DUE DATE All periods: Friday, November 13th at 11:59 pm for a minor grade
Activity 1.2.1 Introduction to Combinational Logic Design: Seat Belt Circuit
INTRODUCTION
Combinational and sequential logic are the fundamental building blocks of digital electronics.
Combinational logic, which is sometimes referred to as combinatorial logic, is characterized by its
output being a function of the current input value.
A variety of different logic gates can be used to implement combinational logic circuits. Many of
these gates will be studied in future units of this course. In this introductory unit, we will limit our
designs to AND, OR, and INVERTER gates for the sake of simplicity.
In this activity, you will use the Circuit Design Software (CDS) to build and test your first
combinational logic circuits.
EQUIPMENT

Multisim Live
PROCEDURE
It’s time for you to implement your first AOI combinational logic circuit. The circuit we will use for
this purpose is a Car Safety Buzzer design. The design specifications are as follows:
Logic Statement: The buzzer is on whenever the door is open or when the key is in the ignition and
the seat belt is not buckled.
1. Create a table that describes these design specifications in terms of “highs” (1) and “lows” (0).
This is when a sensor or indicator is active or not active.
Seat Belt
0=
1=
Key
0=
1=
Door
0=
1=
Buzzer
0=
1=
Seatbelt is off
Seatbelt is on
Key is unavailable
Key is in ignition
Door is closed
Door is open
Buzzer is off
Buzzer is on
DUE DATE All periods: Friday, November 13th at 11:59 pm for a minor grade
2. Using the Circuit Design Software (CDS), enter the Car Buzzer circuit shown below. Use switches
for the inputs Seat Belt, Key, and Door and a probe for the output Buzzer.
3. Based on the design specification you defined, enter a “1” in the Buzzer Output Expected column
when the BUZZER should be ON. Toggle the input switches to complete the Buzzer
Output Actual column in the truth table below.
Inputs
Buzzer Output
Expected
(Prediction)
Actual
(from CDS)
Seat Belt
Key
Door
0
0
0
0
0
1
1
1
0
1
0
1
1
0
1
1
1
1
1
0
0
1
0
1
0
1
1
1
1
1
0
0
0
1
1
1
1
1
0
0
DUE DATE All periods: Friday, November 13th at 11:59 pm for a minor grade
4. Take a screenshot of your circuit and paste it in the box below:
DUE DATE All periods: Friday, November 13th at 11:59 pm for a minor grade
RUBRIC
#1 Table w/ highs and lows defined
8 pts
#3 Table w/ expected/predicted values
8 pts
#3 Table w/ correct actual values
8 pts
#4 Screenshot of completed circuit
10 pts
Total Points
34 points
SCORING
33/34
32/34
31/34
30/34
29/34
28/34
27/34
26/34
25/34
24/34
23/34
22/34
21/34
20/34
19/34
18/34
17/34
16/34
15/34
14/34
13/34
12/34
11/34
10/34
9/34
8/34
7/34
6/34
5/34
4/34
3/34
2/34
1/34
97%
94%
91%
88%
85%
82%
79%
76%
74%
71%
68%
65%
62%
59%
56%
53%
50%
47%
44%
41%
38%
35%
32%
29%
26%
24%
21%
18%
15%
12%
9%
6%
3%