has a timing function, it can solve some problems in practical applications. This ensures that the temperature is accurate, but also makes the response faster and more timely. Temperature control is a very important part of the production process and has a crucial influence on the quality of the products produced.
Timing temperature control system has the characteristics of simple operation, high practical application flexibility, and more stable in operation. Although there are many kinds of MCUs on the market, each one has its own characteristics, but in recent years, AT89C51 is the most widely used MCU. The main application of this system is the AT89C51 type single-chip microcomputer. The temperature sensor DS18B20 is responsible for the collection of temperature signals. The DS18B20 temperature sensor can change the temperature of a controlled object to a digital quantity and feed it back to the AT89C51 microcontroller. The hardware part is divided into real-time temperature measurement circuit, temperature intelligent control circuit and multiple interface circuits. After the MCU processes the corresponding signal, it can achieve the purpose of the control signal. In order to be more organized, the software part adopts a modular approach to implement design. The modules are digital tube display module, main scanning and main processing module, temperature signal processing module, relay control and high temperature alarm.
In everyday life, there are MCUs everywhere, ranging from fans and water heaters to air conditions and washing machines. Our lives are changing intangibly and our lifestyle is changing quietly. And our dependence on it is even more serious. The integrated level of the sing let's go -chip microcomputer is high, the performance is good, can realize our desired function through expanding some simple circuit in the periphery. We should continue to develop and research more powerful MCUs than the existing ones in performance and other aspects. We can only m take progress if we continue to explore.
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Key words: 89C51 Microcontroller DS18B20 Temperature Sensor DS12887 Clock chip
Contents
1 Introduction
1.1 Purpose and significance
1.2 Research status at home and abroad
1.2.1 Research on temperature management system based on PLC
1.2.2 Research on temperature detection and alarm system
1.3 Content and innovation of the article
1.3.1 Research content
1.3.2 Innovation point
2 Overall design of hardware system
2.1 Overall design of hardware system
2.2.1 Selection of system hardware
2.2.2 DS18B20 temperature sensor
2.2.3 Digital tube
3 Hardware circuit operating system 3.1
DS18B20 temperature measurement circuit
3.2 DS12887 chip clock circuit
3.2.1 DS12887 pin description 3.2.2 DS12887
chip clock circuit diagram
3.3 Power supply circuit
3.4 Independent keyboard
4 Control operating system software
design 4.1 Main program module design
4.2 Temperature collection module program design
4.2 .1 Timing sequence of DS18B20
4.2.2 Initialization timing sequence
4.2.3 Writing timing sequence
4.2.4 Reading timing sequence
4.3 Temperature setting module program design
4.3.1 Keyboard scanning subroutine
4.3.2 Temperature display module design
4.3.3 Setting value display subroutine
4.4 Temperature Control Module Design
5 Conclusions
5.1 PROTEUS Simulation
5.1.1 Keyboard Setting Temperature Simulation
5.1.2 Temperature Acquisition Simulation
5.1.3 Overall Simulation
5.2 Actual Operation Results
6 Summary and Prospect
6.1 Summary
6.2
Prospect Acknowledgments
References Appendix
Procedure
1 Introduction
1.1 Purpose and Significance
Since the Industrial Revolution in the 18th century, the production efficiency has increased rapidly worldwide, especially in the industrial field. , temperature control plays an important role. At the same time, one of the key factors that affect boiler transfer energy and affect equipment life is temperature. For this example in life, we can use the feedback control theory to transform the boiler to achieve accurate temperature control. While meeting the needs of industrial production, it can increase the production quantity and increase the production speed. And with the continuous development of innovation in modern science and technology, the types of temperature sensors [3] have also sprung up in the public's field of vision, and our production and life have also become colorful [1].
The process of realizing temperature control is to obtain parameters from the production process first, and then through scientific calculation methods, combined with various advanced technologies, so as to ensure that each production link can basically achieve accurate control.
The great changes of the times have invisibly affected the direction of people's lives. We have higher and higher requirements for the functions of single-chip microcomputers. Its advantages such as high efficiency, stability, and safety have become more and more prominent, and it also plays an irreplaceable role in life.
One of the characteristics of the single-chip microcomputer is its small size and high integration. It is used as a core component. In addition, as long as some simple circuits are added to its periphery, a complete small system can be formed. In a small range, it has the same functions as ordinary computers, but its advantage is that it has a stronger ability to process data.
In this era of rapid development, with the support of theoretical research, application technology has also been greatly improved. There are also many sensors with many performances emerging gradually, and people's choices have become very diverse. Each sensor has its own unique performance, and people apply them in their respective fields according to different performances.
The purpose of this system is to control the temperature more precisely. After all, when precise temperature control is required, manual controls are sometimes not very accurate. Automatic and accurate temperature control becomes our only requirement, and this is our ultimate goal. In production and life, the impact on us is very far-reaching. For example, in the northern region, the temperature in winter is extremely low, and vegetables cannot be stored. However, with greenhouses, people can use greenhouses to store vegetables. Even in the cold winter, we don’t need to worry about it; After the substance is extracted, it is necessary to use temperature to heat the mineral, and the requirements for the temperature value are also very strict, so our control over the temperature has become a crucial step. For example, the air conditioner is one of the very common electrical appliances in our life. We think its existence is very common, but it brings us warmth and coolness. All this makes us realize that temperature control plays a huge role in our lives [2].
1.2 Research status at home and abroad
1.2.1 Research on PLC-based temperature management system
Since the 1970s, science and technology have developed rapidly around the world, which is always affecting industrial development. The design of integrated circuit technology is combined with computer technology. And it is also widely used in automatic control. On this basis, the temperature control system has obtained a good development opportunity and is more suitable for the needs of current life. Among them, intelligent applications are deeply loved by people, and the parameters have also been greatly improved. progress. In this regard, some developed countries in the West are more advanced in technology, and have produced many commercial high-performance temperature controllers and instruments that are now widely used in various industries.
The widely used temperature control system includes the temperature control system based on single-chip microcomputer and the temperature control system based on PLC [3].
The growth history of single-chip microcomputer is not very long in our memory, but it has grown very vigorously. First of all, it quickly occupied the market due to its small size and low manufacturing cost, becoming the leader in the industry. Secondly, its functions are more powerful, and its safety or reliability performance has been greatly improved, so it is widely used in various industries or fields of society, and is deeply loved and welcomed by users. With the passage of time, the single chip has also been updated and iterated, from the original 4-bit machine to today's 32-bit machine, its performance has also undergone tremendous changes, and it has become more flexible and intelligent. Based on the single-chip microcomputer, a temperature control system is designed and realized, and such a system will be very safe and reliable. However, compared with other temperature control systems, the MCU has a slow response speed and few interrupt sources, which is not conducive to use in a more complex and high-standard environment.
PLC is a digital electronic computer, which uses programmable memory to store various instructions, such as timing, sorting, counting and other functions, and controls various machinery or working procedures. The advantages of PLC include high reliability, great anti-interference ability and easy to be learned and applied by everyone, so it is widely used in various industrial fields. And the cost of PLC is relatively low, this advantage is one of its most attractive places. Therefore, PLC occupies a large proportion in the market, and the prospect of future development is very optimistic.
The temperature control system is advancing steadily in the trend of the times, and the speed of progress is also very gratifying. In the domestic control system industry, the temperature control system occupies the vast majority of shares and has a good prospect and market demand.
As far as the entire production cycle is concerned, although the level of production technology is steadily improving, compared with some developed countries in the West, my country still has a long way to go in terms of control systems. control and conventional PID controllers. This kind of product is more dependent on the low temperature system control, and it is difficult to control, the delay is relatively strong, and the temperature system control changes with time. In order to adapt to the more advanced demand management situation, the domestic development technology is still immature, but there are many mature products abroad. The basic reason for this phenomenon is that the domestic development technology lags behind that of foreign countries, and the strict secrecy of western technology makes us only import relevant systems and use them according to their requirements, so we cannot get technical support and cannot develop products that belong to own control system. Most of the control parameters are obtained with the help of daily experience and personnel on-site debugging [4].
1.2.2 Research on temperature detection and alarm system
The temperature control system is based on the embedded system technology, and has gradually grown up through the combination with computer technology and programming language development. Embedded systems originated in the era of microcomputers. In today's era, the development speed of the domestic economy has been greatly improved, and people's quality of life is improving day by day. The stability and accuracy of microcomputers cannot meet our living needs. Therefore, embedded systems must find new ways. It will be chipped. Putting the computer on a chip ushered in the era of autonomous development of microcontrollers for embedded systems. In the late 1970s, single-chip microcomputers appeared in people's field of vision, and gradually developed and expanded. There are three main aspects of the growth process, namely SCM, MCU and SOC.
Using the AT89C51 microcontroller makes the control easier, the operation configuration has been optimized a lot, and the flexibility of use has been greatly enhanced. These remarkable advantages make it advance steadily in the industry. And greatly improved the quality of products, increased the number of products. Can greatly improve the technical index of controllable control temperature. In industrial production, the temperature control problem of SCM is unavoidable. At the same time, the existence of temperature is one of the characteristics of life, and people pay a lot of attention to it. It is not only closely related to our living environment, but more importantly, how we want to control it and let it serve us. Its existence not only has a direct impact on the product, but also accelerates the damage of mechanical equipment or various other parts, which has a serious impact on our safety. For example, in daily life, if the temperature is too high or too low, it will have more or less influence. In general, thermostats are widely used in industrial and agricultural production, scientific research and life, and the number is increasing day by day. In the past hundred years, the development of thermostats has roughly gone through three stages: 1. Analog temperature controllers; 2. Integrated temperature controllers; 3. Functional temperature controllers; Digital, from integrated to intelligent, networked direction [5].
1.3 Contents and innovations of the article
1.3.1 Research content
The subject to be studied in this paper is the design of a temperature control system based on a single chip microcomputer. The system should display time, set temperature and actual temperature, and can automatically start or Turn off heat. The error between the actual temperature controlled and the set temperature will not exceed 1°C. The main goal is to realize the display of the set value of the temperature, the real-time measurement and display of the actual value. The temperature adjustment device connected to the single-chip microcomputer realizes real-time temperature control through the cooperation of software and hardware circuits, and the display can be controlled by software and displayed in the digital tube. Compare the collected temperature with the set value and the upper and lower limits, and then make a corresponding response to control whether the actuator is cooled or heated.
The core of the system is the AT89C51 chip, combined with it, a single-chip temperature control system is developed and designed. And the ultimate goal of this design is to realize all the functions of this system. For the collection of temperature signal, the DS18B20 temperature sensor is used in the design to collect and transmit the temperature, and the digital signal conversion device is integrated in the single-chip microcomputer, so the single-chip microcomputer can process the incoming digital signal accordingly. In this way, it is very beneficial to achieve the purpose of temperature control. The C language is used as the technical support of this system in the development, and the program is programmed with it, and the p3.1 pin of the microcontroller is used as the control terminal to connect to the solid state relay [8]. In terms of software, the PID control algorithm is used to control the constant temperature part. control design.
In terms of timing measurement, a clock chip is used, which can provide accurate time. We use this time as a standard to measure the temperature regularly. The MCU will receive the return value of the measured temperature, and the MCU will transmit the data to the display in a timely and accurate manner, while comparing the temperature set in advance with the actual measured temperature data transmitted, and judging the temperature between them Poor, so as to determine whether adjustment is required. You can first input an initial temperature setting, and then update the time of the clock chip, and the system will be started at this time. Make the system have the following functions:
①Real-time detection of temperature;
②Can display the set temperature value and actual value;
③Realize alarm function outside the set temperature range
1.3.2 Innovation points
(1) There are three in this system The functions are real-time detection, automatic control, and timing heating. And the system also provides multiple functions such as setting time parameters, timing, starting or stopping. The system is also widely used in brewing, refrigerators, incubators and other fields.
(2) Set the controllable temperature range from 0 to 40°C according to the requirements of the topic. Time display, temperature measurement, etc., can be operated manually, and it is very convenient to set when to heat or stop.
(3) The water heater is mainly used as the application object, and the hardware part and software are designed from this. At the same time, the principles of simplicity, environmental protection and practicality have been followed in real life.
