Introduction to AVR microcontrollers: structure and application of microcontroller embedded systems

Single-chip microcomputer, full name of single-chip microcontroller, single-chip microcomputer (Single-Chip Microcomputre), also known as embedded microcontroller (Embedded Microcontroller). The embedded system composed of single-chip microcomputer as the main control core is called single-chip microcomputer embedded system, which is generally referred to as single-chip microcomputer system in China.

1. Structure of a single-chip embedded system

A single-chip embedded system generally consists of two parts: hardware and software. The hardware part is divided into a single-chip control chip (i.e., a single-chip microcomputer) and peripheral circuits. The peripheral circuits are divided into basic system circuits and interface circuits. The interface circuits are divided into forward channel interface circuits, backward channel interface circuits, interactive channel interface circuits, and data communication interface circuits.

1. Basic system circuit

Basic system circuits refer to the basic circuits required for the operation of the single-chip microcomputer system, such as clock circuits, reset circuits, system power supply circuits, drive circuits, and extended memory.

2. The forward channel interface circuit is mainly the input interface

The forward channel interface circuit is mainly an input interface, which usually refers to the measurement sensors and converter input channels of various physical quantities. Common ones include sensors, signal conditioners, analog/digital converters ADC, switch inputs, frequency measurement interfaces, etc.

3. The back channel interface circuit is mainly an output interface

The backward channel interface circuit is mainly an output interface, usually including a digital/analog converter DAC, switch output, power drive interface, PWM output control, etc.

4. Human-computer interaction interface

As the name implies, the human-computer interaction interface circuit is mainly used for human-computer interaction circuits, such as keyboards, toggle switches, LED light-emitting diodes, digital tubes, LCD liquid crystal displays, printers and other input and output interfaces.

5. Data communication interface circuit

Data communication interface circuit is an interface that meets the requirements of remote data communication or constitutes a multi-machine network application system, such as RS232, PSI, I2C, CAN bus, USB bus and other communication interface circuits.

6. Software for single-chip embedded systems

The software of a single-chip embedded system refers to all the programs written into the single-chip microcomputer. If the hardware circuit is the body of the single-chip embedded system, then the single-chip microcomputer is the brain, the peripheral circuit is the body and limbs, and the software is the soul or thinking. In the entire single-chip embedded system, the program determines the function of the system, and all the hardware circuits are controlled by the program to complete the corresponding functions.

Compared with the application layer program, the biggest difference of the single-chip embedded program is that it is more oriented to the bottom layer. The program of the single-chip embedded system is more about directly driving the hardware circuit rather than facing the user. Therefore, the software development of the single-chip embedded system is still very different from the application program development. The program development of the single-chip embedded system requires the developer to have a clear understanding of the hardware circuit of the system. A programmer who does not understand the hardware circuit cannot do a good job of embedded system program development. In fact, most of the time, the hardware development and software development of the single-chip embedded system are not distinguished. An embedded system developer usually has a deep understanding of both software and hardware.

2. Application fields of single-chip embedded systems

Single-chip embedded systems are widely used in modern industrial fields, and can even be said to be ubiquitous. They can be seen in various fields such as missile navigation, aircraft flight control, computer networks, industrial automation, etc. The main reason for its widespread use is that the chip size of the single-chip microcomputer is extremely small, the cost is relatively low, and the object-oriented control method is very easy to control, which makes the single-chip embedded system have great cost, design, and operability advantages in industrial applications.

Specifically, single-chip microcomputers are widely used in the following areas:

1. Smart home. With the rapid development of the Internet of Things, home appliances are becoming more and more intelligent. The introduction of single-chip embedded systems in home appliances such as refrigerators, air conditioners, and washing machines can well realize intelligent operations such as automatic temperature control and intelligent adjustment.

2. Intelligent manufacturing. Since the advent of Industry 4.0, intelligent manufacturing has increasingly become the development direction of manufacturing, and the country is also vigorously promoting the automation process of China's manufacturing. The introduction of single-chip embedded systems into traditional mechanical equipment can easily simplify product structure and realize intelligent control. It can be predicted that single-chip embedded systems will play an important role in Industry 4.0.

3. Intelligent instruments and meters. The application of single-chip embedded systems in instruments and meters is mainly reflected in the intelligence and digitization of instruments and meters. The application of single-chip embedded systems can realize the integration of instrument measurement, processing, and control functions, giving traditional instruments and meters a new look.