Design Project

StopWatch

Done

by Anwer Alsomaily

200841680

&

Abdullah Al-Karairi

200923910

For Dr. K QURESHI

Department of Electrical Engineering

EE 200 DIGITAL LOGIC CIRCUIT DESIGN

Introduction:

Due to importance of time in exams competition and other situations in our life, we

found that stopwatch is the most useful project we may do. This stopwatch should

have START/STOP/RESET functions and it counts up to 100 minutes (99:59)

then it rests itself.

:Equipment & ICs

4- Hexadecimal display

4- BCD counter (74-161)

1- 7408 AND Gate

1- 7400 NAND Gate

1- 7432 OR Gate

Clock Start/Stop

Reset

:Circuit logic work implantation

Lab Work

+5 V (RED)

We used it as a power supply for all IC's

0V "ground" (Blue)

We use it to set the initial value of the inputs (A,B,C,D) to be 0

To Ground All IC's.

Load (Orange)

We Connect it As Shown in the logic work Diagram; By that way

1st Counter will count up to 9 and rest it self at the same moment it gives a clock

pulse to 2nd Counter

2nd Counter Will count up to 5 then repeat it self, Once It is be came 5 & 1st Counter 9

they will give a clock pulse to the 3rd Counter which will count up to 9 and by the

same way 4th counter will be pulsed.

Clock (white)

Connected with SWETCH using And Gate to deactivate it when we want to stop

counting and the output of this and is connected to this clock of 1st counter.

Output "QA,QB,QC,QD" (Green)

The output of the counters are connected to hexadecimal display.

Clear (Black)

We connected all the clear together and connect it to active high pulser.

The stopwach was working duo to this table:

ClK Clear (invert) Load Display

up 1 1 Next state

up 0 x 0

up 1 0 Intial state (ABCD)

Defficalies:

At the beginning of our project we used 7493 BCD counter but we faced a

problem that 7493 counter before it goes to the next state it go back to the initial

state and start counting up to the needed state. So we tride to make the Counter

using JK FF But when we did the simulation on logicworks we found the the

connection was very complicated and it is very difficuat to do it on minilab. By

searching on the Internet we found BCD counter 74_161 (Fig 2 Last PIG) wich is

fuction well with our project.

7-segment displayer needs to be connected to a 7-segment decoder

in order to reduce the number of ICs and the cost of the circuit we used Hex-

Dicimal Diplayer. (Fig1 Last PG)

Conclusion:

At the end of our work the stopwatch was working as we planned. In this project

we touched the exciting part of digital design every issue was exciting challenge. The

most important part of this project that we covered what we have studied

experimentally and practice a new experience; also we had a good review for the

final Exam.

Hexadecimal Display connection

74-161 Internal structure

74-161 connection

BI

ABCD

49

ABCDEFG

5124

3

11

10

98613

12

BI

ABCD

49

ABCDEFG

5124

3

11

10

98613

12

BI

ABCD

49

ABCDEFG

5124

3

11

10

98613

12

BI

ABCD

49

ABCDEFG

5124

3

11

10

98613

12

a

gdot

a

gdot

a

gdot

+5V

a

gdot

62

30

QA

QB

QC

QD

R0

2R

01

CL

KB

CL

KA9

33 2

1

14

12

9811

QA

QB

QC

QD

R0

2R

01

CL

KB

CL

KA9

33 2

1

14

12

9811

QA

QB

QC

QD

R0

2R

01

CL

KB

CL

KA9

33 2

1

14

12

9811

QA

QB

QC

QD

R0

2R

01

CL

KB

CL

KA9

33 2

1

14

12

9811

QA

QB

QC

QD

16

1

RC

O

P T ABCD LO

AD

CL

R

CL

K

107

19

2 3456

14

13

12

11

15

QA

QB

QC

QD

16

1R

CO

P T ABCD LO

AD

CL

R

CL

K

107

19

2 3456

14

13

12

11

15

QA

QB

QC

QD

16

1

RC

O

P T ABCD LO

AD

CL

R

CL

K

107

19

2 3456

14

13

12

11

15

QA

QB

QC

QD

16

1

RC

O

P T ABCD LO

AD

CL

R

CL

K

107

19

2 3456

14

13

12

11

15