How to Write a Lab Report for Switching Circuits

How to Write a Lab Report for Switching Circuits

February 18, 2007

How to Write a Lab Report for Switching Circuits

Written by the TAs, especially Richard Griffiths

Read the part of the Course Rules covering reports, on the course web site.

These rules may change between courses and are not covered here. They also take precedence over these general suggestions.

The report is expected to cover the design, construction

and testing of the circuit.

The first six topics below correspond closely to what we

would expect in a report. The paragraphs ordered by letters

are general comments.

1.0 Introduction

Introduce the circuit you are required to design. What does

it do, and why is this function useful? Can you suggest

some applications. For example a comparator is essential

for an electronic blackjack game, or a money changer.

2.0 Specifications

You must show the design specifications. What are the

locations and format of the required inputs and outputs. Is

it 4-bit binary numbers, 2’s complement numbers? Are

they set by switches? Are the inputs from a test program.

Will the circuit be built, or only simulated. How will it be


Is the design limited in other ways? Must it fit in the logic

trainer? Did software liberate the design from constraints

like converting to NANDs and NORs. Is there a size,

power or time limit? These are the major factors that influence

the design. Lists are useful.

3.0 Design

Describe the design process. How does each step connect

with the other steps? How does the design meet the

requirements? Answers to the prelab questions make up

much of the design, but do not just step through the prelab.

Connect the steps into a single logical process that

explains the design. If a specific method was used where

another option was available, mention the option. Diagrams

and tables are usually used to describe the design.

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Connect all the figures with text explaining why/how the

design flows.

When you get a question on an exam, about parts of the

design, you should be able to use the design section to

quickly jog your mind about details. Remember the exam

is open book.

All figures copied from other sources, including the lab

sheets, must be acknowledged. Text must be acknowledged

and be in quotes.

4.0 Implementation and Testing

For circuits you constructed, make a list of unique parts

like logic gates; how many are required? How do the parts

available for construction limit your design? Map the

design into the construction of the circuit, where are things

physically located?

For computer designed CPLD implemented circuits, consider

describing the hierarchy in the design. How common

subcircuits are reused. They might make a flowchart of the

design. Graphical entry->translation of schematics into

machine readable netlists-> simulation->correction ... ->


Report on the construction and testing of the circuit. Were

subcircuits individually tested against truth tables? Refer

to Fig.~X and Table~Y. Mention the tests performed, how

they were done, and what would be considered a failed

test. Do your tests cover the complete specifications? In

some cases this means looking at the output of a test program

written by someone else, and seeing just what tests

were done.

Mention any debugging you had to do. How did you find

your error? Did you read the error messages? Did the TA

have to find it? Did you logically deduce it had to be in a

certain subcircuit?

Annotate waveforms in detail. This has a heavy mark


5.0 Summary

State what you accomplished. Were you able to meet the

objective set out in the specification? Did you have to

make some design choices? If so, give the reasons why

you picked a particular choice. Did you do something

slightly different from average? Brag about it here. Where

were the difficult parts of the lab, design, construction or

testing? This part will be read looking for inovation marks.

Were there alternative possibilities in the design process,

the testing, or the construction? Mention them. Are there

extensions to the circuit that could be made easily? Suggest

what could be done.

6.0 Commentary

Comment on the lab. Was the task too hard, or the lab

equipment in a poor state? Did you find anything really

helpful? What could be done differently to make it better.

Do you see applications for the circuits or concepts used?

For example, did you decide that a MUX is a very useful

gate, and easier to visualize than two ANDs and an OR.

You might expand on, not cut and paste, an application

suggested in the introduction.

A. Overall Presentation

A number of things can be done to improve the appearance

and quality of your report:

- Have a lot of subsections with headings

- Number your pages.

- Use a ruler for long straight lines.

- Put good explanatory captions on your figures.

- Title and reference the graphs by description and number

as “the logic diagram for the half adder as in Fig. 2, p.3”

We love original thought. If you do a derivation with a different

twist from the lab sheet, tell us. You might put it in a

paragraph with a heading like, “Different way to reduce a

full adder.”

B. Cooperation and Collaboration

The partner doing Section 3 normally has the most work.

Some of the design specific to the implementation, like


adjusting the logic to fit on the logic trainer, probably

should go into Section 4 under implementation.

Work with your partner. After completing the lab take a

few minutes to decide what will be included in the report.

Consider the diagrams, tables, derivations, and testing

Before leaving the lab make a list of figures by number

and title. Both of you can then work on your parts from the

list. Assemble the text and figures a day (maybe even two)

before they are due to check for compatibility. Both of you

should review the results.

C. Typing and Photocopying

We do not require computer generated pictures. Hand

drawing is all right, provided you attempt reasonable neatness.

Use a ruler!

If you use figures that are not your own, including those

taken from the lab sheet, you must acknowledge them all.

Too many students copy the wrong picture. Copying a

wrong or incomplete picture from the lab notes will be

judged more harshly than a mistake in your own drawing.

D. Covers

You will need a title page which clearly lists:

The number of the course.

The number and title of the experiment.

The name and number of the person responsible for

the theory, followed by the word (SECT 3, DESIGN)

The name and number of the person writing the other

sections followed by the words (SECT 1,2,4,5,6)

The day you are scheduled to perform the lab, i.e.

“odd Tuesdays, a.m.”, or “Lab L3O.”

Any special notes you want the marker to see, i.e.

“This lab is late because I was on the Space Shuttle,

and its landing was delayed past the due date.”

We hate labs in envelopes. If you want your report to stand

out, please use a colored cover, not an envelope.

E. The Prelab’s Place In The Report

Your prelab, initialled by the teaching assistant, should be

attached as an appendix to your laboratory report. You are

not expected to rewrite it.

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