30-10-2012, 01:13 PM
EMBEDDED SYSTEMS
Embedded.docx (Size: 1.03 MB / Downloads: 48)
Embedded Systems SID.ppt (Size: 1.47 MB / Downloads: 36)
INTRODUCTION:
The first question that needs to be asked, is "What exactly is an embedded system?" To be fair, however, it is much easier to answer the question of what an embedded system is not, than to try and describe all the many things that an embedded system can be. An embedded system is frequently a computer that is implemented for a particular purpose. In contrast, an average PC computer usually serves a number of purposes: checking email, surfing the internet, listening to music, word processing, etc... However, embedded systems usually only have a single task, or a very small number of related tasks that they are programmed to perform.
Every home has several examples of embedded computers. Any appliance that has a digital clock, for instance, has a small embedded microcontroller that performs no other task than to display the clock. Modern cars have embedded computers onboard that control such things as ignition timing and anti-lock brakes using input from a number of different sensors.
Embedded computers rarely have a generic interface, however. Even if embedded systems have a keypad and an LCD display, they are rarely capable of using many different types of input or output. An example of an embedded system with I/O capability is a security alarm with an LCD status display, and a keypad for entering a password.
VARIOUS APPLICATIONS OF EMBEDDED SYSTEMS:
The uses of embedded systems are virtually limitless, because every day new products are introduced to the market that utilize embedded computers in novel ways. In recent years, hardware such as microprocessors, microcontrollers, and FPGA chips have become much cheaper. So when implementing a new form of control, it's wiser to just buy the generic chip and write your own custom software for it. Producing a custom-made chip to handle a particular task or set of tasks costs far more time and money. Many embedded computers even come with extensive libraries, so that "writing your own software" becomes a very trivial task indeed.
From an implementation viewpoint, there is a major difference between a computer and an embedded system. Embedded systems are often required to provide Real-Time response. A Real-Time system is defined as a system whose correctness depends on the timeliness of its response. Examples of such systems are flight control systems of an aircraft, sensor systems in nuclear reactors and power plants. For these systems, delay in response is a fatal error. A more relaxed version of Real-Time Systems, is the one where timely response with small delays is acceptable.
DOWNFALLS OF EMBEDDED SYSTEMS:
Embedded computers may be economical, but they are often prone to some very specific problems. A PC computer may ship with a glitch in the software, and once discovered, a software patch can often be shipped out to fix the problem. An embedded system, however, is frequently programmed once, and the software cannot be patched. Even if it is possible to patch faulty software on an embedded system, the process is frequently far too complicated for the user.
Another problem with embedded computers is that they are often installed in systems for which unreliability is not an option. For instance, the computer controlling the brakes in your car cannot be allowed to fail under any condition. The targeting computer in a missile is not allowed to fail and accidentally target friendly units. As such, many of the programming techniques used when throwing together production software cannot be used in embedded systems. Reliability must be guaranteed before the chip leaves the factory. This means that every embedded system needs to be tested and analyzed extensively.
WHY STUDY EMBEDDED SYSTEMS:
Embedded systems are playing important roles in our lives every day, even though they might not necessarily be visible. Some of the embedded systems we use every day control the menu system on television, the timer in a microwave oven, a cellphone, an MP3 player or any other device with some amount of intelligence built-in. In fact, recent poll data shows that embedded computer systems currently outnumber humans in the USA. Embedded systems is a rapidly growing industry where growth opportunities are numerous.
MICROCONTROLLER AND MICROPROCESSOR:
Microcontrollers differ from microprocessors in several ways. The main characteristic of microcontrollers is their wide variety of on-chip peripheral functions and memory that enable them to provide a single chip solution to many dedicated embedded designs.
Microprocessors such as the Pentium inside a personal computer have only the Central Processing Unit and Math Co-processing unit. These microprocessors do not have built in memory, input or output functions such as parallel ports or serial ports etc. They are optimized to provide only the raw arithmetic and logic functions required by the operating system at the highest speed. All other components required to make the computer such as memory, input/output ports, serial, parallel, and mass storage are provided by external chips and devices. The Pentium is designed to meet a broad range of general computing needs that are provided with a personal computer.
ABOUT 8051:
The Intel 8051 is an 8-bit microcontroller which means that most available operations are limited to 8 bits. There are 3 basic "sizes" of the 8051: Short, Standard, and Extended. The Short and Standard chips are often available in DIP form, but the Extended 8051 models often have a different form factor, and are not "drop-in compatable". All these things are called 8051 because they can all be programmed using 8051 assembly language, and they all share certain features (although the different models all have their own special features).
HISTORY OF 8051:
Intel Corporation fabricated the 8 – bit microcontroller which was referred as MCS-51 in 1981. This microcontroller was also referred as “system on a chip” because it has 128 bytes of RAM, 4Kbytes of ROM, 2 Timers, 1 Serial port, and four ports on a single chip. The CPU can work for only 8bits of data at a time because 8051 is an 8-bit processor. In case the data is larger than 8 bits then it has to be broken into parts so that the CPU can process conveniently. Most manufacturers have put 4Kbytes of ROM even though the quantity of ROM can be exceeded up to 64 K bytes.
Intel permitted other manufacturers to fabricate different versions of 8051 but with the limitation that code compatibility should be maintained. This has added advantage that if the program is written then it can be used for any version of 8051 despite of manufacturer.
Embedded.docx (Size: 1.03 MB / Downloads: 48)
Embedded Systems SID.ppt (Size: 1.47 MB / Downloads: 36)
INTRODUCTION:
The first question that needs to be asked, is "What exactly is an embedded system?" To be fair, however, it is much easier to answer the question of what an embedded system is not, than to try and describe all the many things that an embedded system can be. An embedded system is frequently a computer that is implemented for a particular purpose. In contrast, an average PC computer usually serves a number of purposes: checking email, surfing the internet, listening to music, word processing, etc... However, embedded systems usually only have a single task, or a very small number of related tasks that they are programmed to perform.
Every home has several examples of embedded computers. Any appliance that has a digital clock, for instance, has a small embedded microcontroller that performs no other task than to display the clock. Modern cars have embedded computers onboard that control such things as ignition timing and anti-lock brakes using input from a number of different sensors.
Embedded computers rarely have a generic interface, however. Even if embedded systems have a keypad and an LCD display, they are rarely capable of using many different types of input or output. An example of an embedded system with I/O capability is a security alarm with an LCD status display, and a keypad for entering a password.
VARIOUS APPLICATIONS OF EMBEDDED SYSTEMS:
The uses of embedded systems are virtually limitless, because every day new products are introduced to the market that utilize embedded computers in novel ways. In recent years, hardware such as microprocessors, microcontrollers, and FPGA chips have become much cheaper. So when implementing a new form of control, it's wiser to just buy the generic chip and write your own custom software for it. Producing a custom-made chip to handle a particular task or set of tasks costs far more time and money. Many embedded computers even come with extensive libraries, so that "writing your own software" becomes a very trivial task indeed.
From an implementation viewpoint, there is a major difference between a computer and an embedded system. Embedded systems are often required to provide Real-Time response. A Real-Time system is defined as a system whose correctness depends on the timeliness of its response. Examples of such systems are flight control systems of an aircraft, sensor systems in nuclear reactors and power plants. For these systems, delay in response is a fatal error. A more relaxed version of Real-Time Systems, is the one where timely response with small delays is acceptable.
DOWNFALLS OF EMBEDDED SYSTEMS:
Embedded computers may be economical, but they are often prone to some very specific problems. A PC computer may ship with a glitch in the software, and once discovered, a software patch can often be shipped out to fix the problem. An embedded system, however, is frequently programmed once, and the software cannot be patched. Even if it is possible to patch faulty software on an embedded system, the process is frequently far too complicated for the user.
Another problem with embedded computers is that they are often installed in systems for which unreliability is not an option. For instance, the computer controlling the brakes in your car cannot be allowed to fail under any condition. The targeting computer in a missile is not allowed to fail and accidentally target friendly units. As such, many of the programming techniques used when throwing together production software cannot be used in embedded systems. Reliability must be guaranteed before the chip leaves the factory. This means that every embedded system needs to be tested and analyzed extensively.
WHY STUDY EMBEDDED SYSTEMS:
Embedded systems are playing important roles in our lives every day, even though they might not necessarily be visible. Some of the embedded systems we use every day control the menu system on television, the timer in a microwave oven, a cellphone, an MP3 player or any other device with some amount of intelligence built-in. In fact, recent poll data shows that embedded computer systems currently outnumber humans in the USA. Embedded systems is a rapidly growing industry where growth opportunities are numerous.
MICROCONTROLLER AND MICROPROCESSOR:
Microcontrollers differ from microprocessors in several ways. The main characteristic of microcontrollers is their wide variety of on-chip peripheral functions and memory that enable them to provide a single chip solution to many dedicated embedded designs.
Microprocessors such as the Pentium inside a personal computer have only the Central Processing Unit and Math Co-processing unit. These microprocessors do not have built in memory, input or output functions such as parallel ports or serial ports etc. They are optimized to provide only the raw arithmetic and logic functions required by the operating system at the highest speed. All other components required to make the computer such as memory, input/output ports, serial, parallel, and mass storage are provided by external chips and devices. The Pentium is designed to meet a broad range of general computing needs that are provided with a personal computer.
ABOUT 8051:
The Intel 8051 is an 8-bit microcontroller which means that most available operations are limited to 8 bits. There are 3 basic "sizes" of the 8051: Short, Standard, and Extended. The Short and Standard chips are often available in DIP form, but the Extended 8051 models often have a different form factor, and are not "drop-in compatable". All these things are called 8051 because they can all be programmed using 8051 assembly language, and they all share certain features (although the different models all have their own special features).
HISTORY OF 8051:
Intel Corporation fabricated the 8 – bit microcontroller which was referred as MCS-51 in 1981. This microcontroller was also referred as “system on a chip” because it has 128 bytes of RAM, 4Kbytes of ROM, 2 Timers, 1 Serial port, and four ports on a single chip. The CPU can work for only 8bits of data at a time because 8051 is an 8-bit processor. In case the data is larger than 8 bits then it has to be broken into parts so that the CPU can process conveniently. Most manufacturers have put 4Kbytes of ROM even though the quantity of ROM can be exceeded up to 64 K bytes.
Intel permitted other manufacturers to fabricate different versions of 8051 but with the limitation that code compatibility should be maintained. This has added advantage that if the program is written then it can be used for any version of 8051 despite of manufacturer.