The brilliant past of 51 single chip microcomputer
51 single-chip microcomputer refers to MCS-51 series single-chip microcomputer, CICS instruction set. Developed by Intel Corporation, its architecture adds instructions such as multiply (MUL), divide (DIV), subtract (SUBB), compare (CMP), 16-bit data pointers, Boolean algebra operations, and serial communication capabilities and 5 interrupts. The source has 128 RAM cells and 4K ROM. Its representative model is ATMEL's AT89 series, which is widely used in industrial measurement and control systems. At present, the domestic 51 single-chip market is mainly for the domestically produced Hongjing products STC series, which is characterized by low power consumption, stability and low cost.
Learning the misunderstanding of 51 MCU
Myth 1:51 is the basis of learning
The phrase "51 MCU is the basis of learning" is not wrong in itself. When I was studying undergraduate, it was undoubtedly the basis of learning at that time. After all, there was no more advanced MCU available for use at that time. There is no more advanced textbooks for reference in China. The level of teachers is also uneven, and 51 MCUs are positive. In line with such a demand, not only a large number of shaped teaching materials, but also a wide range of examples, the actual project at that time was also based on 51 single-chip microcomputers, so 51 single-chip microcomputers became the basis of learning at that time. I want to know that when I read the undergraduate course, it was 2004, that is, 10 years ago. According to Moore's Law, the electronics industry is updated every 18 months, and the technology 10 years ago has now been updated for six generations - and it is true.
At present, various tutorials of 32-bit Crtex-M series single-chip microcomputers have been popularized, and the difficulty of learning is continuously reduced. In the case of STMicroelectronics' STM32F series of single-chip microcomputers, STMicroelectronics presented a large number of core boards at the beginning of the promotion of the products. The free core board not only has the popular 32-bit Cortex-M series microprocessor, but also integrates an in-circuit debugger on the board. The accompanying CD-ROM or link provides a lot of sample source code. We only need to install the development environment to compile and download and debug directly. At this time, if we say that 51 single-chip microcomputer is the basis for learning embedded, it is definitely out of place.
Myth 2: 51 MCU can learn the operation of the register
51 single-chip microcomputer can learn the operation of the register, this is unquestionable. Let's analyze the reasons for its deeper. In the programming environment of the MSC-51 microcontroller, the assembly language was originally used as the main programming language. To know that assembly language is to directly manipulate registers, assembly language can not be called and encapsulated in C language functions. If the 51 single-chip microcomputer is based on the operation register, I think it should be said that the 51 single-chip operation register is a helpless, there is only one option.
Can't our current Cortex-M series microcontrollers learn registers? Obviously not. In hardware design, the way the hardware operates is the operation of registers, but its implementation can be different. The essence of the C language library function package provided by each microprocessor is to encapsulate the instructions of the operation register in the C language environment. Here we use the ST official library function to give an example:
Void USART_Init (USART1, *USART_InitStruct);//Implementation of serial port 1 initialization, simple and clear, no comments required
The easy-to-understand C language, the portable C language and the compiler corresponding to the hardware platform can complete the hardware operation. With a simple and convenient way, why should we consider cumbersome, complex assembly language and register operations?
Myth 3: 51 low cost microcontroller
Cost is the main factor in the application. The project's project mainly considers the cost and the main cost of sales pricing. A low-cost solution will have an advantage in the market. However, is the 51 MCU really the lowest cost? Not also. Now according to the function division, the cost of some 32-bit microcontrollers of the Cortex-m0 series can also be 3 yuan. Its performance is several times that of the 51 MCU, and it is easier to develop and maintain.
There is another cost: the difficulty of development. 51 MCU does not support online debugging. Some problems are not found in the initial stage of programming. It will only appear when connected with hardware, such as the delay often used in control operations. At this time, the huge advantage of online debugging is reflected. It can extremely conveniently view the state of the microprocessor at that time, making the analysis of the problem simple and transparent. Thereby, the development difficulty is effectively reduced, the development cycle is shortened, and development funds are saved.
Misunderstanding 4: 51 single-chip introduction is simple
51 single-chip introduction is simple? I have reservations about this point of view. Want to get started with 51 MCU, I am not only familiar with the peripherals of this MCU, but also fully understand the meaning of a certain bit of the register. For the clock, the configuration of the timer must be well known. This will undoubtedly increase my learning difficulty and familiar cycle. If we use the 32-bit microcontroller library function mode, we only need to have the knowledge of C language, understand the API function, directly look at the meaning of the already annotated registers, do not need to understand the underlying hardware implementation, not need to know some The meaning of a specified bit in the register. This reduces my workload and reduces development difficulty. You said that the introduction of 51 single-chip microcomputer is simple, or is the 32-bit Cortex core microprocessor simple?
Learning embedded systems is a very tedious and challenging task. Since it is directly connected to the actual hardware, it is necessary to consider not only the correctness of the writing but also the reliability of the hardware. At this time, simple and efficient software writing has changed the difficulty and risk of our development. 51 single-chip microcomputer is already tomorrow's yellow flower, it is development when looking forward. It is time to say goodbye to 51 MCU!
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