Ordinary MCU Teaching——Lecture 1: Overview of MCU

1. What is a single-chip computer? A working computer must consist of several 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 installed on a printed circuit board called a motherboard. In a single-chip computer, all these parts are made into an integrated circuit chip, so it is called a single-chip (single-chip) machine, and some single-chip computers, in addition to the above parts, also integrate other parts such as A/D, D/A, etc.

My God! The CPU in a PC costs thousands of dollars. If you put so many things together, the price will definitely be sky-high! Besides, this chip must be very large.

No, the price is not high, ranging from a few yuan to dozens of yuan, and the size is not large. It is generally packaged in 40 pins. Of course, microcontrollers with more functions also have more pins, such as 68 pins, while those with fewer functions have only more than 10 or 20 pins, and some even have only 8 pins.

Why is this so?

Functions vary. For example, some stereo systems on the market only cost a few hundred yuan, but some amplifiers cost thousands. In addition, the production volume of this type of chip is large, and the technology is mature. The 51 series of single-chip microcomputers have been produced for more than ten years, so the price is low.

In this case, the functions of the microcontroller must not be very strong, so why should we learn it?

That's not true. In actual work, not every occasion that requires a computer requires a high performance. Does a computer that controls the temperature of a refrigerator need to use PIII? The key to application is whether it is sufficient and whether it has a good performance-price ratio. Therefore, 8051 has not been eliminated for more than ten years and is still developing.

2. The relationship between MCS51 microcontroller and 8051, 8031, 89C51, etc.

We usually talk about 8051, 8031, and now there is 89C51. 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 (yes, the famous INTEL). This series of single-chip microcomputers includes many varieties, such as 8031, 8051, 8751, 8032, 8052, 8752, etc. Among them, 8051 is the earliest and most typical product. The other single-chip microcomputers in this series are based on 8051. The functions are added, reduced, and changed. Therefore, people are accustomed to using 8051 to call the MCS51 series of single-chip microcomputers. 8031 ​​was the most popular single-chip microcomputer in my country in the past few years, so the name of 8031 ​​can be seen in many occasions. INTEL has authorized the core technology of MCS51 to many other companies, so many companies are making single-chip microcomputers with 8051 as the core. Of course, the functions have changed more or less to meet different needs. Among them, 89C51 is a very popular single-chip microcomputer in my country in recent years. It is developed and produced by the American ATMEL company. In the future, we will use 89C51 to complete a series of experiments.