The Player Guitar

Advised by T Baird SoulesTeam members:Joshua Libby, Stephen Monska,Simon Leung, Robert Williams

20 October, 2006 2

Outline Background and Motivation Deliverables of Design Project System Block Diagram MIDI Tablature Player Guitar Mechanics

Fretting Strumming Guitar Design Alternatives

Power Product Cost Q&A

20 October, 2006 3

Background and Motivation

Learning how to play guitar is not an easy task for most. Plucking the strings at the right tone could be hard enough as is, but executing the complicated techniques on the guitar as well could cause some problems.

Our proposed ‘Player Guitar’ will attempt to solve this problem. The user would be allowed to input files to the guitar, thus allowing the person to not worry about the semantics of how to play the guitar and spend more time on other factors, such as the composure of music.

20 October, 2006 4

The Design

Designing a machine to play the guitar chords properly Ability to:

Pluck Slide/Fretting Dampen

The input will be coming from the MIDI Guitar Tablature Display that can be read real time MIDI Guitar Tablature Display reads in a Musical

Instrument Digital Interface (MIDI) signal and outputs the appropriate finger placement on LEDS

We plan to rework the former project to drive the input of our project, telling our machine where to place its “fingers”

Background and Motivation

20 October, 2006 5

Deliverables A working prototype will be

completed for demonstrational purposes. Able to play an audible sound from the

guitar. There will be full documentation of how

to use the Player Guitar. With examples of how to operate the user

interface. Pre-designed music files for demonstration

purposes.

20 October, 2006 6

DeliverablesUser Interface The user interface will be done through the MIDI Guitar Tablature Display. It will

consist of a 4x20 alpha (LCD Screen) and an optical encoder that serves both as a button and a selector switch. This display is controlled by a PIC 16 and was designed to change the mode of the main PIC as well as the settings. The mode of the PIC was used to change to an instrument other than a guitar, so it will not be changed in our project. The settings can be altered to change to any of the 16 different channels MIDI format uses.

Input The input will be from the MIDI Guitar Tablature Display that will read in a MIDI

signal and calculate where the finger placements will be on the LEDS. These finger placements will be sent to the processor, which will know where to locate the frets and communicate that to the stepper motors.

Output The output will be the sound created by the mechanical fretter and strummer. The

strumming will be done by servos and silencer solenoids that receive a single from the processor. The fretting will be done by the moving stepper motors.

Acceptance Tests The system must be properly converting the inputs from the MIDI Guitar Tablature

Display and outputting it to the stepper motors.

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System Block Diagram

Guitar

Power

StepperMotor

Springboard

StepperMotor

Springboard

StepperMotor

Springboard

StepperMotor

Springboard

StepperMotor

Springboard

StepperMotor

Springboard

x6 Strum Servos

X6Silence

Solenoids

5 V

Music Tablature

AVR Processor

Power: |Mechanical: |

Signal: |

12 V

MIDIInterface

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MIDI Tablature What it can do: Receive one channel of MIDI data and display the

message in a 6x25 LED matrix representing the fret board of a guitar.

Receive six channels of MIDI input, one from each string of a played guitar, and display the message in the LED matrix which will exactly describe the fingering of the guitar being played.

What it can do for us: It will serially drive the input of our AVR processor

chip with the selected notes via SPI data.

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MIDI Tablature

Uses an two 8-bit PIC processor One for a user

interface to configure the settings.

One for the main processor.

Forward the SPI Data by altering the .asm files from the LEDs to the AVR chip.

PIC

18

Data Ready BitData Received Bit

Status Bit

Data Bit

Data BitData Bit

Data Bit

Data Bit

DATA Ready Bit1 – Set by PIC16 to indicate that data is ready to be read by the PIC18.

DATA Received Bit1 – Set by PIC18 to indicate that data has been received.

Status Bit0 – FUNCTION is selecting the Mode of the device.1 – FUNCTION is selecting the Setup of the device

Data ByteIf Status Bit = 0

00000 – Standard ModeIf Status Bit = 1

00000 – Channel 100001 – Channel 200010 – Channel 300011 – Channel 4

Etc.

Specifications

SPI D

ata

To L

ED

s

20 October, 2006 10

MIDI Tablature: Block Diagram

LED DRIVER

LED DRIVER

LIQUID CRYSTAL DISPLAY

48 LED’S

MIDI IN

MIDI THRU

48 LED’S

48 LED’SOPTICAL ENCODER

USER INTERFACE PIC

LED DRIVER

AVR Processor

MIDI PROCESSING PIC Retrieve from SPI

From each LED with Ribbon Cables

20 October, 2006 11Guitar

Power

Combined System Block Diagram

StepperMotor

Springboard

StepperMotor

Springboard

StepperMotor

Springboard

StepperMotor

Springboard

StepperMotor

Springboard

StepperMotor

Springboard

x6 Strum servos

X6Silence

solenoids

5 V

Music Tablature

AVR Processor

LIQUID CRYSTAL DISPLAY

MIDI THRU

USER INTERFACE PIC

MIDI IN

OPTICAL ENCODER

MIDI PROCESSING PIC

Power: |Mechanical: |

Signal: |

12 V

20 October, 2006 12

Player Guitar Mechanics

Stepper MotorsSpring Boards

Strum ServosGilmore Belts*

Silencer Solenoids

Fretter

Strummer

*: or a Cog Belt

Clothes Pins Coil Spring

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Six stepper motors turn six gilmore belts

Since the motor is larger than belt, three will be placed on both ends of the bar stock

As the belt moves, it drags the spring board “fingers” over the strings to the appropriate position

Stepper Motors

Player Guitar Mechanics: Fretting

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Player Guitar Mechanics: Strumming

Servos are controlled through Pulse Coded Modulation The length of a pulse

expected ever 20 ms determines how far the servo turns

Placed over the string, the servos moves back and forth, in a 180 degree motion, hitting the string

Strum Servos

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Player Guitar Mechanics: Strumming

Silencer Solenoids Attach eraser or rubber

material onto solenoids. When the solenoids push down onto string it will silence their sound.

These silence solenoids will be attached near the sound hole of the guitar with the servos, but could work anywhere past the frets on the guitar strings

20 October, 2006 16

Player Guitar Mechanics: Guitar Design Alternatives

If there is not enough room between the strings of the neck of the guitar Use fewer strings on the neck

This would either limit notes available, or require more necks and/or guitars

Widen neck of guitar Would lose acoustics, so may need to be

implemented as an electric guitar, which would add the overhead of adding pickups

20 October, 2006 17

Power At least two power sources

12v standard amount for most stepper motors and solenoids

Isolation the power to the processor

Power

StepperMotor

Springboard

StepperMotor

Springboard

StepperMotor

Springboard

StepperMotor

Springboard

StepperMotor

Springboard

StepperMotor

Springboard

x6 Strum Servos

X6Silence

Solenoids

5 V

AVR Processor

12 VPower: |Signal: |

20 October, 2006 18

Product Cost Estimated costs for electronics:

Stepper Motor = $2 x 6 = $24 Solenoid/Servos = $4 x 18 = $72 Guitar* = $0 x 4 = $ 0 Total $96

This leaves plenty of money in our budget for getting a processor and handling any additional parts required.

*: Three Guitars were obtained for free and one pizza box guitar was made at almost no cost to use in testing.

20 October, 2006 19

Question & Answer

Stepper MotorsSpring Boards

Strum ServosGilmore Belts

Silencer Solenoids

Fretter

Strummer