The CPLD Provides a Third Option in the Introductory Logic Circuits Course

Abstract

We have recently adopted complex programmable logic devices (CPLDs) in our introductory logic circuits course at University of Hartford. While we have long introduced programmable devices in advanced courses, with the state of the art in logic circuits rapidly moving forward, there is a growing push to make more and earlier use of programmable logic devices (PLDs) in the electrical and computer engineering curriculum. Until recently, our introductory logic circuits course was taught with transistor-transistor logic (TTL) family devices, following a very traditional lecture and laboratory format. In response to such pressure, we have adopted CPLDs in our introductory logic course. We use a CPLD module to provide an alternative to using TTL devices or adopting a field programmable gate array (FPGA). While both the FPGA and CPLD are configurable, the FPGA is a system component with the capability of many CPLDs, as such the FPGA demands the use of a development board. We found that when our colleagues adopted an FPGA, the purely hands-on TTL experience is replaced entirely by the use of an FPGA development board where no actual wiring is involved. Rather, the CPLD module provides a viable third option, allowing for some hands-on experience, along with that of computer aided design tools. Students use a CPLD module with a classic breadboard and perform educational activities. We have found that the CPLD is identifiable to students, and that with only modest wiring they can construct demonstrative circuits that they feel are satisfying and engaging. Given the potentially wide reaching impact on the curriculum, we are taking this change to the introductory logic circuits course in steps. In the Fall 2011 semester we introduced CPLDs with several clearly defined goals, all of which have been met. We developed entirely new laboratory content with new projects and activities, however there were few changes to the lecture content. In particular, we were most concerned that our students have a meaningful laboratory experience. The CPLD module was implemented and a tutorial was written for the computer aided design (CAD) tools. In this paper we present the results from the Fall 2011 semester along with our recommendations for the next course offering. The rest of this paper starts with the introduction, followed by sections that describe the CAD software, the tutorial, and CPLD module, respectively. The project content and activities are presented, followed by discussion of medium-scale integration (MSI) parts and functionality. Finally, the course assessment, our recommendations, and the conclusion are presented.