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unda ental Hardware esi n

Embedded Systems

- Forwar Part II

Yuhua Chen

Sept 1st, 2009

University of Houston

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Outline

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Real-Time System Real-Time System

the system must respond to designated external or internalevents within a s eci ied ti e interval.

Soft Real-Time System if failure to meet the time constraint results only in degradederformance.

Hard Real-Time System If a time constraint is not met, the system is said to have

failed. Catastrophic: It can result in considerable risk to people, to

the environment, or to a system being monitored or controlled. Firm Real-Time System

Falls in between with a mix of the two kinds of tasks.

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Embedded Design and Development Process

Not too many years ago wra ed some re isters lo ic and busses around

the microprocessor. wrote a few lines of assembly language code

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e ugge , an s ppe .

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Good Old Days

Such an approach worked great when all wehad to concerns was

Microprocessor A handful of inputs and outputs

ew sma -sca e me um-sca e n egra e ga es Firmware that fits into a couple of PROMs

Conte orar e bedded a lications tend tofall into two groups Simple ones: run a toaster, microwave oven etc.

Sop isticate ones: contro a jet aircra t, managean entertainment system, or help to control anuclear reactor.

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Todays Embedded System

Today, delivering robust, reliable and well-

that easy.

magnitude more complex than any of those we

used to build. Designing by hand is no longer feasible. We cant simply wire a few parts together, hack out

,debug the collection. We need tools; we need formal methods.

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Design Tools Needed

Need tools

to perform simulations to simplify and interactively optimize the hardware,

software, and firmware.

to synthesize portions of that design either as a.

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Embedded System Development Life Cycle

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Embedded System Development Life Cycle (cont)

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Embedded System Development Life Cycle

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Hardware and Software Design

Hardware Design involves the design, development, and test of the physical

sys em arc ec ure Packaging Printed circuit boards And the individual components.

Software Design Entai s t e tas s or a gorit mic portion o t e

application. Ma be written in a hi h- level lan ua e assembler

or a mixture of the two. Work in assembly requires detailed knowledge of

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structure.

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Traditional Design Approach

Design the hardware components e gn e o ware com onen

Bring the two together

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Contemporary Methodologies Contemporary methodologies favor the combined and

simultaneous design of both the hardware and the.

The objective is to meeting system-level requirementsthrough trade- offs between these two.

rocess Ensuring a sound hardware and software

s ecification and in ut to the rocess Formulating the architecture for the system to be

designed

Providing an iterative approach to the design ofhardware and software

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Development Considerations

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Important Steps in Developing an Embedded System

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Interfacing to Outside World

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Debugging Skills

Debugging skills are essential, especially with .

All too often, magic replaces critical problem.

This circuit only operates properly in the

afternoon when the sun is out and I work on thisenc . . . y t e w n ow.

Gee, why? I dont know it ust does . . . I tried other laces

or times and it never works. Could it be the warmer temperature thats affecting

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,

as the answer?

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Summary

Our goal in designing embedded systems is to.

Our designs can affect peoples lives.

safe and as reliable as you can for each

a lication.Finally, remember that our responsibility for a

design does not end with design release.

Good luck and have fun.

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Review Questions

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Review Questions (cont)

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Review Questions (cont)

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