Development history of modern computer technology
(1) Embedded application began in the microcomputer era.
Electronic digital computer was born in 1946. In the long historical process since then, computers have always been large and expensive equipment to realize numerical calculation in special computer rooms. It was not until the advent of microprocessors in the 1970s that computers experienced historic changes. Microprocessor-based microcomputers are rapidly coming out of the computer room because of their small size, low price and high reliability. Microcomputer based on high-speed numerical calculation ability has aroused the interest of control professionals, and it is required to embed microcomputer into the object system to realize intelligent control of the object system. For example, after electrical and mechanical strengthening, a microcomputer is equipped with various peripheral interface circuits and installed on a large ship to form an autopilot or marine engine condition monitoring system. In this way, the computer lost its original form and general computer functions. In order to be different from the original general computer system, the computer is embedded into the object system to realize the intelligent control of the object system, which is called embedded computer system. Therefore, the embedded system was born in the microcomputer era, and the embedded essence of the embedded system is to embed a computer into an object system, which are the basic starting points for understanding the embedded system.
(2) Two branches of modern computer technology.
Because the embedded computer system should be embedded into the object system to realize intelligent control of the object, it has completely different technical requirements and development direction from the general computer system.
The technical requirement of general computer system is high-speed and massive numerical calculation; The development direction of technology is the infinite improvement of bus speed and the infinite expansion of storage capacity. The technical requirement of embedded computer system is the intelligent control ability of the object; The development direction of technology is embedded performance, control ability and control reliability closely related to the object system.
In the early days, people reluctantly reformed the general computer system to realize embedded applications in large-scale equipment. However, for many object systems (such as household appliances, instrumentation, industrial control units, etc.). ), it is impossible to embed into general computer system, and the technical development direction of embedded system and general computer system is completely different. Therefore, it is necessary to develop general computer system and embedded computer system respectively, which has formed two branches of the development of modern computer technology.
If the appearance of microcomputer makes the computer enter the stage of modern computer development, then the birth of embedded computer system marks that the computer has entered the era of parallel development of general computer system and embedded computer system, which led to the high-speed development of computers at the end of the 20th century.
(3) the milestone of the development of the two branches
The specialized development between general-purpose computer system and embedded computer system led to the rapid development of computer technology in the late 20th century and early 20th century. The computer professional field concentrates on developing the software and hardware technology of general computer system, regardless of the embedded application requirements, and the general microprocessor changes rapidly from 286, 386 and 486 to Pentium series; The operating system has rapidly expanded the computer's file processing ability based on high-speed and massive data, making the general computer system enter a perfect stage.
Embedded computer system has embarked on a completely different road, which is the road of single chip development. It mobilized the original manufacturers and professionals in the traditional electronic system field, took over the embedded system originated from the computer field, and undertook the historical task of developing and popularizing the embedded system, so that the traditional electronic system quickly developed into the era of intelligent modern electronic system.
Therefore, the milestone significance of the two branches of modern computer technology development lies in that it not only forms a specialized division of labor in computer development, but also extends the task of developing computer technology to the traditional electronic system field, making computers a powerful tool for human society to enter the era of comprehensive intelligence.
condition
The meaning and classification of 1 embedded system
Embedded system refers to a special computer system which is application-centered, based on computer technology, customized in software and hardware, and meets the strict requirements of application system on function, reliability, cost, volume and power consumption.
Embedded system is the product of advanced computer technology, semiconductor technology and electronic technology combined with specific applications in various industries, which determines that it must be a technology-intensive, capital-intensive, highly decentralized and innovative knowledge integration system.
At present, in addition to some 32-bit processors, there are a large number of 8-bit and 16-bit embedded microcontrollers (MCU) in embedded systems. Embedded system is another form of computer application, which is different from the general computer application mentioned above: embedded computer is a specific computer system with highly specialized software and hardware hidden in various devices, products and systems in the form of embedded system. At present, according to its development, embedded computers can be divided into the following categories:
(1) embedded microprocessor unit (Empu)
Embedded microprocessor is based on CPU in general computer. In application, the microprocessor is assembled on a specially designed circuit board, and only the motherboard functions related to embedded applications are reserved, which can greatly reduce the system volume and power consumption. In order to meet the special requirements of embedded applications, although the functions of embedded microprocessors are basically the same as those of standard microprocessors, the working temperature, electromagnetic interference resistance and reliability are generally enhanced.
(2) embedded microcontroller unit (MCU)
Embedded microcontroller is also called single chip microcomputer. Embedded microcontrollers generally take a microprocessor core as the core, and the chip integrates ROMPEPROM, RAM, bus, bus logic, timer P counter, watchdog, IPO, serial port, pulse width modulation output, APD, DPA, Flash RAM, E2PROM and other necessary functions and peripherals. In order to meet different application requirements, a series of single-chip microcomputer generally has a variety of derivative products, and the processor core of each derivative product is the same, the only difference is the configuration and packaging of memory and peripherals. This can make the single chip microcomputer match the application requirements to the maximum without adding more functions, thus reducing power consumption and cost. Compared with embedded microprocessor, the biggest feature of microcontroller is monolithic and its size is greatly reduced, thus reducing power consumption and cost and improving reliability.
(3) Embedded Digital Signal Processor (EDSP).
The DSP processor specially designed the system structure and instructions to make it suitable for executing DSP algorithms, with high compilation efficiency and fast instruction execution speed. In digital filtering, FFT, spectrum analysis and so on, DSP algorithm is entering a large number of embedded fields, and the application of DSP is changing from realizing DSP function with ordinary instructions in general single chip microcomputer to adopting embedded DSP processor.
(4) Embedded system on chip.
With the popularization of EDI, the popularization of VLSI design and the rapid development of semiconductor technology, the era of realizing more complex systems on a silicon chip has arrived, which is the system on a chip (SOC). All kinds of general processor cores will be used as the standard library of SOC design company, and like many other embedded system peripherals, they will become standard devices in VLSI design, described by standard VHDL and stored in the device library. Users only need to define their own entire application system, and after the simulation is completed, they can submit the design drawings to the semiconductor factory for samples. In this way, except for a few devices that cannot be integrated, most of the whole embedded system can be integrated on one or several chips, and the application system circuit board will become very simple, which is very beneficial to reduce the volume and power consumption and improve the reliability.
2 characteristics of embedded system industry
(1) The embedded system industry is a highly decentralized industry, and it is impossible to monopolize it.
In a sense, the technology of general computer industry is monopolized. The PC industry, which accounts for 90% of the whole computer industry, 80% adopts Intel's 8x86 architecture, and the chips are basically from Intel, AMD, Cyrix and other companies. In almost every computer's necessary operating system and Word processor, Microsoft's Windows and Word account for 80-90%, and other applications can match the operating system. Therefore, the foundation of the contemporary general computer industry is considered to be an industry monopolized by Wintel (an alliance established by Microsoft and Intel in the early 1990s).
Embedded systems are different. This is a decentralized industry, full of competition, opportunities and innovation. No one series of processors and operating systems can monopolize the whole market. Even if there is a mainstream architecture, different application fields determine that a few companies and products cannot monopolize the whole market. Therefore, the products and technologies in the field of embedded systems must be highly dispersed, leaving a lot of room for innovation for small and medium-sized high-tech companies in various industries. In addition, the continuous development of various application fields in society requires the synchronous development of embedded processor cores, which also constitutes a powerful driving force to promote the development of embedded industry.
Equipment is the foundation of embedded system industry, which is based on application-centered "chip" design technology and application-oriented software product development technology.
(2) Product characteristics of embedded system
Embedded system is user-oriented, product-oriented and application-oriented. If you develop independently from the application, you will lose the market. The power consumption, volume, cost, reliability, speed, processing capacity and electromagnetic compatibility of embedded processors are all restricted by application requirements, and are also the hot spots of semiconductor manufacturers' competition.
Different from general computer, the hardware and software of embedded system must be designed with high efficiency, customization and redundancy, and strive to achieve higher performance on the same silicon chip area, so as to be more competitive in processor selection in specific applications. Embedded processor should customize and add chip configuration according to the specific needs of users to achieve ideal performance; But it is also restricted by the user's order quantity. So different processors face different users, which may be general users, industrial users or single users.
Embedded system is organically combined with specific applications, and its upgrade is also synchronized with specific products, so once embedded system products enter the market, their life cycle is long. The software in embedded system is generally solidified in read-only memory, not on disk, and can be replaced at will, so the life cycle of application software in embedded system is as long as that of embedded products. In addition, different from general computer software, the application systems and products of various industries rarely jump suddenly, so the software in embedded system emphasizes inheritance and technical convergence, and develops stably.
The development of embedded processors also shows stability. Generally, a building will exist for 8- 10 years. An architecture and its related on-chip peripherals, development tools, library functions and embedded application products are a complex knowledge system, and neither users nor semiconductor manufacturers will give up a processor easily.
(3) Characteristics of embedded system software
The application software of embedded processor is the key to realize the function of embedded system, and the requirements for embedded processor system software and application software are also different from those of general computers.
① Software needs solid-state storage.
In order to improve the execution speed and system reliability, the software in embedded system is generally solidified in the memory chip or single chip microcomputer itself, rather than stored in the carrier such as disk.
② The software code has high quality and strong reliability.
Although the development of semiconductor technology makes the processor speed increase and the on-chip storage capacity increase, in most applications, the storage space is still precious and there is still a real-time requirement. Therefore, the quality of programming and compiling tools is required to reduce the length of program binary code and improve the execution speed.
③ High real-time performance of system software (OS) is the basic requirement.
In multi-task embedded system, it is the key to ensure the timely execution of each task to schedule tasks with different importance reasonably. It is impossible and inefficient to simply improve the speed of the processor. This task scheduling can only be completed through optimized system software, so the real-time performance of system software is the basic requirement.
④ Multi-task operating system is the platform of knowledge integration and the foundation of industrial standardization.
(4) Embedded system development needs development tools and environment.
General-purpose computer has a perfect man-machine interface, and you can add some development applications and development environments on it to develop yourself. But the embedded system itself does not have the ability of bootstrap development. Even after the design is completed, users usually cannot modify the program functions. Only one set of development tools and environment can be developed. These tools and environments are based on hardware and software devices on general-purpose computers, various logic analyzers and mixed-signal oscilloscopes.
(5) Embedded system software needs RTOS development platform.
General-purpose computer has a perfect operating system and application program interface (API), which is an inseparable part of the computer. Both the development of application programs and the completed software run on the operating system (OS) platform, but they are generally not real-time. Embedded systems are different. Applications can run directly on the chip without an operating system. However, in order to reasonably schedule multiple tasks and make use of system resources, system functions and interfaces with expert database functions, users must choose their own RTOS development platform, so as to ensure the real-time and reliability of program execution, reduce development time and ensure software quality.
(6) Embedded system developers are mainly application experts.
Developers of general-purpose computers are generally professionals in computer science or computer engineering, while embedded systems need to be combined with applications in different industries and need more professional knowledge besides computers, and their developers are often experts in various application fields. Therefore, the development tools are easy to learn, easy to use, reliable and efficient.
prospect
3 application prospect of embedded system
The application of embedded controller is almost everywhere: mobile phones, household appliances, cars ... all have its traces. Embedded controller has been widely used in industry, agriculture, education, national defense, scientific research and daily life because of its small size, high reliability, strong function, flexibility and convenience, and has played an extremely important role in promoting technological transformation, product upgrading, accelerating automation process and improving productivity in all walks of life.
Embedded computers far exceed all kinds of general-purpose computers in the number of applications. A general-purpose computer contains 5- 10 embedded microprocessors in its external devices. In manufacturing, process control, network, communication, instruments, meters, automobiles, ships, aviation, aerospace, military equipment, consumer products and other aspects, it is the application field of embedded computers.
Embedded system industry is a special computer industry, and its purpose is to make everything simpler, more convenient, more universal and more applicable. General-purpose computers have developed into functional computers and generally entered the society. The development goal of embedded computer is a special computer to realize "general computing", so it can be said that embedded intelligent chip is the "digital gene" that constitutes the future world. As academician Shen Xubang, a senior embedded system expert in China, predicted, "In the next ten years, there will be embedded smart chips with the head size and the operation amount exceeding 1 100 million times", which will provide us with unlimited creative space. In short, "embedded microcontroller or single chip microcomputer seems to be a black hole, which will attract many technologies and achievements today." China should attach importance to the development of intelligence-intensive industries ".
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[1] Lu Jingjian. BOL Systems sees Y2K problem from the reliability and credibility of embedded system.
[2] Mu Yugang et al. "Research on Embedded System and Its Debugging Means" Journal of Shanghai Institute of Technology (Vol 18 No.4. 1999.
[3] Lv Jingjian, et al. Embedded Internet technology and its application.
Lv Jingjian, Xiao Haiqiao. Classification and present situation of embedded processors.
[5] Lv Jingjian, Xiao Haiqiao. Overview of embedded system facing 2 1 century.
[6] Clarke Esler, TASKING Inc and Christopher S. Sontag, emWare "Embedded Network for 8-bit and 16-bit Microprocessors" electronic components. April 1999.
7 Warren Weber. Nesting technology promotes automobile reform.
Lv Jingjian, Xiao Haiqiao. Embedded system development tools and RTOS platform.
[9] TASKING is committed to embedded communication and promotes Internet and communication solutions. ht2tp:ppwww.bol-system.com。
[10] year 2000 problem of embedded system. China Taiwan Province Provincial Executive Yuan Accounting Department Electronic Processing Data Center.
[1 1] He Limin. Build a single-chip microcomputer application platform and implement the platform development strategy.
Embedded Internet access of 8-bit and 16-bit microcontrollers.
[13] A low-cost controller that can provide C programming capability. EDN editorial department, EDN 2000.