DESIGN OF AN INTERACTIVE LISSAJOUS DISPLAY SYSTEM JORDAN MEYER STEPHEN MIRANDA MATTHEW KNABEL Sponsored by: Dr. Walsh & the University of Louisville Electrical and Computer Engineering Department

BACKGROUND INFORMATION Electrical Engineering kiosk in the Schumaker Research Building Electrical Engineering kiosk in the Schumaker Research Building Goal: to increase admissions to Electrical Engineering Department Goal: to increase admissions to Electrical Engineering Department Project: develop low-cost custom system for displaying lissajous patterns on readily available monitors Project: develop low-cost custom system for displaying lissajous patterns on readily available monitors

LISSAJOUS PATTERNS Classically created using a 2 channel function generator and an oscilloscope Classically created using a 2 channel function generator and an oscilloscope Channel 1 is X-input Channel 1 is X-input Channel 2 is Y-input Channel 2 is Y-input Function Parameters Function Parameters Shape Shape Phase angle Phase angle Amplitude Amplitude Frequency Frequency

SYSTEM REQUIREMENTS Continuously display lissajous patterns Continuously display lissajous patterns Adjustable input parameters Adjustable input parameters Educational Educational Cost < $300 Cost < $300 Utilize 120VAC/60Hz power Utilize 120VAC/60Hz power

OPERATIONAL CONCEPT Graphical Display Graphical Display System will be compatible with standard monitor/television System will be compatible with standard monitor/television Control Panel Control Panel Pushbuttons to select waveform type Pushbuttons to select waveform type Knobs to set amplitude, frequency, and phase difference Knobs to set amplitude, frequency, and phase difference Informational Posters Informational Posters Provide introduction to basic theory and instructions to use the system Provide introduction to basic theory and instructions to use the system Peripheral Devices (administrator interface) Peripheral Devices (administrator interface) Keyboard and mouse for start-up and maintenance tasks Keyboard and mouse for start-up and maintenance tasks

DETAILED DESIGN

DISPLAY MONITOR Provided by ECE department Provided by ECE department Displays the generated lissajous patterns Displays the generated lissajous patterns HDMI input Use 120 V AC 60 Hz utility power Max dimensions: 8’ 6” wide by 5’ long by 2’ deep

COMPUTER W/ SD CARD Rapsberry Pi Model B+ (Pi) Rapsberry Pi Model B+ (Pi) 5VDC power input via Micro B USB 5VDC power input via Micro B USB Micro SD card for loading Raspbian OS and programs Micro SD card for loading Raspbian OS and programs Must be 8GB or larger Must be 8GB or larger 4 USB 2.0 input ports: connect keyboard and mouse 4 USB 2.0 input ports: connect keyboard and mouse HDMI output: connect to display HDMI output: connect to display 40 pin GPIO header: connect to buttons and knobs 40 pin GPIO header: connect to buttons and knobs 40 line ribbon cable used to breakout and connect to buttons and knobs 40 line ribbon cable used to breakout and connect to buttons and knobs

POWER CONVERTER Provides power to the Pi Provides power to the Pi UpBright Switching AC Adapter UpBright Switching AC Adapter Input: V AC 0.35 A Hz utility power Output: 5 V, 2 A DC power over a Micro B USB connector

PUSH BUTTONS 1 hard reset button 1 hard reset button 6 used for waveform selection (3 choices per channel) 6 used for waveform selection (3 choices per channel) Sine, Triangle, Sawtooth Sine, Triangle, Sawtooth LED illumination to show currently selected waveforms LED illumination to show currently selected waveforms 30 mm in diameter, 43.4 mm long 30 mm in diameter, 43.4 mm long M24 screw thread (BS 3643 Standard) M24 screw thread (BS 3643 Standard) Mounted to the top of the enclosure through a 1” diameter hole Mounted to the top of the enclosure through a 1” diameter hole Arcade quality microswitch is reliable to 10,000,000 cycles Arcade quality microswitch is reliable to 10,000,000 cycles

POTENTIOMETERS & KNOBS Amplitude knobs: 0 to 5 in 0.5 increments Frequency knobs: Coarse Frequency: range of 0Hz to 10Hz in 1Hz increments Fine Frequency: range of 0Hz to 0.20 Hz in 0.02 Hz increments. Potentiometers: 3 pin, 0.2 W, 10K Ω linear rotary potentiometers w/10 detents (11 fixed positions) Knobs: 30 mm diameter, mated directly to potentiometer shaft

ANALOG-TO-DIGITAL CONVERTERS 2 Adafruit ADS1015 ADC Breakout Boards 2 Adafruit ADS1015 ADC Breakout Boards Uses Texas Instruments ADS1015 ADC chip Uses Texas Instruments ADS1015 ADC chip 12-bit ACD with 4 channel input and programmable gain amplifier 12-bit ACD with 4 channel input and programmable gain amplifier Can use 3.3VDC or 5VDC Can use 3.3VDC or 5VDC I 2 C output to interface to Pi I 2 C output to interface to Pi Pi does not have built-in ADC Pi does not have built-in ADC Could use up to 4 chips simultaneously while only requiring two GPIO pins on PI: SCL and SDA Could use up to 4 chips simultaneously while only requiring two GPIO pins on PI: SCL and SDA VDD and GND from Pi VDD and GND from Pi

EDUCATIONAL POSTERS Provide educational content Provide educational content Fundamentals / underlying principles Fundamentals / underlying principles Instructions / things to try Instructions / things to try 2 posters 2 posters printed in full color on Epson premium luster photo paper in order to ensure durability Dimensions: 24” x 36”

KEYBOARD & MOUSE For administrative use only For administrative use only Start-up and maintenance Start-up and maintenance Connect to Pi via USB 2.0 ports Connect to Pi via USB 2.0 ports Stored within enclosure Stored within enclosure

ENCLOSURE 1/2” thick oak wood 1/2” thick oak wood Laser cut into panels Laser cut into panels Secured by 1 1/8” phillips head screws Secured by 1 1/8” phillips head screws 3/16” plexiglass 3/16” plexiglass Water cut to size, holes and etching done by laser Water cut to size, holes and etching done by laser Secured with glue Secured with glue 2 hinges and cam lock fastened to back-panel door 2 hinges and cam lock fastened to back-panel door Wood painted with black Do-It All Purpose Spray Paint Wood painted with black Do-It All Purpose Spray Paint 25” wide,18.5” deep,10” tall back & 0.5” tall front (22 °) 25” wide,18.5” deep,10” tall back & 0.5” tall front (22 °)

PROGRAMMING Linux operating system installed on Pi Linux operating system installed on Pi Wrote original programming in Python language Wrote original programming in Python language Read input parameters from GPIO Read input parameters from GPIO Generate 2-D plot of parametric equations (input waveforms) Generate 2-D plot of parametric equations (input waveforms) Animate function creates rotation Animate function creates rotation Update waves based on user-adjusted parameters Update waves based on user-adjusted parameters

TESTING Verified adjustable parameters via the print command in Terminal Adjustments were necessary – parameter limits were incorrect due to differences in voltage readings across potentiometers Verified real-time updates by changing parameters during system operation and observing changes in plot as well as through Terminal Posters were evaluated for clarity and accuracy by a panel of education professionals

RECOMMENDATIONS FOR FUTURE IMPROVEMENTS Addition of color to pattern and background Addition of color to pattern and background Make display more visually enticing Make display more visually enticing Addition of sound Addition of sound Make interaction more entertaining Make interaction more entertaining GUI to display current parameter setting on screen GUI to display current parameter setting on screen Randomly generated patterns as screen-saver Randomly generated patterns as screen-saver

QUESTIONS? Thank you for your time and attention Special thanks to Dan Whitlow, Matt Buckley, and Owen Johnson for support on this project