Question 2: What is an embedded system What is an embedded system
Embedded system generally refers to non-PC systems, computer functions but not called computer equipment or devices. It is application-centered, hardware and software can be reduced to adapt to the application of the system on the function, reliability, cost, volume, power consumption and other comprehensive and strict requirements of the special computer system. Simply put, the embedded system set system application software and hardware in one, similar to the PC in the BIOS way of working, with software code is small, highly automated, fast response speed and other characteristics, especially suitable for the requirements of real-time and multi-tasking system. Embedded systems are mainly composed of embedded processors, related support hardware, embedded operating systems and application software systems, which can work independently of the "device".
Embedded systems include almost all the electrical equipment in life, such as handheld PDA, mobile computing devices, TV set-top boxes, cell phones, digital TV, multimedia, automobiles, microwave ovens, digital cameras, home automation systems, elevators, air conditioning, security systems, vending machines, cellular telephones, consumer electronics, industrial automation instrumentation and medical instruments.
The hardware part of an embedded system includes the processor/microprocessor, memory and peripheral devices and I/O ports, graphics controllers, and so on. Embedded system is different from the general computer processing system, it does not have a high-capacity storage media like hard disk, and most of the use of EPROM, EEPROM or flash memory (Flash Memory) as a storage medium. The software component consists of operating system software (requiring real-time and multitasking operation) and application programming. The application program controls the operation and behavior of the system; and the operating system controls the interaction between the application program and the hardware.
II Embedded processors
The core of an embedded system is the embedded microprocessor. Embedded microprocessors generally have four characteristics: (1) strong support for real-time and multi-tasking, can complete multi-tasking and have a shorter interrupt response time, so that the internal code and the real-time operating system execution time is reduced to a minimum; (2) has a strong memory protection function, which is due to the embedded system's software structure has been modularized, and in order to avoid incorrect cross-talk between software modules, it is necessary to avoid the software module. (3) scalable processor architecture, in order to be able to quickly expand to meet the application of high-performance embedded microprocessors; (4) embedded microprocessors must be very low power consumption, especially for portable wireless and mobile computing and communications equipment in the battery-powered embedded system (4) The power consumption of the embedded microprocessor must be very low, especially for battery-powered embedded systems in portable wireless and mobile computing and communication devices.
According to incomplete statistics, the total number of varieties of embedded processors around the world has exceeded 1,000, and there are more than 30 series of popular architectures. Among them, 8051 system accounts for more than half, the production of this microcontroller semiconductor manufacturers have more than 20, **** more than 350 kinds of derivatives, only Philips has nearly 100 kinds. Almost every semiconductor manufacturer now produces embedded processors, and more and more companies have their own processor design departments. Embedded processors generally range from 64kB to 16MB of addressing space, with processing speeds of 0.1-2000MIPS, and are commonly available in packages of 8 to 144 pins.
According to the current situation, embedded computers can be divided into the following categories.
(1) Embedded Microprocessor Unit (EMPU)
Embedded microprocessors use "enhanced" general-purpose microprocessors. Since embedded systems are often used in harsh environments, embedded microprocessors require higher operating temperatures, electromagnetic compatibility, and reliability than general-purpose standard microprocessors. However, embedded microprocessors are basically the same as standard microprocessors in terms of functionality. According to the actual embedded application requirements, the embedded microprocessor will be assembled on a specially designed motherboard, only retaining and embedded applications related to the motherboard functions, which can significantly reduce the size of the system and power consumption. Compared with industrial control computers, systems composed of embedded microprocessors have the advantages of small size, light weight, low cost and high reliability, but on their circuit boards must include ROM, RAM, bus interfaces, various peripherals and other devices, thus reducing the reliability of the system, and the technical confidentiality is poor. By embedded ...... >>
Question 3: There are several classifications of embedded software systems There should be a variety of
Question 4: What are the types of interfaces to embedded systems Embedded hardware systems Embedded processors Various types of memory Analog circuits and power supply Interface controllers Embedded software systems Real-Time Operating Systems Board-level support packages Device Drivers Protocol Stacks Applications
p> Question 5: Embedded microprocessors are usually divided into which types? Embedded microprocessor classification:
According to the microprocessor word length width: microprocessors can be divided into 4-bit, 8-bit, 16-bit, 32-bit, 64-bit. Those with 16 bits and below are generally referred to as embedded microcontrollers, and those with 32 bits and above are referred to as embedded microprocessors.
According to the microprocessor system integration, it can be divided into two categories: general-purpose microprocessors, i.e., microprocessors that contain only a pure central processing unit inside; and single-chip microcontrollers, i.e., parts such as CPU, Rom, RAM, and I/O are integrated into the same chip.
According to the purpose of the embedded microprocessor: it can be divided into the following categories:
1. Embedded microcontroller (MCU), also known as a microcontroller. Microcontrollers are usually rich in on-chip peripheral resources and are suitable for control, hence the name microcontroller. Microcontroller chip internal integration of ROM/EPROM, RAM, bus, bus logic, timer/counter, watchdog, I/O, serial port, pulse width modulation output (PWM), A/D, D/A, Flash, EEPROM and other various necessary functions and peripherals. The most important features of microcontrollers are monolithic, low power cost and high reliability. Commonly used 8051, MCS series, C540, MSP430 series, etc. Currently, microcontrollers account for about 70% of the market share of embedded systems.
2, embedded microprocessor (EMPU). By the development of general-purpose computers in the CPU, the main feature is that it has more than 32-bit processor, with relatively high performance and high prices. Different from the computer CPU, in the actual embedded applications, only to retain and embedded applications closely related to the functional hardware, remove other redundant functional parts, so its small size, light weight, low power consumption, low cost and high reliability. Usually embedded microprocessor CPU, ROM, RAM and I/O components to do the same chip, also known as single-board computer. At present, the main embedded microprocessors are ARM, MIPS, POWER PC and X86-based 386EX.
3, embedded DSP processor. It is dedicated to signal processing processor, Polygon in the system structure and instruction algorithms for special design, with high compilation efficiency and instruction execution rate, mainly used in digital filtering, FFT, spectrum analysis and other instruments.
DSP internal program and data storage and transmission of the Harvard structure separately, with a special hardware multiplier, widely used pipeline operation, to provide special DSP instructions, can be used to quickly implement a variety of digital signal processing algorithms, coupled with the optimization of the integrated circuit design, the speed of the fastest than even the fastest CPU several times faster.
4, embedded system-on-chip (SOC). It is the pursuit of the product system to maximize the inclusion of integrated devices. the biggest feature of the SOC is the successful realization of a seamless combination of hardware and software, directly in the processor embedded in the operating system code module. The SOC is characterized by a seamless integration of hardware and software, embedding the operating system code module directly on the processor chip.
A search on Baidu a whole lot of questions, how the old love to ask here, the processor according to the structural design of the different, Harvard structure and Von Neumann, the typical Harvard structure for the 51 series, Von Neumann needless to say, the difference between the former data and program instructions are stored separately.
Question 6: Embedded processors can be divided into those types of 5 points The CPU used in embedded systems can be divided into four categories:
1, microcontroller or SoC, which is the most typical. Commonly used chips based on the PowerPC core, chips based on the
ARM core, and a variety of microcontroller chips based on SPARC and MIPS core.
Most of these cores are RISC, but there are also CISC chips, such as the traditional Intel 8051.
2. RISC microprocessor chips that are composed of cores or similar cores and are relatively small in size and power consumption, i.e., CPU prototypes without
peripheral interfaces.
3, the popular CISC structure of the CPU chip "mobile version", these chips were originally used for laptop computers,
volume and power consumption are relatively small, so also commonly used in embedded systems.
4. Ordinary CPU chips. There are CISC CPUs, such as Pentium, and RISC CPUs, such as PowerPC.
Question 7: What are the different basic types of embedded software architectures that are commonly used? 1 Simple Polling Architecture
2 Polling Architecture with Interrupts
3 Supervisory Operating System + Application Software
4 General Purpose Embedded OS + Application Software
Question 8: What type of software is embedded software Classification and Composition of Embedded Software
The development of embedded systems is very fast, and the development of embedded software is even faster. Embedded software development is like the development of biology, from single-cell organisms to multi-cell, has been to the intelligent biological human beings, in the process, the structure of embedded software is becoming more and more complex, but the complex system is still evolving at the same time, the simple system is still indispensable. According to the division of software structure, the classification of embedded software is shown in Figure 1.
For single-threaded programs, there is no master control program, the structure is shown in Figure 2, a cyclic polling system, a finite state machine. For example, an arc cycle polling structure of the product packaging system, the system uses light sensing to determine whether there is a product needs to be packaged, once found on the conveyor belt there are objects, the main body of the program to control the execution of the packaging action. Single-threaded program has the advantage of a simple program, the execution of high efficiency, the disadvantage is that once the failure, the system can not automatically control and recovery, security is poor. Such as "cat and mouse" in the conveyor belt is not a product to be packaged, but a cat, the system will also be packaged, this time if the cat so that the packaging equipment failure, the program is still the same as in the past to find out whether there is a product, there is the implementation of the packaging instructions.
An interrupt-driven system solves this security problem. In the interrupt-driven system, there is a cyclic polling of the main program to control the execution of the interrupt response program, the program structure shown in Figure 3. For multiple interrupt requests occurring at the same time, to consider the interrupt request priority, as well as the response to the occurrence of errors, the main program will have to deal with more complex task management, when the main program has become a simple embedded operating system. If the packaging system above uses an interrupt-driven system, once an error occurs, there will be an error interrupt requesting the execution of an error response program, and the error response program will handle the error and return the system to normal.
Consider the case of a multi-tasking system with more tasks, multiple interrupt handling processes, such as to consider the allocation and management of storage, I/O control and management, multiple tasks or interrupt requests occurring at the same time, etc., interrupt-driven system will not be able to cope with it, and then the support of the embedded operating system is indispensable to complete the switching of tasks, scheduling, communication, synchronization, mutual exclusion, interrupt management It has to accomplish task switching, scheduling, communication, synchronization, mutual exclusion, interrupt management, clock management, etc. In some systems also need embedded database support, such as a micro customer management system (CRM) on the PDA. As shown in Figure 4, although we use a simple block diagram to describe the hierarchical structure of single-computer multitasking embedded software, we know that its program structure is far more complex than the several described earlier.
The needs of embedded systems have become more and more complex, and almost all applications on PCs have the need to be moved to embedded systems, such as online games through cell phones, PDAs, and other mobile devices, online shopping, online banking transactions, etc., which makes the embedded software even more complex, and requires not only an embedded operating system, embedded databases, but also network communication protocols, application support platforms, and so on. The architecture of the application software on this basis also becomes complex. As shown in Figure 5, the distributed embedded software system may be Peer-to-Peer structure, or B/S structure, etc..
Question 9: What are the job positions available in embedded systems? What types of companies offer them? What are the requirements? Job position requirements:
Industry: generally this kind of work are electronic R & D companies, Internet-related companies.
I hope my answer can help you, have a nice life!
Question 10: What kinds of embedded processors are categorized Embedded processor is the core of the embedded system, is the control, assist the system operation of the hardware unit. The scope is extremely broad, from the initial 4-bit processor, is still in large-scale application of 8-bit microcontroller, to the latest widely favored 32-bit, 64-bit embedded CPU. embedded microprocessor embedded microprocessor (Micro Processor UNIt, MPU) is evolved by the general-purpose computer in the CPU. It is characterized by a 32-bit processor or higher, with higher performance, and of course its price is correspondingly higher. However, unlike computer processors, in practical embedded applications, only the functional hardware that is closely related to the embedded application is retained and other redundant functional parts are removed, so that the special requirements of embedded applications can be realized with the lowest power consumption and resources. Compared with industrial control computers, embedded microprocessors have the advantages of small size, light weight, low cost and high reliability. Currently the main types of embedded processors are Am186/88, 386EX, SC-400, Power PC, 68000, MIPS, ARM/ StrongARM series. Among them, Arm/ StrongArm is an embedded microprocessor developed specifically for handheld devices and belongs to the mid-range price point. Embedded microcontroller embedded microcontroller (Microcontroller Unit, MCU) is typically represented by a microcontroller, from the late 1970s microcontroller appeared to today, although it has been more than 20 years of history, but this 8-bit electronic devices are still in embedded devices still have an extremely wide range of applications. The microcontroller chip internally integrates ROM/EPROM, RAM, bus, bus logic, timer/counter, watchdog, I/O, serial port, pulse width modulation output, A/D, D/A, Flash RAM, EEPROM, and other necessary functions and peripherals. Compared with embedded microprocessors, the most important feature of microcontrollers is monolithic and greatly reduced in size, which leads to a reduction in power consumption and cost, and an increase in reliability. Microcontrollers are currently the mainstream of the embedded systems industry. Microcontrollers are generally richer in on-chip peripheral resources and are suitable for control, hence the name microcontroller. Due to the MCU low price, excellent features, so have the most varieties and number of more representative, including 8051, MCS-251, MCS-96/196/296, P51XA, C166/167, 68K series and MCU 8XC930/931, C540, C541, and there is support for I2C, CAN-Bus, LCD and many specialized MCUs and compatible series. MCU currently accounts for about 70% of the market share of embedded systems. Recently Atmel produced Avr microcontroller due to its integrated FPGA and other devices, so it has a high cost-effective, is bound to promote the microcontroller to obtain a higher level of development. Embedded DSP processor Embedded DSP processor (Embedded Digital Signal Processor, EDSP), is a processor dedicated to signal processing, its system structure and instruction algorithms in the special design, with high compilation efficiency and instruction execution speed. In digital filtering, FFT, spectral analysis and other instruments, DSP has gained large-scale applications. the theoretical algorithms of DSP have appeared in the 1970s, but because the specialized DSP processor has not yet appeared, the theoretical algorithms can only be realized by discrete components such as MPUs, etc. MPUs' lower processing speed can not satisfy the algorithmic requirements of DSPs, and their application areas are only limited to some cutting-edge high-tech fields. Its application areas are only limited to some cutting-edge high-tech fields. With the development of large-scale integrated circuit technology, the world's first DSP chip was born in 1982. Its operation speed is dozens of times faster than MPU, and it is widely used in speech synthesis and coding decoder. To the mid-80s, with the progress and development of CMOS technology, the second generation of DSP chips based on CMOS process came into being, its storage capacity and computing speed have been exponentially improved, and become the basis of voice processing, image hardware processing technology. By the late 80's, the computing speed of DSP was further improved, and the application areas were expanded from the above scope to communications and computers. after the 90's, DSP developed to the fifth generation of products, with a higher degree of integration, and the use of a wider range. The most widely used is TI's TMS320C2000 ...... >>