Lab 8 1
Lab 5: Traffic Light design using Boolean simplification and K-Maps (200 pts)
Learning Objectives:
1. Familiarize yourself with constructing basic logic circuits on a
eadboard
2. Practice using Tinkercad to simulate circuits
3. Explore different methods of simplifying a circuit using either Boolean alge
a rules or K-maps
Concepts to Practice and Learn:
• Building virtual circuits on TinkerCAD and real circuits on Breadboard
• Simplifying circuits using any of the techniques you have learned about
• Converting a wording design problem into a truth table
This table lists deliverables for Lab 5. Please check off the tasks as you complete them.
Step No. and Description
Completed
successfully
Comments or questions
Pre-LAB (100 pts)
TinkerCAD circuit (30 pts)
LAB Breadboard circuit (85 pts)
Reflection Questions (15 pts)
Show your Tinkercad and
eadboard circuits to the TA to verify:
• Co
ect logic ICs used
• Co
ect, neat wiring
• Verify functionality
Student Name: _____________________ XXXXXXXXXXID@__________________
TA: ___________________________ XXXXXXXXXXDate: ___________
Lab 8 2
Lab 5: Traffic Light Controller
Design a digital logic circuit which will implement an intersection traffic light controller for a highway intersection.
Vehicle-detection sensors are placed along lanes A and B in the N-S directions, and in lanes C and D in the E-W
direction lanes. The sensors will generate a HIGH signal when a vehicle is present in that lane and a LOW when no
vehicle is present.
Design a simplified logic circuit to control the traffic light. There should be two outputs, NS and EW, which go
HIGH (1) when the co
esponding light is green. Traffic control logic for this intersection must follow these
ules:
1. The east-west (EW) traffic light must be green whenever both lanes C and D are occupied.
2. The EW light will be green whenever either lane C or D is occupied but lanes A and B are not both occupied
3. The NS light will be green whenever both lanes A and B are occupied but C and D are not both occupied
4. The NS light will also be green when either A or B is occupied while C and D are both vacant
5. The EW light will be green when no vehicles are present (in any lane)
6. Obviously, EW and NS cannot both be green at the same time, nor can they be both red at the same time;
therefore, if one light is green the other must be red – use this to your advantage.
Lab 8 3
Pre-Lab XXXXXXXXXXpts
1. Create the truth table that will describe the behavior of the traffic light controller. Fill in all the possible inputs,
then follow the steps for each individual rule below to understand how the circuit works. Once you complete the
truth tables for all six rules, you can come back and fill in the output values of EW and NS.
(notice that you will need to do the steps below first before you can fill in the truth table XXXXXXXXXXpts
A B C D EW NS
0 0 0 0
0 0 0 1
0 0 1 0
0 0 1 1
0 1 0 0
0 1 0 1
0 1 1 0
0 1 1 1
1 0 0 0
1 0 0 1
1 0 1 0
1 0 1 1
1 1 0 0
1 1 0 1
1 1 1 0
1 1 1 1
Rule 1: The east-west (EW) traffic light must be green whenever both lanes C and D are occupied.
Which combinations of inputs in the truth table should satisfy this condition?
Hint: The rule determines that C and D are both occupied. Nothing was mentioned about lanes A and B (which
means A and B will not affect the decision if they are vacant or occupied in this situation). You have 4 choices in the
truth table that will satisfy this rule.
A B C D EW
1
1
1
1
Lab 8 4
Rule 2: The EW light will be green whenever either lane C or lane D is occupied, and lanes A and B are not both occupied.
Which combinations of inputs in the truth table should satisfy this condition?
Hint: C and D cannot both be vacant or occupied. So, if C is occupied then D must be vacant and vice versa. Also,
lanes A and B cannot both be occupied. Which means A and B are either both vacant, or one is vacant while the
other is not. You have 6 choices in the truth table that will satisfy this rule.
A B C D EW
1
1
1
1
1
1
Rule 3: The NS light will be green whenever both lanes A and B are occupied, and lanes C and D are not both occupied.
Which combinations of inputs in the truth table should satisfy this condition?
Hint: The rule determines that A and B are occupied. For C and D, they are not both occupied but only one has to be
occupied while the other is not. You have 3 choices in the truth table that will satisfy this rule.
A B C D NS
1
1
1
Rule 4: The NS light will be green when either A or B is occupied, and C and D are both vacant.
Which combinations of inputs in the truth table should satisfy this condition?
Hint: The rule determines that only one of the lanes A and B can be occupied but not both. However, they can both
e vacant. For C and D, the rules determine that they are both vacant. You have 2 choices in the truth table that will
satisfy this rule.
A B C D NS
1
1
Rule 5: The EW light will be green when no vehicles are present (in any lane).
Which combinations of inputs in the truth table should satisfy this condition?
Hint: The rule determines that All lanes are vacant. You have 1 choice in the truth table that will satisfy this rule.
A B C D EW
1
Lab 8 5
Rule 6: EW and NS cannot both be green at the same time, nor can they both be red at the same time.
Write a Boolean expression that expresses this complementary relationship between the EW and NS lights. This will
e helpful for filling in gaps in your truth table: XXXXXXXXXX5pts
2. Write the SOP form for each of the East-West and North-South XXXXXXXXXXpts
EW=
NS=
3. Using Boolean alge
a rules and/or K-Maps, simplify the (EW and NS) SOP standard forms into a simplified
form. XXXXXXXXXX10 pts
Simplified SOP form for
EW=
NS=
4. Look at the circuit outputs (EW, NS) in the truth table. What is the logical relationship between the two outputs?
5 pts
Lab 8 6
5. Implement the schematic diagram for the Traffic light controller XXXXXXXXXX10 pts
6. Build the circuit using TinkerCAD with EW and NS as two outputs. Each output is connected to a red LED
and green LED to represent the red light and green light respectively. (30 pts)
Lab 8 7
Lab 5: PART XXXXXXXXXXpts)
During lab, you will implement the complete circuit that will have four inputs and two outputs. Use the simplified
circuits design that you came up with in Part XXXXXXXXXXpts)
Verify the operation of the complete circuit with your instructo
TA.
Reflection Questions:
Please, answer the following question from your lab 4 experience: (15 pts)
(I) What went well for you during this lab? What was easy for you?
(II) What was most challenging for you in this lab?
XXXXXXXXXXIII) How did you overcome the challenge and/or what did you learn through it?