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How it was born
The microcontroller was born in 1971 and has gone through three stages: SCM, MCU, and SoC. The microcontroller consists of the previous 1-bit, 4-bit, 8-bit, and 16-bit. Early microcontrollers were all 4-bit. bit or 8 bits. The most successful one is Intel's 8031, which has received great praise for its simplicity, reliability and good performance. Since then, the MCS51 series of microcontroller systems based on this system are still widely used. Focusing on the field of industrial control With the improvement of demand, 16-bit microcontrollers began to appear, but they were not widely used because of the unsatisfactory cost performance. With the rapid development of consumer electronics after the 1990s, microcontroller technology has been greatly improved to 32-bit and even 32-bit microcontrollers. 64 bits. With the rapid development of consumer electronics after the 1990s, microcontroller technology has been greatly improved, and a number of market-proven products have been born. A microcontroller manufacturer with a good reputation.
has great power and is available everywhere.
In actual work, not all situations require high performance of the computer. The key to the application is whether it is sufficient and has good cost performance. . The microcontroller is the key to the operation of electrical appliances. For example, it receives input signals from buttons or keys and directs the peripheral function circuits of motors and LCDs to operate.
Why do we use a single-chip microcomputer to light up LED circuits? Take as an example
(right) The circuit without a microcontroller is a simple circuit consisting of an LED, a switch and a resistor. Obviously, the circuit using a microcontroller is much more complicated, and it takes effort and money to design the circuit. It seems that there is no cost to using a microcontroller. What advantages, in fact, it is not the case.
If we let this circuit do some more complex operations , what will happen? For example: If you want the LED to light up or go out after a period of time after pressing the switch, then for a circuit equipped with a microcontroller, you only need to change the program in the microcontroller. The original circuit needs to be modified. On the other hand, for circuits without a microcontroller, a timer IC must be added to the original circuit, or a standard logic IC and FPGA must be used. This function can only be achieved by forming a logic circuit. In other words, when changing and adding new functions, circuits with microcontrollers are obviously easier to implement.
microcontrollers are usually used in the control, life and control fields of industrial production. Microcontrollers are more suitable for embedded systems than dedicated processors, so they have the most applications. In fact, microcontrollers are the most numerous computers in the world. Microcontrollers are integrated into almost every electronic and mechanical product used in modern human life. Mobile phones, telephones, calculators, household appliances, electronic toys, handheld computers, mice and other computer accessories are all equipped with 1-2 microcontrollers. There will also be a large number of microcontrollers working in personal computers. It is understood that a car is equipped with more than 40 microcontrollers, and a complex industrial control system may even have hundreds of microcontrollers working at the same time. Calculated in this way, the number of microcontrollers has far exceeded the number of people on the earth.
So what components are the "omnipotent" microcontrollers made of?
Taking PC as an example, a computer mainly consists of the following parts: central processing unit CPU (for calculation and control), random access memory RAM (data storage), memory ROM (program storage), input/output device I/O (Serial port, parallel output port, etc.). In a personal computer, these parts are divided into several chips and mounted on a printed circuit board called a motherboard. In a single-chip microcomputer, all these parts are integrated into an integrated circuit chip, so it is called a single-chip microcomputer. In addition to the above-mentioned parts, some single-chip microcomputers also integrate other parts such as analog/digital conversion (A /D) and digital/analog conversion (D/A), etc. In addition, the vast majority of current microcontrollers are based on the von Neumann structure.
Take 51 microcontroller as an example. Its functional components and functions mainly include:
1, CPU main chip (device expanded internally through bus connection)
2, clock circuit (providing oscillation pulses for the microcontroller)
3 , power circuit (provides power for the microcontroller)
4, internal data memory RAM (including general data register and special register SFR, mainly data storage area.)
5, program memory ROM (mainly stored program , 51 series has 4K internal Program ROM, can be external Expansion 64K.)
6, parallel port 4*8 bits (P0, P1, P2, P3 are mainly data exchange interfaces.)
7, serial port (TXD, RXD are used for serial communication.)
8, interrupt system (external interrupt 0 , timer count T0, external interrupt 1, timer count T1, serial port Interrupt.)
9, timer/counter (16 bits are used for external counting and timing functions.)
In these components, the memory is the memory device of the microcontroller, which mainly stores programs and data, but there is a difference between ROM and RAM:
ROM is Abbreviation for read-only memory. The data stored in ROM cannot be deleted and will not be lost due to power outage. ROM is mainly used to save user programs and constants that remain unchanged during program execution.
RAM is the abbreviation of random read/write memory. Data can be read and written at any time, but after shutting down, the data stored in RAM will disappear. Mainly used to store variables in programs. In single-chip microcontrollers, SRAM is often used as internal RAM. SRAM allows high-speed access, but the internal structure is too complex and difficult to achieve high-density integration, making it unsuitable for large-capacity memory. In addition to SRAM, DRAM is also a common RAM. The structure of DRAM is relatively easy to achieve high-density integration, so it has a larger capacity than SRAM. However, it is difficult to install high-speed logic circuits and DRAM on the same chip. Therefore, they are rarely used in single-chip microcontrollers and are basically used as peripheral circuits.
working principle
Although the CPU is equivalent to the human brain, it cannot think consciously and spontaneously like the human brain. The CPU can only sequentially read and execute a combination of instructions stored in memory in advance.
microcontroller automatically completes the task process assigned to it, that is, the instruction process executed one by one. The so-called instructions are to write down the form of commands for various operations that are required to be performed by the microcontroller. This is determined by the instruction system given to it by the designer. , an instruction corresponds to a basic operation; all instructions that a single-chip computer can execute are the instruction systems of the single-chip computer. Different types of single-chip computers have different instruction systems.
Therefore, the problem must be compiled into a series of instructions. The collection of this series of instructions becomes a program, and the program needs to be stored in the memory in advance. The memory is composed of many storage units. You can think of it as a hotel room. Instructions are stored in these rooms. The instructions in the room are fetched and executed. Just like allocating a room when checking in, each storage unit must also be assigned a unique address. The address number is called the address of the storage unit. In this way, as long as the address of the storage unit is known, the storage unit can be found, and the instructions stored in it can be fetched and then executed.
mainstream microcontrollers
Current mainstream microcontrollers include:
51 series microcontrollers - a collective name for all microcontrollers compatible with the Intel 8031 instruction system. The 51 microcontroller is a basic microcontroller for entry-level, and it is also the most widely used one.
PIC series microcontroller - an integrated circuit developed to control peripheral devices. It has computing and memory functions, average processing power, and very limited memory capacity.
AVR series microcontrollers - the biggest advantages of AVR are the fast speed of Harvard structure; rich on-chip resources; strong driving ability; low power consumption; many types of models to choose from; high cost performance; good confidentiality; with PWM pulse width modulation, serial peripherals Interface SPI, on-chip RC oscillator, SRAM is larger than 51.
These are the three most commonly used series of microcontrollers. Its main features are: the 51 series microcontroller is a von Neumann structure, and the latter two are Harvard structures.
Typical player introduction
After years of development, MCU manufacturers can be said to be diverse. Let’s briefly introduce
1, a typical player in this circle. NXP (acquired Freescale)
microcontroller is a microcontroller based on the 80C51 core. It has embedded functions such as power-down detection, simulation, and on-chip RC oscillator, which makes 51LPC highly integrated. , low-cost, low-power application design can meet various performance requirements. NXP's MCUs almost all use the Cortex-m series architecture.
2. Renesas Electronics
NEC Electronics and Renesas Technology merged to form "Renesas Electronics" on April 1, 2010. It is now the world's leading supplier of microcontrollers, as well as SoC system chips and various analog and power supply devices. One of the leading brands in advanced semiconductor solutions. The RL78 series of MCU products they launched for the Chinese market are divided into general-purpose products and products with integrated LCD drivers. The upgraded models of general-purpose products have been expanded accordingly around specific application fields such as sensors, small systems, and motor drives.
3. Microchip Technology (Microchip) (acquired Atmel)
Microchip Technology is the world's leading supplier of microcontrollers and analog semiconductors. Microchip microcontrollers are the microcontrollers with the largest market share growth. They emphasize cost-saving optimized design, high-volume, low-grade, price-sensitive products.
4. Samsung (Samsung)
Samsung microcontrollers include KS51 and KS57 series 4-bit microcontrollers, KS86 and KS88 series 8-bit microcontrollers, KS17 series 16-bit microcontrollers and KS32 series 32-bit microcontrollers.
5. STMicroelectronics (ST)
STMicroelectronics has a strong product lineup of microcontrollers, ranging from the robust low-power 8-bit microcontroller STM8 series to various Arm based Cortex-M0 and M0+, Cortex-M3, Cortex -M4, Cortex-M7 core 32-bit flash microcontroller STM32 family. The STM32 series of 32-bit microcontrollers is based on the Arm® Cortex®-M processor and is designed to provide MCU users with a new degree of development freedom. It includes a family of products that combine high performance, real-time capabilities, digital signal processing, low power/low voltage operation, connectivity and more while maintaining high integration and ease of development.
6. Infineon
was formerly the semiconductor department of Siemens Group. Infineon's 8-bit microcontroller can realize high-performance motor drive control and has extremely high reliability in harsh environments (high temperature, EMI, vibration). The XMC1000 industrial microcontroller launched by Infineon for the Chinese market has a high cost performance in the field of motor control.
7. Texas Instruments (TI)
TI is the world's leading analog and digital semiconductor IC design and manufacturing company. In addition to providing analog technology and digital signal processing (DSP), TI is also deeply involved in the field of microcontrollers, launching a series of 32-bit microcontrollers, among which the Piccolo series of microprocessors are the most representative, with specific models such as the C2000 and F28x series.
8. Toshiba (Toshiba)
Toshiba microcontrollers have a wide range of features ranging from 4-bit to 64-bit. 4-bit machines still have a large market in the field of home appliances. 8-bit microcontrollers mainly include 870 series, 90 series, etc. This type of microcontroller allows the use of slow mode, and the power consumption is as low as 10uA when using a 32K clock. The use of multiple sets of registers within the CPU makes interrupt response and processing faster. Toshiba's 32-bit microcontroller adopts the MIPS3000ARISC CPU structure and is targeted at VCD, digital cameras, image processing and other markets.
9. Silicon Laboratories
Silicon Laboratories was founded in 1996 and is located in Austin, Texas, USA. It is a company specializing in the research, development and design of analog circuits and mixed-signal ICs, providing a wide range of applications for the design of the rapidly growing communications industry. It ranks among the leading companies in the field of 8051 series MCU. This company acquired an energy-saving MCU company called Energy Micro in 2013, so the product has two models.
10. Maxim
Maxim’s ultra-low-power 32-bit Arm® Cortex®-M4 FPU microcontroller (microcontroller) can help you send and receive other ultra-low-power MCU products anywhere. The ultra-low-power MCU series products are both smart and power-saving. They released a revolutionary chip called MAX78000 last year. This low-power neural network acceleration microcontroller can push artificial intelligence (AI) to the edge. More importantly, because of its low power consumption, it means that it can be used even in battery-powered Internet of Things. In (IoT) devices, chip performance has not been affected.
11. ADI
ADI offers a growing portfolio of DSPs, mixed-signal control processors, embedded processors and analog microcontrollers for a wide range of general-purpose and specialized needs. For example, products include: ADuC844 and ADuC846, analog-to-digital conversion chips with microprocessors, for IoT ultra-low power MCU ADuCM4050.
12. Qualcomm (Qualcomm)
Qualcomm's MCU is mainly used in smartphones, tablets, wireless modems, etc., and is very powerful. Mainly provide 16-bit and 32-bit MCU.
See pictures for other manufacturers.
MCU, as an important branch of microcomputers, has a wide range of applications and is developing rapidly. Since the birth of MCU, it has developed into hundreds of series and nearly a thousand models. And with the continuous development of semiconductor integration technology, MCUs will be more integrated, smaller in size, and more functional.
