Lab 3

1. Objectives

The objectives of this lab are:

• To become more comfortable using the simulator

• To become more familiar with a binary decoder

• To practice implementations with multiple output

• To gain introduction to two new components

  • The counter

  • The clock

2. Prelab

• Read this document before coming to class

• Review Binary Decoders

• Finish HW2 problem 2.

3. Tasks

3.1 Task 1

Design a 3:8 binary decoder (3 inputs and 8 outputs). Use only 2-input AND and 2-input OR gates. You may also use the NOT gate. Design by hand using CSOP or CPOS form and come up with a logic diagram. Implement your diagram in the simulator.

• You will need this circuit again later so you should save the circuit in order to reload your circuit later.

3.2 Task 2

In HW 2 problem 2 you are given two functions to implement simultaneously. Write out the full truth table with all inputs and outputs.

• Implement the circuit in the simulator.

• Confirm that your circuit works by checking all inputs and compare the outputs to your truth table.

• Again, you will need this circuit in task 4 so I would save the circuit so that you can load it again.

3.3 Task 3

We will learn how to build counters later in the class. Even if we have not learned how to build the internals yet, we can still use them. This task is to learn how counters work.

• In your simulator create a new circuit and draw a counter (Check the Digital Chips Menu)

• Also draw a clock (check the input menu)

• Connect the clock and the counter as shown below.

• Investigate the output.

  1. What is the output of the counter at each clock cycle? If the changes are too fast, double click the CLK and adjust the frequency to something you are more comfortable with.

  2. What does increasing the frequency of the clock do? What about decreasing the frequency of the clock?

  3. Do you recognize the sequence?

  4. Find out what the R is by setting the R HIGH and LOW using a logic input. What does R do?=

• If you understand how counters work then you can move on to Task 4

3.4 Task 4

• Use a counter to test your circuits in task 1 and task2 to test all your outputs. By using the counter, we don't have to manually cycle through all the possible inputs. The counter can be used to cycle through all inputs automatically. Adjust the frequency of the clock in order to observe the inputs and outputs better.

What you turn in

Create one pdf document for your solutions to this lab.

• Task 1: include all your work during design and a screenshot of your simulation

• Task2: include the truth table and a screenshot of your simulation

• Task3: Include your answers for questions 1-4 in task3. Include a screen shot of your circuit

• Task4: Include a screenshot of all your circuits using the counter used to test them.