What is MCU?

A microcontroller unit (MCU), also known as a Single-Chip Microcomputer, is a computer that integrates the frequency and specifications of the Central Process Unit (CPU), memory, Timer, USB, A/D converter, UART, PLC, DMA, and other peripheral interfaces into a single chip. It integrates peripheral interfaces such as memory, timer, USB, A/D converter, UART, PLC, DMA, and even LCD driver circuitry on a single chip to form a chip-level computer for different combinations of applications. MCU can be found in cell phones, PC peripherals, remote controls, automotive electronics, industrial stepper motors, robot arm control, etc.

Development history

The history of MCU is not long, but the development is very rapid. Its emergence and development and microprocessor generation and development roughly the same time, since 1971, the United States Intel Corporation first introduced the 4-bit microprocessor. Its development so far can be roughly divided into five stages. The following is a representative of the development of Intel's microcontroller to introduce.

1971-1976

The primary stage of microcontroller development. In November 1971, Intel first designed a 4-bit microprocessor Intel 4004, with 2000 transistors/piece of integration and equipped with RAM, ROM, and shift registers, constituting the first MCS-4 microprocessor, and then launched the 8-bit microprocessor Intel 8008 and other companies have launched The first MCS-4 microprocessor was introduced, followed by the 8-bit microprocessor Intel 8008, and other companies introduced 8-bit microprocessors.

1976-1980

Low-performance microcontroller stage. In 1976, Intel launched the MCS-48 series as the representative, using the 8-bit CPU, 8-bit parallel I/O interface, 8-bit timer/counter, RAM and ROM, etc., integrated with a semiconductor chip monolithic structure. However, its addressing range is limited (not more than 4 KB), and there is no serial I/O, RAM, or ROM capacity, although its addressing range is limited (greater than 4 KB). There is no serial I/O, RAM and ROM capacity is small, and the interrupt system is simple. Still, the function can meet the needs of general industrial control and intelligent instruments and meters.

1980-1983

High-performance microcontroller stage. This stage of the introduction of high-performance 8-bit microcontrollers generally with serial ports, a multi-level interrupt processing system, and multiple 16-bit timer/counters. On-chip RAM, ROM capacity increased, and the addressing range of up to 64 KB, individual chips also have an A/D conversion interface.

1983 - late 80s

16-bit microcontroller stage. In 1983, Intel introduced the high-performance 16-bit microcontroller MCS-96 series, which had an integration level of 120,000 transistors/chips due to its new manufacturing process.

The 1990s

Microcontrollers developed higher in terms of integration, functionality, speed, reliability, and application areas.

According to a microcontroller's characteristics, a microcontroller's application is divided into single-computer and multi-computer applications. An application system uses only one microcontroller called a single-computer application. The range of single-computer applications of microcontrollers include.

(1) measurement and control systems. A microcontroller can form a variety of less complex industrial control systems, adaptive control systems, data acquisition systems, etc., to achieve the purpose of measurement and control.

(2) intelligent instrumentation. Transformation of the original measurement and control instruments with microcontrollers promotes the development of digital, intelligent, multi-functional, integrated, flexible direction.

(3) electromechanical integration products. Microcontroller and the traditional combination of mechanical products, so that the traditional mechanical product structure simplification, control intelligence.

(4) intelligent interface. The computer control system, especially in the larger industrial measurement control system, with a microcontroller for interface control and management, plus the parallel work of the microcontroller and the host, greatly improves the system's operating speed.

(5) Intelligent civil products. Such as in household appliances, toys, games, audio and video equipment, electronic scales, cash registers, office equipment, kitchen equipment, and many other products, the introduction of a microcontroller controller not only greatly enhances the function of the product, performance has been improved, and to obtain good results.

Microcontroller multi-computer application systems can be divided into a functional set of decentralized systems, parallel multi-computer processing, and local network systems.

(1) Functional hub-and-spoke system. The multi-functional set-distribution system is a multi-computer system to meet the requirements of multiple peripheral functions of engineering systems.

(2) Parallel multi-computer control system. A parallel multi-computer control system mainly solves the rapidity of the engineering application system to constitute a large-scale real-time engineering application system.

(3) Local network system.

The microcontroller can be divided into general-purpose and special-purpose according to the scope of application.

Dedicated is designed for a specific product, such as microcontrollers for thermometers, microcontrollers for washing machines, and so on. The general-purpose microcontroller can be divided into 4-bit, 8-bit, and 16/32-bit word lengths. Although the computer microprocessor is now almost a 32/64-bit world, 8-bit and 16-bit microprocessors have tended to shrink. Still, the situation is the different microcontrollers, 8-bit microcontroller low cost, cheap, easy to develop, its performance can meet most of the needs, only in aerospace, automotive, robotics, and other high technology Only in aerospace, automotive, robotics and other high-tech fields, the need for high-speed processing of large amounts of data, the need to choose 16/32-bit. In general industrial areas, an 8-bit general-purpose microcontroller is still widely used.

Main classification

Classified by application.

General purpose: all the resources that can be developed (ROM, RAM, I/O, EPROM) are provided to the user.

Dedicated: Its hardware and instructions are designed for a specific purpose, such as recorder movement controller, printer controller, motor controller, etc.

Classification by the number of data bits handled by its basic operation.

According to the width of the bus or data staging, MCU is further classified into 1-bit, 4-bit, 8-bit, 16-bit, 32-bit, and even 64-bit MCU.

    4-bit MCUs are mostly used in calculators, car meters, car anti-theft devices, pagers, wireless phones, CD players, LCD driver controllers, LCD game machines, children's toys, scales, chargers, tire pressure meters, temperature and humidity meters, remote controls, and dumb cameras, etc.

    8-bit MCUs are mostly used in electric meters, motor controllers, electric toy machines, inverter air conditioners, pagers, fax machines, CallerID, telephone    recorders, CRT monitors, keyboards, and USB.

    8-bit and 16-bit MCUs are mainly used in the general control field without an operating system. 16-bit MCUs are mostly used in mobile phones, digital cameras, camcorders, etc.

    32-bit MCUs are mostly used in Modem, GPS, PDA, HPC, STB, Hub, Bridge, Router, workstation, ISDN phones, laser printer, and color fax machines; 32-bit is used in network operation, multimedia processing, and other complex processing occasions, generally using the embedded operating system.

    64-bit MCUs are mostly used in high-end workstations, interactive multimedia systems, TV games (such as SEGA's Dreamcast and Nintendo's GameBoy), terminals, etc.

    8-bit MCUs operate at frequencies between 16 and 50 MHz, emphasizing simple performance and low-cost applications, and still have a certain position in the MCU market.

    16-bit MCUs, the mainstream specifications are 16-bit operation, 16/24-bit addressing capability, and frequency from 24 to 100MHz. Some 16-bit MCUs provide additional 32-bit add/subtract/multiply/divide special instructions. Due to the emergence of 32-bit MCUs and their continuous price reduction and the low price advantage of 8-bit MCUs, which are simple, durable, and inexpensive, the 16-bit MCU market has been squeezed in the middle. It has become a relatively low percentage of products shipped.

    32-bit MCUs are the mainstream MCU market, with prices ranging from $1.5 to $4 per unit, operating frequencies mostly between 100 and 350 MHz, better execution performance, and a wide range of applications. However, due to the increase in the number of operations and memory length, the length of program code for the same function increases by 30~40% compared to 8/16bit MCUs, which leads to the embedded OTP/FlashROM memory capacity cannot be too small. And the number of external pins of the chip increases dramatically, further limiting the cost reduction capability of 32bit MCUs.