Abstract:

The aim of the article is to share our experience in creating experimental modules controlled with an open source platform and used for teaching modern Digital-to-Analog Converters in university digital circuits courses.

The modules were created using the Texas Instruments' ASLK PRO lab kit, an Arduino Mega 2560 microcontroller development platform built with the ATmega2560 AVR MCU and precise measuring equipment. They are intended for students trained in engineering majors at the Paisii Hilendarski University of Plovdiv and are utilized when studying the processes of digital-to-analog conversion.

The first module was developed to experimentally study integral DACs so that the trainees can learn the principles of converting digital code into analog value. The module is implemented using a 12-bit DAC 7821, OPAMP-TL 082CP, operating as a voltage to current converter and Arduino Mega 2560, which provides the digital levels of the input signals.

During the study process, students make a series of measurements. The results for the measured and calculated values of the output analog voltage at different values of the input signals and the value of the reference voltage Uref=5V are presented and analyzed. The waveforms of the output signals observed using an oscilloscope are also analyzed.

To enable trainees to study the precision of digital-to-analog conversion, a second module was developed to examine and compare the work of two DACs simultaneously. The output voltage of the second DAC is filtered through a suitable low pass filter. Thus, trainees can examiine and compare the stages of digital-to-analog conversion without filtering the converted signal and in the presence of a low-pass filter, which increases the precision of the digital-to-analog conversion process. The waveforms of the two output signals for the same digital input codes generated by Arduino are analyzed.

The third module enables students to develop DAC control skills using LED indication and a keyboard. The LED indication provides an opportunity to monitor the change of the input combination of bits. Connecting the keyboard to the microprocessor module allows flexible control of the parameters of the output signal. With this module, students develop practical skills for software management of peripherals through microcontrollers.

The article presents snippets of the source codes used to manage the performance of the three modules.

The proposed hardware and software tools for teaching DAC in engineering education increase the students' motivation to master the principles of digital-to-analog signal conversion and boost their willingness to conduct and manage engineering research and to present the results of experimental work. The skills developed can be applied in the educational process and research practice and in other university engineering courses.

Keywords:

Digital-to-Analog Converters, Arduino, teaching, student motivation, research practice.