What are the characteristics of the 51 microcontroller?

The MCS-51 single-chip microcomputer was launched by the American INTE company in 1980. Compared with the MCS-48 single-chip microcomputer, it has a more advanced structure and stronger functions. It adds more circuit units and instructions on the original basis, with the number of instructions reaching 111. The MCS-51 single-chip microcomputer can be regarded as a very successful product. Until now, the MCS-51 series or its compatible single-chip microcomputers are still the mainstream products used. The training materials of various universities and professional schools still use the MCS-51 single-chip microcomputer as a representative for theoretical basic learning. We also use this representative model for systematic explanation.

The MCS-51 series of microcontrollers mainly include general-purpose products such as 8031, 8051 and 8751. Its main functions are as follows:

8-bit CPU

4kbytes program memory (ROM)

128 bytes of data memory (RAM)

32 I/O lines

111 instructions, most of which are single-byte instructions

21 special registers

·2 programmable timer/counters

5 interrupt sources, 2 priority levels

One full-duplex serial communication port

External data memory addressing space is 64kB

External program memory addressing space is 64kB

Logical operation bit addressing function

·Dual in-line 40PinDIP package

Single +5V power supply

MCS-51 is a "famous machine" with its typical structure and perfect centralized management of bus-specific registers, numerous logic bit operation functions and rich control-oriented instruction system, which laid the foundation for the development of other single-chip microcomputers in the future. Because of its superior performance and perfect structure, many manufacturers later adopted or referred to its architecture. Many world-class electrical companies enriched and developed MCS-51 single-chip microcomputers. Famous semiconductor companies such as PHILIPS, Dallas, and ATMEL have launched single-chip microcomputer products compatible with MCS-51. Even Taiwan's WINBOND company has developed single-chip microcomputer varieties compatible with C51 (people are accustomed to abbreviating MCS-51 as C51. If there is no special statement, the two refer to the MCS-51 series of single-chip microcomputers).

In recent years, C51 has achieved rapid development. INTEL, the birthplace of C51, was too busy developing PCs and high-end microprocessors to continue developing its own single-chip microcomputers, so other manufacturers developed it, the most typical of which are PHILIPS and ATML. PHILIPS mainly improved its performance, and developed high-speed I/O ports, A/D converters, PWM (pulse width modulation), WDT and other enhanced functions on the original basis, and improved it with low voltage, micro power consumption, extended serial bus (I2C) and control network bus (CAN) and other functions.

PHILIPS has made a lot of contributions to the development of C51's low power consumption, high speed and enhanced functions. It was the main company that developed the C51 microcontroller in the beginning. Their 83Cxx and 87Cxx series eliminated the parallel expansion bus and were suitable as economical microcontrollers for controlling household appliances.

The AT89Cxx series of C51-compatible microcontrollers launched by ATMEL perfectly combines Flash (non-volatile flash memory technology) EEPROM with the 80C51 core, and still uses the overall structure and instruction system of C51. The rewritable program memory of Flash can effectively reduce development costs and enable the microcontroller to be reused many times. [page]

Siemens also uses the C51 core and has launched the C500 series of microcontrollers. While maintaining compatibility with C51 instructions, the performance of its products has been further improved, especially in anti-interference performance, electromagnetic compatibility and communication control bus functions. Its products are often used in harsh working environments and are also suitable for communication and home appliance control fields.

Taiwan's WINBOND company has also developed a series of C51-compatible microcontrollers. Its products usually have rich functional features and have a certain market share due to their high quality and low price.

The following table shows the main classification and functional characteristics of the 80C51 series microcontrollers:

Typical chips in the series I/O port Timer/Counter Interrupt source Serial communication port On-chip RAM On-chip ROM Description

51 series 80C31 4x8 bit 2x16 bit 5 1 128 bytes No

80C51 4x8 bit 2x16 bit 5 1 128 bytes 4kB mask ROM

87C51 4x8-bit 2x16-bit 5 1 128-byte 4kBEPROM

89C51 4x8 bit 2x16 bit 5 1 128 bytes 4kBEEPROM

52 series 80C32 4x8 bit 2x16 bit 6 1 256 bytes No

80C51 4x8 bit 2x16 bit 6 1 256 bytes 8kB mask ROM

87C52 4x8 bit 2x16 bit 6 1 256 bytes 4kBEPROM

89C52 4x8 bit 2x16 bit 6 1 256 bytes 4kBEEPROM

8051 is the representative product of the MCS-51 series of microcontrollers. It integrates a powerful central processing unit, including a hardware multiplier and divider, 21 dedicated control registers, 4kB of program memory, 128 bytes of data memory, 4 groups of 8-bit parallel ports, two 16-bit programmable timers/counters, a full-duplex serial port and a Boolean processor.

MCS-51 has a relatively large addressing space, with an address line width of 16, that is, the addressing range of the external data memory and program memory is 216=64kB, which is relatively large for single-chip control, and it also has the ability to access the I/O port. In addition, MCS-51 adopts a modular structure, and it is easy to add or delete a module to produce a new product with compatible pins and instructions. This makes it easy to form a series of products.

Since MCS-51 integrates an almost perfect 8-bit central processing unit with powerful processing capabilities, the central processing unit integrates convenient and flexible special registers, hardware addition, subtraction, multiplication, division and Boolean processors as well as various logical operations and transfer instructions, which provides great convenience for applications.

The instruction system of MCS-51 is almost perfect. It includes comprehensive data transfer instructions, complete arithmetic and logical operation instructions, convenient logical operation and control instructions, and is quite flexible and convenient for programming.

The operating frequency of the MCS-51 microcontroller is 2-12MHz. When the oscillation frequency is 12MHz, one machine cycle is 1us, which is relatively fast.

8051 integrates a complete range of interrupt sources, and users can easily control and use its functions, which expands its application range. It can be said that it can meet most application scenarios.

MCS-51 integrates the main components of the microcomputer on a single chip, which greatly shortens the data transmission distance, improves reliability, and runs faster. As it is a chip-based microcomputer, the layout and structure of each functional component in the chip are optimized, the anti-interference ability is enhanced, and the operation is relatively stable. Therefore, in industrial measurement and control systems, the use of single-chip microcomputers is the most ideal choice. Single-chip microcomputers are typical embedded systems, so they are the best devices for low-end control systems.

The development environment requirements of MCS-51 are relatively low, and the software resources are very rich. Books introducing its functions and features and development software are available everywhere. All you need is a PC (personal computer - there are basically no requirements for the computer configuration) and an emulator programmer to develop products. Early development software mostly used DOS versions. With the popularization of Windows software, almost all of them now use Windows versions, and there are many types of software. Among the many types of single-chip microcomputers, C51 has the richest environmental resources, which brings great convenience to C51 users.