An embedded system is a "dedicated computer system that is fully embedded in a controlled device and designed for a particular application." According to the definition of the UK Institution of Electrical Engineer, the embedded system is controlled , Monitoring or auxiliary equipment, equipment, or equipment for plant operation. Unlike general-purpose computer systems such as personal computers, embedded systems typically perform pre-defined tasks with specific requirements. Because the embedded system only for a special task, the designer can optimize it, reduce the size of the cost reduction. Embedded systems are usually mass-produced, so a single cost savings can be scaled with hundreds of outputs.
An embedded system is a system used to control or monitor large-scale equipment such as machines, devices, factories, and so on. Domestic embedded system is generally defined as: application-centric, based on computer technology, hardware and software can be tailored to adapt to the application system on the function, reliability, cost, size, power and other strict requirements of the special computer system. Typically, the embedded system is a control program stored in the ROM in the embedded processor control board. In fact, all devices with digital interfaces, such as watches, microwave ovens, video recorders, cars, etc., are using embedded systems, some embedded systems also include operating systems, but most embedded systems are implemented by a single program logic.
The core of an embedded system consists of one or more microprocessors or microcontrollers that are pre-programmed to perform a few tasks. Unlike general-purpose computers that can run user-selected software, the software on an embedded system is usually temporarily invariant; it is often referred to as a "firmware."
Embedded system is user-oriented, product-oriented, application-oriented, it must be combined with the specific application will have the vitality, it is more advantages. Therefore, we can understand the above three-oriented meaning, that is, embedded systems are closely integrated with the application, it has a strong specificity, must be combined with the actual system requirements for reasonable use.
◆ embedded system is the advanced computer technology, semiconductor technology and electronic technology and the specific application of various industries after the combination of products, which determines it must be a technology-intensive, capital-intensive, highly dispersed, innovative knowledge Integrated Systems. Therefore, involved in the embedded system industry, there must be a correct positioning. For example, the reason why the Palm in the PDA field occupies more than 70% of the market, because it is based on personal consumer electronics, focusing on the development of graphical interface and multi-task management; and Wind River Vxworks why the application of the rover, it is because of its High real-time and high reliability.
◆ embedded system must be based on application requirements for cutting hardware and software to meet the application system functions, reliability, cost, volume and other requirements. So, if we can build a relatively common hardware and software foundation, and then develop a system to adapt to their needs, is a better development model. The core of the current embedded system is often only a few K to several tens of K micro-kernel, the need for the actual use of functional expansion or reduction, but because of the existence of micro-kernel, making this expansion can be very smooth.
In fact, the embedded system itself is a very broad term, all with the product with the embedded characteristics of the control system can be called embedded systems, and sometimes it is difficult to give it the next accurate definition. Now people talk about embedded systems, to some extent refers to the hotter in recent years with the operating system embedded system, this article in the analysis and outlook, also follow this view.
In general, the architecture of an embedded system can be divided into four parts: processor, memory, input and output (I / O), and software (since most embedded devices are well-suited for application software and operating systems, No distinction between it, which is the embedded system and the general PC operating system, the biggest difference).
There have been several reasons for the upsurge of embedded systems applications over the years: First, the development of chip technology has made it possible for a single chip to have more processing power, and it has become possible to integrate multiple interfaces. Many chip manufacturers have Focus on this aspect. Another reason is the need for the application, due to product reliability, cost, upgrading requirements, making the embedded system from pure hardware and the use of general-purpose computer applications to come to the fore, has become concerned in recent years focus.
From the above definition, we can see several important features of the embedded system:
1. Small system kernel. As the embedded system is generally applied to small electronic devices, the system resources are relatively limited, so the kernel than the traditional operating system is much smaller. Such as Enea's OSE distributed system, the kernel is only 5K, and the Windows kernel? There is no comparability.
2. Particularly strong. Embedded system of personalization is very strong, in which the combination of software systems and hardware is very close, generally for the hardware system for transplantation, even in the same brand, the same series of products also need to change according to the system hardware and constantly to modify. At the same time for different tasks, often need to make a big change to the system, the program download and download to the system, this modification and general software "upgrade" is completely two concepts.
3. System streamlining. Embedded systems generally do not have a clear distinction between system software and application software, do not require their functional design and implementation is too complex, so on the one hand conducive to control system costs, but also conducive to the realization of system security.
4. High real-time system software (OS) is the basic requirement of embedded software. And software requires solid-state storage to increase speed; software code requires high quality and high reliability.
5. Embedded software development To move towards standardization, you must use a multitasking operating system. Embedded system applications can be no operating system directly on the chip to run; but in order to properly schedule the multi-task, the use of system resources, system functions and expert library function interface, the user must own RTOS (Real-Time Operating System) Development platform, so as to ensure the implementation of real-time procedures, reliability, and reduce development time to protect the quality of software.
6. Embedded system development requires the development of tools and environments. Because it does not have the ability to develop self-boot, even after the completion of the design of the user usually can not modify the program function, there must be a set of development tools and environment to develop, these tools and the environment is generally based on the general computer soft Hardware devices and a variety of logic analyzers, mixed-signal oscilloscope. Development often have the concept of host and target machine, the host for the development of the program, the target machine as the final executive machine, the development of the need to be combined.
7. Embedded system and the specific application of organic combination, upgrading is also carried out simultaneously. Therefore, the embedded system products once into the market, with a longer life cycle.
8. In order to improve the speed and system reliability, embedded systems, software is generally solidified in the memory chip.
Embedded system technology has a very broad application prospects, and its application areas can include:
Based on the embedded chip industrial automation equipment will be developed by leaps and bounds, there are already a large number of 8,16,32 embedded microcontrollers in the application, the network is to improve production efficiency and product quality, reduce the main way of human resources, such as Industrial process control, digital machine tools, power systems, grid safety, grid equipment monitoring, petrochemical systems. On the traditional industrial control products, the low-end type is often used 8-bit microcontroller. But with the development of technology, 32-bit, 64-bit processor has gradually become the core of industrial control equipment, in the next few years will be developed by leaps and bounds.
In the vehicle navigation, flow control, information monitoring and automotive services, embedded system technology has been widely used, embedded GPS module, GSM module mobile positioning terminal has been in a variety of transport industry has been successfully used. GPS equipment has been from the cutting-edge products into the ordinary people's family, only a few thousand dollars, you can find your location anytime, anywhere.
This will be called the largest application of embedded systems, refrigerators, air conditioning and other network, intelligent will lead people's lives into a new space. Even if you are not at home, you can also through the telephone line, the network for remote control. In these devices, the embedded system will be very useful.
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Water, electricity, gas meter remote automatic meter reading, security fire, anti-theft system, which embedded in the special control chip will replace the traditional manual inspection, and achieve higher, more accurate and more secure performance. Currently in the service areas, such as remote ordering machine has already embodied the advantages of embedded systems.
Public transport contactless smart card (Contactless Smartcard, CSC) distribution system, public telephone card issuance system, vending machines, a variety of intelligent ATM terminal will be fully into the people's lives, when a card can be a hand over the world.
Real-time monitoring of hydrological data, flood control system and soil and water quality monitoring, dam safety, earthquake monitoring network, real-time meteorological information network, water and air pollution monitoring. In many harsh environments, complex systems, embedded systems will achieve unattended monitoring.