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1、Structure and function of the MCS-51 series Structure and function of the MCS-51 series one-chip computer MCS-51 is a name of a piece of one-chip computer series which Intel Company produces. This company introduced 8 top-grade one-chip computers of MCS-51 series in 1980 after introducing 8 one-chip
2、 computers of MCS-48 series in 1976. It belong to a lot of kinds this line of one-chip computer the chips have,such as 8051, 8031, 8751, 80C51BH, 80C31BH,etc., their basic composition, basic performance and instruction system are all the same. 8051 daily representatives- 51 serial one-chip computers
3、 . An one-chip computer system is made up of several following parts: ( 1) One microprocessor of 8 (CPU). ( 2) At slice data memory RAM (128B/256B),it use not depositting not can reading /data that write, such as result not middle of operation, final result and data wanted to show, etc. ( 3) Procedu
4、re memory ROM/EPROM (4KB/8KB ), is used to preserve the procedure , some initial data and form in slice. But does not take ROM/EPROM within some one-chip computers, such as 8031 , 8032, 80C ,etc. ( 4) Four 8 run side by side I/O interface P0 four P3, each mouth can use as introduction , may use as e
5、xporting too. ( 5) Two timer / counter, each timer / counter may set up and count in the way, used to count to the external incident, can set up into a timing way too, and can according to count or result of timing realize the control of the computer. ( 6) Five cut off cutting off the control system
6、 of the source . ( 7) One all duplexing serial I/O mouth of UART (universal asynchronous receiver/transmitter (UART) ), is it realize one-chip computer or one-chip computer and serial communication of computer to use for. ( 8) Stretch oscillator and clock produce circuit, quartz crystal finely tune
7、electric capacity need outer. Allow oscillation frequency as 12 megahertas now at most. Every the above-mentioned part was joined through the inside data bus .Among them, CPU is a core of the one-chip computer, it is the control of the computer and command centre, made up of such parts as arithmetic
8、 unit and controller , etc. The arithmetic unit can carry on 8 persons of arithmetic operation and unit ALU of logic operation while including one, the 1 storing device temporarilies of 8, storing device 2 temporarily, 8s accumulation device ACC, register B and procedure state register PSW, etc. Per
9、son who accumulate ACC count by 2 input ends entered of checking etc. temporarily as one operation often, come from person who store 1 operation is it is it make operation to go on to count temporarily , operation result and loopback ACC with another one. In addition, ACC is often regarded as the tr
10、ansfer station of data transmission on 8051 inside . The same as general microprocessor, it is the busiest register. Help remembering that agreeing with A expresses in the order. The controller includes the procedure counter , the order is depositted, the order decipher, the oscillator and timing ci
11、rcuit, etc. The procedure counter is made up of counter of 8 for two, amounts to 16. It is a byte address counter of the procedure in fact, the content is the next IA that will carried out in PC. The content which changes it can change the direction that the procedure carries out . Shake the circuit
12、 in 8051 one-chip computers, only need outer quartz crystal and frequency to finely tune the electric capacity, its frequency range is its 12MHZ of 1.2MHZ. This pulse signal, as 8051 basic beats of working, namely the minimum unit of time. 8051 is the same as other computers, the work in harmony und
13、er the control of the basic beat, just like an orchestra according to the beat play that is commanded. There are ROM (procedure memory , can only read ) and RAM in 8051 slices (data memory, can is it can write ) two to read, they have each independent memory address space, dispose way to be the same
14、 with general memory of computer. Procedure 8051 memory and 8751 slice procedure memory capacity 4KB, address begin from 0000H, used for preserving the procedure and form constant. Data 8051- 8751 8031 of memory data memory 128B, address false 00FH, use for middle result to deposit operation, the da
15、ta are stored temporarily and the data are buffered etc. In RAM of this 128B, there is unit of 32 byteses that can be appointed as the job register, this and general microprocessor is different, 8051 slice RAM and job register rank one formation the same to arrange the location. It is not very the s
16、ame that the memory of MCS-51 series one-chip computer and general computer disposes the way in addition. General computer for first address space, ROM and RAM can arrange in different space within the range of this address at will, namely the addresses of ROM and RAM, with distributing different ad
17、dress space in a formation. While visiting the memory, corresponding and only an address Memory unit, can ROM, it can be RAM too, and by visiting the order similarly. This kind of memory structure is called the structure of Princeton. 8051 memories are divided into procedure memory space and data me
18、mory space on the physics structure, there are four memory spaces in all: The procedure stores in one and data memory space outside data memory and one in procedure memory space and one outside one, the structure forms of this kind of procedure device and data memory separated form data memory, call
19、ed Harvard structure. But use the angle from users, 8051 memory address space is divided into three kinds: (1) In the slice, arrange blocks of FFFFH , 0000H of location , in unison outside the slice (use 16 addresses). (2) The data memory address space outside one of 64KB, the address is arranged fr
20、om 0000H 64KB FFFFH (with 16 addresses ) too to the location. (3) Data memory address space of 256B (use 8 addresses). Three above-mentioned memory space addresses overlap, for distinguishing and designing the order symbol of different data transmission in the instruction system of 8051: CPU visit s
21、lice, ROM order spend MOVC , visit block RAM order uses MOVX outside the slice, RAM order uses MOV to visit in slice. 8051 one-chip computer have four 8 walk abreast I/O port, call P0, P1, P2 and P3. Each port is 8 accurate two-way mouths, accounts for 32 pins altogether. Every one I/O line can be u
22、sed as introduction and exported independently. Each port includes a latch (namely special function register ), one exports the driver and a introduction buffer . Make data can latch when outputting, data can buffer when making introduction , but four function of passway these self-same. four port t
23、hese may serve as accurate two-way mouth of I/O in common use. Expand among the system of memory outside having slice, P2 mouth see high 8 address off; P0 mouth is a two-way bus, send the introduction of 8 low addresses and data / export in timesharing Output grade , P3 of mouth , P1 of mouth , conn
24、ect with inside have load resistance of drawing , every one of they can drive 4 Model LS TTL load to output. As while inputting the mouth, any TTL or NMOS circuit can drive P1 of 8051 one-chip computers as P3 mouth in a normal way . Because draw resistance on output grade of them have, can open a wa
25、y collector too or drain-source resistance is it urge to open a way, do not need to have the resistance of drawing outerly . Mouths are all accurate two-way mouths too. When the conduct is input, must write the corresponding port latch with 1 first . As to 80C51 one-chip computer, port can only offe
26、r milliampere of output electric currents, is it output mouth go when urging one ordinary basing of transistor to regard as, should contact a resistance among the port and transistor base , in order to the electricity while restraining the high level from exporting P1P3 Being restored to the throne
27、is the operation of initializing of an one-chip computer. Its main function is to turn PC into 0000H initially , make the one-chip computer begin to hold the conduct procedure from unit 0000H. Except that the ones that enter the system are initialized normally,as because procedure operate it make mi
28、stakes or operate there arent mistake, in order to extricate oneself from a predicament , need to be pressed and restored to the throne the key restarting too. It is an input end which is restored to the throne the signal in 8051 China RST pin. Restore to the throne signal high level effective , sho
29、uld sustain 24 shake cycle (namely 2 machine cycles ) the above its effective times. If 6 of frequency of utilization brilliant to shake, restore to the throne signal duration should exceed 4 delicate to finish restoring to the throne and operating. Produce the logic picture of circuit which is rest
30、ored to the throne the signal:Restore to the throne the circuit and include two parts outside in the chip entirely. Outside that circuit produce to restore to the throne signal (RST ) hand over to Schmitts trigger, restore to the throne circuit sample to output , Schmitt of trigger constantly in eac
31、h S5P2 , machine of cycle in having one more , then just got and restored to the throne and operated the necessary signal insidly. Restore to the throne resistance of circuit generally, electric capacity parameter suitable for 6 brilliant to shake, can is it restore to the throne signal high level d
32、uration greater than 2 machine cycles to guarantee. Being restored to the throne in the circuit is simple, its function is very important. Pieces of one-chip computer system could normal running,should first check it can restore to the throne not succeeding. Checking and can pop ones head and monito
33、r the pin with the oscillograph tentatively, push and is restored to the throne the key, the wave form that observes and has enough range is exported (instantaneous), can also through is it restore to the throne circuit group holding value carry on the experiment to change.译文51系列单片机的功能和结构 MCS51电脑芯片的
34、结构和功能。MSC51是因特尔公司生产的一系列电脑芯片的名称。这家公司在1976年推出了一款8级的电脑芯片MCS48之后，又在1080年推出了一个8级的电脑芯片MCS51。它属于一个种类繁多的电脑芯片家族，都如8051、8031、8751、80c51bh,80c31bh等,其基本组成、性能和基本指令系统,都是一样的。 51电脑芯片的代表产品是8051。 一个电脑芯片是由以下几个方面组成的: (1)8微处理器(CPU). (2)片上数据存储(128B/256B),不可读的数据写入存储,就像结果而不能中途操作改变的，最后结果要和数据显示等. (3)存储器存储程序/可擦写可编程只读存储器(4KB/8
35、KB),用于保存程序和片内的初始数据，而且并不需要片内的存储器/可擦写可编程只读存储器,如8031、8032、80c等. （4)并行的4*8的I/O P0 4 P3接口,每个接口都可作为一个输入口,也可以用作输出口。 (5)两个计时/计数,每个计时/计数器可设定而且可以在线上进行计数,用来计算的外部事件,也可以建立成一个计数方式，并能根据数或结果时间实现控制的计算机。(六)五钟切断源头上控制系统. (七)一个全通的串行双工I/O口UART(通用异步接收机/发送(UART),它实现了一个计算机芯片或一个计算机芯片和电脑的通讯. (8)弹性振荡器和时钟生产电路、水晶石英细调需要外部电容.现在允许的
36、最大震荡频率是12HZ, 每个上述地区内的数据都加入到了数据总线上.其中,CPU是基于单片机为核心的,这就是它的控制电脑及指挥中心,由算术装置等部件和控制器,等。算术单位可以进行8位的算术运算而单位ALU的同时包括逻辑运算,其中包括1个8位的临时寄存器1、暂时贮存器2、8的积累装置ACC、寄存器B和程序PSW国家登记等. 积累ACC的数字的人检查了2输入结束等. 暂存作为一个频繁的操作,来自一个存储了一个是否进行宁外一个暂存操作数的人；操作结果在回馈给ACC. 此外,在8051年的内部，ACC通常被视为数据中转站. 和一般微处理器一样,他是最繁忙的. 帮助记住在队列中同意了的程序. 该控制器包
37、括程序计数器,订货,命令存储解读,振荡器电路和时间等. 程序计数器是由2个8进制的数组成，即16进制.事实上这只是一个字节计数器程序的地址，电脑运行的内容将是下一个.改变这一程序执行的内容就可以改变这一程序执行的方向. 调整8051电子芯片的数字电路,只需要将其外部的石英晶体和频率与电子电容相协调，其范围是12mhz的频率1.2mhz. 这一脉冲信号,作为8051年工作的基本节拍,即最低时间单位. 8051和是计算机一样,在和谐节拍的基本控制下工作得以正常进行，就像一个管弦乐团在指挥的要求下演奏一样. 8051年在片内有只读存储器(程序存储器,只能读),存储器(存储数据,是可以写也可以读取),
38、他们每个有独立的内存地址空间,处理方式是一样的,都是电脑存储的一个方式. 8051程序寄存器和8751片程序寄存器的容量是4kb,从0000h地址开始,用于保存程序和方式不变. 8051-8751 8031 的数据存储空间是 128b,00fh假地址,用于存放中间操作结果,暂时储存数据和数据缓冲等。在这128b的内存中,有32个单位字节可以起到登记功能,这是与一般微处理器不一样的、8051内存和工作寄存器形成队列，安排位置时也是这样. MCS51系列电脑芯片在添加寄存器的方法上和其他普通芯片是不一样的. 一般的电脑再为第一个地址分配存储空间的时候,只读存储器和随机存储器可以在不同的空间的人为它
39、分配空间,即只读存储器和随机存储器的地址,形成不同的地址空间分布.在访问寄存器时只能访问一个，可能是只读存储器，也可能是随机存储器. 这种记忆结构称为普林斯顿结构. 8051记忆分为程序存储空间和数据存储空间在物理结构上,有四个存储空间:我们的程序储存在一个数据存储空间之外，数据存储和一个程序存储空间、这种结构形式的程序分离设备和数据存储器的数据格式的记忆,称为哈佛结构. 但从用户的角度,8051的记忆空间分为三类:(1)在片内安排块的地址为ffffh，0000h为位置，与外部保持一致（使用16位地址）. (二)处理数据存储空间地址在64kb内,地址从0000h到Ffffh64kb(使用16位
40、地址),存储单元也是一样的.（三)256B数据存储空间(使用8位地址). 上述三个存储空间地址重叠,鉴别设计,象征不同的数据传输的语言系统8051:片内CPU访问,以MOVC控制只读存储器,使用片外的MOVX访问随机存储器，使用MOV访问片内的随机存储器 8051有4个8位并行的I/O口,叫P0、P1、P2和P3. 每个端口都是8准确双向口,共使用32个插脚. 每一个I/O口都可以独立的输入与输出. 每一个端口包括门闩(即特殊功能注册)、一个出口驱动，以及一个入门缓冲区. 当门闩打开时数据可以输入,数据可以从缓冲区进入,但这通道的四个功能是完全一样的.这四个I/O端口常用来进行准确双向通信。
41、在扩大对外开放记忆系统具有时代意义,P2管脚代表高8位地址. P0口是一个双向数据通信通道 ， 在输出时把进程的数据和地址分开. 输出阶段，P3口，P1口，与负载端电路图有关 .他们的每一个都可以以4模式LS TTL方式输出 。当作为输入口的时候，任何TTL或NMOS都可以以一种通常使用P3口的方式使用P1口.因为电阻对输出品质有很大的影响，能不能开发一种集电极电阻或漏源极电阻来实现它，使得画电路而产生的额外电阻不存在.端口都是精确的双向端口.当有输入操作时，必须给对应的端脚输入1 .像8053一类的单片机，端口只能以毫安级别输出电流，输出口是以普通晶体管为基础输出的，应该与晶体管管脚和基座的
42、阻抗联系起来，在单片机初始化的时候，P1-P3口高频率的运作时节约电能。它的主要功能是把计算机变成0000H最初,使单片机开始从0000H标号程序。除了那些在初始化时经常进入系统的程序，由于程序操作而产生的错误，或操作没有错误，为了从某种状态中回复过来，就需要重新启动。他是一种输入信号被转换到数字信号的RST中国密码。为了保证高频信号的效率，应维持24摇周期(即2机周期）上述它的有效时间。如果6的频率多型变换,4信号完成恢复的宝贵时间就有了。产生逻辑电路的信号： 恢复的保护电路，在片内包含2部分：外部的电路产生恢复信号(RST）,交给史密斯触发器，由恢复电路输出，史密斯触发器不断的由S5P2输出，机器的循环有一个,那就得到并恢复到初始化所必须的信号。恢复电路的电阻、电容参数电路通常用6频率驱动,可保证恢复信号的高频的持续时间大于2个机器周期。恢复电路的结构简单,它的功能是很重要的。一个单片机系统能够正常运行,应该先检查初始化有没有成功。检查和运行就像一个人的“头”和用示波器检测的问题,推动是初始化的关键问题,观察和波形,有足够的范围是出口(瞬间),也可以通过它恢复电路的变化来实现调整。