25-08-2017, 09:32 PM
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WHAT IS A SYSTEM?
“A system is a way of working, organizing or doing one or many tasks
according to a fixed plan, program, or set of rules”.
or
“A system is also an arrangement in which all its units assemble and work together according to the plan or program”.
DEFINITION- EMBEDDED SYSTEM
Embed” means “To fix firmly and deeply”.
“An embedded system is a microcontroller or microprocessor - based, software- driven, reliable, real time control system, autonomous or human or network- interactive, operating on diverse physical variables and in diverse environments and sold into a competitive and cost-conscious market”.
Or
“Information processing systems embedded or fixed into a larger system”.
CHARACTERISTICS OF EMBEDDED SYSTEMS
Intelligent Systems.
Must be dependable:
Reliability
Maintainability
Safety
Security
“Even perfectly designed systems can fail if the assumptions about the workload and possible errors turn out to be wrong. Making the system dependable must not be an after-thought, it must be considered from the very beginning”.
Must be efficient:
Energy efficient.
Code-size efficient (especially for systems on a chip).
Run-time efficient.
Weight efficient.
Cost efficient.
Dedicated towards a certain application.
Dedicated user interface.
Many Embedded Systems must meet real-time constraints:
A real-time system must react to stimuli from the controlled object (or the operator) within the time interval dictated by the environment.
For real-time systems, right answers arriving too late (or even too early) are wrong.
Frequently connected to physical environment through sensors and
actuators.
CLASSIFICATION OF EMBEDDED SYSTEMS
Small Scale Embedded Systems:
Designed with a single 8- or 16-bit microcontroller.
Have little hardware and software complexities.
Usually ‘C’ language is used to program.
Limited memory is available.
Medium Scale Embedded Systems:
Based on single or a few 16- or 32-bit microcontrollers or DSPs or RISCs.
RTOS, Simulator, Debugger, Source Code Engineering Tool, IDE programming tools are used.
Sophisticated Embedded Systems:
Have enormous hardware and software complexities.
Need scalable or configurable processors and programming logic
arrays.