Lecture #1Page 1ECE 4110– Digital SystemDesign

ECE 4110– Digital System DesignLecture #1

Agenda

1. Course Logistics2. Course Content3. Digital Review

Announcements

1. Welcome2. Homework #1 assigned

Lecture #1Page 2

Course Overview Instructor: Omar Elkeelany Office : 332 Brown Hall

Phone : (931)-372-3450Email :

oelkeelany@tntech.edu Web :http://iweb.tntehc.edu/oelkeelany

Lecture #1Page 3

Course Overview Textbook: “Digital Design: Principles and

Practices", 4th Addition

John F. Wakerly, Prentice Hall, 2006

Website:http://iweb.tntech.edu/oelkeelany/4110F13 all handouts, homework assignments are

ONLINE it is your responsibility to download assignments

Lecture #1Page 4

Course Overview Pre-requisites: ECE2110 / ECE3160

Grading: Homework/VHDL and Quizzes 20%Combo System project 20%Exam #1 20% Exam #2 20% Final Exam 20%

- Homework Assignments are due at the beginning of class.

- No Late homework will be accepted.

- No make up exams will be given, unless pre-excuesd before the test.

Plan on being available on the exam dates.

- Term paper assignment will be given for 5110 graduate level.

Lecture #1Page 5

Course OverviewWhere does this course fit into the Electrical Engineering

curriculum?

Lecture #1Page 6

Course Overview Where does this course fit into the Computer

Engineering curriculum?

Lecture #1Page 7

Course Content What is this course?

- In ECE2110 you learned: - basic combinational logic design - basic sequential logic design

- In ECE3160 you learned:

- how to implement logic circuits using off-the-shelf parts

- ECE4110 is a follow-on course that looks at:

- Large scale digital designs - Performance of digital circuitry - Programmable Logic

Lecture #1Page 8

Course Content What does "Large" mean?

- Large means that you can't do it by hand. We need a way to design and simulate Millions of gates

- K-maps for a Pentium would take too much paper

Lecture #1Page 9

Course Content We will learn VHDL in order to describe large digital designs

- VHDL is a text based Hardware Description Language

- We can simulate our digital designs created in VHDL

Lecture #1Page 10

Course Content We can also prototype our designs using an FPGA

- FPGA = Field Programmable Gate Array

- An FPGA is a programmable logic device

- In this course, we will implement our designs and test them in FPGA

hardware

Lecture #1Page 11

Course Content What topics will be covered?

1) VHDL (Exam #1 Topics)

2) Medium Scale Combinational Logic Devices3) More Complex Finite State Machines (Exam #2

Topics) 4) Computer Systems5) FPGA Timing and Implementation

For the 5110 level, a special assignment is to: Write an original research paper on a topic related to those in this course, such as:

Modern programmable logic devices, survey, features, comparisons, usage, etc.. Hardware description languages: survey, comparisons, usage, IP, etc. Sequential Logic Design methods

Lecture #1Page 12

Lecture #1Page 13

Digital Review

Combinational Logic

Combinational Logic Gates :

- Output depends on the logic value of the inputs

- no storage

Lecture #1Page 14

Digital Review

NOT out = in’ = in f(in) = in’ = in

OR out = a+b f(a,b) = a+b

AND out = a·b f(a,b) = a·b

Lecture #1Page 15

Digital Review

XOR out = ab f(a,b) = ab

NOR out = a+b f(a,b) = a+b

NAND out = a·b f(a,b) = a·b

Lecture #1Page 16

Digital Review

XNOR out = ab f(a,b) = ab

Also remember about XOR Gates:

f(a,b) = ab = (a’b + b’a)

Also remember the priority of logic operations (without parenthesis) is:

NOT, AND, OR

Lecture #1Page 17

Digital Review

DeMorgan’s Theorems

- Inverting the output of any gate results in the same function as the opposite gate (AND/OR) with inverted inputs

Lecture #1Page 18

Digital Review

DeMorgan’s Theorems

- Graphically : breaking the bar changes the logic function (AND-OR) under the break

out = a+b

out = a+b

out = a·b

1) Break bar

2) Change + to · under break

Lecture #1Page 19

Digital Review

Boolean Expressions Using SOP

- Logic functions can be described using a Sum of Products techniques- Sum of Products (SOP) is the summation of all minterms resulting in the truth table- A minterm is the expression for an input configuration which yields a TRUE output- A minterm expression is the AND’ing of the input "1" signal configuration

SOP Expression : f(a,b) = a’·b + a·b’

Note : un-minimized Boolean expression

Truth Tablea b out0 0 00 1 1 minterm m1 = a’·b1 0 1 minterm m2 = a·b’1 1 0

Lecture #1Page 20

Digital Review

Boolean Expressions Using POS

- Logic functions can be described using a Product of Sums techniques- Product of Sums (POS) is the multiplication of all maxterms resulting in the truth table- A maxterm is the expression for an input configuration which yields a FALSE output- A maxterm expression is the OR’ing of the input "0" signal configuration

POS Expression : f(a,b) = (a+b) · (a'+b')

Truth Tablea b out0 0 0 maxterm m0 = a+b (input configuration of 0's)0 1 11 0 11 1 0 maxterm m3 = a'+b' (input configuration of 0's)

Lecture #1Page 21

Digital Review

Boolean Expressions Using SOP & POS

- SOP and POS functions are equivalent

SOP Expression : f(a,b) = a’·b + a·b’

is equal to

POS Expression : f(a,b) = (a+b) · (a'+b')

Lecture #1Page 22

Digital Review

Karnaugh Maps

- K-maps provide a graphical method to find SOP/POS expressions

- K-maps also provide a graphical method to perform logic minimization

K-map SOP Process

1) Circle minterms to create SOP

2) Circle in Horizontal & Vertical manner

3) Circle in groups with powers of 2 (1,2,4,8,…)

Truth Table

a b out0 0 00 1 11 0 11 1 1

0 1

1 1

a 0 1

b 0 1

No dependency on b, minterm = a

No dependency on a, minterm = b

SOP expression : f(a,b) = a + b

Lecture #1Page 23

Digital Review

Karnaugh Maps

- K-maps provide a graphical method to find SOP/POS expressions

- K-maps also provide a graphical method to perform logic minimization

K-map POS Process

1) Circle maxterms to create SOP

2) Circle in Horizontal & Vertical manner

3) Circle in groups with powers of 2 (1,2,4,8,…)

Truth Table

a b out0 0 00 1 11 0 11 1 1

0 1

1 1

a 0 1

b 0 1

Dependency on a' and b', maxterm = a+b

POS expression : f(a,b) = a + b

Lecture #1Page 24

Digital Review

Sequential Logic- Concept of “Storage Element”

- With Storage, logic functions can depend on current & past values of inputs

- Sequential State Machines can be created

D-Flip-Flop

- on timing event (i.e., edge of clock input), D input goes to Q output

D Q

Q

D

Q

Q

CLK

tc2q

Lecture #1Page 25

Digital Review

State Machines

- Moore : Outputs depend on present state

- Mealy : Outputs depend on present state and current inputs

Lecture #1Page 26

Digital Review

State Machine Example : Design a 2-bit Gray Code Counter

00

01

11

10

1) Number of States? : 4

2) Number of bits to encode states? : 2n=4, n=2

3) Moore or Mealy? : Moore

For this counter, we can make the outputs be the state codes

Lecture #1Page 27

Digital Review

State Machine Example : Design a 2-bit Gray Code Counter

00

01

11

10

STATE

Current NextAcur Bcur Anxt Bnxt

0 0 0 1

0 1 1 1

1 1 1 0

1 0 0 0

0 1

0 1

Bcur 0 1

Acur 0 1

Anxt Logic

Anxt = Bcur

1 1

0 0

Bcur 0 1

Acur 0 1

Bnxt Logic

Bnxt = Acur’

D Q

Q

D Q

Q

A B

CLK

A

Bcounteroutput