One of the major problems in creating new exercises for the basic microcontroller lab course is the limited access to the electronics lab and test equipment. These instruments are sometimes distributed over different labs, making it difficult to have the right tools at a specific time. Most electronics labs are fully booked for teaching, which sometimes makes it difficult to test and develop during lab courses.
Last year the Section Electricity, Electronics and ICT of the Technology department invested in 10 NI ELVIS II platforms. We already used NI Multisim software to draw schematics and for simulation in different electronics courses. Therefore, using the NI ELVIS platform for hardware implementation seemed like the next logical step in our faculty’s electronic courses development.
The platform has given our department a creative boost in developing new exercises and new experiments. With the NI ELVIS platform, students are no longer constrained to an electronics lab. The platform has all the instruments in one compact, easy-to-use format, the breadboard makes it easy to compose a circuit from scratch, and each subcircuit can be tested step by step. In addition, test signals can be generated in any form, and measuring signals is very easy.
This platform reduces the amount of time needed to create exercises and experiments, which leaves more time to improve the quality of the exercises. NI ELVIS is fast, flexible, and mobile, which makes it the hardware equivalent of a rapid software application development system.
Visualizing Signals in Hardware Debugging
One of the core challenges in an introductory lab course for microcontrollers is the process of debugging. The student can only see the behaviour of the hardware and has to deduce where the underlying problem is situated. This is not always straightforward. Problems can arise in hardware (bad/wrong connections) or in software (bad programming). Testing for bad or wrong connections is easy on the breadboard, so the majority of these problems can be solved quite quickly. Much more difficult is the process of finding software problems. The only thing the student sometimes sees is “strange” behaviour of the circuit i.e. it doesn’t do what it is supposed to do. A solution in this case can be the use of the on-board led’s to indicate if a part of the program has already been executed. This way, the flow of the program can be visualized.
This year students had to program an R/C servomotor using a PWM signal with a frequency of 50 Hz and a variable pulse width limited from 1 to 2 ms. Several things can go wrong during this procedure including too many pulses, too few pulses, bad signal levels, signal inversion, a pulse that is too wide, or a pulse that is too small. It can be very difficult to detect the location of the problem from the hardware behavior. Using the NI ELVIS platform, students can visualize the signal and locate the anomaly. The measurements and images of the different devices can be saved and manipulated with the PC, which results in better reports and, more importantly, a better understanding of problem solving techniques.
The NI ELVIS platform has solved many lab problems. It gives the students all tools needed to design and test electronic circuits on a systematic basis. By having all tools readily at hand, the focus of the courses can be directed towards the content.
University College Ghent, Department of Technology
Voskenslaan 270 9000 Gent
Tel: +32 (0)9 242 42 62
Fax: +32 (0)9 243 87 79