What is the difference and connection between single chip microcomputer and embedded system?
With the development of electronic information science and technology informatization, intelligence, and networking, microcontrollers and embedded systems have also gained broad application space. This article briefly analyzes the basic knowledge of the connection between the single-chip microcomputer and the embedded system, and the composition structure comparison, and lists several embedded real-time operating systems suitable for the PIC18F series of single-chip microcomputers.
Comparison of composition structure between single chip microcomputer and embedded system
(1) Basic structure of single chip microcomputer
The single-chip microcomputer is composed of arithmetic unit, controller, memory, input and output equipment.
(2) Embedded system is part of:
Embedded systems generally consist of the following groups of embedded microprocessors, peripheral hardware devices, embedded operating systems, and specific application programs.
The first step of embedded system design is to combine specific applications, comprehensively consider the system's requirements for cost, performance, scalability, development cycle and other aspects, determine the main control device of the system, and build the system hardware platform with it as the core .
The connection between single chip microcomputer and embedded system
The earliest single-chip microcomputer is Intel Corporation's 8048, which appeared in 1976. Motorola launched 68HC05 at the same time, and Zilog launched the Z80 series. These early microcontrollers all contained 256 bytes of RAM, 4K of ROM, 4 8-bit parallel ports, 1 full-duplex serial port, and two 16-bit timers. . Later in the early 1980s, Intel further improved the 8048 and successfully developed the 8051 based on it. This is a memorable page in the history of single-chip microcomputers. So far, the 51-series single-chip microcomputers are still the most successful single-chip microcomputer chips. , Has a very wide range of applications in various products.
The emergence of embedded systems was originally based on single-chip microcomputers. From the emergence of single-chip microcomputers in the 1970s to today’s various embedded microprocessors and large-scale applications of microcontrollers, automobiles, home appliances, industrial machines, and communication devices And thousands of products can get better performance through embedded electronic devices: easier to use, faster, and cheaper. These devices have initially possessed the characteristics of embedded applications, but the applications at this time only use 8-bit chips to execute some single-threaded programs, and there is no "system" concept.
Since the early 1980s, programmers of embedded systems began to write embedded application software with commercial-grade "operating systems", which made it possible to obtain shorter development cycles, lower development funds and higher development efficiency. "Embedded systems" really appeared. To be precise, the operating system at this time is a real-time core. This real-time core contains many traditional operating system features, including task management, inter-task communication, synchronization and mutual exclusion, interrupt support, memory management and other functions.
Among the more famous ones are Ready System's VRTX, Integrated System Incorporation (ISI)'s PSOS, IMG's VxWorks, and QNX's QNX. These embedded operating systems all have the typical characteristics of embedded: they all adopt preemptive scheduling, the response time is very short, and the task execution time can be determined; the system kernel is small, and it is tailorable, expandable and portable. Can be transplanted to various processors; strong real-time and reliability, suitable for embedded applications. The emergence of these embedded real-time multitasking operating systems frees application developers from small-scale development, and at the same time promotes a broader application space for embedded systems.
Since the 1990s, with the increase in real-time requirements, the scale of software has continued to rise, and the real-time kernel has gradually developed into a real-time multitasking operating system (RTOS), and as a software platform has gradually become the mainstream of current international embedded systems. At this time, more companies saw the broad development prospects of embedded systems and began to vigorously develop their own embedded operating systems. In addition to the above-mentioned established companies, Palm OS, Win CE, embedded Linux, Lynx, Nucleux, and domestic embedded operating systems such as Hopen and Delta Os have also appeared. As the development prospects of embedded technology become increasingly broad, it is believed that more embedded operating system software will appear.
Several embedded real-time operating systems suitable for PIC18F series microcontrollers
As shown below:
â—†The embedded system is user-oriented, product-oriented, and application-oriented. It must be combined with specific applications to have vitality and advantages. Therefore, the meaning of the above three aspects can be understood in this way, that is, the embedded system is closely integrated with the application, it has a strong specificity, and must be reasonably reduced and utilized in accordance with the actual system requirements.
◆Embedded system is a product that combines advanced computer technology, semiconductor technology and electronic technology with specific applications in various industries. This determines that it must be a technology-intensive, capital-intensive, highly dispersed, and constantly innovative knowledge Integrated system. Therefore, to enter the embedded system industry, there must be a correct positioning. For example, the reason why Palm occupies more than 70% of the market in the PDA field is because it is based on personal consumer electronics, focusing on the development of graphical interfaces and multi-task management; and the reason why Wind River’s Vxworks is applied on the rover is because of its High real-time and high reliability.
â—†The embedded system must tailor the software and hardware according to the application requirements to meet the application system's function, reliability, cost, volume and other requirements. Therefore, if a relatively general software and hardware foundation can be established, and then a system that meets various needs can be developed on it, it is a better development model. The core of the current embedded system is often a microkernel with only a few K to tens of K, which needs to be expanded or reduced according to actual use. However, due to the existence of the microkernel, this expansion can be carried out very smoothly.
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