What is the difference between arm architecture, ARM7, ARM9, STM32, cortex m3 M4, 51 and AVR

ARM framework 、ARM7、ARM9、STM32、Cortex M3 M4、51、AVR What are the differences and connections between them ？

ARM framework ： By the UK ARM The company designed a series of 32 Bit RISC Microprocessor architecture , existing ARMv1~ARMv8 species .

ARM7： One class uses ARMv3 or ARMv4 Architecturally , Using the kernel of von Neumann structure .

ARM9： One class uses ARMv4 or ARMv5 Architecturally , Using the Harvard architecture kernel .

Cortex M3： Adopted ARMv7 Architecturally , Using the Harvard architecture kernel .

Cortex M4： Adopted ARMv7 Architecturally , Using the Harvard architecture kernel .（ The largest area compared with the former ： Don't add one DSP Processing functions ,SIMD Single instruction multiple data function . Please experience other differences in actual project development ）

STM32： Italian French semiconductor company （ST） The series launched is based on Cortex-M0/Cortex-M3/Cortex-M4 And so on / Microcontroller chip .

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51： Intel stay 1981 Introduced in by 8031 Microcontroller chip transformation and upgrading 、 Use CISC The instruction set 、 The structure of von Neumann 、8 Bit 8051 Micro controller . after Intel take 8051 The kernel of the microcontroller is licensed to other chip manufacturers , Make the market widely appear similar to 8051 Chip , This adoption 8051 The core chip is called 51.

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AVR： A series of ATMEL The company launched a series in the 1990s 8 Bit 、 Adopt the improved Harvard structure 、 Use RISC Instruction set microprocessor chip .

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At the very beginning Intel Companies are developing processor chips from scratch . from 4004、8008、8086、80286……TI The company's TMS 1000…… There are programmable chips developed by other companies . Because it's a different company , And there can be no communication between companies （ Prevent the disclosure of trade secrets ）, So all the chips they make are inside CPU、 Bus 、 Storage unit 、 Differences on the instruction set （ If there is the same , That is patent infringement , such as INTEL In those days, he made persistent accusations AMD）. However, the new and old chips developed by each company have certain structure and technical inheritance , So there are different architectures in the chips developed by different companies .

framework  architecture： It's an abstract concept , It is the product of a subjective mapping of elements in a structure and the relationship between elements . For conceptual things, see microarchitecture .

For example, we often say that the computer processor has 486、Ivy Bridge、Pentium M…… This is the difference in architecture （ They all belong to x86 framework ）, Wiki only mentions common hardware architectures in computer processors , Without mentioning what you want to know 、 A microprocessor in an embedded system / The architecture used in the microcontroller chip .

And the connection you said , That's what I separated with a dividing line in front of me ：ARM Architecture to STM32 These names belong to ARM The scope of Architecture .

These two days, I was busy thinking about the program design of controlling the stepping motor , So my brain is not enough , There is a little difficulty in expressing . If you've ever focused on computers CPU History can understand what I mean by architecture .

kernel  IP core： See the concept IP nucleus . so to speak IP The core is the concrete implementation of the abstract concept of hardware architecture in the chip .

It says , In the beginning, each manufacturer did it by themselves , From architecture development to chip forming , This benefit is that you have completely mastered the core technology . But the disadvantage is the huge investment , Once a large investment but the design of the chip because of the unreasonable architecture led to the loss of the market , The previous investment has been wasted .

And then INTEL Of 8031 and 8051 It is popular in the field of embedded industrial control （ In fact, there are still some industrial control fields that insist on using 8031, Because it's stable , I'll talk about this later ）. and intel It may be from the production cost and expansion field （ People make more money by making computer microprocessors ）, I gradually gave up 8051 Chip production , In turn, it is allowed to authorize other companies to produce . Inside the integrated chip is a collection of transistors , The hardware description language is used to specify the arrangement and combination of transistors so as to realize the central processing unit 、 Bus , Storage unit ……,Intel How to realize 8051 The hardware description language of the architecture is licensed to other companies （ Buy kernel ）, Authorized companies can produce products with 8051 The core chip .

Micro controller MCU/ Microprocessor μP：

At first, there were only microprocessors used in small microcomputers , later Intel from 4004 Develop to 8086 In addition to being specially used in industrial control 8031 To 8051, Then the microprocessors used in computers slowly developed into ultra-high integration 、 The large capacity 、 High frequency 、 Large processing capacity to meet the growing needs of computer technology . and 8051 Then it develops steadily to high stability 、 Multifunctional integrated microcontroller , In order to meet the memory demand in the industrial control field, it is relatively not too large , But it has high stability 、 There are many peripheral functions 、 Requirements for small occupation area .

The first distinction is that the microcontroller has an internal RAM（ Equivalent to a computer memory module , Of course, there will not be so much memory integrated in the chip , Usually I'm dead 128K Memory ）、 and ROM（ Equivalent to a computer's hard disk , Of course, it will not have the capacity as large as the hard disk ）, And other peripheral functions （ Such as serial port 、spi、I2C And so on ）. Simply put, put a computer with reduced resource capacity into a chip . Because of this, a single chip integrates a complete computer system in it , The mainland area is 80、90 Electronic engineers in the s called it “ Single chip microcomputer ”, Then it has affected the present .

（ Be careful , A complete computer system is a processor 、 Bus 、 Storage structure 、 Input output structure , So don't tell me why there is no monitor, mouse and keyboard. The single-chip microcomputer also dares to inherit a computer system , You can turn over 《 The principle of computer system 》 textbook ）

Computer microprocessors need to be considered from the point of view of data processing , Only upgrade the processing , So in the first distinction , Microprocessors are not integrated RAM、ROM、 And other peripheral functions .

Just because PowerPC To embedded development , And later on ARM Appearance , It began to narrow the difference between microprocessor and microcontroller , These microprocessors are also beginning to integrate RAM、ROM、 Other peripherals ……

But now there is no unified , The general standard says what is the difference between microprocessors and microprocessors . Follow “ Single chip microcomputer ” equally , They were all called by the engineers themselves . Also someone 8051 It has also become a microprocessor ……

And from what I've done Ti Of DSP、ARM7、ARM9 Wait for the chip to see ：

Microprocessor μP It needs to be expanded through parallel port RAM、ROM, And the program from the outside ROM start-up , On the outside RAM Running .

Micro controller MCU Through the interior ROM Start the program , Inside or outside RAM Running the program .

This is just my personal opinion , Because some chips can be configured as microprocessors , Can also be configured as a microcontroller , The difference after configuration is where the program starts and runs . Like Texas Instruments TI Of TMS320F2812 DSP chip .

BTW：DSP The chip is essentially a microprocessor / Microcontroller chip , It just contains DSP Digital signal processing function , Like the one above Cortex-M4 It's also integrated DSP Digital signal processing function , but ARM The company does not call it DSP, These are what engineers call themselves . There is no uniform standard . I mentioned in another answer . I won't paste it .

ARM and  Intel Who can replace  DSP？

------------------------------------ About von Neumann structure ----------------------------------------------

Von Neumann structure ： It is a computer design conceptual structure that combines program instruction memory and data memory . It should be said ARMv3 The storage structure mode and addressing mode of such kernels use this von Neumann structure , A complete microprocessor architecture also requires instruction set and other serial structures .

If the Lord doesn't understand the von Neumann structure , Suggest learning 《 Computer system 》 or 《 The principle of computer system 》 This kind of books . In my memory, it seems that it is a compulsory course for freshmen and sophomores 《 Computer theory 》 This kind of people will mention （ The textbook used to test the level-1 and level-2 computer god horse ）.

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IEEE and IEC For embedded systems （Embedded System） The interpretation of , From the earliest 4004、8031、8051, Until now, it's popular ARM And hard to learn PowerPC, If these chips are used in “ Used to control the 、 A device for monitoring or assisting in the operation of machines and equipment ” Upper time , Should be embedded .（ Others have put X86 Architecturally 80386 For embedded systems ）

So don't ask me how to switch from MCU to embedded again . Because doing single-chip microcomputer development itself is embedded development . Ask me if you want to live 8051 to turn to ARM still PowerPC.

Last , I want to mention CPU The concept ： Ordinary people hear CPU I think of the heat sink in my personal computer 、 The big chip under the heavy pressure of the fan . In fact, strictly speaking, this is a wrong concept .

CPU:(zh.wikipedia.org/wiki/CPU) Strictly speaking CPU It only refers to microprocessors / The central processing unit in the microcontroller chip is the module , But everyone exaggerates a major function 、 The thought of ignoring other necessary auxiliary functions . So sometimes I heard of an electronic engineer 、 Embedded engineers say CPU When you output something , Don't think he is talking about the big chip in the computer , He may be saying ARM、PowerPC、51、AVR Chips like that .

（ I remember this question was mentioned in the civil servant examination in a certain year CPU The actual concept of , It's asking questions “ What are the necessary chips in a computer ？”, And give a few options “A、 Microprocessor ;B、CPU;C、…” A simple multiple-choice question may have taken many people off the exam ）