1. Date of Birth Design Problem
Digital Electronics
2.3 Date of Birth Design Problem
Date of Birth Design Problem
Digital Electronics
Project Lead The Way, Inc.
Copyright 2009

2. Design Specifications
Date of Birth Design Problem
Digital Electronics
2.3 Date of Birth Design Problem
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.
Date of Birth
7-Segment Display
Driver Logic Circuit a b c d e f g X Y Z
This slide contains the design specifications for the “Date of Birth” project.
Project Lead The Way, Inc.
Copyright 2009

3. Date of Birth Design Problem
Digital Electronics
2.3 Date of Birth Design Problem
Example – DOB 02/13/10 X Y Z
Display 1
February 13, 1910 ( ) 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.
This is an example of the “Date of Birth” problem using the birth date
Project Lead The Way, Inc.
Copyright 2009

4. Date of Birth Design Problem
Digital Electronics
2.3 Date of Birth Design Problem
DOB Truth Table X Y Z
Display a b c d e f g 1
This is the truth table column for Segment (a). After reviewing how this truth table was developed, pause the presentation and allow the students to complete the truth table columns for segments (b) thru (g). The complete truth table is on the next slide.
Project Lead The Way, Inc.
Copyright 2009

5. Date of Birth Design Problem
Digital Electronics
2.3 Date of Birth Design Problem
DOB Truth Table X Y Z
Display a b c d e f g 1
This is the completed truth table. If you print handouts, do not print this page.
Note that segment (a) & (d) are the same, thus you only need to design one circuit to be used for both segments.
Project Lead The Way, Inc.
Copyright 2009

6. Date of Birth Design Problem
Digital Electronics
2.3 Date of Birth Design Problem
K-Map for Segment (a) X Y Z
Display a 1 1
This is the truth table column, its associated K-Map, & simplified logic expressions for segment (a).
Project Lead The Way, Inc.
Copyright 2009

7. Date of Birth Design Problem
Digital Electronics
2.3 Date of Birth Design Problem
Segment (a) – AOI Logic
X Y Z
This is logic diagram for segment (a). The circuit was implemented using AOI logic for demonstration purposes. It could have also been implemented with NAND or NOR logic. a
Project Lead The Way, Inc.
Copyright 2009

8. Date of Birth Design Problem
Digital Electronics
2.3 Date of Birth Design Problem
K-Map for Segment (b) X Y Z
Display b 1 1
This is the truth table column, its associated K-Map, & simplified logic expressions for segment (b).
Note : In this example, the K-Map could have been grouped differently resulting in a different but equally simple logic expression (i.e., b = X’ Z + Y’ Z’ + X Y).
Project Lead The Way, Inc.
Copyright 2009

9. Segment (b) – NAND Logic
Date of Birth Design Problem
Digital Electronics
2.3 Date of Birth Design Problem
Segment (b) – NAND Logic
X Y Z
This is a logic diagram for segment (b). The circuit was implemented in NAND for demonstration purposes. It could also have been implemented with AOI or NOR logic. b
Project Lead The Way, Inc.
Copyright 2009

10. Date of Birth Design Problem
Digital Electronics
2.3 Date of Birth Design Problem
K-Map for Segment (c) X Y Z
Display c 1 1
This is the truth table column, its associated K-Map, & simplified logic expressions for segment (c).
Note : Again, in this example, the K-Map could have been group differently resulting in a different but equally simple logic expression (i.e., b = Y’ Z’ + Y Z + X Z’).
Project Lead The Way, Inc.
Copyright 2009

11. Date of Birth Design Problem
Digital Electronics
2.3 Date of Birth Design Problem
Segment (c) – NOR Logic
X Y Z
This is a logic diagram for segment (c). The circuit was implemented in NOR for demonstration purposes. It could also have been implemented with AOI or NAND logic. c
Project Lead The Way, Inc.
Copyright 2009

12. Date of Birth Design Problem
Digital Electronics
2.3 Date of Birth Design Problem
All Segments
Here are all of the segments (a) – (g). Simplification and implementation of the segments (d) – (g) are left as an exercise that the students can complete as class work or homework.
Project Lead The Way, Inc.
Copyright 2009

13. Date of Birth Design Problem
Digital Electronics
2.3 Date of Birth Design Problem
X Y Z
Complete Date of Birth Circuit
Common Cathode
7-Segment Display
AOI
Segment a & d
NAND
Segment b
NOR
Segment c
This is the complete solution for the DOB problem for DOB DON’T FORGET THE CURRENT LIMITING RESISTORS. The design will work in simulation without them, but if you build the circuit (i.e., in hardware) and do not include the resistors, the SSD will be destroyed.
AOI
Segment e
NAND
Segment f
NOR
Segment g
Project Lead The Way, Inc.
Copyright 2009