Combinational Logic
Student Design Problem: Date of Birth
Digital Electronics
© 2014 Project Lead The Way, Inc.
Design Specifications
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.
X
Y
Z
Date of Birth
7-Segment
Display
Driver Logic
Circuit
a
b
c
d
e
f
g
2
Example – DOB 02/13/10
X
Y
Z
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
Display
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
Date of Birth Truth Table
X
Y
Z
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
Display
a
b
c
d
e
f
g
4
Date of Birth Truth Table
X
Y
Z
a
b
c
d
e
f
g
0
0
0
1
1
1
1
1
1
0
0
0
1
1
1
0
1
1
0
1
0
1
0
0
0
0
0
0
0
1
0
1
1
0
1
1
0
0
0
0
1
0
0
1
1
1
1
0
0
1
1
0
1
0
0
0
0
0
0
1
1
1
0
0
1
1
0
0
0
0
1
1
1
1
1
1
1
1
1
0
Display
5
K-Map for Segment (a)
X
Y
Z
0
0
0
1
0
0
1
1
0
1
0
0
0
1
1
0
Display
a
1
0
0
1
1
0
1
0
1
1
0
0
1
1
1
1
XY
Z
Z
1
1
XY
0
0
XY
0
1
XY
1
0
XY
XYZ
YZ
a XYYZ XYZ
6
Segment (a) – AOI Logic
X
Y
Z
a
7
K-Map for Segment (b)
X
Y
Z
0
0
0
1
0
0
1
1
0
1
0
0
0
1
1
1
Display
b
1
0
0
1
1
0
1
0
1
1
0
1
1
1
1
1
XY
Z
Z
1
1
XY
0
1
XY
1
1
XY
1
0
XY
YZ
XZ
b XYYZ XZ
8
Segment (b) – NAND Logic
X
Y
Z
b
9
K-Map for Segment (c)
X
Y
Z
0
0
0
1
0
0
1
0
0
1
0
0
0
1
1
1
1
0
0
Display
c
Z
Z
XY
1
0
XY
0
1
XY
1
1
XY
1
0
YZ
YZ
1
1
0
1
0
1
1
0
1
1
1
1
1
XY
c  YZYZ XY
10
Segment (c) – NOR Logic
X
Y
Z
c
11
All Segments
a XYYZ XYZ
b XYYZ XZ
c  YZYZ XY
da
eXYXYZ
f  XYZ XYZ
g XY XYZYZ
12
X
Y
Z
Complete Date of Birth Circuit
02-13-10
AOI
Common Cathode
7-Segment Display
Segment a & d
NAND
Segment b
NOR
Segment c
AOI
Segment e
NAND
Segment f
NOR
Segment g
13