517 341: Digital 517 341: Digital Logic DesignLogic Design

Apisake HongwitayakornApisake Hongwitayakorn

e:e: apisake@cp.su.ac.th apisake@cp.su.ac.th

w:w: http://www.cp.su.ac.th/~apisake/course/5173http://www.cp.su.ac.th/~apisake/course/5173

41 41

What is this course all What is this course all about?about?

The fundamental of Digital LogicThe fundamental of Digital Logic Binary numbers and relate number Binary numbers and relate number

systemssystems Digital circuit building blockDigital circuit building block

How to designHow to design Combinational logic circuitsCombinational logic circuits Sequential logic circuitsSequential logic circuits

Course Course ManagementManagement

ClassClass

Lectures (2 hrs/week)Lectures (2 hrs/week) Apisake HongwitayakornApisake Hongwitayakorn Time: Thu 8:30-10:15Time: Thu 8:30-10:15 Venue: 1239 SciBldg-1Venue: 1239 SciBldg-1

Labs (3 hrs/week)Labs (3 hrs/week) Noppadol SukklomcheepNoppadol Sukklomcheep Time: Wed 12:05-14:45Time: Wed 12:05-14:45 Venue: 1227 SciBldg-1Venue: 1227 SciBldg-1

AssessmentAssessment Lecture : Lab = 75% : 25%Lecture : Lab = 75% : 25% Lecture:Lecture:

Assignments & QuizzesAssignments & Quizzes 20%20% MidtermMidterm 25%25% FinalFinal 30%30%

Lab: Lab: (details will be described)(details will be described) AttendanceAttendance Lab ReportsLab Reports MidtermMidterm FinalFinal

CoursewareCourseware

Lecture:Lecture: SlidesSlides** A tool called “WinLogiLab”A tool called “WinLogiLab”****

Lab:Lab: WorksheetsWorksheets

** Will be available on my webpage. Will be available on my webpage.**** Get this from http://www.gu.edu.au/??? Get this from http://www.gu.edu.au/???

Introduction to Introduction to Digital SystemsDigital Systems

Digital TechnologyDigital Technology

The term The term digitaldigital is derived from the is derived from the way computer perform operations way computer perform operations by counting digits.by counting digits.

Today, digital tech is applied in a Today, digital tech is applied in a wide range of areas.wide range of areas.

The tech has progressed from The tech has progressed from vacuum-tube to discrete transistors vacuum-tube to discrete transistors to complex ICs.to complex ICs.

Digital and Analog Digital and Analog QuantitiesQuantities

2 categories of electronic circuits:2 categories of electronic circuits: AnalogAnalog DigitalDigital

Analog quantity = continuous valuesAnalog quantity = continuous values Digital quantity = a discrete set of Digital quantity = a discrete set of

valuesvalues

Analog QuantityAnalog Quantity

Most things in nature Most things in nature analog form analog form Temperature, pressure, distance, etcTemperature, pressure, distance, etc

Smooth, continuous curve like this:Smooth, continuous curve like this:

Temp

Time

Digital QuantityDigital Quantity

Sampled-value representation Sampled-value representation (quantization)(quantization)

Each dot can be Each dot can be digitizeddigitized as a digital as a digital code (consists of 1s and 0s)code (consists of 1s and 0s)

Temp

Time

Digital AdvantagesDigital Advantages

Digital data can be processed and Digital data can be processed and transmitted more efficiently and transmitted more efficiently and reliably than analog data.reliably than analog data.

Digital data has a great advantage Digital data has a great advantage when storage is necessary.when storage is necessary.

Let’s talk about digital music…Let’s talk about digital music…

Digital MusicDigital Music

The media is very The media is very compact but higher-compact but higher-density (and density (and counting):counting): CDsCDs Memory cardsMemory cards

No more bulky and No more bulky and noise-prone media noise-prone media like cassette tapelike cassette tape

http://www.dpreview.com/news/0303/sandisk512mb1gbsdcard.jpghttp://www.wwwk.co.uk/images/homepage/compact-disc.jpg

http://www.cricketsoda.com/images/music/cassette_tape.jpg

Digital systems Digital systems are everywhere!!!are everywhere!!!

Binary Digits,Binary Digits,Logic Levels, &Logic Levels, &

Digital Digital WaveformsWaveforms

Binary DigitsBinary Digits

Binary system (either 0 or 1)Binary system (either 0 or 1) Bit (comes from Bit (comes from binary digitbinary digit))

Digital circuits:Digital circuits: 1 represents HIGH voltage1 represents HIGH voltage 0 represents LOW voltage0 represents LOW voltage

Groups of bits (combinations of 0s Groups of bits (combinations of 0s and 1s) are called and 1s) are called codescodes Being used to represent numbers, Being used to represent numbers,

letters, symbols, (i.e. ASCII code), letters, symbols, (i.e. ASCII code), instructions, and etc.instructions, and etc.

Logic LevelsLogic Levels

The voltages used to The voltages used to represent a 1 and 0 are represent a 1 and 0 are called called logic levelslogic levels.. Ideally, there is only HIGH (1) Ideally, there is only HIGH (1)

and LOW (0).and LOW (0). Practically, there must be Practically, there must be

thresholds to determine which thresholds to determine which one is HIGH or LOW or neither one is HIGH or LOW or neither of them.of them.

CMOS CMOS (2V to 3.3V (2V to 3.3V HIGH) HIGH) (0V. To 0.8V (0V. To 0.8V LOW) LOW)

HIGHHIGH(binary 1)(binary 1)

Not allowed

LOWLOW(binary 0)(binary 0)

VH(max)

VH(min)

VL(max)

VL(min)

Digital WaveformsDigital Waveforms

Voltage levels that are changing back Voltage levels that are changing back and forth between HIGH and LOWand forth between HIGH and LOW

(Ideal) pulse(Ideal) pulse

At At tt00 leading edge, at leading edge, at tt11 trailing trailing edgeedge

HIGH HIGH

LOW LOW

Positive-going pulse Negative-going pulse

t0 t1 t0 t1

Non-Ideal PulseNon-Ideal Pulse

Rise time Fall time

tr tf

tw

Pulse width

90%

50%

10%

Amplitude

Waveform Waveform CharacteristicsCharacteristics

Waveforms = series of pulses (called Waveforms = series of pulses (called pulse train)pulse train) PeriodicPeriodic

PeriodPeriod ( (TT) = ) = TT11 = = TT22 = = TT33 = … = = … = TTnn

FrequencyFrequency ( (ff) = 1/) = 1/TT

NonperiodicNonperiodic

T1 T2 T3

Duty CycleDuty Cycle

Ratio of the pulse width (Ratio of the pulse width (ttww) to the ) to the period (period (TT))

Duty cycle = ( Duty cycle = ( ttww / / TT ) x 100% ) x 100%

ExampleExample

From a portion of a periodic From a portion of a periodic waveform (as shown) determine:waveform (as shown) determine:

a)a) PeriodPeriod

b)b) FrequencyFrequency

c)c) Duty cycleDuty cycle

ttww

TT

0 1 10 11 t (ms)

Waveform & Binary Waveform & Binary InformationInformation

Bit time

1

0clock

1

0A

1 0 1 0 0 1 1 0 0 1 0 1Bit sequence represent

ed by waveform

A

Data TransferData Transfer

Binary data are transferred in two Binary data are transferred in two ways:ways: Serial – bits are sent one bit at a timeSerial – bits are sent one bit at a time Parallel – all the bits in a group are sent Parallel – all the bits in a group are sent

out on separate lines at the same time out on separate lines at the same time (one line for each bit) (one line for each bit)

Serial over ParallelSerial over Parallel Advantage: less transmission lineAdvantage: less transmission line Disadvantage: takes more timeDisadvantage: takes more time