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The Self Tuning Guitar Kit Group 5 ECE 445: Senior Design Tom DaMario & KyungJin Lee December 4, 2008.

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Presentation on theme: "The Self Tuning Guitar Kit Group 5 ECE 445: Senior Design Tom DaMario & KyungJin Lee December 4, 2008."— Presentation transcript:

1 The Self Tuning Guitar Kit Group 5 ECE 445: Senior Design Tom DaMario & KyungJin Lee December 4, 2008

2 Introduction Kit provides fast, easy way to tune almost any guitar automatically Combines TI DSP, a simple microcontroller, and a stepper motor Gives easy user interface to make anyone could tune the guitar

3 Features Universal Design 3 different tuning configurations –Standard, Drop-D, Open-G Simple operation Accurate to +/- 4.906Hz

4 Objectives Portability: 100% Battery Powered Device and should be able to fit in guitar case Universal: Device should fit on any guitar Functionality: Device should have multiple tuning modes

5 Tuning Configurations String Number Standard TuningDrop-D TuningOpen-G Tuning Note Frequency [Hz]Note Frequency [Hz]Note Frequency [Hz] 6E82.4*D73.4*D73.4 5A110A *G98 4D146.8D D 3G196G G 2B246.9B B 1e329.6e *D293.6 * Strings that change from standard tuning. Source:

6 Hardware Overview DSP: C6713 DSK –Takes analog signal from guitar and runs ADC –Runs FFT on digital signal –Takes difference between desired signal and received signal PIC 16F877A –Takes string number from DSK and outputs to Hex display –Receives two signals from DSK to turn motor Motor: Parallax #900-00008 –Turns guitar tuning peg until desired frequency is reached

7 Software Overview Code Composer Studio v3.3 –Used to connect to DSK –Program/Run DSK –Flashburn PIC C compiler and MPLAB IDE –Used to convert.c program to assembly to load program on PIC 16F877A

8 Project Flowchart

9 Output from Guitar Without Amplification: Ave noise level = 22.8mV p-p Ave signal level = 150.3mV p-p Noise % = 1- { (150.3 - 22.8) / 150.3 } = 15.16% Noise Level:String 3 without Amplification:

10 Signal After Amplification After Amplification:Amplifier Circuit:

11 Original plan: Use C5509A Has built-in A/D converter Design to draw low power (Easy to make Portable) Problems: Emulator could not detect target DSP chip Back current between CVdd and DVdd

12 C6713 DSK Board

13 C6713 Board DIP switches for user input Built-in LED for tuning config Analyze the audio input from guitar to find different frequency in real time Send the motor control output to PIC

14 Flowchart of DSP Software Holding DIP Switch 3 Analyzes the Signal in Real Time Simplify the output to PIC to control the motor Only two bits of GPIO are required Simplify the output to PIC to control the motor Only two bits of GPIO are required To ignore any input when guitar is not plucked, we add this part in the code.

15 Only Run FFT When String is Plucked Without any audio inputWith guitar audio input String 6 Max 90 String 6 Max 4

16 Calculating the Frequency Lowest sampling frequency of A/D converter is 8kHz # of sample = 2048 Step size in frequency = 8000/2048 3.906Hz Frequency = (step)(3.906Hz) 1 st Peak: 84 2 nd Peak: 168 3 rd peak: 252 Mean difference 84 Freq = (84)(3.906) = 328.1Hz Frequency difference = 1.496Hz

17 Testing the DSP To test the user input from DIP switch, use LED on the board and check desired frequency from the memory To test the FFT, compare graphs from CCS to make sure the peak frequency of FFT is same as the frequency of input signal

18 DSK Challenges Find the common ground – to solve this problem we use TP32 as common ground from DSP board Find I/O from DSP – Use HPI to output as GPIO Cannot find the way to send any input to DSP – Use DIP switch as the user input Get the right speed for motor to turn, and prevent any delay

19 Increasing the Accuracy Increase the number of samples taken by the DSP –Would make the running time longer –Requires more memory space Formula that filters out unclear guitar inputs –When the first peak of FFT is smaller than other peaks of FFT

20 Daughter Card

21 Wire Wrapping Technique Disadvantages: Wires not soldered in place Time requirement Messy

22 Voltage Regulator for Battery Power

23 Motor Specifications Parallax Continuous Rotation Servo #900-00008 Stepper Motor Powered with 5VDC Torque = 3.40 kg-cm (47 oz-in) Need about 37 oz-in to turn peg

24 Motor Power Consumption String Number Average Current [A]Max Current [A]Average Power [W]Max Power [W] Clockwise Counter Clockwise Clockwise Counter Clockwise Clockwise Counter Clockwise Clockwise Counter Clockwise 60.350.170.450.181.750.852.250.9 50.330.180.360.181.650.91.80.9 40.310.190.340.21.550.951.71 30.340.190.350.21.70.951.751 Max Power Consumed: 2.25 Watts (String 6 Clockwise) Average Power Consumed: 1.25 Watts

25 Motor Resolution Find Hz/Degree for each peg using motorRes.c while (input(PB1)==1) //Push Button 1 is pressed, rotate clockwise { delay_ms(500); //wait for button to be depressed so that exact //number of pulses measured for (k=0; k<85; k++) //send 85 pulses to motor { output_high(motor); delay_ms(1); output_low(motor); delay_ms(20); } Adjust k until motor turns exactly 360

26 Data Taken from Pic.c String Number Clockwise 360 Turn [Steps] Counter Clockwise 360 Turn [Steps] Clockwise Resolution [/Step] Counter Clockwise Resolution [/Step] No Load51497.067.36 656846.434.29 5608164.44 4608164.44 3608464.29 262815.814.44 163865.714.19

27 Motor Resolution (continued) String Number Frequency at θ = 0 [Hz] Frequency at θ = 360 [Hz] Frequency at θ = 720 [Hz] Frequency at θ = 1080 [Hz] 652.6382.65105.26125 582.65108.7129.87142.86 4119.05144.93166.67181.82 3156.25196.08223.21263.16 2211.86250280.9333.33 1297.62333.33362.32384.62 Θ = Standard Tuning – Frequency of 360 Peg Turn

28 Motor Resolution (continued) String NumberEquation 6f = 0.067θ+79 5f = 0.056θ+110 4f = 0.058θ+140 3f = 0.097θ+190 2f = 0.110θ+250 1f = 0.081θ+330 Observations: Strings 6-4 have different slopes than strings 3-1 due to manufacturing process

29 Motor Resolution Results String Number Frequency/Rotation [Hz/]Rotation/Step [/Pulse]Resolution [Hz/Pulse] ClockwiseCounter ClockwiseClockwiseCounter ClockwiseClockwiseCounter Clockwise 60.067 6.4304.2900.4310.287 50.056 6.0004.4400.3360.249 40.058 6.0004.4400.3480.258 30.097 6.0004.2900.5820.416 20.110 5.8104.4400.6390.488 10.081 5.7104.1900.4630.339 Average Clockwise Resolution =.467 Hz/Pulse Average Counter Clockwise Resolution =.340 Hz/Pulse

30 Motor Challenges Motor designed to run on up to 6VDC –Running on 5VDC reduced torque Running daughter card and motor on same power supply reduced current to motor –Gave motor separate battery –More power supplies tied to common ground Needed to slow motor & still provide adequate torque

31 Motor Bracket

32 Future Improvement Increase Frequency Accuracy Flashburn Create PCB with DSP chip embedded –No need to have unused board components –Power consumption at a minimum Convert entire project to battery power –Reduces size Increase Number of Tuning Configurations

33 Ethical Considerations Complies with IEEE Code of Ethics Tried to make kit as universal as possible –One guitar maker will not benefit over others

34 Cost Analysis ItemManufacturerCost Per ItemQuantityTotal Cost C6713 DSK BoardSpectrum Digital$415.001 PIC 16F877AMicrochip$3.711 Voltage RegulatorEstek$0.902$1.80 Crystal OscillatorFox$0.401 Capacitors/Resistors/DiodesN/A$0.1015$1.50 Hex DisplayHP$10.561 Battery 9VDuracell$4.002$8.00 ProtoboardSilicon Labs$15.001 DaughterCardSpectrum Digital$99.991 Code Composer Studio v3.3Texas Instruments$995.051 Guitar Tuner TU-80Boss$24.951 Audio Cable 20'Peavy$19.951 Stepper Motor #900-00008Parallax$12.991 Mounting BracketMachine Shop$50.001 TOTAL $1,658.90 Parts: Labor: $40.00/Hr x 2.5 x 200Hr x 2 People = $40,000 Total = $40,000 + $1,658.90 = $41,658.90

35 Special Thanks Professor Gary Swenson Ben Graf Texas Instruments University Division ECE Machine Shop ECE Parts Shop

36 Questions ???

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