單片機(jī)基礎(chǔ)電氣工程及其自動(dòng)化畢業(yè)論文中英文翻譯

1、fundamental of single-chip microcomputersthe single-chip microcomputers is the culmination of both the development of the digital computer and the integrated circuit, arguably the two most significant inventions of the 20th century.these two types of architecture are found in single-chip microcomput

2、ers. some employ the split program/data memory of the harvard architecture, shown in fig. 3-4a-1, others follow the philosophy, widely adopted for general-purpose computers and microprocessors, of making no logical distinction between program and data memory as in the princeton architecture, shown i

3、n fig. 3-4a-2.in general terms a single-chip microcomputer is characterized by the incorporation of all the units of a computer into a single device, as shown in fig. 3-4a-3.read only memory (rom) rom is usually for the permanent, non-volatile storage of an applications program. many microcomputers

4、and microcontrollers are intended for high-volume applications and hence the economical manufacture of the devices requires that the contents of the program memory be committed permanently during the manufacture of the chips. clearly, this implies a rigorous approach to rom code development since ch

5、anges cannot be made after manufacture. this development process may involve emulation using a sophisticated development system with a hardware emulation capability as well as the use of powerful software tools.some manufacturers provide additional rom options by including in their range devices wit

6、h (or intended for use with) user programmable memory. the simplest of these is usually a device which can operate in a microprocessor mode by using some of the input/output lines as an address and data but for accessing external memory. this type of device can behave functionally as the single-chip

7、 microcomputer from which it is derived albeit with restricted i/o and a modified external circuit. the use of these romless devices is common even in production circuits where the volume does not justify the development costs of custom on-chip rom ; there can still be a significant saving in i/o an

8、d other chips compared to a conventional microprocessor based circuit. more exact replacements for rom devices can be obtained in the form of variants with piggy-back eprom (erasable programmable rom) sockets or devices with eprom instead of rom. these devices are naturally more expensive than the e

9、quivalent rom device, but do provide complete circuit equivalents. eprom based devices are also extremely attractive for low-volume applications where they provide the advantages of a single-chip device, in terms of on-chip i/o, etc, with the convenience of flexible user programmability.random acces

10、s memory (ram) ram is for the storage of working variables and data used during program execution. the size of this memory varies with device type but it has the same characteristic width (4, 8, 16 bits, etc.) as the processor. special function registers，such as a stack pointer or timer register are

11、 often logically incorporated into the ram area. it is unnecessary to make a distinction between ram and processor register as is done in the case of a microprocessor system since ram and registers are not usually physically separated in a microcomputer.central processing unit (cpu) the cpu is much

12、like that of any microprocessor. many applications of microcomputers and microcontrollers involve the handing of binary-coded decimal (bcd) data (for numerical displays, for example), hence it is common to find that the cpu is well adapted to handing this type of data. it is also common to find good

13、 facilities for testing, setting and resetting individual bits of memory or i/o since many controller applications involve the turning on and off of single output lines or the reading of a single line. these lines are readily interfaced to two-state devices such as switches, thermostats, solid-state

14、s relays, valves, motors, etc.parallel input/output parallel input and output schemes vary somewhat in different microcomputers; in most a mechanism is provided to at least allow some flexibility of choosing which pins are outputs and which are inputs. this may apply to all or some of the ports. som

15、e i/o lines are suitable for direct interfacing to, for example, fluorescent displays, or can provide sufficient current to make interfacing to other components straightforward. some devices allow an i/o port to be configured as a system bus to allow off-chip memory and i/o expansion. this facility

16、is potentially useful as a product range develops, since successive enhancements may become too big for on-chip memory and it is undesirable not to build on the existing software base.serial input/output serial communication with terminal devices is a common means of providing a link using a small n

17、umber of lines. this sort of communication can also be exploited for interfacing special function chips or linking several microcomputers together. both the common asynchronous and synchronous communication schemes require protocols that provide framing (start and stop) information. this can be impl

18、emented as a hardware facility or u(s) arp (universal (synchronous) asynchronous receiver/transmitter) relieving the processor (and the applications programmer) of this low-level, time-consuming, detail. it is merely necessary to select a baud-rate and possibly other options (number of stop bits, pa

19、rity, etc.) and load (or read from) the serial transmitter (or receiver) buffer. serialization of the data in the data in the appropriate format is then handled by the hardware circuit.timer/counter facilities many applications of single-chip microcomputers require accurate evaluation of elapsed rea

20、l time. this can be determined by careful assessment of the execution time of each branch in a program but this rapidly becomes inefficient for all but the simplest programs. the preferred approach is to use a timer circuit that can independently count precise time increments and generate an interru

21、pt after a preset time has elapsed. this type of timer is usually arranged to be preloadable with the required count. the timer then decrements this value producing an interrupt or setting a flag when the counter reaches zero. better timers then have the ability to automatically reload the initial c

22、ount value. this relieves the programmer of the responsibility of reloading the counter and assessing the elapsed time before the timer is restarted, which otherwise would be necessary if continuous precisely timed interrupts were required (as in a clock, for example). sometimes associated with a ti

23、mer is an event counter. with this facility there is usually a special input pin, that can drive the counter directly.timing components the clock circuitry of most microcomputers requires only simple timing components. if maximum performance is required, a crystal must be used to ensure the maximum

24、clock frequency is approached but not exceeded. many clock circuits also work with a resistor and capacitor as low-cost timing components or can be driven from an external source. this latter arrangement is useful if external synchronization of microcomputer is required.單片機(jī)基礎(chǔ)單片機(jī)是數(shù)字計(jì)算機(jī)和集成電路發(fā)展中的一個(gè)頂峰，而

25、這二者可以說(shuō)是20世紀(jì)的兩項(xiàng)最有意義的發(fā)明。在單片機(jī)中有兩種類型的體系結(jié)構(gòu)。 一些采用的是分離的程序或數(shù)據(jù)存儲(chǔ)器的哈佛建筑學(xué)結(jié)構(gòu)，如下圖3-4a-1所示，其他的一些根據(jù)原則，廣泛采用通用計(jì)算機(jī)和微處理器，程序或數(shù)據(jù)存儲(chǔ)器之間沒(méi)有明確的區(qū)分開(kāi)來(lái)的普林斯頓建筑學(xué)結(jié)構(gòu)，如圖3-4a-2所示。如圖3-4a-3所示，概括地說(shuō)一個(gè)單片機(jī)是把組成微型計(jì)算機(jī)的各個(gè)功能部件集成在一塊芯片中，構(gòu)成一個(gè)完整的微型計(jì)算機(jī)。只讀程序存儲(chǔ)器(rom) rom通常是為永久的應(yīng)用程序。很多微型計(jì)算機(jī)的非易變性存儲(chǔ)器和微型控制器供大容積應(yīng)用使用，并且設(shè)備的制造要求在芯片的制造期間，記憶的內(nèi)容永久地被保存。很清楚，因?yàn)樽儎?dòng)不可能

26、在制造以后，這就暗示著對(duì)只讀存儲(chǔ)器代碼發(fā)展有了一定的限制。在這個(gè)發(fā)展過(guò)程中可能需要包含一個(gè)穩(wěn)定開(kāi)放的計(jì)算機(jī)系統(tǒng)以及使用強(qiáng)有力的硬件仿效能力的軟件工具。有些制造商提供另外的rom選擇通過(guò)包含在他們的范圍設(shè)備內(nèi)有(或打算供用途使用)用戶可編程序的記憶。這些最簡(jiǎn)單的方法通常是通過(guò)使用某些輸入/輸出線作為數(shù)據(jù)和地址總線訪問(wèn)在微處理器方式下運(yùn)行的外部設(shè)備。作為單片機(jī)，此種設(shè)備可能在功能上表現(xiàn)為來(lái)自限制的i/o和改進(jìn)的外部電路。在生產(chǎn)的集成電路中使用這些只讀存儲(chǔ)器附加設(shè)備是非常常見(jiàn)的，其容量在片內(nèi)rom的擴(kuò)展是不容發(fā)展的; 與一條基于微處理機(jī)的常規(guī)電路相比，在輸入/輸出和其他芯片上的容量可能仍然比較小。

27、rom設(shè)備的替換可以得到以與背負(fù)式的 eprom (可擦除的可編程序存儲(chǔ)器)的插口而不是rom。eprom比等效rom設(shè)備昂貴，但是與提供的完全電路等值。 eprom在設(shè)備上的低音量應(yīng)用也是非常有吸引力的，因?yàn)樗鼈兲峁┝烁鶕?jù)在片內(nèi)的輸入/輸出，等等，以及為用戶提供一個(gè)方便靈活的可編程性的單片機(jī)設(shè)備。隨機(jī)存取存儲(chǔ)器(ram) ram是用于存放所有在執(zhí)行過(guò)程中的結(jié)果和中間數(shù)據(jù)。其存儲(chǔ)容量的大小隨設(shè)備型號(hào)的變化而變化，但是它有同樣典型寬度(4，8，16位等等)作為處理器。特殊功能計(jì)數(shù)器，例如堆棧指針或定時(shí)器記數(shù)器經(jīng)常在邏輯上被合并到ram區(qū)域里。在微處理器系統(tǒng)情況下，ram和處理器的記數(shù)器之間的區(qū)分是多余的，因?yàn)閞am和記數(shù)器通常在微型計(jì)算機(jī)沒(méi)有完全被分離。中央處理單元(cpu) cpu是整個(gè)單片機(jī)的核心部件。 微型計(jì)算機(jī)和微型控制器的許多應(yīng)用都介入了十進(jìn)制(bcd)數(shù)據(jù)(例如為數(shù)字顯示)，因此，共同發(fā)現(xiàn)了cpu能很好的適應(yīng)傳遞此種數(shù)據(jù)。因?yàn)樵S多控制器的應(yīng)用都介入了打開(kāi)和關(guān)上這唯一的一條輸出線或訪問(wèn)這條線路的數(shù)據(jù)，這也是共同性發(fā)現(xiàn)用于設(shè)置和重新設(shè)置各自的位記憶或輸入/輸出的好的設(shè)備。這些線很理所當(dāng)然的成為了被連接的二狀態(tài)設(shè)備例如開(kāi)關(guān)、溫箱、固態(tài)繼電器、閥門(mén)、馬達(dá)等等。并行的輸入/輸出 在不同的微型計(jì)算機(jī)系統(tǒng)中，其并行的輸入/輸出也不相同；在大多數(shù)