14-10-2016, 04:46 PM
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Introduction
An Embedded System is a combination of computer hardware and software, and perhaps additional mechanical or other parts, designed to perform a specific function. A good example is the microwave oven. Almost every household has one, and tens of millions of them are used every day, but very few people realize that a processor and software are involved in the preparation of their lunch or dinner.
This is in direct contrast to the personal computer in the family room. It too is comprised of computer hardware and software and mechanical components (disk drives, for example). However, a personal computer is not designed to perform a specific function rather; it is able to do many different things. Many people use the term general-purpose computer to make this distinction clear. As shipped, a general-purpose computer is a blank slate; the manufacturer does not know what the customer will do wish it. One customer may use it for a network file server another may use it exclusively for playing games, and a third may use it to write the next great American novel. At the possible risk of confusing you, it is important to point out that a general-purpose computer is itself made up of numerous embedded systems. For example, my computer consists of a keyboard, mouse, video card, modem, hard drive, floppy drive, and sound card-each of which is an embedded system. Each of these devices contains a processor and software and is designed to perform a specific function.
History and Feature
Given the definition of embedded systems earlier is this chapter; the first such systems could not possibly have appeared before 1971. That was the year Intel introduced the world's first microprocessor. This chip, the 4004, was designed for use in a line of business calculators produced by the Japanese Company Busicom. In 1969, Busicom asked Intel to design a set of custom integrated circuits-one for each of their new calculator models. The 4004 was Intel's response rather than design custom hardware for each calculator, Intel proposed a general-purpose circuit that could be used throughout the entire line of calculators. Intel's idea was that the software would give each calculator its unique set of features.
The microcontroller was an overnight success, and its use increased steadily over the next decade. Early embedded applications included unmanned space probes, computerized traffic lights, and aircraft flight control systems. In the 1980s, embedded systems quietly rode the waves of the microcomputer age and brought microprocessors into every part of our kitchens (bread machines, food processors, and microwave ovens), living rooms (televisions, stereos, and remote controls), and workplaces (fax machines, pagers, laser printers, cash registers, and credit card readers).
1.3 Real Time Systems
One subclass of embedded is worthy of an introduction at this point. As commonly defined, a real-time system is a computer system that has timing constraints. In other words, a real-time system is partly specified in terms of its ability to make certain calculations or decisions in a timely manner. These important calculations are said to have deadlines for completion. And, for all practical purposes, a missed deadline is just as bad as a wrong answer.
The issue of what if a deadline is missed is a crucial one. For example, if the real-time system is part of an airplane's flight control system, it is possible for the lives of the passengers and crew to be endangered by a single missed deadline. However, if instead the system is involved in satellite communication, the damage could be limited to a single corrupt data packet. The more severe the consequences, the more likely it will be said that the deadline is "hard" and thus, the system is a hard real-time system. Real-time systems at the other end of this discussion are said to have "soft" deadlines.
1.4 Characteristics of Embedded System
Embedded systems have a micro controller/microprocessor and a memory. Some embedded systems have a serial port or a network connection. They usually do not have key board screens or disk devices.
The characteristics of embedded systems are
1. Response
2. Testability
3. Reliability
4. Memory space
5. Program installation
6. Program consumption
7. Cost
8. Throughput
1.5 Applications
1. Military and aero space embedded software applications.
2. Communication applications.
3. Industrial automation and process control software.
4. Mastering the complexity of application.
5. Reduction of product design time.
6. Real time processing of ever increasing amounts of data.
7. Intelligent, autonomous sensor.
1.6 Overview of Embedded System Architecture
Every embedded system consists of custom-built hardware built around a Central Processing Unit (CPU). This hardware also contains memory chips onto which the software is loaded. The software residing on the memory chip is also called the ‘firmware’. The operating
System runs above the hardware, and the application software runs above the operating system. The same architecture is applicable to any computer including a desktop computer. However, there are significant differences. It is not compulsory to have an operating system in every embedded system. For small appliances such as remote control units, air conditioners, toys etc., there is no need for an operating system and you can write only the software specific to that application. For applications involving complex processing, it is advisable to have an operating system. In such a case, you need to integrate the application software with the operating system and then transfer the entire software on to the memory chip. Once the software is transferred to the memory chip, the software will continue to run for a long time you don’t need to reload new software.
1.7 BUILDING BLOCKS OF EMBEDDED SYSTEM
Now, let us see the details of the various building blocks of the hardware of an embedded system.
1. Central Processing Unit (CPU)
2. Memory (Read-only Memory and Random Access Memory)
3. Input Devices
4. Output devices
5. Communication interfaces
6. Application-specific circuitry
1.7.1 Central Processing Unit (CPU)
The Central Processing Unit (processor, in short) can be any of the following: microcontroller, microprocessor or Digital Signal Processor (DSP). A micro-controller is a low-cost processor. Its main attraction is that on the chip itself, there will be many other components such as memory, serial communication interface, analog-to digital converter etc. So, for small applications, a micro-controller is the best choice as the number of external components required will be very less. On the other hand, microprocessors are more powerful, but you need to use many external components with them. D5P is used mainly for applications in which signal processing is involved such as audio and video processing.
1.7.2 Memory
The memory is categorized as Random Access 11emory (RAM) and Read Only Memory (ROM). The contents of the RAM will be erased if power is switched off to the chip, whereas
ROM retains the contents even if the power is switched off. So, the firmware is stored in the ROM. When power is switched on, the processor reads the ROM; the program is program is executed.
1.7.3 Input devices
Unlike the desktops, the input devices to an embedded system have very limited capability. There will be no keyboard or a mouse, and hence interacting with the embedded system is no easy task. Many embedded systems will have a small keypad-you press one key to give a specific command. A keypad may be used to input only the digits. Many embedded systems used in process control do not have any input device for user interaction; they take inputs from sensors or transducers 1’fnd produce electrical signals that are in turn fed to other systems.
1.7.4 Output devices
The output devices of the embedded systems also have very limited capability. Some embedded systems will have a few Light Emitting Diodes (LEDs) to indicate the health status of the system modules, or for visual indication of alarms. A small Liquid Crystal Display (LCD) may also be used to display some important parameters.
1.7.5 Communication interfaces
The embedded systems may need to, interact with other embedded systems at they may have to transmit data to a desktop. To facilitate this, the embedded systems are provided with one or a few communication interfaces such as RS232, RS422, RS485, Universal Serial Bus (USB), and IEEE 1394, Ethernet etc.
1.7.6 Application-specific circuitry
Sensors, transducers, special processing and control circuitry may be required fat an embedded system, depending on its application. This circuitry interacts with the processor to carry out the necessary work. The entire hardware has to be given power supply either through the 230 volts main supply or through a battery. The hardware has to design in such a way that the power consumption is minimized.
1.7.7 Conclusion
Embedded Systems plays a vital role in our day today life. They are used for household appliances like microwave oven to the satellite applications. They provide good man to machine interface.
Automation is the further step in the world of Embedded Systems, which includes the elimination of the human being in the mundane applications. They are cost effective, accurate and can work in any conditions and round the clock.
DESIGN APPROACH
2.1 INTRODUCTION
Automobile information can be viewed on electronic maps via internet or specialized software. But they are easy to steal and the average motorist has very little knowledge of what it is all about. To avoid this kind of steal we are going to implement a system which provides more security to the vehicle.
In the existing system security log can be implemented in any kind of automobiles. If a burglar alarm can break open the lock then it becomes easy for the burglar to steal the vehicle. If the car is stolen then it is out of the owner control. User doesn’t have any awareness about the current location of the vehicle.
In the proposed system the GPS antenna is attached with the vehicle which has it’s own identification. The GPS locates the position of vehicle and transmits the data to the micro controller. The data will continuously transmit to the GSM modem connected to the micro controller. It automatically sends the location value of the vehicle to its owner as a SMS through GSM modem. This will be a much simpler low cost technique compared to others.
Circuit Explanation
The hardware interfaces to the microcontroller are LCD display, GSM modem, GPS modem. The design uses relay trigger for serial communication between the modems and microcontroller. A serial driver IC is used for converting TTL voltage levels to required voltage level. A GSM modem is used to send the position (Latitude and Longitude) of the vehicle from a remote place. The GPS locates the position of the vehicle and transmits the data to the microcontroller. This data will be continuously transmitted to the GSM modem to the microcontroller. It automatically sends the location of the vehicle toit’s owner as a SMS through GSM modem. An EEPROM is used to store the data received by the receiver.
HARDWARE DESCRIPTION
3.1 MICRO CONTROLLER
3.1.1 Introduction
Micro controller is a chip through which we can connect many other devices and also those are controlled by the program the program which burn into that chip. Microprocessors and microcontrollers are widely used in embedded systems products. Microcontroller is a programmable device. A microcontroller has a CPU in addition to a fixed amount of RAM, ROM, I/O ports and a timer embedded all on a single chip. The fixed amount of on-chip ROM, RAM and number of I/O ports in microcontrollers makes them ideal for many applications in which cost and space are critical.
The Intel 8051 is Harvard architecture, single chip microcontroller (µC) which was developed by Intel in 1980 for use in embedded systems. It was popular in the 1980s and early 1990s, but today it has largely been superseded by a vast range of enhanced devices with 8051-compatible processor cores that are manufactured by more than 20 independent manufacturers including Atmel, Infineon Technologies and Maxim Integrated Products.
8051 is an 8-bit processor, meaning that the CPU can work on only 8 bits of data at a time. Data larger than 8 bits has to be broken into 8-bit pieces to be processed by the CPU. 8051 is available in different memory types such as UV-EPROM, Flash and NV-RAM.
3.1.2 Features
1. 8K Bytes of Re-programmable Flash Memory.
2. RAM is 256 bytes.
3. 4.0V to 5.5V Operating Range.
4. Fully Static Operation: 0 Hz to 33 MHz’s
5. Three-level Program Memory Lock.
6. 256 x 8-bit Internal RAM.
7. 32 Programmable I/O Lines.
8. Three 16-bit Timer/Counters.
9. Eight Interrupt Sources.
10. Full Duplex UART Serial Channel.
11. Low-power Idle and Power-down Modes.
12. Interrupt recovery from power down mode.
13. Watchdog timer.
14. Dual data pointer.
15. Power-off flag.
3.1.3 Description
The AT89s52 is a low-voltage, high-performance CMOS 8-bit microcomputer with 8K bytes of Flash programmable memory. The device is manufactured using Atmel’s high density non-volatile memory technology and is compatible with the industry-standard
MCS-51 instruction set. The on chip flash allows the program memory to be reprogrammed
in system or by a conventional non-volatile memory programmer.
In addition, the AT89s52 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port and interrupt system to continue functioning. The power-down mode saves the RAM contents but freezes the oscillator disabling all other chip functions until the next hardware reset.
Introduction
An Embedded System is a combination of computer hardware and software, and perhaps additional mechanical or other parts, designed to perform a specific function. A good example is the microwave oven. Almost every household has one, and tens of millions of them are used every day, but very few people realize that a processor and software are involved in the preparation of their lunch or dinner.
This is in direct contrast to the personal computer in the family room. It too is comprised of computer hardware and software and mechanical components (disk drives, for example). However, a personal computer is not designed to perform a specific function rather; it is able to do many different things. Many people use the term general-purpose computer to make this distinction clear. As shipped, a general-purpose computer is a blank slate; the manufacturer does not know what the customer will do wish it. One customer may use it for a network file server another may use it exclusively for playing games, and a third may use it to write the next great American novel. At the possible risk of confusing you, it is important to point out that a general-purpose computer is itself made up of numerous embedded systems. For example, my computer consists of a keyboard, mouse, video card, modem, hard drive, floppy drive, and sound card-each of which is an embedded system. Each of these devices contains a processor and software and is designed to perform a specific function.
History and Feature
Given the definition of embedded systems earlier is this chapter; the first such systems could not possibly have appeared before 1971. That was the year Intel introduced the world's first microprocessor. This chip, the 4004, was designed for use in a line of business calculators produced by the Japanese Company Busicom. In 1969, Busicom asked Intel to design a set of custom integrated circuits-one for each of their new calculator models. The 4004 was Intel's response rather than design custom hardware for each calculator, Intel proposed a general-purpose circuit that could be used throughout the entire line of calculators. Intel's idea was that the software would give each calculator its unique set of features.
The microcontroller was an overnight success, and its use increased steadily over the next decade. Early embedded applications included unmanned space probes, computerized traffic lights, and aircraft flight control systems. In the 1980s, embedded systems quietly rode the waves of the microcomputer age and brought microprocessors into every part of our kitchens (bread machines, food processors, and microwave ovens), living rooms (televisions, stereos, and remote controls), and workplaces (fax machines, pagers, laser printers, cash registers, and credit card readers).
1.3 Real Time Systems
One subclass of embedded is worthy of an introduction at this point. As commonly defined, a real-time system is a computer system that has timing constraints. In other words, a real-time system is partly specified in terms of its ability to make certain calculations or decisions in a timely manner. These important calculations are said to have deadlines for completion. And, for all practical purposes, a missed deadline is just as bad as a wrong answer.
The issue of what if a deadline is missed is a crucial one. For example, if the real-time system is part of an airplane's flight control system, it is possible for the lives of the passengers and crew to be endangered by a single missed deadline. However, if instead the system is involved in satellite communication, the damage could be limited to a single corrupt data packet. The more severe the consequences, the more likely it will be said that the deadline is "hard" and thus, the system is a hard real-time system. Real-time systems at the other end of this discussion are said to have "soft" deadlines.
1.4 Characteristics of Embedded System
Embedded systems have a micro controller/microprocessor and a memory. Some embedded systems have a serial port or a network connection. They usually do not have key board screens or disk devices.
The characteristics of embedded systems are
1. Response
2. Testability
3. Reliability
4. Memory space
5. Program installation
6. Program consumption
7. Cost
8. Throughput
1.5 Applications
1. Military and aero space embedded software applications.
2. Communication applications.
3. Industrial automation and process control software.
4. Mastering the complexity of application.
5. Reduction of product design time.
6. Real time processing of ever increasing amounts of data.
7. Intelligent, autonomous sensor.
1.6 Overview of Embedded System Architecture
Every embedded system consists of custom-built hardware built around a Central Processing Unit (CPU). This hardware also contains memory chips onto which the software is loaded. The software residing on the memory chip is also called the ‘firmware’. The operating
System runs above the hardware, and the application software runs above the operating system. The same architecture is applicable to any computer including a desktop computer. However, there are significant differences. It is not compulsory to have an operating system in every embedded system. For small appliances such as remote control units, air conditioners, toys etc., there is no need for an operating system and you can write only the software specific to that application. For applications involving complex processing, it is advisable to have an operating system. In such a case, you need to integrate the application software with the operating system and then transfer the entire software on to the memory chip. Once the software is transferred to the memory chip, the software will continue to run for a long time you don’t need to reload new software.
1.7 BUILDING BLOCKS OF EMBEDDED SYSTEM
Now, let us see the details of the various building blocks of the hardware of an embedded system.
1. Central Processing Unit (CPU)
2. Memory (Read-only Memory and Random Access Memory)
3. Input Devices
4. Output devices
5. Communication interfaces
6. Application-specific circuitry
1.7.1 Central Processing Unit (CPU)
The Central Processing Unit (processor, in short) can be any of the following: microcontroller, microprocessor or Digital Signal Processor (DSP). A micro-controller is a low-cost processor. Its main attraction is that on the chip itself, there will be many other components such as memory, serial communication interface, analog-to digital converter etc. So, for small applications, a micro-controller is the best choice as the number of external components required will be very less. On the other hand, microprocessors are more powerful, but you need to use many external components with them. D5P is used mainly for applications in which signal processing is involved such as audio and video processing.
1.7.2 Memory
The memory is categorized as Random Access 11emory (RAM) and Read Only Memory (ROM). The contents of the RAM will be erased if power is switched off to the chip, whereas
ROM retains the contents even if the power is switched off. So, the firmware is stored in the ROM. When power is switched on, the processor reads the ROM; the program is program is executed.
1.7.3 Input devices
Unlike the desktops, the input devices to an embedded system have very limited capability. There will be no keyboard or a mouse, and hence interacting with the embedded system is no easy task. Many embedded systems will have a small keypad-you press one key to give a specific command. A keypad may be used to input only the digits. Many embedded systems used in process control do not have any input device for user interaction; they take inputs from sensors or transducers 1’fnd produce electrical signals that are in turn fed to other systems.
1.7.4 Output devices
The output devices of the embedded systems also have very limited capability. Some embedded systems will have a few Light Emitting Diodes (LEDs) to indicate the health status of the system modules, or for visual indication of alarms. A small Liquid Crystal Display (LCD) may also be used to display some important parameters.
1.7.5 Communication interfaces
The embedded systems may need to, interact with other embedded systems at they may have to transmit data to a desktop. To facilitate this, the embedded systems are provided with one or a few communication interfaces such as RS232, RS422, RS485, Universal Serial Bus (USB), and IEEE 1394, Ethernet etc.
1.7.6 Application-specific circuitry
Sensors, transducers, special processing and control circuitry may be required fat an embedded system, depending on its application. This circuitry interacts with the processor to carry out the necessary work. The entire hardware has to be given power supply either through the 230 volts main supply or through a battery. The hardware has to design in such a way that the power consumption is minimized.
1.7.7 Conclusion
Embedded Systems plays a vital role in our day today life. They are used for household appliances like microwave oven to the satellite applications. They provide good man to machine interface.
Automation is the further step in the world of Embedded Systems, which includes the elimination of the human being in the mundane applications. They are cost effective, accurate and can work in any conditions and round the clock.
DESIGN APPROACH
2.1 INTRODUCTION
Automobile information can be viewed on electronic maps via internet or specialized software. But they are easy to steal and the average motorist has very little knowledge of what it is all about. To avoid this kind of steal we are going to implement a system which provides more security to the vehicle.
In the existing system security log can be implemented in any kind of automobiles. If a burglar alarm can break open the lock then it becomes easy for the burglar to steal the vehicle. If the car is stolen then it is out of the owner control. User doesn’t have any awareness about the current location of the vehicle.
In the proposed system the GPS antenna is attached with the vehicle which has it’s own identification. The GPS locates the position of vehicle and transmits the data to the micro controller. The data will continuously transmit to the GSM modem connected to the micro controller. It automatically sends the location value of the vehicle to its owner as a SMS through GSM modem. This will be a much simpler low cost technique compared to others.
Circuit Explanation
The hardware interfaces to the microcontroller are LCD display, GSM modem, GPS modem. The design uses relay trigger for serial communication between the modems and microcontroller. A serial driver IC is used for converting TTL voltage levels to required voltage level. A GSM modem is used to send the position (Latitude and Longitude) of the vehicle from a remote place. The GPS locates the position of the vehicle and transmits the data to the microcontroller. This data will be continuously transmitted to the GSM modem to the microcontroller. It automatically sends the location of the vehicle toit’s owner as a SMS through GSM modem. An EEPROM is used to store the data received by the receiver.
HARDWARE DESCRIPTION
3.1 MICRO CONTROLLER
3.1.1 Introduction
Micro controller is a chip through which we can connect many other devices and also those are controlled by the program the program which burn into that chip. Microprocessors and microcontrollers are widely used in embedded systems products. Microcontroller is a programmable device. A microcontroller has a CPU in addition to a fixed amount of RAM, ROM, I/O ports and a timer embedded all on a single chip. The fixed amount of on-chip ROM, RAM and number of I/O ports in microcontrollers makes them ideal for many applications in which cost and space are critical.
The Intel 8051 is Harvard architecture, single chip microcontroller (µC) which was developed by Intel in 1980 for use in embedded systems. It was popular in the 1980s and early 1990s, but today it has largely been superseded by a vast range of enhanced devices with 8051-compatible processor cores that are manufactured by more than 20 independent manufacturers including Atmel, Infineon Technologies and Maxim Integrated Products.
8051 is an 8-bit processor, meaning that the CPU can work on only 8 bits of data at a time. Data larger than 8 bits has to be broken into 8-bit pieces to be processed by the CPU. 8051 is available in different memory types such as UV-EPROM, Flash and NV-RAM.
3.1.2 Features
1. 8K Bytes of Re-programmable Flash Memory.
2. RAM is 256 bytes.
3. 4.0V to 5.5V Operating Range.
4. Fully Static Operation: 0 Hz to 33 MHz’s
5. Three-level Program Memory Lock.
6. 256 x 8-bit Internal RAM.
7. 32 Programmable I/O Lines.
8. Three 16-bit Timer/Counters.
9. Eight Interrupt Sources.
10. Full Duplex UART Serial Channel.
11. Low-power Idle and Power-down Modes.
12. Interrupt recovery from power down mode.
13. Watchdog timer.
14. Dual data pointer.
15. Power-off flag.
3.1.3 Description
The AT89s52 is a low-voltage, high-performance CMOS 8-bit microcomputer with 8K bytes of Flash programmable memory. The device is manufactured using Atmel’s high density non-volatile memory technology and is compatible with the industry-standard
MCS-51 instruction set. The on chip flash allows the program memory to be reprogrammed
in system or by a conventional non-volatile memory programmer.
In addition, the AT89s52 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port and interrupt system to continue functioning. The power-down mode saves the RAM contents but freezes the oscillator disabling all other chip functions until the next hardware reset.