17-08-2013, 03:34 PM
Concepts of Embedded System
[attachment=57208]
Embedded system
If we look around, we will find ourselves to be surrounded by computing systems. Every year
millions of computing systems are built destined for desktop computers (Personal Computers,
workstations, mainframes and servers) but surprisingly, billions of computing systems are built
every year embedded within larger electronic devices and still goes unnoticed. Any device
running on electric power either already has computing system or will soon have computing
system embedded in it.
What constitutes an embedded system?
Is it a piece of Hardware? Or is it software? Or is it a combination of both? The word Embedded
System refers to ―A Computer (similar to Desktop or Laptop) which has been designed to do
specialized tasks (unlike Desktop or Laptop)‖. A desktop is designed to serve as a general
purpose computer - it can perform a variety of functions (can act as a music system, as a business
machine, as a software development platform etc). Whereas, an embedded system is designed for
only a specific functionality (e.g. a Vending machine, or Media Player or a Printer). The
resources (memory and processor bandwidth) are tightly constrained in an embedded system.
Also the software which runs in embedded system generally has a close control over the system
hardware.
Hardware
Core element of an embedded system is the processor or a computational unit. Processors can act
as brain of the system. They can be programmed to do perform a task. This can be designed
using variety of options.
General Purpose Microprocessors
General purpose microprocessors are single chip semi conductor device which is a computer on
chip, but not a complete computer. Its CPU contains an Arithmetic & Logic Unit (ALU), a
Program Counter (PC), a Stack Pointer (SP), registers, a clock and interrupts circuit on a single
chip. To make complete micro computer, one must add memory usually ROM and RAM,
memory decoder, an oscillator, a number of serial and parallel ports
RELEVANT IMPORTANT CONCEPTS
Computer Architecture
Two common prevalent processor architectures are Neumann Vs Harvard. Von Neumann
architectures have same program and data memory space; both shares address bus and data bus.
Harvard architecture has different memory space for program and data. For each of them,
separate data bus and address bus are provided.
Instruction Set Architecture (ISA)
Reduced Instruction Set Computer (RISC) and Complex Instruction Set Computer
(CISC) stand for two different competing philosophies in designing modern computer
architecture.
RISC has simple primitive instructions and addressing modes. The instructions are of uniform
length, execute in one clock cycle & support pipelining. CISC chips have a large amount of
variable length, different and complex instructions and take longer than a clock cycle to execute.
CISC chips are relatively slow per instruction compared to RISC chips, but use fewer
instructions than RISC. Thus, RISC systems shorten execution time by reducing the clock cycles
per instruction, whereas CISC shorten execution time by reducing MIPS R2000 is a typical
product of pure RISC and Intel 80386 is a typical kind of pure CISC chip.
Introduction to Embedded C
Looking around, we find ourselves to be surrounded by various types of embedded systems.
Associated with each processor is the embedded software. If hardware forms the body of an
embedded system, embedded processor acts as the brain, and embedded software forms its soul. It is
the embedded software which primarily governs the functioning of embedded systems.
During infancy years of microprocessor based systems, programs were developed using assemblers
and fused into the EPROMs. There used to be no mechanism to find what the program was doing.
LEDs, switches, etc. were used to check correct execution of the program.
EMBEDDED SYSTEMS PROGRAMMING
Embedded systems programming is different from developing applications on a desktop
computers. Key characteristics of an embedded system, when compared to PCs, are as follows:
Embedded devices have resource constraints (limited ROM, limited RAM, limited stack
space, less processing power)
Components used in embedded system and PCs are different; embedded systems typically
uses smaller, less power consuming components. ·
Embedded systems are more tied to the
hardware.
Two salient features of Embedded Programming are code speed and code size. Code speed is
governed by the processing power, timing constraints, whereas code size is governed by
available program memory and use of programming language. Goal of embedded system
programming is to get maximum features in minimum space and minimum time.
Open Source
Generically, open source refers to a program in which the source code is available to the general
public for use and/or modification from its original design free of charge, i.e., open. Open source
code is typically created as a collaborative effort in which programmers improve upon the code
and share the changes within the community.
The free software movement was launched in 1983. In 1998, a group of individuals advocated
that the term free software should be replaced by open source software (OSS) as an expression
which is less ambiguous and more comfortable for the corporate world.[4]Software developers
may want to publish their software with an open source license, so that anybody may also
develop the same software or understand its internal functioning. With open source software,
generally anyone is allowed to create modifications of it, port it to new operating systems and
processor architectures, share it with others or, in some cases, market it.
[attachment=57208]
Embedded system
If we look around, we will find ourselves to be surrounded by computing systems. Every year
millions of computing systems are built destined for desktop computers (Personal Computers,
workstations, mainframes and servers) but surprisingly, billions of computing systems are built
every year embedded within larger electronic devices and still goes unnoticed. Any device
running on electric power either already has computing system or will soon have computing
system embedded in it.
What constitutes an embedded system?
Is it a piece of Hardware? Or is it software? Or is it a combination of both? The word Embedded
System refers to ―A Computer (similar to Desktop or Laptop) which has been designed to do
specialized tasks (unlike Desktop or Laptop)‖. A desktop is designed to serve as a general
purpose computer - it can perform a variety of functions (can act as a music system, as a business
machine, as a software development platform etc). Whereas, an embedded system is designed for
only a specific functionality (e.g. a Vending machine, or Media Player or a Printer). The
resources (memory and processor bandwidth) are tightly constrained in an embedded system.
Also the software which runs in embedded system generally has a close control over the system
hardware.
Hardware
Core element of an embedded system is the processor or a computational unit. Processors can act
as brain of the system. They can be programmed to do perform a task. This can be designed
using variety of options.
General Purpose Microprocessors
General purpose microprocessors are single chip semi conductor device which is a computer on
chip, but not a complete computer. Its CPU contains an Arithmetic & Logic Unit (ALU), a
Program Counter (PC), a Stack Pointer (SP), registers, a clock and interrupts circuit on a single
chip. To make complete micro computer, one must add memory usually ROM and RAM,
memory decoder, an oscillator, a number of serial and parallel ports
RELEVANT IMPORTANT CONCEPTS
Computer Architecture
Two common prevalent processor architectures are Neumann Vs Harvard. Von Neumann
architectures have same program and data memory space; both shares address bus and data bus.
Harvard architecture has different memory space for program and data. For each of them,
separate data bus and address bus are provided.
Instruction Set Architecture (ISA)
Reduced Instruction Set Computer (RISC) and Complex Instruction Set Computer
(CISC) stand for two different competing philosophies in designing modern computer
architecture.
RISC has simple primitive instructions and addressing modes. The instructions are of uniform
length, execute in one clock cycle & support pipelining. CISC chips have a large amount of
variable length, different and complex instructions and take longer than a clock cycle to execute.
CISC chips are relatively slow per instruction compared to RISC chips, but use fewer
instructions than RISC. Thus, RISC systems shorten execution time by reducing the clock cycles
per instruction, whereas CISC shorten execution time by reducing MIPS R2000 is a typical
product of pure RISC and Intel 80386 is a typical kind of pure CISC chip.
Introduction to Embedded C
Looking around, we find ourselves to be surrounded by various types of embedded systems.
Associated with each processor is the embedded software. If hardware forms the body of an
embedded system, embedded processor acts as the brain, and embedded software forms its soul. It is
the embedded software which primarily governs the functioning of embedded systems.
During infancy years of microprocessor based systems, programs were developed using assemblers
and fused into the EPROMs. There used to be no mechanism to find what the program was doing.
LEDs, switches, etc. were used to check correct execution of the program.
EMBEDDED SYSTEMS PROGRAMMING
Embedded systems programming is different from developing applications on a desktop
computers. Key characteristics of an embedded system, when compared to PCs, are as follows:
Embedded devices have resource constraints (limited ROM, limited RAM, limited stack
space, less processing power)
Components used in embedded system and PCs are different; embedded systems typically
uses smaller, less power consuming components. ·
Embedded systems are more tied to the
hardware.
Two salient features of Embedded Programming are code speed and code size. Code speed is
governed by the processing power, timing constraints, whereas code size is governed by
available program memory and use of programming language. Goal of embedded system
programming is to get maximum features in minimum space and minimum time.
Open Source
Generically, open source refers to a program in which the source code is available to the general
public for use and/or modification from its original design free of charge, i.e., open. Open source
code is typically created as a collaborative effort in which programmers improve upon the code
and share the changes within the community.
The free software movement was launched in 1983. In 1998, a group of individuals advocated
that the term free software should be replaced by open source software (OSS) as an expression
which is less ambiguous and more comfortable for the corporate world.[4]Software developers
may want to publish their software with an open source license, so that anybody may also
develop the same software or understand its internal functioning. With open source software,
generally anyone is allowed to create modifications of it, port it to new operating systems and
processor architectures, share it with others or, in some cases, market it.