What is a Microcontroller(MCU)?
A microcontroller(MCU) is integrated by the processor (CPU), memory, timer/calculator and various I/O circuits to a chip, forming a basic and complete computing system.


Compared with the computer, the microcontroller does not have such a powerful computing power, and does not have the memory management unit (MMU), which makes the micro -controller only handle some relatively simple control, logic and other tasks. Microcontrollers are widely wide Apply in the fields of device control, sensor signal processing, such as automobile engine control systems, medical devices, remote controls, office machines, appliances, power tools, toys and other embedded systems.

Microcontroller classification
A microcontroller's processor will vary by application,so microcontroller can be divided into: 4-bit, 8-bit, 16-bit, and 32-bit. In practical applications, 32-bit accounted for 55%, 8-bit accounted for 43%, 4-bit accounted for 2%, 16-bit accounted for 1%.It can be seen that 32-bit and 8-bit microcontrollers are the most widely used microcontrollers today.

The difference between digits does not mean that microprocessors are good or bad. It is not that microcontrollers with higher digits are better, nor that microcontrollers with lower digits are worse.

8-bit MCUs are multi -function; they provide simple programming, energy efficiency and small packaging size (some have only six pins). But these microcontrollers are usually not used to implement network and communication functions.

The most common network protocols and communication software stacks are 16 or 32 bits. Communication peripheral equipment can be used for some 8 -bit devices, but 16 and 32 -bit MCUs are often more effective choices. Nevertheless, 8 -bit MCUs are usually used in various control, sensing and interface applications.

From the architecture, the microcontroller can be divided into: RISC (Reduced Instruction Set Computers) and CISC (Complex Instruction Set Computers).

CISC generally has around 80 instructions while RISC has about 30, as well as more addressing modes, 12-24 compared to RISC's 3-5. While CISC can be easier to implement and has more efficient memory use, it can have performance degradation due to the higher number of clock cycles needed to execute instructions. RISC, which places more emphasis on software, often provides better performance than CISC processors, which put more emphasis on hardware, due to its simplified instruction set and, therefore, increased design simplicity, but because of the emphasis it places on software, the software can be more complex. Which ISC is used varies depending on application.
Types of microcontrollers
There are different microcontrollers available in the market manufactured by different companies.

8051 Microcontrollers

8051 microcontroller series is the one of the most popular general purpose microcontroller. It is first manufactured by Intel. Nowadays we can see a lot of clones of 8051 microcontrollers with difference in RAM, ROM, Peripherals etc., manufactured by different companies like Atmel, Texas Instruments, Philips, Infineon etc. 8051 series microcontrollers is a popular choice among hobbyists and educational purposes.

PIC Microcontrollers

PIC stands for Peripheral Interface Controller. It is a series of microcontrollers manufactured by Microchip Inc. It is popular among professionals, students and electronics hobbyists. It is low cost and commonly available in the market, also comes in 8-bit, 16-bit and 32-bit architectures.

ARM Microcontrollers

ARM stands for Advanced RISC Machine, it is a reduced instruction set computer (RISC) microcontroller. ARM microcontrollers are the most popular among professionals. ARM microcontrollers are manufactured by different companies like NXP Semiconductors, STMicroelectronics, Microchip Inc., Atmel etc.

AVR Microcontrollers

AVR microcontrollers are common among hobbyists and students. AVR microcontrollers are developed by Atmel, later acquired by Microchip. The popular Arduino boards uses AVR microcontroller.
Microcontroller vs microprocessor(MCU vs MPU)

Different characteristics

The characteristics of microcontroller are high -efficiency, low energy consumption, independent operation and easy use.

The characteristics of microprocessors are small, light weight, high computing power and easy modularization.

Different application areas

Micro -processor is usually used as a CPU in a miniature computer system. Its design is for this application, which is also the advantage of microprocessors. However, microcontrollers are usually used for controlled applications. Its system design pursues miniaturization and minimizes the number of components as much as possible. In the past, these applications usually need to be achieved with dozens or even hundreds of digital integration circuits. The use of microcontroller can reduce the number of components. Only a microcontroller, a small amount of external components, and the control program stored in ROM can achieve the same function. Microcomputers are suitable for the occasion where the input/output device is controlled by small components, and the microprocessor is suitable for information processing in the computer system.