MCU is the abbreviation of Microcontroller Unit. It is called microcontroller in Chinese and is commonly known as single chip microcomputer., is to appropriately reduce the frequency and specifications of the CPU, and integrate peripheral interfaces such as memory, counter, USB, A/D conversion, UART, PLC, DMA, and even LCD driver circuits on a single chip to form a chip-level computer, which can perform different combinations of control for different applications, such as mobile phones, PC peripherals, remote controls, automotive electronics, industrial stepper motors, and robotic arm control. MCUs can all be seen.


       

1

A brief history of the development of microcontrollers          
 

The history of microcontrollers is not long, but it has developed very rapidly. Its production and development are generally synchronized with the production and development of microprocessors (CPUs). Since Intel Corporation of the United States first launched a 4-bit microprocessor in 1971, its development so far can be roughly divided into five stages. The following is an introduction to the development of microcontrollers from Intel Corporation.

  1971~1976The initial stage of the development of microcontrollers. In November 1971, Intel first designed the Intel 4004, a 4-bit microprocessor with an integration of 2,000 transistors/chip, equipped with RAM, ROM and shift register, forming the first MCS-4 microprocessor. Then it launched the 8-bit microprocessor Intel 8008, and other 8-bit microprocessors launched by other companies.  
  1976~1980Low-performance microcontroller stage. Represented by the MCS-48 series launched by Intel in 1976, it uses a monolithic structure that integrates an 8-bit CPU, 8-bit parallel I/O interface, 8-bit timer/counter, RAM and ROM on a semiconductor chip. Although its addressing range is limited (no more than 4 KB), there is no serial I/O, RAM and ROM capacity is small, and the interrupt system is relatively simple, but its functions can meet the needs of general industrial control and intelligent instruments and meters.  
  1980~1983High-performance microcontroller stage. The high-performance 8-bit microcontrollers launched at this stage generally have serial ports, multi-level interrupt processing systems, and multiple 16-bit timers/counters. The capacity of the on-chip RAM and ROM is increased, and the addressing range can reach 64 KB. Some chips also have an A/D conversion interface.  
  1983~late 1980s16-bit microcontroller stage. In 1983, Intel launched the high-performance 16-bit microcontroller MCS-96 series. Due to its adoption of the latest manufacturing technology, the chip integration level is as high as 120,000 transistors/chip.  
  1990sMicrocontrollers are developing to a higher level in all aspects of integration, functionality, speed, reliability, and application fields.

2

Classification and application of single chip microcomputer

MCU can be divided intoNo on-chip ROM typeandWith on-chip ROM typeTwo kinds. For chips without on-chip ROM, an external EPROM must be connected before they can be used (typically 8031); chips with on-chip ROM are divided into on-chip EPROM type (typical chip is 87C51), MASK on-chip mask ROM type (typical chip is 8051), on-chip Flash type (typical chip is 89C51) and other types.  
Can be divided intoUniversalandSpecial type;According to the width of the data bus and the length of data bytes that can be processed at one time, it can be divided into8, 16, 32-bit MCU。  
At present, the most extensive domestic MCU application market isconsumer electronicsfield, followed byIndustrial field, and automotive electronics market. Consumer electronics includes household appliances, televisions, game consoles, audio and video systems, etc. Industrial fields include smart homes, automation, medical applications, and new energy generation and distribution. The automotive field includes automotive powertrain and safety control systems.

       

3

Basic functions of microcontroller

   

For most MCUs, the following functions are the most common and basic. For different MCUs, the way they are described may be different, but they are essentially the same:

  1. TImer (timer):Although there are many types of TImers, they can be summarized into two major categories:One type is TImer with fixed time intervals,That is to say, the timing time is set by the system and cannot be controlled by the user program. The system only provides several fixed time intervals for the user program to choose, such as 32Hz, 16Hz, 8Hz, etc. This type of TImer is common in 4-bit MCUs, so it can be used to implement clock, timing and other related functions.  
  The other type is Programmable Timer (programmable timer).As the name suggests, the timing time of this type of Timer can be controlled by the user's program. The control methods include: selection of clock source, selection of frequency division (Prescale) and setting of preset number. Some MCUs have all three at the same time, while others may have one or two of them. This type of Timer application is very flexible, and its actual use is also ever-changing. One of the most common applications is to use it to implement PWM output.  
Since the clock source can be freely selected, this type of Timer is generally combined with the Event Counter.  
  2. IO port:Any MCU has a certain number of IO ports. Without IO ports, the MCU loses its communication channels with the outside world. According to the configurability of the IO port, it can be divided into the following types:
  Pure input or pure output port:This type of IO port is determined by the MCU hardware design and can only be input or output. Software cannot be used for real-time settings.  
  Directly read and write IO port:For example, the IO port of MCS-51 belongs to this type of IO port. When the read IO port instruction is executed, it is an input port; when the write IO port instruction is executed, it is automatically an output port.  
  Programming to set the input and output direction:The input or output of this type of IO port is set by the program according to actual needs. The application is relatively flexible and can realize some bus-level applications, such as I2C bus, various LCD, LED Driver control buses, etc.  
For the use of IO ports, an important point that must be kept in mind is: for the input port, there must be a clear level signal to ensure that it cannot float (this can be achieved by adding a pull-up or pull-down resistor); and for the output port, the output status level must consider its external connection conditions, and it should be ensured that there is no pulling or sinking current in the standby or static state.  
  3. External interrupt:External interrupts are also the basic functions of most MCUs. They are generally used for real-time triggering of signals, data sampling and status detection. The interrupt methods include rising edge triggering, falling edge triggering and level triggering. External interrupts are generally implemented through input ports. If it is an IO port, its interrupt function will be turned on only when it is set to input; if it is an output port, the external interrupt function will be automatically turned off (there are some exceptions in ATMEL's ATiny series, which can also trigger the interrupt function when it is an output port). The applications of external interrupts are as follows:
  Detection of external trigger signals:One is based on real-time requirements, such as thyristor control, sudden signal detection, etc., while the other is the need to save power.  
  Measurement of signal frequency:In order to ensure that signals are not missed, external interrupts are the ideal choice.  
  Decoding of data:In the field of remote control applications, in order to reduce the design cost, it is often necessary to use software to decode various encoded data, such as the decoding of Manchester and PWM encoding.  
  Key detection and system wake-up:For an MCU that enters the sleep state, it generally needs to be awakened through an external interrupt. The most basic form is a button, and the level changes are caused by the action of the button.  
  4. Communication interface:The communication interfaces provided by MCU generally include SPI interface, UART, I2C interface, etc., which are described as follows:
  SPI interface:This type of interface is the most basic communication method provided by most MCUs. Its data transmission is controlled by a synchronous clock. The signals include: SDI (serial data input), SDO (serial data output), SCLK (serial clock) and Ready signal; in some cases, there may be no Ready signal; this type of interface can work in master mode or Slave mode. The popular saying is that it depends on who provides the clock signal. The party providing the clock is the master, and the opposite party is the Slaver.  
  UART（Universal Asynchronous Receive Transmit）：It is the most basic asynchronous transmission interface, with only two signal lines: Rx and Tx. The basic data format is: Start Bit + Data Bit (7-bits/8-bits) + Parity Bit (Even, Odd or None) + Stop Bit (1~2Bit). The time occupied by one bit of data is called Baud Rate.  
For most MCUs, the length of data bits, data check mode (odd check, even check or no check), stop bit (Stop Bit) length and Baud Rate can be flexibly set through program programming. The most commonly used method of this type of interface is to communicate with the serial port of a PC.  
  I2C interface:I2C is a data transmission protocol developed by Philips. It is also implemented using 2 signals: SDAT (serial data input and output) and SCLK (serial clock). Its biggest benefit is that multiple devices can be attached to this bus and identified and accessed through addresses; one of the biggest benefits of the I2C bus is that it is very convenient to use software to implement it through the IO port. Its transmission data rate is completely controlled by SCLK, which can be fast or slow, unlike the UART interface, which has strict rate requirements.  
  5. Watchdog (watchdog timer):Watchdog is also a basic configuration of most MCUs (some 4-bit MCUs may not have this function). The Watchdog of most MCUs can only allow the program to reset it but not turn it off (some are set when the program is burned in, such as Microchip PIC series MCUs), while some MCUs use a specific method to decide whether to turn it on, such as Samsung's KS57 series. As long as the program accesses the Watchdog register, it is automatically turned on and cannot be turned off again. Generally speaking, the reset time of watchdog can be set programmably. The most basic application of Watchdog is to provide a self-recovery capability for MCUs that crash due to unexpected failures.

4

Global mainstream microcontroller manufacturer

The following is a list of microcontrollers from mainstream manufacturers (there may be some omissions), in no particular order.

Europe and America

  1. Freescale+NXP (Freescale+NXP):The Netherlands mainly provides 16-bit and 32-bit MCUs. Applications: Automotive electronics, LED and general lighting, healthcare, multimedia convergence, home appliances and power tools, building automation technology motor control, power supplies and power converters, energy and smart grids, automation, computer and communication infrastructure.  
  2. Microchip+Atmel (Microchip Technology + Atmel):The United States mainly provides 16-bit and 32-bit MCUs. Applications: automotive electronics, industrial use, motor control, automobiles, building automation, home appliances, home entertainment, industrial automation, lighting, Internet of Things, smart energy, mobile electronic equipment, computer peripherals.  
  3. Cypress+Spansion (Cypress+Spansion):The United States mainly provides 8-bit, 16-bit, and 32-bit MCUs. Applications: automotive electronics, home appliances, medical, consumer electronics, communications and telecommunications, industry, wireless.  
  4. ADI (Analog Devices):The United States mainly provides 8-bit, 16-bit, and 32-bit MCUs. Applications: Aerospace and defense, automotive applications, building technology, communications, consumer electronics, energy, healthcare, instrumentation and measurement, motors, industrial automation, security.  
  5. Infineon:Germany mainly provides 16-bit and 32-bit MCUs. Applications: automotive electronics, consumer electronics, engineering, commercial and agricultural vehicles, data processing, electric transportation, industrial applications, medical equipment, mobile equipment, motor control and drive, power supply, for motorcycles, electric bicycles and small electric vehicles, smart grids, lighting, solar system solutions, wind energy system solutions.  
  6. ST Microelectronics:Italy/France, mainly provides 32-bit MCU. Applications: LED and general lighting, transportation, healthcare, multimedia convergence, home appliances and power tools, building automation technology motor control, power supplies and power converters, energy and smart grids, automation, computer and communication infrastructure.  
  7. Qualcomm:The United States mainly provides 16-bit and 32-bit MCUs. Applications: Smartphones, tablets, wireless modems.  
  8. Texas Instruments:The United States mainly provides 16-bit and 32-bit MCUs. Application scope: automotive electronics, consumer electronics, medical equipment, mobile devices, communications.  
  9. Maxim:The United States mainly provides 32-bit MCUs. Application scope: automotive electronics, consumer electronics, industrial applications, security.  
  Japan and South Korea  
  1. Renesas:Japan mainly provides 16-bit and 32-bit MCUs. Application scope: computers and peripherals, consumer electronics, health and medical electronics, automotive electronics, industry, and communications.  
  2. Toshiba:Japan mainly provides 16-bit and 32-bit MCUs. Application scope: automotive electronics, industrial use, motor control, wireless communications, mobile phones, computers and peripheral equipment, imaging and audio and video, consumer (home appliances), LED lighting, security, power management, entertainment equipment.  
  3. Fujitsu:Japan mainly provides 32-bit MCUs. Application scope: automobile, medical, machinery, home appliances.  
  4. Samsung Electronics:South Korea mainly provides 16-bit and 32-bit MCUs. Applications: automotive electronics, industrial use, motor control, automobiles, building automation, home appliances, home entertainment, industrial automation, lighting, Internet of Things, smart energy, mobile electronic equipment, computer peripherals.  
  China region  
  ▍Mainland China
 
  1. Sigma Microelectronics:Mainly provides 32-bit MCU, application scope: telecommunications, manufacturing, energy, transportation, electric power, etc.  
  2. Zhuhai Orbit:Mainly providing 32-bit MCU, application scope: aerospace: satellite station ships, aircraft; high-end industrial control: embedded computers; ship control, industrial control, power equipment, environmental monitoring.  
  3. GigaDevice Innovation:Mainly providing 32-bit MCU, application scope: industrial automation, human-machine interface, motor control, security monitoring, smart home, Internet of Things.  
  4. Shengsi Microelectronics:Mainly providing 8-bit and 32-bit MCUs, application scope: small household appliances, consumer electronics, remote controls, mice, lithium batteries, digital products, automotive electronics, medical instruments and measurement, toys, industrial control, smart home and security and other fields.  
  5. Chipsea Technology:Mainly providing 16- and 32-bit MCUs, application scope: instrumentation, Internet of Things, consumer electronics, home appliances, automotive electronics.  
  6. Lianhua Integrated Circuit:Mainly providing 8-bit and 16-bit MCUs, application scope: consumer electronics, white goods, industrial control, communication equipment, automotive electronics, computers.  
  7. Zhuhai Jianrong:Mainly provides 8-bit MCU, application scope: household appliances, mobile power supply.  
  8. Juxin Technology:Mainly providing 8-bit to 32-bit MCUs, application range: tablet computers, smart home, multimedia, Bluetooth, wifi audio.  
  9. Aisco Microelectronics:Mainly providing 8-bit and 16-bit MCUs, application scope: consumer chips, communication chips, information chips, home appliances.  
  10. Huaxin Microelectronics:Mainly providing 8-bit and 4-bit MCUs, application scope: satellite receivers, mobile phone chargers, perpetual calendars, all-in-one remote controls.  
  11. Shanghai Belling (Huada Semiconductor Holdings):Mainly providing 8-bit, 16-bit, and 32-bit MCUs, application scope: computer peripherals, HDTV, power management, small appliances, digital appliances.  
  12. Haier integrated circuit:It mainly provides 14-bit, 15-bit, and 16-bit MCUs. Application scope: consumer electronics, automotive electronics, industry, and smart instruments.  
  13. Beijing Junzheng:Mainly provides 32-bit MCU, application scope: wearable devices, Internet of Things, smart home appliances, automobiles, consumer electronics, tablet computers.  
  14. China Micro Semiconductor:Mainly providing 8-bit MCU, application scope: smart home appliances, automotive electronics, security monitoring, LED lighting and landscape, smart toys, smart homes, consumer electronics.  
  15. China Loongson Integrated Circuit:Mainly provides 32-bit MCU, application scope: power monitoring, smart grid, industrial digital control, Internet of Things, smart home, data monitoring.  
  16. Ziguang Microelectronics:Mainly provides 8-bit and 16-bit MCUs, application scope: smart home appliances.  
  17. Times Minxin:Mainly provides 32-bit MCU, application scope: car navigation, traffic monitoring, fishing vessel supervision, power telecommunications network.  
  18. China Resources Silicon Microelectronics (a subsidiary of China Resources Microelectronics):Mainly provides 8-bit and 16-bit MCUs, application scope: consumer electronics, industrial control, home appliances.  
  19. Guoxin Technology:Mainly provides 32-bit MCU, application scope: information security field, office automation field, communication network field, information security field.  
  20. Zhongtian Micro:Mainly providing 32-bit MCU, application range: smart phones, digital TVs, set-top boxes, automotive electronics, GPS, e-readers, printers.  
  21. China Resources Microelectronics:Mainly provides 8-bit and 16-bit MCUs, application scope: general control circuits for home appliances, consumer electronics, and industrial automation control.  
  22. Zhongying Electronics:Mainly provide 4-bit, 8-bit, 16-bit, and 32-bit MCUs, application scope: home appliances, motors.  
  23. Smart Microelectronics:Mainly providing 32-bit, application range: motor control, Bluetooth control, high-definition display, wireless charging, drones, micro printers, smart labels, electronic cigarettes, LED dot matrix screens, etc.  
  24. Nuvoton Technology:Mainly provides 32-bit MCU, application scope: lighting, Internet of Things, etc.  
  25. Neusoft Carrier:Mainly providing 8-bit and 32-bit MCUs, application scope: home appliances, smart homes, instrumentation, LCD panel controllers, industrial control, etc.  
  26. Betley:Mainly provides 32-bit MCU, application scope: smart home, industrial control and consumer products.  
  27. Shengquan Technology:Mainly provides 8-bit MCU, application range: small and medium-sized display panels for automotive, education, industrial control, medical, etc.  
  28. Hangshun chip:Mainly provides 8-bit and 32-bit MCUs, application scope: automotive, Internet of Things, etc.  
  29. Fudan Microelectronics:Mainly provides 16-bit and 32-bit MCUs, application scope: smart meters, smart door locks, etc.  
  30. Huada Semiconductor:It mainly provides 8-bit, 16-bit, and 32-bit MCUs, with application ranges: industrial control, intelligent manufacturing, smart life, and the Internet of Things.  
  ▍Taiwan, China  
  1. Hongjing Technology:Mainly provide 8-bit MCU. Application scope: communications, industrial control, information appliances, and voice.  
  2. Holtek Semiconductor:Mainly provide 8-bit and 32-bit MCU. Application scope: consumer electronics, LED lighting, etc.  
  3. Lingyang Technology:Mainly provides 8-bit and 16-bit MCUs. Application scope: home audio and video.  
  4. Zhongying Electronics:Mainly provides 4-bit and 8-bit MCUs. Application scope: chargers, mobile power supplies, home appliances, industrial control.  
  5. Songhan Technology:Mainly provide 8-bit and 32-bit MCU. Application scope: remote controls, smart chargers, large and small systems, electronic scales, ear thermometers, blood pressure monitors, tire pressure gauges, various measurement and health equipment.  
  6. Winbond Electronics:Mainly provides 8-bit and 16-bit MCUs. Application scope: automotive electronics, industrial electronics, network, computer, consumer electronics, Internet of Things.  
  7. Ten Speed ​​Technology:Mainly provide 4-bit, 8-bit, and 51-bit MCUs. Application scope: remote controls, small household appliances.  
  8. Youhua Microelectronics:Mainly provides 4-bit and 8-bit MCUs. Application scope: recording integrated circuit products, consumer electronics, household products.  
  9. Yingguang Technology MCU:Mainly provides 4-bit and 8-bit MCUs. Application scope: machinery, automation, home appliances, robots.  
  10. Elan Electronics:Mainly provides 8-bit and 16-bit MCUs. Application scope: consumer electronics, computers, smartphones.

       

5

Tips for learning microcontrollers

The basic principles and functions of any MCU are similar.The only difference is the configuration and quantity of its peripheral function modules, command system, etc.。  
As for the command system, although it seems to be very different in form,But in fact it’s just a difference in symbols,The meanings they represent, the functions to be completed, and the addressing methods are basically similar.  
To understand an MCU, you first need to know itsROM space, RAM space, number of IO ports, number of timers and timing methods, provided peripheral function modules (Peripheral Circuit), interrupt sources, operating voltage and power consumption, etc.  
After understanding these MCU Features, the next step is to compare the functions of the selected MCU with the functions required for actual project development, and clarify which resources are currently needed and which are not used in this project.  
For functions that need to be used in the project but are not provided by the selected MCU, you need to carefully understand the relevant information of the MCU in order to use indirect methods to implement them. For example, if the project you are developing needs to communicate with the PC COM port, and the selected MCU does not provide a UART port, you can consider using external interrupts to implement it.  
For the resources needed for project development, you need to carefully understand and read the Manua*, while you can ignore or browse the unnecessary functional modules. For MCU learning, application is the key and the main purpose.  
After clarifying the relevant functions of the MCU, you can start programming.  
For beginners or designers who are using this MCU for the first time, they may encounter many unclear descriptions of the functions of the MCU. For such problems, there are two methods to solve them. One is to write a special verification program to understand the functions described in the data; the other is to temporarily ignore it and write the MCU program according to your current understanding, leaving it to be modified and improved during debugging. The former method is suitable for projects with loose time and beginners, while the latter method is suitable for people with certain experience in microcontroller development or when the project schedule is tight.  
 

Don't take any special time to understand the command system. The instruction system is just a symbol of logical description. You can only view the relevant instructions according to your own logic and the logical requirements of the program during programming. As programming progresses, you will become more and more proficient in the instruction system, and you can even memorize it unconsciously.

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