SCM development history1.The general situation of list slice machineThe single chip microcomputer referred to as SCM, is typical of embedded micro- controller (SCM Unit), the commonly used letters of the abbreviation MCU MCU, it was first used in the field of industrial control. Master SCM technology to enable more people in the industry, students, enthusiasts, product developers, and the question arose due to the extensive application of SCM in the field of industrial control, SCM development board, the more famous such as e- DZR - 01A SCM development board. SCM evolved by the only dedicated processor CPU chip. The first design concept by a large number of peripherals and CPU integrated in a single chip, the computer system is smaller, and more easily integrated into complex and require strict control equipment on the volume. INTEL Z80 is the first processor designed in accordance with this idea, since then, the development of SCM and dedicated processor has grown apart.Early SCM are 8 or 4. One of the most successful is the INTEL 8031, because the simple and reliable performance good a lot of praise. Later in 8031 on the development of MCS51 series SCM system. Is still in wide use of SCM system based on this system until now. Began with the industrial control area requires improvement of a 16-bit SCM, but not ideal because the price has not been a very wide range of applications. The 1990s, consumer electronics, SCM technology has been a huge increase. With the INTEL The i960 series, especially the ARM series of widely used 32- bit SCM quickly replaced the 16-bit single - chip high-end status, and enter the mainstream market. Traditional 8-bit MCU performance has also been a rapid increase processing capacity than a few times in the 1980s. At present, high-end 32-bit SCM clocked more than 300MHz, performance, catching up with a dedicated processor in the mid-1990s, while the ordinary model prices drop to $ 1, the most high-end model is only $ 10. Contemporary SCM system is no longer only in the bare metal environment to develop and use a large number of dedicated embedded operating system is widely used in a full range of SCM. As handheld computers and mobile phones core processing high-end SCM can even use a dedicated Windows and Linux operating systems.The SCM is more than a dedicated processor for embedded systems, so it has been up to the application. In fact SCM is the world’s largest number of computer. Of modern human life in almost every electronic and mechanical products will be integrated SCM. Mobile phone, telephone, calculator, household appliances, electronic toys, handheld computers, as well as mouse and othercomputer accessories with 1-2 Ministries SCM. The PC will have a large number of SCM work. Generally equipped with more than 40 single-chips in the car, even in complex industrial control systems may have hundreds of single chip at the same time! The number of SCM is not only far more than the sum of PC and other computing even more than the number of human beings even more .The single-chip, also known as single-chip SCM, it is not the completion of a logical function of the chip, but a computer system integrated onto one chip. Equivalent to a mini- computer and computer, SCM only the lack of me / O devices. Speaking in general terms: a chip has become a computer. Its small size, light weight, inexpensive, and provide favorable conditions for learning, application and development. At the same time, learning to use the SCM is the best choice for the understanding of computer theory and structure.Internal SCM with a similar module and the computer functions, such as CPU, memory, parallel bus, the same memory and hard disk role, different performance of these components are relatively weak a lot of our home computer, but the price is low generally not more than 10 Yuan can be use it for control appliances of a class is not very complex work enough. We are using household appliances inside of the drum fully automatic washing machine, exhaust hood, VCD and so on can be seen in its presence, and it is mainly as part of the core parts.It is an online real-time control computer, on-line site control need is a strong anti-jamming capability, lower cost, this is also off-line computer (such as home PC) the main difference.SCM rely on the program is running, and can be modified. Different functions through different programs, especially the special unique function, which is the other devices, require much effort to do, while others make great efforts it is difficult to do. A not very complex functions using pure hardware to get the words of the 1950s developed 74 series, or 60 during the CD4000 series, the circuit must be a big PCB board! If successful on the market in the United States in the 1970s series of SCM, the result will be different! Just because a program written by the MCU through you can achieve high intelligence, high efficiency and high reliability!SCM for cost sensitive, so accounting for the dominance of the software or the lowest level assembly language, which is the lowest level than binary machine code language, since such low-level why use it? A lot of high-level language has reached a level of visual programming, why not? The reason is simple, is the SCM does not have a home computer as the CPU, also not as hardas mass storage devices. A visual high-level language to write small programs inside even if there is only one button, will reach tens of K of size! Nothing in terms of home Pac’s hard drives, but for SCM in terms of is not acceptable. SCM in the utilization of hardware resources must be high, so the compilation of the original while still in heavy use. The same reason , if the computer giant 's operating system and application software to get home PC run up to the home PC can not afford .It can be said that the twentieth century across the three "power " era of the electrical era , the electronic age and has now entered the computer age . However, such a computer usually refers to a personal computer, or PC. It is by the host, keyboard, monitor, and so on. Another type of computer, not how most people are familiar with. This computer is smart to give a variety of mechanical SCM (also known as micro- controller). The name suggests, the smallest of this computer system using only one IC to make a simple calculation and control. Because of its small, usually hidden in a controlled mechanical "stomach”. Throughout the device, it plays like the role of the human mind, it is wrong, the entire device was paralyzed. Now, this single chip field of use has a very wide, such as smart meters, real-time industrial control, communications equipment, navigation systems, and home appliances and so on. A variety of products using the SCM, you can play the effect of product upgrades, often preceded by an adjective in front of the product name - "sma rt”, such as smart washing machines. Some factories or other amateur electronics developers to engage in out of certain products, not the circuit is too complicated, too simple and can easily be imitation. The reason may be stuck in the product does not use a SCM or other programmable logic devices.2．MCU classificationSCM as an important area of computer development, the application of a more scientific classification. According to the current development situation from different angles SCM can be divided into universal / special type, bus / bus and industrial type / home appliance type.2.1．Universal / private typeUniversal / private type which is to distinguish between the scopes of application by SCM. For example, 80C51 is a general-purpose MCU , it is not some kind of post use ; Dedicated MCU for a product or a product designed and manufactured , for example , in order to meet the requirements of the electronic thermometer in the integrated on-chip ADC interface and other functions temperature measurement and control circuit .2.2．Bus / busBus / bus whether to provide single-chip parallel bus to distinguish. Bus SCM is generally set parallel address bus, data bus, control bus, these pins to extend parallel peripheral devices can be connected through the serial port and MCU In addition, many of the SCM has the required peripheral devices and peripheral interfaces integrated one, so in many cases do not parallel expansion bus, greatly reduce the province of package cost and chip size, the type of SCM called the non- bus -type SCM.2.3. Controlled / appliance typeControlled / appliance type this distinction in accordance with the SCM broadly applied field. In general, the industrial -type addressing range, computing power; SCM for home appliances and more special type, usually the high integration of the small package, low prices, peripheral devices, and peripheral interfaces. Obviously, these categories are not the only and strict. 80C51 class SCM, for example, both general-purpose buses, but also for industrial use.3. The course of their workThe course of their work SCM automatically complete the tasks entrusted to it , that is, single-chip implementation of the program process , the process of an article of instructions executed , the so-called instruction is in the form of single-chip implementation of a variety of operating with the command to write down , which is designer assigned to it by the instruction set , an instruction corresponds to a basic operation; Full instructions can be executed by the SCM , the SCM instruction set , the different types of single-chip , and its instruction set is also different . So that the SCM can automatically complete a specific task, the problem to be solved must be compiled into a series of instructions (these instructions must be selected SCM to the identification and implementation of the Directive), a collection of this series of instructions to become the program, the program need to pre- stored in the components - memory storage capabilities. Memory is composed by a number of storage units ( the smallest unit of storage ) , like a large building has many rooms composed of the same , the instructions stored in these units , the instruction fetch unit and perform like the rooms of large buildings, each assigned to only a room number , each memory cell must be assigned to a unique address number , the address is known as the address of the storage unit , so as long as you know the address of the storage unit , you can find the storage unit that stores instructions can be removed, and then be executed .Programs are usually executed in the order , instruction program is a sequential storage ,single-chip in the implementation of the program to be able to a section of these instructions out and be implemented , there must be a component to track the address of instruction where this part the program counter PC ( included in the CPU ), the start of program execution , endowed the address where the first instruction of the program to the PC , and then made for each command to execute the content into the PC will automatically increase , increase the amount is determined by the instruction length of this article may be 2 or 3, to point to the starting address of the next instruction to ensure the implementation of the instruction sequence .4. SCM historySCM was born in 1971, has gone through three major phases of the SCM, the MCU SOC.4.1. The basic structure of the SCMThe basic structure of the SCM constitutes the computing device, controller, memory, input output devices.4.2. The first model of SCM1. SCM stage of the single chip microcomputer (Single Chip Microcomputer), seeking a monolithic form of embedded systems architecture. Innovative model to be successful, and laid a completely different path of development of the SCM and the general-purpose computer. Independent path of development to create an embedded system, Intel denied.2. MCU SCM (Micro Controller Unit). Stage, the main direction of technology development: expanding a variety of peripheral circuits and interface circuits, embedded applications are met, the object system requirements and to highlight the intelligent control capabilities of its object. It is involved in the field with the object system, therefore, the important task of the MCU development will inevitably fall on electrical and electronics manufacturers. From this perspective, Intel is gradually fading out the MCU development of objective factors. When Philips in the development of MCU, the most famous manufacturers.Philips Company with its huge advantage in embedded applications, the MCS 51 from the single-chip microcomputer, the rapid development of the micro- controller. Therefore, when we look back at the path of development of embedded systems, do not forget the historical achievements of Intel and Philips.5. Embedded systemsSCM is the road of independent development of embedded systems, an important factor to theMCU stages of development, is seeking applications on the chip to maximize the settlement; dedicated SCM development of natural Sock trend. With the development of microelectronics technology, IC design, EDA tools, Sock-based SCM applications development. Therefore, understanding of the SCM from the single-chip microcomputer single-chip SCM extends to the single-chip applications.6. SCM development historyIntel Corporation in 1971 developed the world's first 4-bit microprocessor ; Hoff of Intel Corporation to develop the success of the world's first 4 - bit microprocessor chip , the Intel 4004 , the advent marks the first generation of microprocessor , the microprocessor and The computer era began . The invention of microprocessors, Hough was the British "Economist" magazine as one of the most influential since World War II seven scientists.In November 1971 , Intel introduced the MCS -4 micro- computer system ( including the 4001 ROM chips , the 4002 RAM chip, 4003 shift register chip , and 4004 microprocessor ) of which 4004 (below) contains 2300 transistors , sizes 3mm × 4mm, the computational performance far exceeds that of the ENIAC , was originally priced at $ 200 .In April 1972, Hough, who developed the first 8 -bit microprocessor, the Intel 8008. Since 8008 is a P-channel MOS microprocessor, so still the first generation of microprocessors.Intel Corporation in 1973 developed the 8-bit microprocessor 8080; August 1973, Hoff, who developed the 8-bit microprocessor the Intel 8080 and replaced by a P-channel N-channel MOS circuit, the second generation of microprocessor device thereon was born.Frequency 2MHz 8080 chip computation speed 10 times faster than 8008 , you can access the 64KB memory , using 6000 transistors , based on a 6 - micron technology , processing speed 0.64MIPS ( Million the Instructions Per Second) .In April 1975, the MITS released the first general-purpose the Altair 8800, priced at $ 375, with 1KB memory. This is the world's first micro-computer.Intel Corporation in 1976 developed the MCS -48 series of 8-bit SCM, the advent of the SCM.Silo Z80 microprocessor developed in 1976, is widely used in microcomputers and industrial automation equipment. At that time, the three pillars of Silo, Motorola and Intel in microprocessors.The early 1980s, the Intel Corporation on the basis of the MCS - 48 series SCM, the introduction of the MCS-51 series of eight high-end devices. MCS-51 series MCU on-chip RAMcapacity, I / O port function, the system expansion has been greatly improved.7. Hardware features1. A single-chip integration of high. Single-chip , including CPU , 4KB capacity ROM ( 8031 Nil) , 128 B, the capacity of RAM , 16 - bit counter / timers , four 8-bit parallel port full-duplex serial line port .2. The system is simple, easy to use, modular;3. single-chip high reliability, can work to 10 ^ 6-10 ^ 7 hours of trouble-free;4. The processing functions and speed.5. Low voltage, low power consumption, ease of production of portable products6. The control function8. ApplicationMCU to infiltrate all areas of life, almost difficult to find which areas of the SCM trail. Navigation device of the missile , aircraft , various instrument control , computer network communications and data transmission , industrial automation and process real-time control and data processing , widely used smart card IC , civil luxury car security system , VCR , cameras, the control of automatic washing machines , and program - controlled toys , electronic pets , etc. , which are inseparable from the SCM. Not to mention the field of automatic control, robotics, intelligent instruments, medical equipment and a variety of intelligent mechanical. Therefore, the learning, development and application of the SCM will create a number of computer applications and intelligent control of the scientists, engineers.The SCM is widely used in the field of instrumentation, home appliances, medical equipment, aerospace, equipment for the intelligent management and process control, generally can be divided into the following categories:8.1. On smart instrumentationThe SCM has a small size, low power consumption, and control functions , and expansion of the advantages of flexibility, miniaturization and easy to use , widely used in instrumentation , combined with different types of sensors can be realized such as voltage , power, frequency , humidity, temperature , flow, speed, thickness, angle , length , hardness , elements , pressure and other physical measurement . SCM makes the digital instrumentation, intelligent, miniaturization and more powerful function than the use of electronic or digital circuits. Such as precisionmeasuring equipment (power meter, oscilloscope, analyzer).8.2. In industrial control applicationsMCU can constitute various forms of control systems, data acquisition systems. Such as factory assembly line of intelligent pipe chip, lift intelligent control, and various alarm systems, and computer networking constitute the two control systems.8.3. In Household AppliancesIt can be said that the household appliances is basically using the MCU control, from rice cookers, washing machines , refrigerators , air conditioners , color TVs , audio and video equipment to the electronic weighing equipment , multifarious , ubiquitous .8.4. In the field of computer networks and communicationModern SCM with universal communication interface can be easily and computer data communications , provides excellent material for use in computer networks and communication devices , communication equipment basically to the MCU intelligent control from the mobile phones, telephones , small program-controlled switchboards , building automated communications call systems , train radio communications, and then to the ubiquitous mobile phones in their daily work , trucking mobile communication radios .8.5. Chip in the field of medical equipmentThe SCM uses in medical devices is also quite extensive, such as medical ventilator , a variety of analyzers , monitors , ultrasound diagnostic equipment and hospital beds call system and so on .8.6. Modular applications in a variety of large appliancesSome dedicated SCM designed for specific functions, modular applications in a variety of circuit, without requiring the use of personnel to understand its internal structure. Integrated single-chip, such as music, seemingly simple function, miniature pure electronic chip (as opposed to the principle of the tape drive), you need a complex similar to the principle of the computer. Such as: the music signal in digital form in memory (similar to the ROM), read by the SCM into analog music signal (similar to the sound card).In large circuits , this modular application greatly reduce the size , simplifying the circuit , reducing the damage , error rate , is also convenient to replace .8.7. Chip in the field of automotive equipmentThe SCM is widely used in automotive electronics, such as automotive engine controllers,intelligent electronic controller based on CAN bus automotive engine, GPS navigation system, abs anti-lock systems, braking systems, etc.MCU basis [Revision] [series of textbooks SCM and embedded systems.]单片机基础1.单片机概况单片微型计算机简称单片机，是典型的嵌入式微控制器（SCM Unit），常用英文字母的缩写MCU表示单片机，它最早是被用在工业控制领域。