A Digital Device for Automatic Checking of Homework Assignments in the Digital Circuits Course

Abstract

This paper considers a digital device for automatic checking of homework assignments in the digital circuits course. The assignment is to make a digital circuit corresponding to a given logical expression; the circuit is comprised of elementary logic gates. The process of manual testing the built circuit is very labor-intensive because checking a circuit with N inputs variables requires checking the correctness of the output variable for 2N cases. We propose automating this pro-cess with a special digital device. The device is comprised of a microcontroller connected to the circuit tested. The microcontroller is connected to a personal computer with an application written in C# for executing the main operations of the testing process. During testing, the student chooses from a database or enters the logical expression corresponding to the circuit tested. For the expression, the software generates truth tables where actual and required responses of the circuit are given. Actual circuit responses are acquired by probing the circuit via the microcontroller, and the expected values are calculated from the logical expression. The truth tables are then presented to the student with a message of whether the circuit works correctly or not. The device was integrated into the process of checking homework assignments in the digital electronics course, and it significantly sped up the process of checking homework assignment circuits, resulting in better education quality.