Embedded systems are used to perform
specific tasks and designed to be specific. Basics of embedded systems like
definition, application, examples, block diagram and its different components
are covered in previous section. You can find it here. In this section we are
going to discuss some characteristics of embedded system. Any embedded system,
when decided to design or designed; some parameters are to be considered to
make the system reliable and useful. Following are some basic characteristics
of embedded system.
Characteristics or features of embedded
system: Processor power,
memory, operating system, reliability, performance, power consumption, NRE cost, unit
cost, size, flexibility,
time-to-prototype, time-
to-market, maintainability, correctness
and safety
1. Processor power: Major drawback of any embedded system is power consumption. Most of the embedded systems are remotely operated and needs battery as power source. Energy consumption by processor or controller is hence minimized to reduced power requirement.
2. Memory: Designer of embedded system must consider memory requirement and must make provision for future expansion. In embedded system, different types of memories are used like RAM, ROM, EPROM, PROM, etc. Secondary storage devices like HDD (hard disc drives) can be embedded into the some systems. Where some times flash memory can be used instead of secondary memory.
3. Operating system: Operating system is nothing but the mediator between system hardware and application software. Embedded system uses real time operating systems that are capable to calculate real time constraints and must operate with task deadlines. Generally these operating systems are small in size and can be loaded onto semiconductor memories.
4. Reliability: Reliability is the measure of how much you can rely on the proper functioning of system. Embedded systems are need to reliable over a long time period.
5. Performance: Performance of any embedded system must be same throughout the time used. There are different factors that affect performance of any system like aging, hardware and software.
6. Power consumption: We have already discussed processor power in first point, Systems generally works on battery and design of both software and hardware must take care of power saving techniques
7. NRE cost (Non recurring engineering cost): NRE cost is one time cost of any embedded system. In other words, NRE cost is one time investment done in embedded system like its money invested in design, research and development (R&D), hardware which needs not to change frequently where software might be changed as per requirement.
8. Unit cost: Unit cost is the cost of producing/manufacturing of individual unit of system without including NRE cost.
9. Flexibility: Flexibility of embedded system is the ability of to change the functions of system without investing in additional NRE cost. Embedded system need to flexible i.e. must change the behavior with small or no modification in hardware.
10. Time to prototype and time to market: It is time needed for designing and actual manufacturing of any embedded system till the final system that can be sold to end customers. Prototype is nothing but dummy system or second system which behaves like actual system.
11. Maintainability: Embedded system must be easy to maintain, repair or replace.
12. Correctness: Designed embedded system must give correct output throughout the usage. Some systems performance and sensitivity will lag due to aging or hardware/software issues.
13. Safety: It deals with possible damages that can happen to the operators, public and the environment due to breakdown of embedded system, or due to the emission of radioactive or hazardous materials from embedded products. The probability that the system will not cause harm, safety analysis is a must in product engineering to evaluate the anticipated damages and determine best course of action.
14. Throughput: Embedded: Embedded system may need to handle a lot of data in a short span of time; hence it must be capable to do so without lagging performance and accuracy without any compromise.
15. Response:The embedded system must react or response to the change in any events quickly.
16. Expected life-time: Selection of components for embedded system development decides system life expected to run.
17. Testing and Debug ability: Setting up test conditions will be difficult and determining what is wrong with the software will become a tedious task without testing and debug facility. Every embedded system must have testing and debug facility to rectify the errors or improve the system.
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