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.
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.
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.
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.
Connect all the figures with text explaining why/how the
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
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
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
Annotate waveforms in detail. This has a heavy mark
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.
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
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.
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.
Write Rep-2 How to Write a Lab Report for Switching Circuits