The single chip computer abbreviation Microcontroller is typical of embedded Microcontroller controller (Microcontroller Unit), common English letters is the abbreviation of MCU said Microcontroller, it was first used in industrial control field. SCM by chip inside only CPU dedicated processor. The earliest design concept is through the huge amounts of peripheral and CPU integration in a chip, make the computer system smaller, more easy to integrate into the complex and to volume demanding control equipment of. Intel-based Z80 is the earliest designed according to this kind of thought the processor, henceforth, SCM and dedicated processor development parted.Early microcontroller is 8 bits or 4 digit. One of the most successful intel-based 8031 is simple, reliable performance, because good got a lot of praise. Then in the microcomputer 8031 developed MCS51 series microcontroller systems. Based on this system of SCM system have until now in widespread use. With the improvement of industrial control area requirement, begin to emerge 16-bit single chip, but because the price is not ideal did not get very widely. After the 1990s with consumer electronic products development, microcontroller technology has been a tremendous increase. As the INTEL i960 series especially later ARM series widely, 32-bit SCM rapidly replacing 16-bit single chip of high-end status, and into the mainstream market. While the traditional 8 bit micro-controller performance also obtained the rapid increase, processing power than 1980s raised hundreds times. At present, high-end 32-bit SCM frequency has exceeded 300MHz, performance straight after the middle of 90's of dedicated processor, whereas normal type ex-factory price dropped to $1, the highest-profile [1] type was only ten dollars. Contemporary SCM system no longer only in LuoJi environment, development and use of special embedded operating system is widely used in the whole range of single-chip microcomputer. While in as a handheld computers and mobile phones key processing of high-end microcontroller even can directly use the special Windows and Linux operating system.Single-chip processor more than dedicated suitable for use with embedded system, so it has gained the most applications. In fact microcontroller is the world largest number of the computer. Modern human life that are used in almost every pieces of electronic and mechanical products will be integrated have microcontroller. Mobile, telephone, calculator, home appliances, electronic toys, PDA and mouse and so on computer accessories are equipped with 1-2 department microcontroller. The PCS in also will affect many microcomputer in the work. Cars equipped with more than 40 department generalsingle-chip microcomputer, complex industrial control system even there may be hundredsmicrocomputer in working at the same time! The number of MCU is not only far more than PCS and other calculation combined, and even more than the number of human beings.SCM is also called monolithic micro controller, it is not complete a logic function chips, but it is a computer system integration to a chip. The computer equivalent of a micro computer, and compared, microcontroller lack only the I/O devices. General speaking: a chip became a computer. Its compact size, light quality, cheap, for learning, application and development provides the convenience. Meanwhile, "learning to use a single chip computer is knowledge of computer principle and structureof the best choice.SCM internal also use and computer functions similar module, such as CPU, memory, parallel bus and hard disk storage device functions are the same, the difference is its relative performance all these parts of our home computer weak, but the price is much lower, usually less than 10 yuan can... Use it to do some control electric appliance category is not very complicated work is sufficient. We use now roller washing machine, smoke exhaust hood, VCD and so on the home appliance inside can see the figure! ... It was mainly used as a core part of the control part.It is a kind of on-line real-time control computer, on-line is site control, need is strong anti-jamming ability, low cost, this also is and off-line computer (such as household PC) the main difference.A single chip computer is by program running, and can be modified. Through the different program realization of different function, especially the unique some special function, this is another device needs to spend effort can do that, while some others are great effort also hard to do. One is not very complicated function if use in the United States during the 1950s development of 74 series, or from the 1960s CD4000 series these pure hardware to fix words, circuit must be a large piece of PCB board! But if if use American 1970s success on the market series microcontroller, and the results will be difference! Just because of single chip through your programming can achieve high intelligence, high efficiency and high reliability.Due to cost is sensitive microcontroller, so, at present, the dominant software or lowest assembly language, it is besides the binary machine code above the lowest language, since so low-level why use? Many senior language has reached the level of visual programming is why not? The reason is very simple, that is no home computer microcontroller as the CPU, also did not like hard disk that mass storage device. A visual small programs written in high-level languages inside has even a button, also can achieve dozens of K size! For household PC hard disk speaking nothing, but the SCM speaking isunacceptable. Microcomputer in hardware resources utilization must high to just go, so assembly although original but still in use large. The same way, if the giant computer operating system and application software got home PC came running, household PC is also cannot bear.Can say, the twentieth century across the three "electricity" age, namely the age of electricity, electronic era and now has entered the computer era. However, this kind of computer, usually refers to the personal computer, the abbreviation PCS. It consists of host, keyboard, display etc. And those computer, most people do not so familiar with. This computer is intelligence gives all kinds of mechanical SCM (also called micro controller). As the name suggests, the computer is minimal systems only took a piece of integrated circuits, simple operation and control can be carried out. Because of its small size, usually hidden in the accused of mechanical "stomach". It in the whole device, plays the role of like the human mind, it went wrong, the whole device broke down. Now, this SCM use field has been widely, such as intelligent instruments, real-time control, communication equipment, navigation system, household electric appliances, etc. Various products once usingsingle-chip microcomputer, can have the effect that product upgrading, often in product specialty bariatric adjectives -- "intelligent", such as intelligent washing machines etc. Now some factories technicians or other leisure electronic developers out some of the products, not the circuits are too complex, is functional too simple and the easy be imitators. Investigate its reason, may be stuck in product without using SCM or other programmable logic devices..Microcontroller history1971 Intel company developed the world's first four microprocessor, The Intel company hoff successfully developed the world's first piece of four 4004 Intel microprocessor chips, marks the first generation of microprocessor market, microprocessor and computer era begins. For invention microprocessor, hoff by the British economist magazine named "the most influential since world war ii the seven scientists" one.In 1971, the Intel on November launch MCS - 4 microcomputer system (including 4001 ROM chip, 4002 RAM chips, 4003 shift register chips and 4004 microprocessor) which 4004 (figure below) contains 2,300 transistor, the dimension of 3mm x 4mm, computing performance than that ENIAC, initially sells for $200.April 1972, hoff etc, developed the first eight Intel microprocessor 8008. Because 8008 USES is P in gully MOS microprocessor, and therefore still belong to the first generation of microprocessors.1973 Intel company develop 8 bits of the microprocessor 8080; In 1973, August hoff person such as developed eight microprocessor 8080 to N in gully intel-based MOS circuit replaced P channel, the second generation microprocessor at birth.Frequency of 2MHz 8080 chip speed 8008 10 times faster than, can access 64KB memory, use based on six micron technology 6,000 transistors, processing speed of 0.64 the MIPS (at) Million will conference.In 1975, MITS issued on April first general-purpose Altair 8,800, price $37.5bn, with 1KB memory. This is the world's first microcomputer.1976 the Intel company develop MCS - 48 series of 8 bits of single chip microcontroller, this also is published.Zilog company in 1976 development Z80 microprocessor, widely used in microcomputer and industrial automatic control equipment. At that time, Zilog, Motorola and Intel microprocessor field in Japan.In the early 1980s, the Intel company in MCS - 48 series microcontroller, on the basis of launched MCS - 51 series 8 bits of high-grade microcontroller. MCS - 51 series microcontroller whether pieces (RAM capacity, I/O mouth function, system extension aspects had the very big enhancement. Singlechip the bus: we know that a circuit is always from the components through wires connected, and in analog circuits, the connection does not become a problem, because the devices are generally serial inter-relationship between the various devices connection is not much, but not the same as computer circuits, which is based on the microprocessor as the core, the device must be connected with the microprocessor, the device must be between the mutual coordination and so on need to connect on a lot of If still the same as analog circuits, in the microprocessor and a separate connection between the devices, the quantity line will be many alarmingly so in the microprocessor introduced the concept of bus, all devices share the connection All devices of all eight data lines from eight public online, which is equivalent to all devices in parallel, but only this is not enough, if there is two devices send data simultaneously, a 0, a 1, then , the receiving party received what is it? This situation is not allowed, so to pass the line of control to control the device time job, any time there can be only one device to send data (which may have multiple devices simultaneously receiving). Device's data lines will be referredto as data bus, all the line of control devices known as control bus. Singlechip at internal or external memory and other devices have memory cells, these memory cells to be assigned addresses to use, the allocation of addresses is of course to give the form of electrical signals, and because memory cells are more so for address the allocation of more lines, these lines were known as the address bus.Second, data, address, command: The reason why these three together, because these three are the essence is the same - figure, or are a string of'0 'and'1', composed of sequence . In other words, addresses, instructions are also data. Command: from single-chip chip designer provides a figure, it is consistent with our mnemonic commonly used commands have a strict one-to-one relationship, not by the developer to change the MCU. Address: Singlechip are looking for internal, external storage units, input and output port based on the value of the internal unit's address has been provided for the chip designers, and can not be changed, the external unit can be single-chip developers to decide, but Yes there is some address must be the unit (see procedures for the implementation process). Data: This is the object of treatment by the microprocessor, in a variety of different applications in different circuits, in general, the data may be processed so have several situations:1 ? address (such as MOV DPTR, # 1000H), that address 1000h into the DPTR.2 ? the way the words or control characters (such as MOV TMOD, # 3),3 which controls the characters.3 ? constants (such as MOV TH0, # 10H) 10H that is constant from time to time.4 ? The actual output value (such as the mouth then P1 lantern light to light the whole, then the implementation of instruction: MOV P1, # 0FFH, to light the whole dark, then the implementation of instruction: MOV P1, # 00H) and 00H are here 0FFH actual output value. Another example is the font code for the LED, is the actual output value.Understanding of the address, the nature of instructions, running is not difficult to understand why the process of running fly, the data will be implemented as instructions.Three, P0 mouth, P2 and P3 the mouth of the second function Usage: often on P0 beginner I, P2 and P3 mouth I use the second function puzzled think the second function and the original features have a switch between the process, or that there have to be a directive, in fact, the port's second feature is completely automatic, no need to use command to convert. Such as P3.6, P3.7, respectively, are WR, RD signal, when the micro-chip RAM or external justifications machine has an external I / O port, they were used as the second function, can not be used as general-purpose I / O port to use, as long as one microprocessor implementation of the MOVX instruction 1, there will be a corresponding signal sent from the P3.6 or P3.7, no prior use instructions indicate. In fact 'can not be used as general-purpose I / O port use' is not 'should not' but (user) 'not' as a general-purpose I / O port to use. At command you can arrange a Medium of Instruction SETB P3.7, and when the single-chip implementation of this Article directions, P3.7 will also become high, but users will not do so, because This usually will lead to the collapse of the system.Four, the program implementation process: single-chip power-on reset in 8051 after the program counter (PC) in the value of'0000 ', so the procedure always'0000' unit begin implementation of, that is to say: the system's ROM must exist in the'0000 'in this unit, and'0000' in the storage unit must be a command.Friday, the stack: the stack is a region, are used to store data, the region does not have any unique position, that is a part of internal RAM, special is its data storage and access methods, namely, theso-called 'advanced after that last-in first-out ', and the stack has a special data transmission command, ie' PUSH 'and' POP ', there is a special unit specifically for its services, that is, the stack pointer SP, when they first PUSH instruction, the SP on (at the original value of the foundation on) automatically add one, whenever the implementation of a POP instruction, SP on (at the original value basis) minus one automatically. Because of the value of SP can be used to change directions, so as long as the stage at the beginning of the proceedings to change the value of the SP, you can put the stack set up the required memory units, such as at the beginning of the proceedings, with a MOV SP, # 5FHinstructions when put on the stack from the memory modules installed in the unit 60H start. The normal procedure at the beginning of the total that there is a stack pointer of the instruction set, because at startup, SP initial value of 07H, thus the stack from the beginning the next unit 08h, and 08h to 1Fh in the region 8031 is the second, Three, four working registers area, often used, this will lead to data chaos. The author has prepared a different program, not exactly the same instructions to initialize the stack, which is the author's customary problem. When set up the stack area, does not mean that the region as a dedicated memory, it can be as common as the use of memory region, but under normal circumstances programming will not put it as an ordinary memory use.AVR single chipThe AVR core combines a rich instruction set with 32 general purpose working registers.All the 32 registers are directly connected to the Arithmetic Logic Unit (ALU), allowingtwo independent registers to be accessed in one single instruction executed in one clockcycle. The resulting architecture is more code efficient while achieving throughputs up toten times faster than conventional CISC microcontrollers.The ATmega8 provides the following features: 8K bytes of In-System ProgrammableFlash with Read-While-Write capabilities, 512 bytes of EEPROM, 1K byte of SRAM, 23general purpose I/O lines, 32 general purpose working registers, three flexibleTimer/Counters with compare modes, internal and external interrupts, a serial program-mable USART, a byte oriented Two-wire Serial Interface, a 6-channel ADC (eightchannels in TQFP and MLF packages) where four (six) channels have 10-bit accuracyand two channels have 8-bit accuracy, a programmable Watchdog Timer with InternalOscillator, an SPI serial port, and five software selectable power saving modes. The Idlemode stops the CPU while allowing the SRAM, Timer/Counters, SPI port, and interruptsystem to continue functioning. The Power-down mode saves the register contents butfreezes the Oscillator, disabling all other chip functions until the next Interrupt or Hard-ware Reset. In Power-save mode, the asynchronous timer continues to run, allowing theuser to maintain a timer base while the rest of the device is sleeping. The ADC NoiseReduction mode stops the CPU and all I/O modules except asynchronous timer andADC, to minimize switching noise during ADC conversions. In Standby mode, the crys-tal/resonator Oscillator is running while the rest of the device is sleeping. This allowsvery fast start-up combined with low-power consumption.T he device is manufactured using Atmel’s high density non-volatile memory technology.The Flash Program memory can be reprogrammed In-System through an SPI serialinterface, by a conventional non-volatile memory programmer, or by an On-chip bootprogram running on the AVR core. The boot program can use any interface to downloadthe application program in the Application Flash Memory. Software in the Boot FlashSection will continue to run while the Application Flash Section is updated, providingtrue Read-While-Write operation. By combining an 8-bit RISC CPU with In-System Self-Programmable Flash on a monolithic chip, the Atmel ATmega8 is a powerful microcon-troller that provides a highly-flexible and cost-effective solution to many embeddedcontrol applications.The ATmega8 AVR is supported with a full suite of program and system developmenttools, including C compilers, macro assemblers, program debugger/simulators, In-Cir-cuit Emulators, and evaluation kits.MCU applicationCurrently microcontroller penetrated into every aspect of our lives, almost hard to find which field no trace of single chip. Missile navigation devices, the plane on various kinds of instrument control, computer network communication and data transmission, industrial automation process real-time control and data processing, is widely used in all kinds of intelligent IC card, civil luxury car security system, video camera, video camera, full-automatic washing machine control, as well asprogram-controlled toys, electronic pets, etc, these are inseparable from microcontroller. Mention automatic control field of robot, intelligent instruments, medical equipment and various kinds of intelligent machinery. Therefore, SCM's study, development and application of computer application will create and intelligent control of scientists and engineers.SCM is widely applied in instrumentation, household appliance, medical equipment, aerospace, special equipment of intelligent management and process control and other fields, roughly can divide the following several categories:1. In intelligent instruments on the applicationSingle-chip microcomputer with small size, low power consumption, control function is strong, flexible, miniaturization and extended use convenience etc, which are widely used in instrumentation, combined with different kinds of sensors, which can realize such as voltage, power, frequency, humidity, temperature and flow rate, speed, thickness, Angle, length, hardness, elements and pressures, physical measurement. Adopting SCM control makes instrument digital, intelligent, miniaturization, and functional than by electronic or digital circuit stronger. For example precision measuring equipment (power meter, oscilloscope, various analyzer).2. The application in industrial controlMCU can constitute the various forms of control system, the data acquisition system. For example the production line of the intelligent pipe principle, the elevator intelligent control, various alarm system, network with computer constitute a secondary control system, etc.3. The application in household appliancesIt can be said that now of household appliances basically adopts single-chip microcomputer control, from electric cooker, washing machines, refrigerators, air conditioner, color television, other audio video equipment, arrive again micro-electronic quantity equipment, multifarious, omnipresent.4. In computer network and communication in the field of applicationModern single-chip generally have communication interface can be easily and computer data communications, for in the computer network and communication between devices applied to provide the excellent material conditions of present communication equipment basically realized thesingle-chip microcomputer intelligent control, from mobile, telephone, small pabx, building automatic train communication calling system, wireless communication, arrive again daily work deductions-from the mobile phone, cluster mobile communications, radios, etc.5. Microcomputer in the medical device field of applicationMicrocomputer in the medical equipment of use also is quite widespread, such as medical breathing machines, various analyzer, monitors, ultrasound diagnostic equipment and sickbed call system, etc. 6. In various large-scale electric appliance of modular applicationsSome special MCU designed to accomplish a specific function, and in various circuit of modular application, without asking using personnel understand its internal structure. If music integrated microcontroller, seemingly simple function, miniature in pure electronic chip (different from the principle of tape) be complex resemble computer principle. Such as: music signals in digital form stored in memory (ROM), similar to read by micro controller, into analog signals (similar to the music sound card).In large circuit, this modular application greatly reduced volume and simplify the circuit and reduce the damage, the error rate, also facilitate replacement.7. Microcomputer in the application fields of auto equipmentMicrocomputer in the automobile electronic application is very wide, for example in the car engine control, based on CAN bus automobile engine intelligence electronic controllers, GPS navigation system, abs antilock brakes, braking system, etc.In addition, microcomputer in the industry and commerce, finance, scientific research, education, national defence aerospace and other fields have a wide range of purposes.First, energy feedback unit work principleOn frequency-variable speed-adjustable system, when the motor load is a load of potential energy type such as oil pumping unit, mine hoist, etc; Or large inertia load such as: fan, cement system pipe, Dynamic balancing machines etc; And rolling mill, large longmen planer, spindle etc need fast brake class load, the motor is inevitably exists generating process, namely of motor rotor in external drag or load inertia maintain itself under the actual, making the motor speed is greater than the synchronous speed inverters, motor power will be issued by stored in inverter with dc bus filter capacitance, if you don't use this energy consume, so with dc bus voltage will rise, the influence of the frequency converter working normally.Energy feedback unit, through the automatic detection inverter with dc bus voltage, frequency converter dc link of dc voltage inverter with frequency voltage into with the same phase ac voltage, via multiple noise filter link after connected to exchange network, so as to achieve the purpose of energy feedback network, back to the grid electricity generating energy reached 97%, and effectively save electric energy.Second, energy feedback unit matters needing attention2.1, energy feedback unit and its connected device internal have endanger the personal safety of high pressure, wrong operation or improper installation may lead to personal property loss, so that the proposed by specially trained personnel installation operation.2.2, installation and wiring, in order to ensure the safe, please make sure to energy feedback unit and connected to it inverter power supply all disconnect and waits for 5 ~ 10 minutes, stay inverter internal capacitance stored in electricity discharge is finished, all can only operate.2.3, energy feedback unit and converter as close as possible to the farthest distance, do not exceed 2 meters.2.4, because energy feedback unit interior special design allows the user can not consider the grid sequence, namely: energy feedback unit of A, B and C terminals need not to the grid A, B and C or frequency converter input R, S, T one-to-one. But connection request when energy feedback unit of A, B and C terminals must and inverter communication input terminals R, S, T directly connected, can not through any intermediate switches or contactors, also can not connected to other ac circuits.2.5, energy feedback unit DC (+) terminal and converter DC bus is connected, DC (-) and converter DC bus negative connected the two cable advice adopting soft cable, and stranded inner connection, in order to reduce radiation.2.6, located on the radiator PE site wiring screws, please connect real reserve, could not connect grid neutral (neuter line).2.7, energy feedback unit designs for natural cooling way, so he asked energy feedback unit within the fluctuation, left 100mm 30mm inside cannot have other things influence the air flow shade.Third, energy feedback unit applicable occasions3.1, energy feedback unit used in potential type load such as: oil pumping unit, mine hoist, etc;3.2, energy feedback unit suitable to the large inertia load such as: fan, cement system pipe, dynamic balancing machines, centrifuge, etc;3.3, energy feedback unit applies to need to stop quickly of occasions, such as rolling mill, large longmen planer, spindle etc,3.4, energy feedback unit work may apply to other motors in renewable power state occasions. Four, energy feedback element and braking unit differenceEnergy feedback unit is renewable power of electric motor to power grid (right now meter feedback inversion), supply other equipment use, feedback efficiency can reaches as high as 97% above. And braking unit needs and braking resistance are used together, motor power generation of electricity consumption in regenerative braking resistance into heat wasted.In addition, using braking unit and braking resistance of braking unit, compared with energy feedback braking torque is small, can't achieve motor precision braking .Five.With the development of the technology of computer and control，the temperature control of electric heating furnace is becoming fully developed, the technology has been an important part of industry.To meet the requirement of industrial control, the thesis designs a system which is constituted of temperature detecting device, A/D conversion, monolithic processor keyboard and display apparatus, alarming circuit and D/A conversion based on the control of electric heating furnace. The thesis explains the principle, the concept of design, constitution and characteristic. Because of the great developing speed of automatic temperature controlling, the thesis try to explain the system in detail, and the thesis also reflect the direction of the development of temperature controlling system.This design controlled member is an electric heating stove, adds through the control in the resistance wire beginnings and ends voltage operating time operating time, comes the average power which outputs to the resistance wire to perform to control. Automatic temperature control of the electric furnace is realized by a temperature control circuit of solid state relay on the basis of the single-chip computer. This article put PID algorithm applies in the resistance furnace temperature control system, elaborated PID controller design, the hardware constitution and the software design, have realized set of temperatures gathering and the control design proposal. This control system has such advantages as low cost .control accuracy, good reliability and good resistance to interference.8.the application of single chip in electronic scaleThe development of the modern society has put forward higher request on weighing technology. The desk-top electronic scales have been great application in commercial trade, but they have many shortcomings such as large volume, high cost, AC supply power and not cove nince to carry, so they are restricted to use. The usual portable scales are lever scales which are mostly used by residents, and spring balance which measure through compression or drawing of spring. They are being rejected for their big measuring errors. People have been expecting cheap portable electronic scales which can measure accurately and be carried conveniently for many years.This thesis designs new-type portable electronic scales. It discusses the instrumental working principle, and introduces its error sources and how to distribute the error. And, the instrumental circuit, software-flow-chart and engineering designing technology are presented. Because capacitance。
