LABORATORY11: Digital Logic Circuits

1 / 28

# LABORATORY11: Digital Logic Circuits - PowerPoint PPT Presentation

LABORATORY11: Digital Logic Circuits. General Engineering Polytechnic University. Objectives Logic Functions Sample Problem Truth Table Boolean Equation Karnaugh Maps (K-maps) Simplified Boolean Equation Combinational Logic Circuit. Integrated Circuits (ICs) IC Identification

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about 'LABORATORY11: Digital Logic Circuits' - sebastian

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

### LABORATORY11:Digital Logic Circuits

General Engineering

Polytechnic University

Objectives

Logic Functions

Sample Problem

Truth Table

Boolean Equation

Karnaugh Maps (K-maps)

Simplified Boolean Equation

Combinational Logic Circuit

Integrated Circuits (ICs)

IC Identification

Digital Logic Trainer

Materials for Lab

Problem Statement

Procedure

Written Assignment

Written Topics

Recitation Topics

Closing

Overview
Objectives
• Understand the functions of logic gates
• Become familiar with digital circuits Use you new knowledge to design & implement a combinational logic circuit using the digital trainer
Logic Functions
• AND - “The all or nothing operator”
• Output is high (1) only when ALL inputs are high (1)
• OR gate - “The any or all operator”
• Output is high (1) when at least ONE input is high (1)
• NOT (INVERTER) operator
• Output is opposite of input
• Only one input and one output
Logic Function

Logic Symbol

Boolean

Expression

Truth Table

Inputs Outputs

A

Y

AND

A

B

Y

B

A • B = Y

0

0

0

0

0

1

1

0

0

A

Y

1

1

1

A + B = Y

OR

B

0

0

0

0

1

1

1

0

1

1

A

Ā

1

1

NOT

A = Ā

0

1

1

0

Logic Functions
Sample Problem
• An ATM machine has three options, Print statement, Withdraw money, or Deposit Money
• The ATM machine will charge you \$1.00 if you:
• Want to withdraw
• Only want to print out your statement (no transactions at all)
A truth table is a table

that displays all possible

input combinations and

the resulting outputs.

INPUT OUTPUT

P = print C = charge

W = withdraw

D = deposit

0 = “do not” 0 = \$0.00

1 = “do” 1 = \$1.00

INPUTS

OUTPUT

W

D

C

P

0

0

0

0

0

0

1

0

0

1

0

1

1

0

1

1

1

1

0

0

1

0

1

0

1

1

0

1

1

1

1

1

Truth Table
INPUTS

OUTPUT

W

D

C

P

0

0

0

0

0

0

1

0

0

1

0

1

1

0

1

1

1

1

0

0

1

0

1

0

1

1

0

1

1

1

1

1

Boolean Equation

= PWD

Outputs with a value of “ONE” are kept

C =

+ PWD

+ PWD

+ PWD

+ PWD

Place output ONE in corresponding boxes.

Circle neighboring ONES in multiples of 2, try to find the greatest amount of “neighbors” Only overlap circles as a last resort

Karnaugh Maps (K-maps)

C = PWD+ PWD+ PWD + PWD + PWD

PWD

PWD

PWD

0

0

0

1

1

1

1

0

P

W

P

W

P

W

P

W

1

1

1

0

D

1

1

1

D

_

Why can’t you switch PW and PW?

Why can’t you loop the three

adjacent 1s in the top row together?

_ _

PWD

_

PWD

D

D

_

PWD

P

W

1

1

_ _

PWD

1

1

P

W

_

PWD

1

1

1

P

W

PWD

1

1

1

1

P

W

Simplified Boolean Equation

Opposite values cancel out

C =

W

_

+ PD

W

C =

+

P

D

W

+

P

D

W

+

P

D

D

D

+

P

Combinational Logic Circuit

W

W

P

_

PD

P

_

D

D

Integrated Circuits (ICs)
• Used to implement combinational logic circuits
• We use the TTL family (transistor transistor logic)
1

14

1

1

14

14

2

13

2

2

13

13

3

12

3

3

12

12

4

11

A 1

V cc

4

4

11

11

Y 1

A 6

5

10

5

5

10

10

A 1

V cc

A 2

Y 6

A 1

V cc

B 1

B 4

Y 2

A 5

6

9

B 1

B 4

6

6

9

9

Y 1

A 4

A 3

Y 5

Y 1

A 4

A 2

Y 4

7

8

Y 3

A 2

A 4

Y 4

B 2

7

7

8

8

B 3

B 2

B 3

GND

Y 4

Y 2

A 3

Y 2

A 3

GND

Y 3

GND

Y 3

IC Identification

7404

Inverter Chip

7408

AND Chip

7432

OR Chip

IC Chip

IC Chip

Digital Logic Trainer
• Complete diagram on page 98
• Points with a line through them represent the same connection line
Materials for Lab
• Digital/Analog Trainer
• 7432 2-Input OR gate IC
• 7408 2-Input AND gate IC
• 7404 Hex Inverter (NOT gate) IC
• Hook-up Wire
• Computer equipped with LabVIEW
Problem Statement
• A farmer has two barns
• A hen is free to move about.
• A supply of corn is moved periodically from one barn to the other.
• He wants to protect the hen from a predator fox, and also prevent the hen from eating the supply of corn.
• An engineering student is hired to design an alarm system, using digital electronics. It will activate under the following conditions:
• The fox and the hen are in the same barn.
• The hen and the corn supply are in the same barn.
Problem Statement
• Design a combination logic circuit that will accomplish this task.
• The design should be cost effective, using the least amount of gates and input variables.
• The logical output of the circuit should be connected to a lamp.
• The lamp being “on” indicates alarm activation
• The lamp being “off” indicates alarm deactivation.
• The fox and hen and corn must be present in either barn 1 or barn 2
• Presence in barn 1=“1”
• Presence in barn 2=“0”
Procedure
• Truth Table
• Determine what are the input variables and the output variable
• Decide how many combinations there should be
• Create and complete the truth table on a sheet of paper
• Truth Table
• Boolean Expression
• K-Map
• Simplified Boolean Expression
• Logic Circuit
• Digital Trainer
• LabVIEW Simulation
Procedure
• Boolean Expression
• Gather all the combinations that produced a “1” for the output
• Create a Boolean expression from these smaller expressions
• Truth Table
• Boolean Expression
• K-Map
• Simplified Boolean Expression
• Logic Circuit
• Digital Trainer
• LabVIEW Simulation
Procedure
• K-Map
• Create a K-Map table
• Be sure to only have one variable change states at a time from one box to another
• Use the Boolean expression to fill in the “1’s”
• Truth Table
• Boolean Expression
• K-Map
• Simplified Boolean Expression
• Logic Circuit
• Digital Trainer
• LabVIEW Simulation
Procedure
• Simplified Boolean Expression
• Use the K-Map to circle the pairs of 1’s
• The 1’s may only be circled in multiples of 2, starting from the largest possible combination and working its way down
• Write down the new simplified expression
• Truth Table
• Boolean Expression
• K-Map
• Simplified Boolean Expression
• Logic Circuit
• Digital Trainer
• LabVIEW Simulation
Procedure
• Logic Circuit Diagram
• Use the new simplified expression to design a logic circuit
• Truth Table
• Boolean Expression
• K-Map
• Simplified Boolean Expression
• Logic Circuit
• Digital Trainer
• LabVIEW Simulation
Procedure
• Digital Trainer
• Do NOT plug anything in until your instructor has looked over your work
• Use the logic circuit and IC chip diagram to create the actual circuit on the breadboard
• Be sure to connect each of the ICs to Ground and VCC - 5V
• Truth Table
• Boolean Expression
• K-Map
• Simplified Boolean Expression
• Logic Circuit
• Digital Trainer
• LabVIEW Simulation
AND

OR

NOT

Procedure
• LabVIEW Simulation
• With the use of your logic circuit diagram - recreate the circuit in LabVIEW
• The front panel should have three control switches representing the variables and one Boolean indicator to represent the output
• HINT: LabVIEW has the following built in comparison functions:
• Truth Table
• Boolean Expression
• K-Map
• Simplified Boolean Expression
• Logic Circuit
• Digital Trainer
• LabVIEW Simulation
Written Assignment
• Full Team Report (one report per team)
• Use the guidelines on page 5 for help
• Include original data with instructor’s initials
• Original tables and work should be re-written so it is legible
• Include a printout of the LabVIEW front and diagram panel
• Include the topics found on the next slide
• Remember to create a title page
Written Topics
• Each of the following topics must be addressed in the full report and should be placed in the proper sections
• What are possible applications of digital electronics?
• Account for any error made during the lab
• Compare the problem before and after it was simplified
• What are some advantages of minimization using digital logic?
Recitation Topics
• If your design did not work the first time, discuss why
• Discuss how the digital circuit and its design would be affected if barn one had an alarm bell and barn two has an alarm horn
Closing
• Return all the equipment back to your instructor