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Teaching Digital Filter Implementations Using the 68HC12 Microcontroller

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Conference

2011 ASEE Annual Conference & Exposition

Location

Vancouver, BC

Publication Date

June 26, 2011

Start Date

June 26, 2011

End Date

June 29, 2011

ISSN

2153-5965

Conference Session

ELOS Best Paper Nominations

Tagged Division

Division Experimentation & Lab-Oriented Studies

Page Count

19

Page Numbers

22.1384.1 - 22.1384.19

DOI

10.18260/1-2--18681

Permanent URL

https://peer.asee.org/18681

Download Count

233

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Paper Authors

biography

Li Tan Purdue University, North Central

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Dr. Li Tan is currently with the College of Engineering and Technology at Purdue University North Central, Westville, Indiana. He received his Ph.D. degree in Electrical Engineering from the University of New Mexico in 1992. Dr. Tan is a senior member of IEEE. His principal technical areas include digital signal processing, adaptive signal processing, and digital communications. He has published a number of papers in these areas. He has authored and co-authored three textbooks: Digital Signal Processing: Fundamentals and Applications, Elsevier/Academic Press, 2007; Fundamentals of Analog and Digital Signal Processing, Second Edition, AuthorHouse, 2008, and Analog Signal Processing and Filter Design, Linus Publications, 2009.

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biography

Jean Jiang Purdue University North Central

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DR. JEAN JIANG is currently with the College of Engineering and Technology at Purdue University
North Central, Westville, Indiana. She received her Ph.D. degree in Electrical Engineering from the University of New Mexico in 1992. Her principal technical areas are in digital signal processing, adaptive
signal processing, and control systems. She has published a number of papers in these areas. She has co-authored two textbooks: Fundamentals of Analog and Digital Signal Processing, Second Edition, AuthorHouse,
2008, and Analog Signal Processing and Filter Design, Linus Publications, 2009.

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Abstract

Teaching Digital Filter Implementations Using the 68HC12 MicrocontrollerAbstractIn this paper, we present our pedagogies for teaching digital filter implementations using the68HC12 microcontroller. In the Electrical and Computer Engineering Technology (ECET)curriculum, the microcontroller has been used as a popular platform for teaching the embeddedsystem course in the sophomore year. After completing the embedded system course, studentsbecome familiar with the microcontroller software development tools, and are able to performassembly and C programming and apply necessary hardware for hands-on applications. Inaddition, most microcontrollers have a capability to perform basic digital signal processing(DSP) tasks such as digital filtering. Considering these facts, using the microcontroller in thelater DSP course in the junior year could offer the following benefits to ECET students: (1) themicrocontroller can be used as an alternative and cost effective solution when a DSP processorsuch as TMS320C67xx is not available; (2) students can save a significant amount of time forlearning and familiarizing with the new system architecture, corresponding development toolsand assembly instructions. Instead, they can focus on learning the implementation of digitalfilters and DSP applications; (3) the microcontroller is flexible when it is used to develop variousapplications including signal processing. We instruct the digital filter implementations based on a platform as shown in Figure 1,where it consists of the signal condition circuit, low-cost 68HC12 microcontroller and digital-to-analog converter device (AD557). A simple program to flexibly set up the sampling rate is firstdeveloped and the key assembly instructions for digital filtering are reviewed. Next, we illustratethe fixed-point data format, finite impulse response (FIR) filter and (infinite impulse response)IIR filter structures with the direct form I and form II. After the digital filters are designed byusing MATLAB, real-time FIR and IIR filter implementations are then developed using a linearbuffering technique. Furthermore, we also illustrate filter implementations for tone generation,sampling rate conversion and FIR filter with a circular buffering technique. Finally, we will examine the course assessment according to our collected data from courseevaluation, student surveys and student course work, and address the course improvement basedon our assessment. Output: Sample and hold signal Range: 0-2.55 volts ADC channel 6 P-Port Range: 0-5 volts x(t) Analog input signal Signal 68HC12 AD557 conditioning Microcontroller Figure 1Partial list of References[1] D. J. Pack, S. F. Barrett, 68HC12 Microcontroller: Theory and Applications. Prentice Hall,2002.[2] L. Tan, Digital Signal Processing: Fundamentals and Applications. Elsevier/Academics,2007.[3] T. B. Welch, C. H.G. Wright, M. G. Morrow, Real-Time Digital Signal Processing. CRCPress, 2006.[4] D. Crover, J. R. Deller, Digital Signal Processing and the Microcontroller. Prentice Hall,1999.[5] Axiom Manufacturing: http://www.axman.com/

Tan, L., & Jiang, J. (2011, June), Teaching Digital Filter Implementations Using the 68HC12 Microcontroller Paper presented at 2011 ASEE Annual Conference & Exposition, Vancouver, BC. 10.18260/1-2--18681

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