1. Subject Name: Embedded system Design Subject Code: 10EC74
Prepared By: Aswini N , M N Praphul & Navya Vipin (TE)
Department: ECE
Date: 10/11/14
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2. UNIT 4
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3. TOPICS COVERED Things to consider in a design Product Life Cycle
TOPICS COVERED
Things to consider in a design
Product Life Cycle
Five steps to design
Identifying the Requirements, Formulating the Requirements Specification
The System Design Specification, System Specifications versus System Requirements
Partitioning and Decomposing a System
Functional Design, Architectural Design
Functional Model versus Architectural Model
Prototyping
Achiving the Project

4. Things to consider in a design
When we start thinking about a new product or add new features to an existing one, we need to see many things in detail.
The most important is the customer itself.
We need to learn about market and technology trade-offs.
Old Technlogy New Technology
Old Market
New Market
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5. Life Cycle Models
The life cycle models in embedded application breaks the development process into a series of interrelated activities.
Each activity plays a role of transforming its input (specification) into an output (a selected solution).
The common life cycle models are:-
Waterfall
V Cycle
Spiral
Rapid Prototype
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6. WATERFALL MODEL
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10. FIVE STEPS TO DESIGN Requirements Definition System Specification
Functional Design
Architectural Design
Prototyping
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11. The Design Process Approach is top down and iterative.
1 & 2 steps focus on capturing and formalizing the external behaviour of the system.
3,4 & 5 steps move inside the system and repeat the process for the internal implementation.
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12. Functional Design
Finding an appropriate internal functional architecture for the system.
Eg:- Aircraft Design. The top level functional model will consist of 3 major functions- take off, fly and Land.
All other sub systems design can be postponed later.
Functional description should be written by a knowledgeable person who will do the s/w- h/w development.
Successive refinements need to be done after doing the first round functional design.
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14. Functional Design Counter Example
Identifying the Functions:-
Navigation Radio Measurement System
User
Counter
Future Remote Computer
Factory
Test line
Counter
User
Remote Computer
Radio
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15. Architectural Design
Goal is to select the most appropriate solution to the original problems based on exploration of a variety of architectures.
Choose the best suited s/w-h/w portioning and allocation of functionality.
Map the functions to hardware.
Allocation of the different pieces of system functionality to the appropriate hardware and software blocks.
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16. Architectural Design Constraints that must be included are:-
The geographical distribution
Physical and user interfaces
System performance specifications
Timing constraints and dependability requirements
Power Consumption
Cost
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17. Hardware software Continuum
Hardware Hardware Design Requirements Or Software Software Design
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18. Hardware Architecture of the Counter
Reset
Signal to measure
Display
Counter-divider chain and Control
Microprocessor RAM
ROM
Clock system
Front panel controls
Power Supply
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19. Hardware Architecture of the Counter
Hardware parts:-
Microprocessor
Display
Front panel controls
Power system
Clock system (includes s/w also)
Software tasks include display task, measurement task, counter- divider chain control block and output task.
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20. Functional Vs Architectural Model
Functional Model- Describes a system through a set of interfacing functional elements.
The functional modules will interact using one of the three types of relations:-
Shared variable relation
Synchronization relation
Message transfer by port
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21. Functional Vs Architectural Model
Architectural Model- Describes the physical architecture of the system based on real components such as microprocessors, arrayed logics,SPPs, analog and digital components and the interconnections between them.
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22. Prototyping Leads to an operational system prototype.
Prototype implementation includes:-
Detailed design
Debugging
Validation
Testing
Prototyping is a bottom-up process.
Each level should be validated.
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23. Prototyping- Static Analyzing
Static Analysis should consider three areas:-
Coupling- Related to the complexities of relationships that exist among various system modules.
Cohesiveness- Measure of the functional homogenity of elements in the modules. Need to consider both external and internal relationships.
Complexity- Two types are Functional and Behavioral
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24. Prototyping- Analyzing
Functional Complexity is characterized by:-
No. of internal functions and relational components. Keep them small in number.
Interconnections among modules.
Behavioral Complexity is characterized by:-
Number of inputs an outputs. Target is small number.
Length and ease of reading and understanding the description of the module.
Flow control through the module.
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25. Prototyping- Dynamic Analyzing
Dynamic- determine how system will behave in a context.
Dynamic analysis considers the following factors:-
Behavioral Verification
Performance analysis
Trade-off analysis
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26. Other Considerations Capitalization
Essential to the contemporary design process.
Proper and Efficient exploitation of Intellectual Properties (IPs).
IPs are designs, often patented ,that can be sold to another party to develop and sell their product.
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27. Other Considerations Reuse
It is an activity to be performed during the functional and architectural design phases of the project.
To help designers shorten the development life cycle.
To be reused, a component needs to be:-
Well defined
Properly modularized
In conformance to some interchange standard.
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28. Other Considerations Requirements Traceability
The ability to follow the life of a requirement (from original specification ) in both forward and reverse directions through the entire design process.
Traceability provides many informations like:-
Means for the project manager and customer to monitor the development progress.
Confirms that the requirement has been faithfully implemented.
Means of identifying which h/w and s/w modules are affected, if a requirement changes.
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29. Other Considerations Requirements Management- It addresses:-
Requirement modifications
Changes
Improvements
Corrections
A clear procedure that facilitates a way to accommodate modifications has to be used during the whole design process.
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30. Archiving the Project
During the development of the project, a lot of information has been produced and there is need for retaining them.
Archiving means documentation of the records.
A typical project will have had many contributors:-
Product planning
Design and Development
Test
Manufacturing
Marketing
Sales
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31. Archiving the Project
Each of them will have information, knowledge, documentation and tools That will be important in the future.
Project
Source
Binaries
Libraries
Data Dictionary
Documentation
Make Files
Tools
Specifications
A Typical project software Directory
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32. Archiving the Project
Each of the groups participating in the development should have similar directory documenting their portion of the project.
If the source code or the ability to rebuild from sources is lost, future work on the project will be seriously affected.
All the s/w tools like CAD, CAM, FPGA modeling tool have product life cycle and need to be modified and updated.
So archiving (documenting) the complete developing environment- computer, hard drive, OS and so on is worth considering.
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