Date of Birth Design Problem

Digital Electronics

Date of Birth

7-Segment Display

Driver Logic Circuit

abcdefg

X

Y

Z

Design a combinational logic circuit that meets the following design specifications:•There are three (3) three inputs and seven (7) outputs.

•As the inputs count from 000 to 111, the outputs (a – g) will generate the logic to display a date of birth (DOB) on a 7-segment display.

•The 7-segment display is a common cathode display.

•The DOB will be displayed in the MM-DD-YY format.

Design Specifications

2

X Y Z Display

0 0 0

0 0 1

0 1 0

0 1 1

1 0 0

1 0 1

1 1 0

1 1 1

Example – DOB 02/13/10

February 13, 1910 (02-13-10) is the date of birth of William Shockley. Shockley, along with John Bardeen and Walter Brattain, invented the transistor while working at Bell Labs in the 1940s.

3

X Y Z Display a b c d e f g

0 0 0 1

0 0 1 1

0 1 0 0

0 1 1 0

1 0 0 1

1 0 1 0

1 1 0 0

1 1 1 1

DOB Truth Table

4

X Y Z Display a

0 0 0 1

0 0 1 1

0 1 0 0

0 1 1 0

1 0 0 1

1 0 1 0

1 1 0 0

1 1 1 1

K-Map for Segment (a)

1 1

0 0

0 1

1 0

YX

YX

YX

YX

ZZ

Y X

XYZ

Z Y

Z Y X Z YY Xa 5

Segment (a) – AOI Logic

X Y Z

a

6

K-Map for Segment (b)

Z X

Z X ZY Y Xb

X Y Z Display b

0 0 0 1

0 0 1 1

0 1 0 0

0 1 1 1

1 0 0 1

1 0 1 0

1 1 0 1

1 1 1 1

7

1 1

0 1

1 1

1 0

YX

YX

YX

YX

ZZ

Y X

YZ

Segment (b) – NAND Logic

X Y Z

b

8

K-Map for Segment (c)

Y X

Z Y

YX ZY Z Yc

X Y Z Display c

0 0 0 1

0 0 1 0

0 1 0 0

0 1 1 1

1 0 0 1

1 0 1 0

1 1 0 1

1 1 1 1

9

1 0

0 1

1 1

1 0

YX

YX

YX

YX

ZZ

YZ

Segment (c) – NOR Logic

X Y Z

c

10

All Segments

Z X ZY Y Xb

Z Y X Z YY Xa

ad YX ZY Z Yc

Z Y X Y Xe

Z Y X Z Y Xf Z Y Z Y X Y Xg 11

X Y Z

Segment a & d

Segment b

Segment c

Complete Date of Birth Circuit02-13-10

Segment e

Segment f

Segment g

AOI

NAND

NOR

NAND

AOI

NOR

Common Cathode7-Segment Display

12