project14 design review1

8/8/2019 Project14 Design Review1

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Automatic Guitar Tuner

ECE 445Fall 2007

Group #14

Date: September 21, 2007

Ryan FreebergTiffany KasettratutDarren Pocci

TA: Tony Mangognia

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Automatic Guitar TunerThis project was chosen due to its signal processing capability and control aspect. All

group members are interested and ambitious in these fields, thus this project will provide achallenging, fun, and learning experience.

Objectives

To build a device that will automatically tune a guitar. It will take the signal from theelectrical output of an electric or acoustic/electric guitar and depending on the frequency it willcontrol motors that will then turn the tuning pegs to get the guitar in tune. Our project will be amodification of a standard guitar stand where the musician can put their guitar, attach tuningmotors, input desired tuning configuration on the user interface, and then the machine wouldtune all strings on the guitar. The tuner will be able to quickly and precisely tune a guitar to afew common tuning configurations (e.g., standard, open, and Drop-D) with little humanintervention.

Benefits: Quick and precise tuning of instrument

No modifications to the guitar are necessary

Prevents users involvement of tuning process

Prevent human error in the tuning process

Features:

Several different tuning configurations to choose from

Auto-plucking component so the user doesnt have to pluck

Works with multiple different makes and models of guitars

Block Diagram

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Schematic Diagrams & Software/Code Flowcharts

User Interface Schematic

User InterfaceAuto-Plucker

Signal Processor

Guitar

Motor

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PIC16F877ARA0/AN0 (19)

RA1/AN1 (20)RA2/AN2/Vref-/Cvref (21)

RA3\AN3\Vref+ (22)(7) Vdd(28) Vdd

(18) MCLR/VppRB0/INT (8)

RB1 (9)

RB2 (10)RB3/PGM (11)

RB4 (14)RB5 (15)

RB6/PGC (16)OSC2/CLKO (31)

(30) OSC1/CLKI

RC0/T1OSO/T1CKI (32)

RC1/T1OSI/CCP2 (35)RC2/CCP1 (36)

RC3/SCK/SCL (37)

(6) Vss(29) Vss

LCD: Hitachi HD4478U

(37) DB0

(38) DB1

(39) DB2(40) DB3

(34) RS(35) R/W

(36) E(22) OSC1

Signal Processor

Standard Tuning Selected

Drop-D Tuning SelectedOpen Tuning Selected

Tuning Done

Standard

Tuning

Drop-D

Tuning

Open

Tuning

5K

+5

10 MHz

Enter

User Interface Flowchart

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Signal Processor Schematic

StartStandard

Tuning modeDrop-D Tuning

modeOpen Tuning

mode

Drop-DTuningbutton

OpenTuningbutton

Standard

Tuningbutton

LCD:Select TuningStandard

LCD:Select TuningDrop-D

LCD:

Select Tuning...Open

EnterButton

pressed

EnterButton

pressed

EnterButton

pressed

LCD:StandardTuning

LCD:Drop-DTuning

LCD:OpenTuning

[Inputs tuning style]

Signal Processor

[Outputs signal when done]

LCD:StandardDone

LCD:Drop-DDone

LCD:OpenDone

Enter

Buttonpressed

Restart

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(52) DIOB3

(51) DIOB2

(17) DIOB1

(16) DIOB0

(15) DIOA7

(48) DIOA6

(47) DIOA5

(13) DIOA4

(12) DIOA3

(45 )DIOA2

(44) DIOA1

(10) DIOA0

(11) GND

(1) +5 V

NI 653x I/O Connector

Frequency too high output to motor control

Frequency too low output to motor control

Frequency just right

Select bit 2 for motor MUX



Done to user interface

Open Tuning from user interface

Drop-D tuning from user interface

Standard Tuning from user interface

Pluck to Auto-plucker

Next str ing to Auto-plucker

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OpenTuningChosen

?

Drop-D

TuningChosen?

At leastone tune

signalhigh

Load OpenNote

Frequencies

Load Drop-D

NoteFrequencies

Load StandardNote

Frequencies

Pluck

Frequencywithin

frequencyrange?

Amplitude OK?

FrequencyGreater

thanRange?

Send loosenstring signal

Send tightenstring signal

FinishedLast

String?

Move to NextString

END

Yes

Yes

Yes

Yes

Yes

Yes

Yes

No

No

No

No

No

No

No

SignalProc

essorFlowc

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Motor Schematic

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2

3

4

5

6

7

8

9

10

11

12

24

23

22

21

20

19

18

17

16

15

14

13

+5V

Black

White

Red

Parallax Continuous Rotation

Servo Motor

Model #900-0008

BasicX-24

Output Signalsfrom DSP

Frequency Too High

Frequency Too Low

Frequency Just Right

Output

Input

Input

Input

Gnd

I/O

Gnd

Vcc

I/O

I/O

I/O

S2

S1

S0

1

0

2

3

4

5

6

7

1st String Motor

6th String Motor5th String Motor4th String Motor3rd String Motor

2nd String Motor

Current String

Bits from DSP

7

9

10

11

12

13

14

15

3

2

1

G1

G2AG2B

4

5

6

LS138

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Motor Flowchart

FrequencyJust RightSignal ON

Stop TurningMotors

FrequencyToo HighSignal ON

FrequencyToo LowSignal ON

Loosen Pegs (Turn MotorCounter-Clockwise)

Tighten Pegs (TurnMotor Clockwise)

Yes

Yes

Yes

No

No

No

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Auto-Plucker Schematic

1

2

3

4

5

6

7

8

9

10

11

12

24

23

22

21

20

19

18

17

16

15

14

13

+5V

Black

White

Red

Parallax Continuous Rotation

Servo Motor

Model #900-0008

BasicX-24

Output Signalsfrom DSP

Pluck String

Move to Next String

Output

Input

Input

Gnd

I/O

Gnd

Vcc

I/O

I/O

I/O

Auto-Plucker Flowchart

MoveString?

PluckString?

Signal to Motors tomove string Signal to Motors

to pluck string

Yes

Yes

No

No

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Schematic Descriptions

User Interface

This will be the part where the user will be able to select what type of tuning they wantbased three buttons corresponding to the different tuning styles offered (Standard, Drop-

D, and Open) and enter the style with an enter button to start the tuning. Buttons

o The four buttons will be inputted into the PIC which will then output signals to

the LCD and the Signal Processor

PICo Three more outputs from the PIC are sent to the Signal Processor corresponding

to the tuning style chosen. After tuning has completed the Signal Processor willthen send a signal to the PIC which will then send the corresponding addressregister to the LCD to display that the tuner has finished. The PIC will handle thesoftware necessary to send out the right signals to both the Signal Processor andLCD. Pressing the buttons is the only thing the user has to do (aside from placing

the guitar in the stand and attaching the motors and strummer) to get the guitar intune.

LCDo The LCD will have eight inputs from the PIC. Four of them will correspond to

the register selection address that will tell the user what tuning style they areselecting and the status of the tuner. The four other inputs are for Enable,Register Select, Read/Not Write, and the Clock.

Component Leader: Tiffany Kasettratut

Signal Processor

The signal processor will take the input from the guitar and extract the frequency

component of the signal. It will compare this to what the user selected, represented bythe three tuning set inputs: standard, drop-f, open, and depending upon if the frequency istoo high, too low, or acceptable, tell the motor which direction to turn. These arerepresented in the three output signals: frequency too high, frequency too low, andfrequency just right. The signal processor will send a pluck output to the auto-plucker tobegin operation. In addition, the signal processor will also keep track what string thetuner is on and output that value to the motor represented by the three select bit outputs. Itwill also output a move string signal to the auto-plucker when a string is tuned. Thisprocedure will be done in LabVIEW. With LabVIEW, the guitar can be plugged into themicrophone jack on the computer and easily read. The frequency can be directlyextracted from this signal. The signal processor will make use of the Data Acquisition

Board in the lab to communicate with the other parts of the project. Lastly, the signalprocessor will send a done output signal to the user interface to notify the user of tuningcompletion.

Component Leader: Ryan Freeberg

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Motor

The motors control the tension of the strings, which controls the emitting frequency.

BasicX-24 Controller

o The controller will take inputs from the signal processor: frequency too high,frequency too low, and frequency just right and output a pulse that controls theturning direction and turning magnitude of the motors. Frequency too high willsend out a pulse to loosen the string tension. Frequency too low will send out apulse to tighten the string tension. Frequency just right will tell the motors to stop

3-to-8 Decodero The decoder will receive input from the signal processor to indicate which string

to tune and, thus, which motor to turn. These signals are the three select bits. Inaddition, the decoder will also receive input from the controller, which is a pulsethat determines the turning direction and turning magnitude of the motors.

Motor

o Only viable input is the white wire, which is the pulse that determines the turningdirection and turning magnitude of the motors.

Component Leader: Darren Pocci

Auto-Plucker

This block will be the mechanical device that will automatically pluck the strings of theguitar or move to the next string.

Motoro This will be able to pluck multiple times if the amplitude of the signal in the

Signal Processor degrades to a point where it is unusable. This will also be ableto move to the next string on the guitar once the prior string has been tuned. The

motor has one input pin from the controller that determines the turning directionand turning magnitude.

Controllero This will tell the auto-plucker motors to pluck when the user has initiated tuning.

Also, this block will determine if the string needs to be plucked again or if thecurrent string is in tune and needs to move to the next string based on the signalsfrom the signal processor. The controller has two inputs from the signalprocessor that will tell the Auto-Plucker whether it needs to pluck the string ormove it to the next string and one output to the motor.

Component Leader: Ryan Freeberg

Guitar

Creates the audio output for determining frequency components after the Auto-Pluckerplucks a string. The Tuning Motors will change the frequency depending on thedirection that it turns.

Component Leader: Tiffany Kasettratut

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Performance Requirement

The requirements for our tuner are obviously to get the guitar in tune. We will do this bymaking sure the frequency of the guitar signal is within 2 Hz of the actual frequency of the note.

This is because the smallest difference a musically trained ear can detect is about 2 Hz[1]

. It willalso be able to attach to a wide variety of electric guitar models. Feedback of control system willguarantee no broken strings. Our device must completely tune a guitar within 2 minutes ofinitiation.

Tolerance Analysis

Since our device measures the frequency of a signal generated by the guitar, the signalprocessor is essential to extract the frequency components to get the emitting signal from theguitar in tune. When the string is plucked and the frequency detected by the signal processor iswithin 2 Hz of the actual note, the tuning motor must stop in time without changing the outputfrequency more than 0.5 Hz. In other words, the tuning motors must have a fast enough response

time to not de-tune the guitar string by overturning the tuning peg. In addition, this means thatthe motors will also have to be able to change the frequency by less than 0.5 Hz. Also, the signalprocessor will have to be able to detect the frequency with and accuracy of +/- 2Hz.

Testing

Signal Processor

The signal processor will first be verified by hooking it up to a function generator andmaking sure that it extracts the frequency correctly. We will plot the actual frequency of thefunction generator vs. the results obtained from the signal processor and calculate the percenterror. Then, we will input signals from the guitar to the signal processor. We will compare whatfrequency we find with what frequency a commercial guitar tuner finds and calculate the percenterror. We will then test to make sure the logic works correctly. This will be done by attachingthe inputs to function generators and using indicators in the LabVIEW program to make sure thatcorrect logic values are present at different points in the program.

User Interface

The User Interface can be broken down into three parts (buttons, LCD, and PIC). To testthe buttons, we will connect them to an oscilloscope and make sure that when the buttons arepressed the input voltage will drop from high to low due to the connection to ground.

The LCD will be tested by inputting different register addresses corresponding to eachtuning style during selection, tuning, and finishing that will call upon different sayings on theLCD screen. We will also test the home function of the LCD by inputting the correct inputs totest the reset after a tuning has been completed.

The PIC will be tested by selecting different inputs corresponding to the different tuningbutton selections and the done signal from the Signal Processor. An oscilloscope will be hookedup to all the outputs to make sure the right values are read to the LCD and the Signal Processor.

We will test the User Interface as a whole connecting all the components and selectingdifferent inputs and verifying that the correct information appears on the LCD and that the

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correct signals are outputted from the PIC. This will be compared to a table we have that showswhat the correct outputs should be.

state initialization selection enter selection tuning done reset

inputs

enter RA0 1 1 1 1 0 0 0 x 1 1 1 0

standard RA1 1 0 1 1 x x x x x x x x

drop-d RA2 1 1 0 1 x x x x x x x x

open RA3 1 1 1 0 x x x x x x x x

done RC3 x x x x x x x 0 1 1 1 x

tuning standard standard drop-d open standard drop-d open previous standard drop-d open standard

outputs

db0 RB0 0 0 1 0 1 0 1 x 0 1 0 0

db1 RB1 0 0 0 1 1 0 0 x 1 1 0 0

db2 RB2 0 0 0 0 0 1 1 x 1 1 0 0

db3 RB3 0 0 0 0 0 0 0 x 0 0 1 0

RS RB4 1 1 1 1 1 1 1 x 1 1 1 1

R/W RB5 1 1 1 1 1 1 1 x 1 1 1 1

E RB6 1 1 1 1 1 1 1 0 1 1 1 1

standard RC0 0 0 0 0 1 0 0 previous 0 0 0 0

drop-d RC1 0 0 0 0 0 1 0 previous 0 0 0 0

open RC2 0 0 0 0 0 0 1 previous 0 0 0 0

LCD "standard" "standard" "drop-d" "open""Standardtuning"

"Drop-dtuning"

"Opentuning" previous

"standarddone"

"drop-ddone"

"opendone" "standard"

Motor

The motor control will be verified by using a function generator to simulate differentinputs and then, given these inputs, output the correct turning direction of the motors. Also, whena correct frequency is simulated we will make sure the control unit outputs a signal to stopturning the motors.

The motors will be verified by inputting a signal to the motors to simulate the input fromthe controller and making sure they turn in the correct direction or stop. We will measure tomake sure that the motor will not turn more than 3 degrees.

Auto-Plucker

The auto-plucker control will be tested by simulating the start of the tuning process witha function generator and making sure it outputs a pluck signal to the Auto-Plucker. Also, it will

be tested by inputting a signal that simulates the completion of tuning of one string (determinedby the signal processor) and seeing if the Auto-Plucker moves to the next string. Lastly, we willmake sure the auto-plucker moves the pick a full strings width distance when told to move.

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Cost Analysis

User Interface

Part Quantity Price Total Order StatusLCD Hitachi HD4478U 1 $13.95 $13.95 WFA

Button Omron B3F Switches 4 $0.35 $1.40 WFA

PIC Microchip PIC16F877A 1 $3.71 $3.71 IL

Resistor 5k 4 $0.25 $1.00 WFA

TOTAL $20.06

Signal processor

Part Quantity Price Total Order Status

DAQ NI PCI-32HS 1 $1,199.00 $1,199.00 ILCable SH68-68-DI 1 $129.00 $129.00 IL

TBX-68 Block 1 $159.00 $159.00 IL

LabView 1 $1199.00 $1199.00 IL

1/4 male to 1/8 femaleadapter

1 $9.00 $9.00 Have

TOTAL $2,695.00

Motor


BasicX-24 Microcontroller 1 $49.95 $49.95 ILSN74LS138 Decoder 1 $0.40 $0.40 WFA

Parallax Servo Motor #900-0008 6 $12.95 $77.70 WFA

6 $1.45 $8.70 Have

TOTAL $136.75

Auto-Plucker


BasicX-24 Microcontroller 1 $49.95 $49.95 IL

Machine Shop 4 $35/hr $140 N/A

TOTAL $189.95

Guitar

- User Supplied

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Overall Total: $3041.76

Key

WFA Waiting For ApprovalIL In LabN/A Not Applicable

Addendum

Although we have an idea for the auto-plucker component, we may have been slightlyover-ambitious in the proposal. As a result, we will strive to finish this component but we willwork on it last, as indicated in the schedule.

Rough Mechanical Projections

Auto-Plucker

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Projected Torque Calculations

With no response from the physics lab department, we have included a torque calculationthat will tell us the needed torque to turn the tuning pegs. Note: this example is not our own and

is taken from [2] referenced at the end of this paper.

Simulations: See Appendix 2.

Schedule

WEEK Ryan Tiffany Darren

Sep 10 - Obtain Guitar outputsignals

X - Begin to order parts 0 - Obtain stepper motors 0

Sep 17 - Finish schematicdiagrams for signalprocessor and auto-plucker- Complete softwareflowchart for signal

processor and auto-plucker

X

- Finish schematic diagramfor user interface- Update testing procedureand tolerance analysis

X

- Finish schematic diagramfor motors- Update cost analysis andschedule

X

Sep 24 - Create signal processor inLabView- Test signal processor withsimulated sinusoidal inputscreated in LabView

- Program PIC to takeinputs from buttons andoutput correct signal minusLCD outputs- Test correct PIC bypushing all different buttoncombinations and observing

- Program BasicX-24 tooutput pulses that will rotateservo CW, CCW, and stop- Test all three functions indifferent permutations

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output

Oct 1 - Program LabView toacquire signal from dataacquisition board- Test signal acquisition

with function generator,then guitar

- Program PIC to makeproper display on the LCDwith corresponding tune setchoices

- Test LCD with differentpermutations

- Program BasicX-24 tooutput pulses that will rotateservo CW, CCW or stopbased on input from SP

- Test by simulatingdifferent input combinations

Oct 8 - Program SP to countnumber of tuned strings- Test outputs of SP basedon different emitting tonesfrom guitars and ability tocount # of tuned strings

- Connect buttons, PIC, andLCD to each other- Test correct output anddisplay based on differentinput sequences

- Connect MUX to motorunit to provide six stringfunctionality- Test proper rotation tocorrect motor based onnumber of strings tuned

Oct 15 - Construct bridge thatservo motor moves upon

- Calibrate motor movementto linear movement

- Program BasicX-24 tooutput pulses that moveplucker one string length

back and forthOct 22 - Connect Signal Processor

to User Interface- Test functionality of twomodule unit

- Connect Signal Processorto User Interface- Connect Signal Processorto Auto-Plucker- Test functionality of bothtwo module units

- Connect Signal Processorto Motor unit- Test functionality of twomodule unit

Oct 29 - Debug Signal Processorand Auto-Plucker

- Debug User Interface - Debug Tuning motors- Ensure connection ofmodules for mock-up demo

Nov 5 - Test stringency of signal

processor by calculatingdelay of stop signal aftercorrect frequency attained

- Test durability of auto-

plucker by determining howmany cycles before movedistance is inproper

- Test stringency of motors

by calculating delay of stopafter signal turned off

Nov 12 - Improve robustness ofAGT by improving delayof modular components

- Improve robustness ofAGT by improving delay ofmodular components

- Start final paper

Nov 19 Thanksgiving Break Thanksgiving Break Thanksgiving Break

Nov 26 - Present and Demo AGT- Start final paper

- Present and Demo AGT- Start final paper

- Present and Demo AGT- Start final paper

Dec 3 - Turn in final paper - Turn in final paper - Turn in final paper

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References

[1] Henderson, Tom. Lesson 5: Musical Instruments. 10 Sep 2007.

[2] House, et al. A Self-Tuning Acoustic Guitar. Ohio: Ohio Northern University, 2006.

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