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

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 .

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) Procedure 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 exporting 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 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 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 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, 8's accumulation device ACC, register B and procedure state

register PSW, etc. Person 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 transfer 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 circuit, 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 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 under 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 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 data 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 same 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 address 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 memory 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, called Harvard structure. But use the angle

from users, 8051 memory address space is divided into three kinds: (1) I …… 此处隐藏：17206字，全部文档内容请下载后查看。喜欢就下载吧 ……