Detailed explanation of microcontroller classification

Introduction to microcontroller classification:

51 series microcontroller

51 series microcontrollers The first one was launched by Intel, mainly including 8031 ​​series and 8051 series. Later, Atmel launched the AT89 series microcontrollers based on the 8051 core. Among them, AT89C51 AT89C52 AT89S51 AT89S52 AT89S8252 and other microcontrollers are fully compatible with the 8051 series microcontrollers, and all instruction functions are the same. It is a series of functional expansions. For example, the AT89S series supports ISP function, AT89S52 AT89S8252 adds internal WDT function, adds a timer and other functions. In order to make learning simple, Atmel also launched AT89C2051 AT89C4051 and other microcontrollers with exactly the same 8051 instructions. These microcontrollers can be regarded as simplified 8051 microcontrollers. More suitable for the needs of beginners.
AVR microcontroller

AVR microcontrollers are also products of Atmel. The earliest one is the AT90 series microcontrollers. Now many AT90 microcontrollers have been transformed into Atmega series and Attiny series. The biggest feature of AVR microcontrollers is that they are reduced instruction set microcontrollers. As far as I know, they are the fastest microcontrollers among 8-bit MCUs (under the same oscillation frequency). You can learn AVR microcontrollers directly, but it is recommended to start with the 51 series.
PIC microcontrollers

PIC microcontroller is a product of Microchip. It is also a reduced instruction type microcontroller with a relatively small number of instructions. The mid-range PIC series has only 35 instructions, and the low-end has only 33 instructions. However, if you use assembly language to write programs for PIC microcontrollers, there is a fatal weakness. There is a concept of page turning in the mid- and low-end PIC microcontrollers, which makes it more troublesome to write programs. But I personally think that PIC is still a good 8-bit MCU.

When learning MCU, people usually choose 51 series MCU, such as Intel's 8051 series, Atmel's AT89 series, STC's 51 series, etc., which can be regarded as 51 series MCU. The instruction systems of these MCUs are the same. There are also the most data available. It is recommended to choose Atmel's AT89 series chips, which have the most data. If you want to do experiments yourself, it is recommended to choose AT89S52 AT89S51 AT89S8252 and other chips for learning, because these "S" chips all support ISP (online programming) and only need a download cable (it is recommended to choose AVR download cable, in order to be able to download the program of AVR chip at the same time in the future). The compilation software can be downloaded from www.atmel.com. For burning software, just choose Ssangyong's SLISP. If you learn in this way, you don't need to use an expensive programmer, just a cheap download cable. This type can also learn SPI (synchronous serial expansion interface) and USART (serial universal synchronous/asynchronous receiver and transmitter) at the same time. Besides the abundant information, another advantage of learning 8051 type chips is that it belongs to CISC (complex instruction set) structure type microcontroller. The instruction system is relatively complete, and it is relatively simple and easy to understand to write programs in assembly language. And it also has the C compiler of keilC51. You can use C language to write programs.
Of course, 51 type microcontrollers have many disadvantages:
1. The running speed is very slow (because it is a CISC (centralized instruction) structure, and the chip uses a 12-frequency division method for anti-interference)
2. All I/0 ports are quasi-bidirectional ports, and the driving ability of the I/0 ports is weak. (However, the current of AT89 is relatively large, about 20mA)
3. The P0 port in the chip does not have a pull-up resistor (P1, P2, P3 ports have pull-up resistors). If you want to output a high level or define it as an input port, you generally need to connect an external resistor to pull it up.
4. The chip cannot be defined as an internal reset mode, and can only be reset by an external differential circuit.
5. There is no RC oscillation inside the chip. If the chip is to work properly, an external oscillation source is required (such as crystal oscillator, RC oscillation, PLL oscillation, etc.)
6. The power consumption is relatively high, and the anti-interference ability is not very strong.
However, it is still recommended to choose 8051 type microcontrollers for learning, because this is the basis for learning other 8-bit microcontrollers. If you learn 51 well, it is very fast to learn other microcontrollers. It is recommended to start with assembly language, understand the meaning of all instructions, and how to run. After you are familiar with it, learn C to write programs. Don't copy someone else's program, but you don't understand it and write the program directly into the chip, and then you don't know how the chip runs.

Other common MCUs are as follows:
Microchip's PIC series MCUs
Atmel's AVR series MCUs
Freescal's MC series
Motorola's 6800 series
Zilog's Z80 series (this is an older MCU than 51)
Elan's EM series
McCann's MDT series
Hottech's HT series Hyundai
's ABOV series
ST series MCUs from STMicroelectronics
There are also ARM series 32-bit MCUs.
For example, NEC, LG, Samsung, Philips and other companies all make MCUs.