Chapter 6

PreDES: A PRE-DESIGN TOOL FOR EMBEDDED SYSTEMS

6.1 Motivation for the PreDES

Embedded System design faces many risks and products take too long to get into market.

Products that do get into market may fail in the field causing great financial loss and

company reputation. Due to their very nature, embedded systems require vertical market

expertise, software knowledge, and hardware experience that must all come together in a

single solution. Bringing these disciplines together in a combined solution entails design

integration challenges. Current tool flows, simply do not address the components

selection for the efficient embedded systems design as an integrated approach. Thus there

is a need for a system that provides such technical expertise both in software and

hardware and at the same time considers various design parameters [35, 36, 66], essential

for the designer and thus enabling them to develop systems, which meet their

requirements completely.

Pre Design Tool for Embedded Systems (PreDES) is a framework by which the

designer will be able to select the various components for embedded systems design has

been proposed in this thesis. It primarily focuses on the selection of processor, RTOS,

IDE. In addition to this, it also helps in the selection of the language, input components

and output components which are described below. This system is not only capable of

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providing such expertise allowing users to develop their desired systems but also allow

designers to prioritize their specific requirements in order to provide alternative design

requirements to the designers, in case, their design requirements are not completely met.

6.2 Components Selection using PreDES

PreDES assumes that the designer needs to reuse the existing components to meet the

design constraints such as: time to market, efficiency, and cost. This needs the selection

and evaluation of following components with respective to the project:

Processor

The selection criteria of processor and its importance have been discussed in detail in

chapter 2 and chapter 3. There is a set of countless characteristics such as: number of data

line, number of address lines, cost, size, power consumption, operating temperature, size

of on-chip memory, number of counters, number of ports, number of interrupts, and

support of software. These characteristics will guide the designer for selecting the

processor. The history of the processor, selected for each project is maintained in the

system.

IDE

IDE selection and evaluation have been discussed in chapter 4. There exists several IDEs

in the market. Due to varying nature, embedded software development requires an

extraordinary range of tools which are available from different domains like commercial,

public and proprietary. The capabilities of these IDEs of one vendor are different from

the other and these capabilities are rapidly increasing because of the ever increasing

complexity of the embedded systems applications like medical electronics, defence,

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robotics, consumer electronics etc. The history of the IDE selected for each project is

maintained in the system .

. RTOS

The selection criteria of RTOS and its importance has already been discussed in detail, in

chapter 5. Embedded systems are continuously increasing their hardware and software

complexity moving to single-chip solutions (SoC). RTOS can be used to handle these

complexities. There are various types of RTOSs available with distinct features to meet

the requirements of the various applications. R TOSs are broadly classified into three

types, namely, the Hard Real Time RTOS, Firm Real Time RTOS and Soft Real Time

RTOS. The history of the RTOS selected for each project is maintained in the system.

Other Components Selection

Other I/O components and Languages used for embedded systems are also maintained in

the database of the system, which can be selected by the designer by providing the

required specifications. We have provided the facility to add or delete any design

component in the database.

6.3 Objectives of PreDES

The main objective of the system is to provide a mechanism with which designers are

able to select suitable components for embedded system design as described above. The

system deals with the graphical capture of specifications and requirements for embedded

systems development specified by designers. Based on these specifications and the

available data, a list of the most suitable embedded components is made available to the

designer. The designer can then select these components required for embedded software

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design. A vast database is maintained where specifications of different available

embedded components are stored. This database is searched whenever designers specify

their requirements and the components that match the requirements of the designer are

displayed.

These systems not only provide a mechanism for selection but also allow designers to

compare different components based on their applicability. This system also allows

designers to study various existing embedded systems, their characteristics and design

issues and their applications. Therefore, it acts as a pre-design tool for embedded system

designers where planning of design and development strategies can be done easily and

efficientl y.

6.4 Architecture of the PreDES

The basic architecture of the PreDES is shown in Figure 6.1. We have implemented the

system in VB6 as a front end and MS Access as a backend. The system consists of the

several components such as: Data Base, Search Engine, Front end, History, interface for

Processor selection, IDE Selection, RTOS selection, 110 Devices, and User Management.

The designer interacts with the tool by providing valid login name and password. The

designer may open new design for which he will specify all the requirements or

specifications through easily interactive QUI. Now, the tool will generate the design

report by selecting optimal design components, which are meeting the specifications

given by the designer by searching the existing database. And it also gives the other

alternatives that meet the design requirements so that he may get better design.

Otherwise, it will also link to the related web sites through which he will get the desired

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information if the desired component is not available in the database. We have

implemented different approaches for component selection which have been described in

their respective chapter. Simultaneously multiple designers can access the database and

get their design reports. It provides the facility to reuse the existing designs also.

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6.5 Features

The proposed system provides the following features.

1) Easy to use and maintain.

2) Allows the designer to select different components required for their embedded

system design on the basis of the project requirements.

3) History of the designed systems is maintained for future references and reuse.

4) Allow the designers to study the characteristics of existing embedded systems.

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5) Provision to add a component or a component specific feature and update the

database by individual designers.

6) Provision of a multi-user environment.

7) Providing security to avoid unauthorized use of the design.

8) It generates the pre design document along with the block diagram of every

project and maintains as a record for future reference.

9) Provision to select the IDE on various aspects specified in Chapter 4.

10) It acts as an expert system for embedded systems design.

11) It provides the integrated solution by selecting the appropriate components for

efficient embedded systems design.

Pre Design Document Generation

In the end, after selecting all the required components a design report will be generated

based on the following template:

1) Designer Login Name.

2) Name of Current Embedded System.

3) Processor Selected with its important features.

4) IDE Selected with its important features.

5) RTOS Selected with its important features.

6) Language used for implementing the project.

7) lIO components along with its quantity.

8) Block diagram of the current embedded systems.

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The PreDES will generate this document automatically for every project in as mentioned

in the template. This report can be used for future reference. Apart from this, it provides

with other alternative solutions that meet the designers' requirements.

Advantages:

• Fast access to wide range of components: The system provides a fast and easy access

to a wide range of embedded components and provides a greater choice in component

selection. A high speed searching mechanism helps to search and arrive at the

designer specifications from the database.

• System is scalable: The system provides scalability by supporting addition of latest

information to the database in order to keep the system updated.

• Multi-user support: multiple users can use the system at the same time. In order to

provide concurrency in multi user system, a locking mechanism is used for the

database to prevent the system from simultaneous updation.

• Design security: The system provides security to the designs implemented by

different designers with authentication. The designers are provided with user name

and password so that no designer can interfere with other designer'S design.

• Flexibility to designers: It provides flexibility to designers by allowing them to make

additions to the database. Designers can specify additional features to the

components, which can be utilized by future designers.

• System reliability: The system is highly reliable since stable storage technique has

been used to store data where probability of loss of stored data is minimized as far as

possible.

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• Pre Design Document Generation: It saves the time by generating the design

document automatically once selecting the required components for the current

project.

• Project Management: It maintains the all the projects that are designed for future

reference by individual designers in their respective tables.

• Vendors Database: It maintains the database of the different vendors for each

component along with the contact address, web links, and link to their products.

• Knowledge Provider: Technical information about all the components is provided so

that the designer may refer. This includes the referet:Ice designs, PPT presentations,

documents like word and PDF. These can be played from the PreDES itself so that

designer need not open from the corresponding tool. Thus it save the time and

provides the flexibility. And also provision to search any information through internet

can easily be done through the PreDES.

6.6 Snapshots of the PreDES

Few sample snapshots of the PreDES at different stages are depicted. These are: Designer

Login, Components Selection, Processor Selection, RTOS Selection, IDE Selection, IDE

Add, Design Document and Block Diagram, Processor information and RTOS

information respectively. These are user friendly, interactive, and helps to design efficient

embedded systems.

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Designer Login

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6.7 Feedback Results

Several designers who are involved in the design of embedded systems are evaluated the

performance of the PreDES which is described in this section. In order to do this, we

have designed the questioner which consists of twenty questions [Table6.1].

No 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

18 19 20

PreDES: A Pre Design tool for Embedded Systems Feedback form

Please fill the following profile questionnaire regarding the PreDES

Question Does the tool help in Processor Selection? Does the tool save the time of the designer in processor Selection?

Does the tool chosen the right processor? Would you like to use the tool for future projects to select the processor? Does the tool help in IDE Selection? Does the tool savc~ the time of the designer in IDE Selection? Does the tool chosen the right IDE?

Would you like to use the tool for future projects to select the IDE? . Does the tool help in RTOS Selee;tion? Does the tool save the time ofthe designer in RTOS Selection? Does the tool chosen the right RTOS? Would you like to use the tool for future projects to select the RTOS? Does the tool acts as a Pre Design Tool for Embedded Systems Design? Does it save the designer's time in selection of other 110 components? Does it help in project management? Would you like to recommend the tool for your friends? Does it Satisfies the intended purpose? If no, please give the reason: Does it need any modifications? If yes, what mod ifications? Any other comments would you like to give?

Name and Address Signature

Table 6.1: Feedback form of Pre DES.

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Answer YES/NO YES/NO

YES/NO YES/NO YES/NO YES/NO YES/NO

YES/NO YES/NO YES/NO YES/NO YES/NO YES/NO YES/NO YES/NO YES/NO YES/NO

YES/NO YES/NO YES/NO

The feedback of the PreDES is collected from several designers. Appendix A, gives their

organizations, and Appendix B gives their feedback. These results are analyzed into four

sections such as: Processor Selection, RTOS Selection, IDE Selection, and others.

Processor Selection: Four different questions are asked to see the performance of the

tool in order to select the processor that is given in table 6.2.

Question Yes No No Answer

Does the tool help in Processor Selection? 8 0 1

Does the tool save the time of the designer in processor Selection? 8 0

Does the tool choose the right processor? 8 0

, Would you like to use the tool for future projects to select the processor? 8 0

Table 6.2: Feedback Questions for the Processor Selection.

We have observed from the feedback the tool is performing the processor selection and

meeting the designer's requirements and save the design time. However it is found that

they have not answered population because of the insufficient database of the processors.

RTOS Selection: Four different questions are asked to see the performance of the tool in

order to select the RTOS which is given in table 6.3.

Question Yes No No Answer

Does the tool help in RTOS Selection? 7

Does the tool save the time of the designer in RTOS Selection? 7

Does the tool choose the right RTOS? 7

Would you like to use the tool for future projects to select the RTOS? 5 0 3

Table 6.3: Feedback Questions for the RTOS Selection.

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We have observed that the in the RTOS Selection few questions are not answer because

some of the designers are not using the RTOS in their projects. The answer No is due to

the database limitation.

IDE Selection: Four different questions are asked to see the performance of the tool in

order to select the IDE which is given in table6.4.

Question Yes No No Answer

Does the tool help in IDE Selection?

Does the tool save the time of the designer in IDE Selection?

Does the tool choose the right IDE?

9

9

8

Would you like to use the tool for future projects to select the IDE? 7

Table 6.4: Feedback Questions for the IDE Selection.

o

o o o

o

o

2

We have found from the feedback the PreDES helps in the IDE Selection. Out of all the

questions, only two designers are not answered the question number 4(Q4). This is

because he may be going to use the same IDE for the feature project as well.

Overall Performance

On evaluation, it was observed that the designers appreciated the PreDES and has

adopted it as a pre-design tool. This is an evident from t~e compilation shown in Table

6.5. Based on the feedback, some designers suggested enhancing the features by adopting

the following points:

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1. Size of the Database of all the components

2. Updation of the new components into the database

3. More parameters list

4. Recent reference designs ofthe embedded systems

5. Placing the order: Once they choose the components

6. Vendors address and contact detail

7. Browsing through the PreDES

8. Internet Enable

9. Provision to add the components by the designers

These suggestions were incorporated in the PreDES. The suggestions on dynamic

updation, and creation of complete database has been addressed in future study.

Question Yes No No Ans.

Does the tool acts as a Pre Design Tool for Embedded Systems Design? 9 0 0

Does it save the designer's time in selection of other I/O components? 9 0 0

Does it help in project management: 9 0 0

Would you like to recommend the tool for your friends? 9 0 0

Does it satisfy the intended purpose? 7 0 2

Does it need any modifications? 6 0 2

Table 6.5: Feedback Questions for overall Questions.

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6.8 Summary

The architecture of the PreDES is presented in this chapter highlights its importance. It

serves as a pre design tool for embedded systems design and acts as a project

management, Knowledge base for embedded systems designers. It helps in increasing the

designer productivity. The feed back results show that the system has wide acceptance

and performing to the intended funr.tionality. However, there is scope for improvement

of the system by incorporating the features like: internet enable, dynamic Updation of the

database by the designers, large database creation etc. These features will be incorporates

in the future work.

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