1 ECE 4950 – Integrated System Design I ECE 4950 - INTEGRATED SYSTEMS I Design - General Design...

1ECE 4950 – Integrated System Design I

ECE 4950 - INTEGRATED SYSTEMS I

Design - General Design Approach

Timothy Burg

ECE 495 – Integrated System Design I

Career Note: Communication Skills are Important

• Cover Letter Mistakes - some employers don't bother reading cover letters, most do. – Using the Wrong Cover Letter Format

• Include the date, the recipient's mailing address and your address.

– Not Proofing for Typos and Grammatical Errors• Employers tend to view typos and grammatical errors as

evidence of your carelessness and inability to write. Proofread every letter you send.

– Writing a Novel

http://career-advice.monster.com/resumes-cover-letters/cover-letter-tips/avoid-7-killer-cover-letter-mistakes/article.aspx?key=gsaa

http://career-advice.monster.com/in-the-office/workplace-issues/catch-common-grammatical-errors/article.aspx


Career Note: Communication Skills are Important

– Making Unsupported Claims• Too many cover letters from college students and recent

grads say the applicant has "strong written and verbal communication skills." Without evidence, it's an empty boast. Give some examples for each claim you make. Employers need proof.

– Not Sending a Real Cover Letter• Some job seekers type up a one or two-sentence "here's

my resume" cover letter, while others attach handwritten letters or sticky notes.

These same basic concepts apply to your technical writing!You need to show that you care about your work and are competent.

The reason I have you write so much in ECE495 is 1) so you can practice writing and 2) it is required to document your project.


Design Example – Design Tools are Required

The Mythical Man-Month: Essays on Software Engineering (1982) by Fred Brooks, whose central theme is that "adding manpower to a late software project makes it later"

A large programming project that does not use good design techniques is equivalent to a tar pit swallowing everything that enters.

http://en.wikipedia.org/wiki/Fred_Brooks


Design Example

IdentifyNeed Research

Specifications

Concepts

Design

Prototype

Testing

Retire

Maintain

Use by Customer(s)

Distribute and Sell

Manufacture

Note: The Design is the end product of the Design Process


Outline: Design Tools

• What is an Electrical Design?– A group of components connected together to

perform a function.• Functional Decomposition

– Top-down approach– Bottom-up approach


What is an Electrical Design?

Enough information to manufacture the system

Printed Wiring Board Layout Bill of Material (Parts List)

Wiring and Cable DiagramSoftware Design

Circuit Diagram

Mechanical Drawings

http://upload.wikimedia.org/wikipedia/commons/7/76/4_bit_counter.svg



• Schematic or Circuit Diagram– Simplified drawing – Symbols to represent components– Connections between the components

that determine functionality

Enough information to analyze and predict circuit behaviorhttp://en.wikipedia.org/wiki/Circuit_diagram

http://upload.wikimedia.org/wikipedia/commons/7/76/4_bit_counter.svg

http://en.wikipedia.org/wiki/File:Circuit_elements.svg



• Wiring and Cable Diagram– Wiring on the

components and between components

– Type of wire, color coding, methods of wire termination, and methods of wire and cable clamping


• Wiring and Cable Diagram– Reminder: Engineers use

Standards when useful or required

– DIN 72552 is an European standard for automobile electric terminal numbers, standardizing almost every contact in an automobile with a number code.

Always know that “30” is a connection to the battery


http://en.wikipedia.org/wiki/Standardization



• Printed Wiring Board (PWB)/Printed Circuit Board (PCB) Layout– Physical arrangement of components and wiring

on a printed circuit board



• Bill of Material (Parts List)

Board Parts Part Name / Description Part Description Digikey Part# Qty Schematic ID

LED diodeDIODE SCHOTTKY 30V 200MA 0603

641-1008-1-ND 2

5V Pwr Bus DecouplingCAP ELECT 47UF 10V VS SMD

PCE3875CT-ND 2C13, C1

24V Pwr Bus DecouplingCAP 220UF 35V ELECT FP SMD

PCE4444CT-ND 3C12, C10, C11

Power conn; board mountCONN HDR 4POS R/A KEY-Y 30GOLD A29446-ND 1J5

data conn; board mountCONN HEADER 18POS 2MM R/A GOLD WM18865-ND 1J4

pull up/down resistorRES 10K OHM 1/10W 5% 0402 SMD P10KJCT-ND 14

R11, R12, R14, R13, R15, R16, R17, R18, R10, R19, R20, R21, R22, R23

current limiting res for 5V LED

RES 274 OHM 1/4W 1% 1206 SMD P274FCT-ND 2R6, R5

current limiting res for 24V LED

RES 1.2K OHM 1/2W 5% 2010 SMD

541-1.2KWCT-ND 2R7, R8

red LEDLED 3.2X1.6MM 635NM RED CLR SMD

754-1165-1-ND 2

24VRedLED, 5VRedLED

green LEDLED 3X1.5MM 525NM GN WTR CLR SMD

754-1115-1-ND 2

24VGrnLED, 5VGrnLED



• Mechanical Drawings



• Software Design– Flowcharts– State transition diagrams– Algorithms

• Cost Estimates



• Prototype



• The product at the end of this class is an Electrical Design:– Schematic or Circuit Diagram– Wiring and Cable Diagram– Printed Circuit Board (PCB) Layout– Bill of Material (Parts List)– Mechanical Drawings– Software Flowcharts, State transition diagrams,

Algorithms– Cost Estimates– Working Prototype


Design Tools

• Need to turn a Technical Concept into an Engineering Solution that satisfies the Requirements

Functional DecompositionTop-down approachBottom-up approach


Functional Decomposition

• Design approach wherein a system is iteratively decomposed into smaller and smaller subsystems until component design is reached.


f(.)x y

f2(.)x2 y2

f1(.)x1 y1x y

f2(.)x2 y2

f1(.)

x1 y1x yf3(.)

x3 y3

f4(.)x4 y4

Top-Down Approach

Define inputs Define outputsDefine function

function

outputsoutputs

function

inputs inputs

N=0

N=1

N=2

outputs

function

inputs

outputs

function

inputs

outputs

function

inputs


Example – Drawing a House

Draw House

Draw Body Draw Roof Draw Door Draw Window

Rectangle Triangle

Rectangle Circle Rectangle Line

Transformer

Rectifier

Functional decomposition is used in a number of fields.

www.cs.washington.edu/education/online/cse142/slides/l-decomposition.ppt


Top-Down Approach

Level 0

Level 1

Level 2

Module f(*)InputsOutputsFunctionality

f1(*) f2(*)

f (*)yx

x yModule f1(*)InputsOutputsFunctionality

Module f2(*)InputsOutputsFunctionality



f1(*)x y

f3(*)

f4(*)


Example – Audio Amplifier

• Amplify signal <0.5V peak• Volume control, 0 – max volume• 50W to 8 Ohm load• Powered by 120V, 60Hz AC


Example – Audio Amplifier (Level 0)

Module Audio Power Amplifier

Inputs -Audio Input Signal: 0.5V peak-Power:120 Volts AC, 60 Hz-User volume control: variable control

Outputs -Audio output signal: 20V Peak at 2.5A

Functionality Amplify the input signal to produce a 50W max. output signal. The amplification should have variable user control. The output volume should be variable between no volume and a max peak volume level.



Module Buffer Amplifier

Inputs -Audio Input Signal: 0.5V peak-Power: +- 25V DC

Outputs -audio output signal: 0.5V peak

Functionality Buffer the input signal and provide unity voltage gain. It should have an input resistance >1M Ohm and an output resistance <100 Ohms

outputsfunction

inputs



outputsfunctioninputs

Module High Gain Amplifier

Inputs -Audio Input Signal: 0.5V peak-User volume control:variable control-Power: +/- 25V DC

Outputs -Audio output signal: 20v peak

Functionality Provide an adjustable voltage gain, between 1 and 40. It should have an input resistance >100k Ohms and an output resistance <100 Ohm

inputs

inputs



outputs

function

inputs

Module Power Supply

Inputs -120 V AC rms

Outputs -Power: +/- 25VDC with up to 3A of current with regulation of <1%

Functionality Convert AC wall outlet voltage to positive and negative DC output voltages, and provide enough current to drive all amplifiers



function

inputs

Module Power Output Stage

Inputs -Audio Input Signal: 20v peak-Power: +/- 25V DC

Outputs -Audio output signal: 20v peak at up to 2.5A

Functionality Provide unity voltage gain with output current as required by a resistive loads of up to 2.5A. It should have an input resistance > 1M Ohm and an output resistance < 1Ohm.

outputs



InputsOutputsFunctionality

Module f1(.)


Module f2(.)

Smoothing Filter

Regulator

Purchase

Purchase Purchase

Purchase ?No -> Another level of decomposition.


Module Transformer


Module Rectifier

Decompose the Power Supply Module


Top-Down Approach

• Some components may be constrained.• May want to incorporate a specific device.• Not best for innovation.


f(.)x y

f2(.)x2 y2

f1(.)x1 y1x y

f2(.)x2 y2

f1(.)

x1 y1x yf3(.)

x3 y3

f4(.)x4 y4

Bottom-Up Approach

Know that your design must include a specific subsystem or component.



Output power

function

inputs

Module Power Supply

Inputs -120 V AC rms

Outputs -Power: +- 12VDC with up to 3A of current with regulation of <1%

Functionality Convert AC wall outlet voltage to positive and negative DC output voltages, and provide enough current to drive all amplifiers

Your company uses the following power supply in ALL designs

Will have to define the functionality of the amplifier based on including this device

Voltage levels



Module Power Output Stage

Inputs -Audio Input Signal: 20V peak-Power: +- 25V DC

Outputs -audio output signal:10V peak at up to 1A

Functionality Provide unity voltage gain with output current as required by a resistive load of up to 2.5A. It should have an input resistance > 1M Ohm and an output resistance < 1Ohm.




Inputs -Audio Input Signal: 0.5v peak-Power:120 volts AC rms, 60 Hz-User volume control: variable control

Outputs -audio output signal:10VPeak value(not given directly, calculate from power output = 12.5W)



Bottom-Up Approach

• Facilitates use of standard or reusable components.• Lego approach – I have all of these pieces, what can I

build with the components I have?

http://www.trendhunter.com/embed-templates/photos?&url_title=lego-sculptures-more-amazing-lego-sculptures&ShortTitle1=10+Amazing+Lego+Sculptures...&picture_count=10&entry_id=21944&default_view=trends&current=8&CustomColor1=FF2D99&google_id=ca-pub-6837537963707689


Top-Down vs. Bottom-Up

• In reality both approaches are used iteratively.



• Build an audio amplifier using the company’s standard Integrated Buffer Amplifier + Power Supply.

Standard Must be Used




Inputs -Audio Input Signal: 0.5v-Power:120 volts AC, 60 Hz-User volume control: variable control

Outputs -audio output signal: ? Peak value(not given directly, calculate from power pain 20V)




BufferAmplifier

and10V, 5W

DC Supply

High GainAmplifier

Power OutputStage

AudioInputSignal

Power120VAC

BufferedInput

10V DC

DC Supply

Control Volume

AudioOutputSignal

This DC Supply is probably not the same as the one specified through the top-down approach.

Continue the rest of the design using a top-down design approach.


Summary

• Many tools available for organizing your design.• Size of the project will determine what tools are

useful.• Key point: Before starting a design project identify

the tools that are appropriate for your project.

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