DESIGN METHODOLOGIES, DESIGN FLOWS, REQ, SPEC, SYSTEM ARCH -CRC, QA

1. EC8791
EMBEDDED AND REAL
TIME SYSTEMS
Mr.C.KARTHIKEYAN
AP/ECE/RMKCET

2. REVIEW UNIT 1 (i)
• COMPLEX SYSTEM & MICROPROCESSOR:
• System, Real time system, ERTS
• Characteristics of ES
• Challenges in ES design
• DESIGN PROCESS
• EX: MODEL TRAIN CONTROLLER

3.  Design methodologies
 Design flows
 Requirement Analysis
 Specifications
System analysis and architecture design
Quality Assurance
UNIT I (ii)SYSTEM DESIGN TECHNIQUES AND
NETWORKS

4. •Development of system
•Design process for Embedded Computing system
DESIGN METHODOLOGIES
When several people work together on a COMPLEX PROJECT, they need to
agree on who will do things and how they will get done.
explicit about process is important when people work together..
Why Design Methodologies?

5. The obvious goal of a design process is to create a product that does
something useful. Typical specifications for a product will include
functionality
manufacturing cost
Performance
power consumption
a design process has several important goals beyond function,
performance, and power. Three of these goals are summarized
below.
■ Time-to-market
-beat competitors to market
■ Design cost
■ Quality

6. Design Flows

7. Design flow
• Design flow: sequence of steps to be followed
in a design.
• 5 Models :
• Waterfall model
• Spiral model
• Successive refinement
• Hierarchical design flows
• Concurrent Engineering

8. 1. Waterfall model
Introduced by Royce , the first model proposed for the software
development process.
requirements
architecture
coding
testing
maintenance

9. Waterfall model 5 steps
• Requirements: determine basic characteristics.
• Architecture: decompose into basic modules.
• Coding: implement and integrate.
• Testing: exercise and uncover bugs.
• Maintenance: Periodical check to upgrade.

10. Waterfall model critique
• Multiple iterations
• Assumptions.
• an unrealistic design process
So, an alternative model of software development called the
spiral model .

11. 2.Spiral model
requirements
design
test
system feasibility
specification
prototype
initial system
enhanced system

12. Spiral model critique
• Successive refinement of system.
– Start with mock-ups, move through simple
systems to complex full-scale systems.
• Working through stages may take too much
time.

13. Successive refinement model
specify
architect
design
build
test
initial system
specify
architect
design
build
test
refined system
The system is built several times. A first system is used as a rough prototype,
and successive models of the system are further refined.

14. Hardware/software design flow
requirements
and
specification
architecture
hardware
design software design
integration
testing
Front end
Back end
Middle end

15. Hierarchical design flow
• Embedded systems must be designed across
multiple levels of abstraction:
– system architecture;
– hardware and software components.
– Eg: GPS interface with satellite

16. A hierarchical design flow for an
embedded system.

17. Concurrent engineering
• Large projects use many people from multiple
disciplines.
• Work on several tasks at once to reduce
design time.
• Feedback between tasks helps improve
quality, reduce number of later design
problems.

18. Concurrent engineering techniques
• Cross-functional teams.
• Concurrent product realization.
• Integrated product management.
• Early and continual supplier involvement
• Early and continual customer focus
Eg: Evolution of Tele Communication

20. Requirements analysis
• Requirements: informal description of what
customer wants.
• Specification: precise description of what design
team should deliver.
• The overall goal of creating a requirements
document is effective communication between
the customers and the designers. The designers
should know what they are expected to design
for the customers

21. 2 Types of requirements
• Functional: Comm.
• Non-functional:
– timing;
– power consumption;
– manufacturing cost;
– physical size;
– time-to-market;
– reliability.

22. A good set of requirements should
meet several tests
• Correctness- exactly what customer needs
• Unambiguousness- clear interpretation
• Completeness- all features must incorporate
• Verifiability-testing Consistency
• Modifiable-can update requirements easily.
• Traceable- monitoring regularly

24. Specifications
• Contract between the customer and architect
• UML is one specification/design language.
• SDL

25. 1.SDL
• State machine specification
language is the SDL language
which was developed by the
communications industry.
• Graphical spec(flowchart)

26. 2.State charts
• Ancestor of UML state diagrams.
• Provided composite states:
– OR states;
– AND states.
• Composite states reduce the size of the state
transition graph.

27. Statechart OR state
S1
S2
S3
S4
i1
i1
i2
i2
i2
traditional
S1
S2
S3
S4
i1
i1 i2
OR state
s123

28. Statechart AND state
S1-3 S1-4
S2-3 S2-4
S5
traditional
c
d
b a
r
c
d
b a
S1 S3
S2 S4
S5
AND state
c d
r
b a
sab
r
sa sb

29. 3. AND-OR tables
• way of specifying complex conditions:
y
y
cond1 T -
cond2 - T
cond3 - F

30. Cond 2

33. System analysis and architecture design
• In this section we consider how to turn a
specification into an architecture design.
• Methodology- CRC card

34. CRC cards
• The acronym CRC stands for the following
three major items
– Classes
– Responsibilities
– Collaborators

35. CRC card format
Class name:
Superclasses:
Subclasses:
Responsibilities: Collaborators:
Class name:
Class’s function:
Attributes:
front back

36. EX: CRC cards for elevator
• Real-world classes:
– elevator car, floor control, car control, car sensor

37. Elevator responsibilities and
collaborators
class responsibilities collaborators
Elevator car* Move up and down Car control, car
sensor, car control
sender
Car state Reads current
position of car
car sensor

39. Quality Assurance
The quality of a product or service can be judged by how well it
satisfies its intended function.
The quality assurance (QA) process is vital for the delivery of a
satisfactory System.
In this section we will concentrate on portions of the methodology
particularly aimed at improving the quality of the resulting system
ISO 9000
If process is crucial,
Documentation , communication are important
CMM-judging the org
Initial, repeatable, defined, manages, optimizing

40. SUMMARY
•DESIGN METHODS (T2M, Q, Cost)
•Design FLOWS (5)
•Requirement Analysis (2)
•SPECIFICATION (SDL)
•System analysis and architecture design (CRC)
•QA