1. What is a microcontroller

Single chip microcomputer is a kind of integrated circuit chip, which is a large-scale integrated circuit technology to select the central processing unit CPU random access memory RAM, read-only memory ROM, multiple I/O ports and suspension system, timer/timer with data processing skills. Equivalent functions (may also include the display drive circuit, pulse width modulation circuit, analog multiplexer, A/D converter and other circuits) are integrated into a small silicon chip to form a complete computer system.

A computer capable of working should have the following parts: CPU (for calculation and control), RAM (data storage), ROM (program storage), input/output devices (for example: serial port, parallel output port, etc.) ). On a personal computer, these parts are divided into several chips, and a printed circuit board called a motherboard is installed. In the MCU, all of these parts are made into an integrated circuit chip, so it is called a single chip (single chip) machine, and some MCUs integrate other parts in addition to the above parts. A/D, D/A, etc.

A single chip microcomputer is a control chip, a miniature computer, plus crystal, memory, address latch, logic gate, seven-segment decoder (display), buttons (similar to a keyboard), expansion chip, interface, etc. SCM system.

day! A CPU in a PC will sell for thousands of dollars, so many things together, you can not buy a sky-high price! Besides, this chip is also very large.

No, the price is not high, from a few yuan to tens of yuan, the volume is not large, generally packaged in 40 feet, of course, more functions, some microcontrollers also have more pins, such as 68 pins, as little as 10 Multiple or more than 20 pins, some even only 8 pins.

Why is this so?

The function is strong or weak. For example, a set of combo speakers on the mall sells for a few hundred dollars, but some amplifiers cost thousands. The output of other such chips is very large, and the skills are also very mature. The 51 series MCU has been done for more than ten years, so the price is low.

In this case, the function of the single chip microcomputer must not be strong, why should we learn it?

It can't be said that, in practice, not every occasion that requires a computer requires a computer with a high function. Does a computer that controls the temperature of the refrigerator use PIII? The key to the application is to see whether it is sufficient and whether there is a good price-performance ratio. Therefore, 8051 has not been screened for more than ten years, and it is still under development.

2. The connection between MCS51 MCU and 8051, 8031, 89C51, etc.

We always talk about 8051, what is 8031, and now there are 89C51, 89s51. What is the relationship between them?

MCS51 refers to the general name of a series of single-chip microcomputers produced by the American INTEL company (by the way, the well-known INTEL). This series of single-chip microcomputers contains many varieties, such as 8031, 8051, 8551, 8032, 8052, 8752, etc., during which 8051 It is the earliest and most typical product. Other MCUs of this series are based on 8051. The functions are increased, decreased, and modified. So people are accustomed to use 8051 to call MCS51 series MCUs, and 8031 is in China in previous years. The most prevalent MCU, so many occasions will see the name 8031. INTEL has authorized the core skills of MCS51 to many other companies, so many companies are doing MCUs centered on 8051. Of course, the functions are more or less modified to meet different needs, during which 89C51 is the past few years. The MCU, which is very popular in China, was developed and produced by the American ATMEL company. In the future, we will use 89C51 microcontroller to complete a series of tests.

SCM is also called Microcontroller, because it was first used in the field of industrial control. The single chip microcomputer is developed by a dedicated processor with only CPU in the chip. The earliest design concept was to integrate many peripheral devices and CPU into a single chip to make the computer system smaller and easier to integrate into the messy and strict volume control equipment. INTEL's Z80 was the first processor designed according to this thinking. From then on, the development of single-chip microcomputers and dedicated processors will have their own future.
The early one-chip computers are all 8-bit or 4-bit. The most successful one was INTEL's 8031, which was highly praised for its simplicity and reliability and good performance. Later, MCS51 series single-chip system was developed on 8031. The single-chip system based on this system is still widely used until now. With the advancement of the requirements in the field of industrial control, 16-bit microcontrollers have appeared, but they have not been widely used because of their low cost performance. With the development of consumer electronics after the 1990s, the single-chip technology has made great progress. With the widespread use of the INTEL i960 series, especially the later ARM series, 32-bit microcontrollers quickly replaced the high-end status of 16-bit microcontrollers and entered mainstream shopping malls. And the function of the traditional 8-bit microcontroller has also been rapidly improved, and the processing ability has improved hundreds of times compared to the 1980s. At present, the main frequency of high-end 32-bit single-chip microcomputers has exceeded 300MHz, and its performance is directly after the dedicated processors in the mid-1990s. The factory price of ordinary types has dropped to $1, and the highest-end type is only $10. Today's single-chip system is no longer only developed and used in the bare metal environment, and many dedicated embedded operating systems are widely used in the whole series of single-chip computers. And the high-end single-chip computers that are handled as the center of handheld computers and mobile phones can even directly use the dedicated Windows and Linux operating systems.



The single chip microcomputer is more suitable for the embedded system than the special processor, so it has been used the most. In fact, the single chip microcomputer is the largest number of computers in the world. Almost every electronic and mechanical product used in modern human life will be integrated with a microcontroller. Computer accessories such as mobile phones, telephones, calculators, household appliances, electronic toys, handheld computers and mice are equipped with 1-2 single-chip computers. There will also be a lot of single chip microcomputers operating in personal computers. More than 40 single-chip computers are generally equipped on cars, and hundreds of single-chip computers may be operating at the same time on the messy industrial control system! The number of MCUs not only far exceeds the sum of PCs and other calculations, but even more than the number of humans.

MCU introduction

The single chip microcomputer is also called a single-chip micro-controller. It is not a chip that accomplishes a certain logic function, but integrates a computer system onto a chip. It is equivalent to a miniature computer. Compared with a computer, a single chip computer only lacks I/O devices. In summary: a chip becomes a computer. Its small size, light weight, and low price provide easy conditions for learning, application, and development. At the same time, learning to use MCU is the best choice to understand the principle and structure of computer.