CS 2204 Laboratory
Digital Design
Haldun Hadimioglu
Computer and Information Science
3/30/2003
CS 2204
Title : Digital Logic and State
Machine Design
Credits : 4
Year : Sophomore
Format : Lectures and Laboratory
3-hour lectures
3-hour laboratory sessions
3/30/2003
Digital Design
2
CS 2204
Content : Digital circuit fundamentals
Theory, analysis, design
Digital clock
Car alarm
Traffic light controller
Vending machine controller
Four function calculator
Precursor to courses :
Computer Architecture : computer design (junior)
Advanced hardware design : chip design (senior)
3/30/2003
Digital Design
3
CS 2204 Laboratory
Emphasis on design
20 students per lab
2-student teams formed first week
Teams do lab projects and homework
How to approach a large design
Problem analysis and solving
3/30/2003
Digital Design
4
CS 2204 Laboratory
Introduces current digital design
techniques and tools
Team-oriented, top-down, core-based
design
Modern hardware development
environment
3/30/2003
Digital Design
5
CS 2204 Laboratory
Hardware development environment
Computer Aided Design (CAD) Software :
Xilinx Foundation (industry software)
Simulates hardware
Testing hardware : Digilent board
FPGA Chip on Digilent board
FPGA : Field Programmable Gate Array
Emulates hardware
3/30/2003
Digital Design
6
CS 2204 Laboratory
Why CAD Design ?
Circuit design and test before
physical implementation
Shorter and cheaper development
Design objectives reached faster
Speed, cost, power consumption, size, weight,
reliability,..
3/30/2003
Digital Design
7
CS 2204 Laboratory
Term Project Spring 2003 :
Game playing circuit
Human vs machine play against each
other
Derived from dominoes
Chance and thinking determine winner
Pieces of circuit completed in 3 to 4
week experiments (deadlines)
3/30/2003
Digital Design
8
Historical Trend
Mechanical components replaced by
Analog components and
Digital components
Analog components replaced by
Digital components
3/30/2003
Digital Design
9
Digital Revolution
Computers (laptops to supercomputers)
Microprocessors (Sun Sparc to Intel
Pentium 4)
Car engine controllers
Calculators
Video games
CD Players
Digital cameras
3/30/2003
Digital Design
10
Benefits of Digital Circuits
Moore’s Law holds since the 1960s
Every two years, number of
transistors on chips doubles
Every two years memory size doubles
Smaller size devices
3/30/2003
Digital Design
11
Digital Chip
Electronic components are placed in
Die area in center of the chip
There can be
50 million components
transistors
on a microprocessor die
A chip
The die
3/30/2003
Digital Design
12
Is It Always A Chip ?
NO !
Design on computers kept as
Circuit diagrams : traditional
Hardware Description Language (HDL)
programs : since 1980s
Companies license their design as
Intellectual Property (IP)
Circuit diagram/HDL program files
Used as core circuits
3/30/2003
Digital Design
13
Digital Circuits
A digital circuit consists of Gates and Flip-Flops
on chips
All chips on Printed Circuit Boards (PCBs)
Notch
A1
B1
Y1
A2
B2
Y2
GND
1
2
3
4
5
14 V cc
13 B 4
12 A 4
11 Y 4
10 B 3
6
9
7
8
A3
Y3
7408 AND gate Chip
3/30/2003
Digital Design
14
CS 2204 Digital Components
Gates
k
k
OR
m
k+m
m
OR gate
AND
k
k.m
NOT
k
NOT gate (inverter)
AND gate
Flip-flops
D
J
Q
Q
K
C
Q
D Flip-flop
3/30/2003
C
Q
J-K Flip-flop
Digital Design
15
A Digital Circuit
Car seat-belt alarm
Alarm sound if engine is running AND
seat-belt is NOT fastened
engine
Seat belt
Digital
circuit
alarm
engine
alarm
AND
Seat belt
3/30/2003
NOT
OR
Digital Design
AND
16
Another Digital Circuit
a
b
c
Digital
circuit
if a is 0 => y =a
if a is 1 => y = c
y(a, b, c)
Circuit
Diagram
(Traditional)
p
a
NOT
q
AND
b
OR
y(a, b, c)
c
3/30/2003
AND
r
Digital Design
17
The Same circuit
a
b
c
Digital
circuit
y(a, b, c)
if a is 0 => y =a
if a is 1 => y = c
VHDL
Program !
3/30/2003
--MULTIPLEXER
--VHDL STRUCTURAL MODELING
entity multiplexer is
port (A, B, C : in
y
: out
end multiplexer;
BIT;
BIT);
architecture structure of
multiplexer is
signal p, q, r: BIT;
begin
p <= NOT a;
q <= p AND b;
r <= a AND c;
y <= p OR q;
end structure;
Digital Design
18
1-bit Adder Design
A 1-bit Adder, Full Adder :
a ci
b
co s
a
s
1-bit
b
0 0
0
0 0
3/30/2003
0 1
1 0
1 1
0
0
...
1
0 1
0 1
1 1
Digital Design
Adder
co
ci
19
The 1-bit Adder
Circuit
Diagram
3/30/2003
Digital Design
20
Designing the 1-bit Adder
--FULL ADDER
--STRUCTURAL MODELING
entity fulladder is
port (A, B, CIN
SUM, COUT
end fulladder;
: in
: out
BIT;
BIT);
architecture structure of fulladder is
signal s1, s2, s3,s4,s5: BIT;
begin
s1 <= A xor B;
SUM <= s1 xor CIN;
s2 <= A and B;
s3 <= B and CIN;
s4 <= A and CIN;
s5 <= s2 or s3;
COUT <= s4 or s5;
end structure;
3/30/2003
Digital Design
VHDL
Program
21