There are few people who truly enjoy writing reports. However, for the student, this is a very important exercise. Good reports are not written by accident. You learn to write good reports through practice. The university is as good as any place to learn to write reports where you can receive constructive criticism. The university is a place to learn. We would be doing students a great disservice if we did not show you how you can improve your report writing skills.
Writing reports helps you to
At the 4th year university level a report should have the quality and style suitable for publication in a scientific journal, trade magazine or similar publication. Read over your work and ask yourself if you would wish to be identified as the author of the report. Take pride in your work.
While we stress good grammar, spelling and writing styles, students are not penalized for mistakes in these areas. By the same token, ESL students (english as a second language) are given consideration. However, we will point out where there is need for improvements.
The point of writing the report early in the design stage must not be taken lightly. The advantage of doing this can be summarized in one word - planning. This allows you set a theme, plan a course, look ahead. Flaws in design or things that you may have overlooked will be revealed in the early stages before you get into deep water.
This is a freebie. There is no reason for not getting full marks for this. The abstract is where you say in a nutshell what you have accomplished. Be efficient with words. Do not begin your abstract with "The purpose if this report is ...". This is a waste of words. Get straight to the point.
A digital thermometer was designed and built utilizing a thermistor and frequency measuring circuit. Temperature
was recorded in the range 0 to 30°C with an accuracy of 0.2°C. Numeric and graphical data were displayed
on a PC using a program written in Visual Basic.
Bear in mind that many electronic search engines will scan only the abstract for keywords. The abstract is a summary of your project and the report. The report is independent of the abstract. Write the report as if the abstract did not exist.
The introduction is not the theory section. Introduce the project, not the history or theory. Give the importance of building this instrument or studying this subject matter. Say what was accomplished.
Some students go overboard with a lot of historical details. Ask yourself how relevant is this information to your project. If you think that this is important to include in your report, then keep it short. Never pad a report just to give it some bulk. If you have to search to find things to say then it probably does not belong here.
The single most common mistake students make is not knowing what constitutes theory. Learn to focus. Ask the question, "What is the project about?". If the topic is about a digital thermometer, then the theory must focus on those two words, thermometer and digital, in that order.
Everbody knows what a thermometer is. You do not need to describe one. What is important in this context is what are the different ways (devices) to electronically measure temperature. Of relevance would be an introduction to the following devices: thermistor, resistance temperature detector (RTD), thermocouple, IC temperature sensors, liquid crystals, and perhaps IR thermal imaging. One can compare cost, availability, complexity, ranges, sensitivity, non-linearity, etc. Conduct some research of your own by checking the library, manufacturers' data sheets, internet, etc.
The digital part of the project refers to digitization of the temperature reading, i.e. the analog-to-digital (ADC) conversion process. Logic gates, counters, ICs, computer interfacing, do not constitute relevant theory in this context. A resistance-to-frequency converter is an ADC. If frequency measurement is the digitization process then this should be discussed. What are the errors associated in the ADC process? The error in counting is 0 or +1, which for our purposes can be simplified as ±½ LSB. What is the error in the timebase?
Writing the project report early helps to keep you focused, allows you to define specifications and set objectives. It also helps to identify flaws in the design. A temperature range of 0 to 30°C with a resolution of 0.2°C means that there must be at least 150 unique temperature steps. Therefore, the digitization process must have at least 8 bits to accomplish this. (Not many reports made this observation.)
How and when is data acquired by the computer? Studying these issues should lead you to realize that some form of hand-shaking is required. How does the program know that data is valid? When can the counter be cleared? These problems are revealed and resolved in the design stage, not the implementation stage. This is the difference between design and implementation.
Since this is a hardware design the report must contain two important drawings:
This is an example of a block diagram.
A timing diagram is not after-the-fact. It is not an oscilloscope drawing of what one would observe. Instead, it describes the behaviour of the circuit or system as the designer wishes it to be. It represents foresight rather than hindsight.
All diagrams should be neatly drawn and should convey useful and important information in a clear manner. Flow of information should be from left-to-right or top-to-bottom. Avoid lines that cross or change directions. Avoid stylish lines, boxes or drawings.
Impementation is NOT design. The design stage has been completed. Implementation is the process of converting the design to the final product, i.e., going from a concept to something real. Implementation is translating a flowchart or pseudocode into program statements or going from block diagrams to a circuit diagram.
A wiring diagram is not a circuit diagram. Do not show IC pin layouts.
This is an example of a circuit diagram.
All pins should be numbered and labelled. Note that the numbering order of the IC pins is not important. It is
more important that the signals appear in some order based on function. Usually inputs are on the left and outputs
are on the right of the box.
Use appropriate symbols for gates, flip-flops and other logic functions, for example:
The appropriate place for the circuit diagram and program listing is in the appendix. You do not need to describe the function of every gate, component or every line of code. This should all be assumed knowlege. However, if there is an item of particular importance or one that needs clarification then this is the place to point that out.
Eventually, there comes a point when data must be recorded and analyzed. Some form of curve fitting is required. But ask the question what does curve fitting mean. It means finding or creating a mathematical model for a set of data. It also means finding a mathematical model to a physical process. In the real world, there are very few objects that exhibit properties that are described by complex mathematical formulas, for example, polynomials higher than the 3rd order.
The first step in analyzing a set of data is to plot a graph. You do not need a computer program in order to do this. A simple sheet of graph paper is quite adequate if you do not have a program that generates graphs. The next question to ask is "Is the relationship a linear one?". If not, "Is the relationship an exponential or logarithmic?" To answer the last question, examine the first graph and determine whether an exponential or logarithmic transformation of either axis would likely give a straight line. Do this transformation and draw a new graph. If the relationship is a straight line then your search is over. If not, go back to the original data and look for a polynomial fit. Choose the lowest order polynomial that gives a reasonable fit. The fact that a higher order polynomial gets a better fit (R2 closest to 1) does not mean that this is a better model.
Students complained about not having sufficient time in the lab in order to complete the project, or to obtain any results. Yet they failed to see how much information was already available to them that would have allowed them to conduct some preparatory analysis as well as provided them with meaningful data for inclusion in the report. For example, data showing the relationship between temperature and resistance of the thermistor was given. The equation describing the frequency of oscillation of the 555 timer circuit is known. From these two, one can generate data representing the recorded number of counts versus temperature. One can immediately model the operation of the circuit and can assess whether the design meets the required criterion for the desired resolution.
In hindsight, you can always find ways of improving a project. Say what you have accomplished, and what are the short comings. What are ways of improving your design? What and how could you have done differently?
Put the circuit diagram and program listing in the appendix. Note that the block diagram and timing diagram are presented in the design stage.
List all sources of information, whether it is a text book, lab manual, past lab reports, website, etc.
2001.04.19
