09-10-2012, 12:29 PM
EMBEDDED SYSTEM
EMBEDDED SYSTEM.docx (Size: 406.45 KB / Downloads: 48)
What is Embedded System?
Embedded system employs a combination of software & hardware to perform a specific function. It is a part of a larger system which may not be a “computer”Works in a reactive & time constrained environment.
Any electronic system that uses a CPU chip, but that is not a general-purpose workstation, desktop or laptop computer is known as embedded system. Such systems generally use microprocessors; microcontroller or they may use custom-designed chips or both. They are used in automobiles, planes, trains, space vehicles, machine tools, cameras, consumer and office appliances, cell phones, PDAs and other handhelds as well as robots and toys. The uses are endless, and billions of microprocessors are shipped every year for a myriad of applications.
In embedded systems, the software is permanently set into a read-only memory such as a ROM or flash memory chip, in contrast to a general-purpose computer that loads its programs into RAM each time. Sometimes, single board and rack mounted general-purpose computers are called "embedded computers" if used to cont
Embedded System Applications :-
• Consumer electronics, e.g., cameras, cell phones etc.
• Consumer products, e.g. washers, microwave ovens etc.
• Automobiles (anti-lock braking, engine control etc.)
• Industrial process controller & defense applications.
• Computer/Communication products, e.g. printers, FAX machines etc.
• Medical Equipments.
• ATMs
• Aircrafts
DIFFERENCE BETWEEN MICROPROCESSORS
AND MICROCONTROLLERS:
• A Microprocessor is a general purpose digital computer central processing unit(C.P.U) popularly known as CPU on the chip. The Microprocessors contain no RAM, no ROM, and no I/P O/P ports on the chip itself.
• On the other hand a Microcontroller has a C.P.U(microprocessor) in addition to a fixed amount of RAM, ROM, I/O ports and a timer all on a single chip.
• In order to make a Microprocessor functional we must add RAM, ROM, I/O Ports and timers externally to them,i.e any amount of external memory can be added to it.
• But in controllers there is a fixed amount of memory which makes them ideal for many applications.
• The Microprocessors have many operational codes(opcodes) for moving data from external memory to the C.P.U
• Whereas Microcontrollers may have one or two operational codes.
Difference between CISC and RISC:
CISC stands for Complex Instruction Set Computer. Most PC's use CPU based on this architecture. For instance Intel and AMD CPU's are based on CISC architectures. Typically CISC chips have a large amount of different and complex instructions. In common CISC chips are relatively slow (compared to RISC chips) per instruction, but use little (less than RISC) instructions. MCS-51 family microcontrollers based on CISC architecture.
RICS stands for Reduced Instruction Set Computer. The philosophy behind it is that almost no one uses complex assembly language instructions as used by CISC, and people mostly use compilers which never use complex instructions. Therefore fewer, simpler and faster instructions would be better, than the large, complex and slower CISC instructions. However, more instructions are needed to accomplish a task. Atmell’s AVR microcontroller based on RISC architecture.
8051 Architecture Overview
The 8051 family is one of the most common microcontroller architectures used worldwide. 8051 based microcontrollers are offered in hundreds of variants from many different silicon manufacturers
.The 8051 is based on an 8-bit CISC core with Harvard architecture. It's an 8-bit CPU, optimized for control applications with extensive Boolean processing (single-bit logic capabilities), 64K program and data memory address space and various on-chip peripherals.
The 8051 microcontroller family offers developers a wide variety of high-integration and cost-effective solutions for virtually every basic embedded control application. From traffic control equipment to input devices and computer networking products, 8051 u.c deliver high performance together with a choice of configurations and options matched to the special needs of each application. Whether it's low power operation, higher frequency performance, expanded on-chip RAM, or an application-specific requirement, there's a version of the 8051 microcontroller that's right for the job.
When it's time to upgrade product features and functionality, the 8051 architecture puts you on the first step of a smooth and cost-effective upgrade path - to the enhanced performance of the 151 and 251 microcontrollers.
ALE/PROG
Address Latch Enable is an output pulse for latching the low byte of the address during accesses to external memory. This pin is also the program pulse input (PROG) during Flash programming. In normal operation, ALE is emitted at a constant rate of 1/ 6 the oscillator frequency and may be used for external timing or clocking purposes. Note, however, that one ALE pulse is skipped during each access to external data memory. If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has no effect if the microcontroller is in external execution mode.
ELECTROMAGNETIC RELAYS
A relay is an electrically controllable switch widely used in industrial controls, automobiles and appliances. It allows the isolation of two separate sections of a system with two different voltage sources. The electromechanical (or electromagnetic) relay (EMR) has 3 components: the coil, spring and contacts. When current flows through the coil, a magnetic field is created around the coil (the coil is energized) which causes the armature to be attracted to the coil. The armature’s contact acts like a switch and closes or opens a circuit.
When the coil is not energized, a spring pulls the armature to its normal state of open or closed.
EMBEDDED SYSTEM.docx (Size: 406.45 KB / Downloads: 48)
What is Embedded System?
Embedded system employs a combination of software & hardware to perform a specific function. It is a part of a larger system which may not be a “computer”Works in a reactive & time constrained environment.
Any electronic system that uses a CPU chip, but that is not a general-purpose workstation, desktop or laptop computer is known as embedded system. Such systems generally use microprocessors; microcontroller or they may use custom-designed chips or both. They are used in automobiles, planes, trains, space vehicles, machine tools, cameras, consumer and office appliances, cell phones, PDAs and other handhelds as well as robots and toys. The uses are endless, and billions of microprocessors are shipped every year for a myriad of applications.
In embedded systems, the software is permanently set into a read-only memory such as a ROM or flash memory chip, in contrast to a general-purpose computer that loads its programs into RAM each time. Sometimes, single board and rack mounted general-purpose computers are called "embedded computers" if used to cont
Embedded System Applications :-
• Consumer electronics, e.g., cameras, cell phones etc.
• Consumer products, e.g. washers, microwave ovens etc.
• Automobiles (anti-lock braking, engine control etc.)
• Industrial process controller & defense applications.
• Computer/Communication products, e.g. printers, FAX machines etc.
• Medical Equipments.
• ATMs
• Aircrafts
DIFFERENCE BETWEEN MICROPROCESSORS
AND MICROCONTROLLERS:
• A Microprocessor is a general purpose digital computer central processing unit(C.P.U) popularly known as CPU on the chip. The Microprocessors contain no RAM, no ROM, and no I/P O/P ports on the chip itself.
• On the other hand a Microcontroller has a C.P.U(microprocessor) in addition to a fixed amount of RAM, ROM, I/O ports and a timer all on a single chip.
• In order to make a Microprocessor functional we must add RAM, ROM, I/O Ports and timers externally to them,i.e any amount of external memory can be added to it.
• But in controllers there is a fixed amount of memory which makes them ideal for many applications.
• The Microprocessors have many operational codes(opcodes) for moving data from external memory to the C.P.U
• Whereas Microcontrollers may have one or two operational codes.
Difference between CISC and RISC:
CISC stands for Complex Instruction Set Computer. Most PC's use CPU based on this architecture. For instance Intel and AMD CPU's are based on CISC architectures. Typically CISC chips have a large amount of different and complex instructions. In common CISC chips are relatively slow (compared to RISC chips) per instruction, but use little (less than RISC) instructions. MCS-51 family microcontrollers based on CISC architecture.
RICS stands for Reduced Instruction Set Computer. The philosophy behind it is that almost no one uses complex assembly language instructions as used by CISC, and people mostly use compilers which never use complex instructions. Therefore fewer, simpler and faster instructions would be better, than the large, complex and slower CISC instructions. However, more instructions are needed to accomplish a task. Atmell’s AVR microcontroller based on RISC architecture.
8051 Architecture Overview
The 8051 family is one of the most common microcontroller architectures used worldwide. 8051 based microcontrollers are offered in hundreds of variants from many different silicon manufacturers
.The 8051 is based on an 8-bit CISC core with Harvard architecture. It's an 8-bit CPU, optimized for control applications with extensive Boolean processing (single-bit logic capabilities), 64K program and data memory address space and various on-chip peripherals.
The 8051 microcontroller family offers developers a wide variety of high-integration and cost-effective solutions for virtually every basic embedded control application. From traffic control equipment to input devices and computer networking products, 8051 u.c deliver high performance together with a choice of configurations and options matched to the special needs of each application. Whether it's low power operation, higher frequency performance, expanded on-chip RAM, or an application-specific requirement, there's a version of the 8051 microcontroller that's right for the job.
When it's time to upgrade product features and functionality, the 8051 architecture puts you on the first step of a smooth and cost-effective upgrade path - to the enhanced performance of the 151 and 251 microcontrollers.
ALE/PROG
Address Latch Enable is an output pulse for latching the low byte of the address during accesses to external memory. This pin is also the program pulse input (PROG) during Flash programming. In normal operation, ALE is emitted at a constant rate of 1/ 6 the oscillator frequency and may be used for external timing or clocking purposes. Note, however, that one ALE pulse is skipped during each access to external data memory. If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has no effect if the microcontroller is in external execution mode.
ELECTROMAGNETIC RELAYS
A relay is an electrically controllable switch widely used in industrial controls, automobiles and appliances. It allows the isolation of two separate sections of a system with two different voltage sources. The electromechanical (or electromagnetic) relay (EMR) has 3 components: the coil, spring and contacts. When current flows through the coil, a magnetic field is created around the coil (the coil is energized) which causes the armature to be attracted to the coil. The armature’s contact acts like a switch and closes or opens a circuit.
When the coil is not energized, a spring pulls the armature to its normal state of open or closed.