School of Rock PDR
Cheyenne Aberle
Drew Veldhuizen
Swain Brooks
Dan Reed
ECEN 4610
Capstone
University of Colorado
Boulder, CO 80303
January 29, 2009
Now Presenting…
ECEN 4610
Capstone
Drew Veldhuizen
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
Capstone PDR
ECEN 4610
2
Project Overview
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
ECEN 4610
Capstone
Capstone PDR
ECEN 4610
3
Design
ECEN 4610
Capstone
 PCB mounted in body of guitar.
 Motors mounted to the back side of the head of
the guitar.
 Using DSP, A/D converters, and microcontroller,
analyze signal and control motor movement to
achieve desired pitch.
 User Interface via LCD touch screen.
 Multi-colored LED’s next to each string to
indicate in tune or out of tune.
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
Capstone PDR
ECEN 4610
4
Block Diagram
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
ECEN 4610
Capstone
Capstone PDR
ECEN 4610
5
Guitar
ECEN 4610
Capstone
 Electric guitar
 Audio output jack on guitar outputs signal for
analysis
 Signal output via magnetic “pick-ups” already
built into the guitar
 Looking for guitar at local shops and online
 Based on measurements, torque on tuning
knobs requires 12 to 16 oz-in
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
Capstone PDR
ECEN 4610
6
PCB Design
ECEN 4610
Capstone
 MSP430 Microcontroller
 Motor Drives
 Six drives will be built and used to control six stepper
tuning motors, one for each tuning knob.
 DSP Processing Chip
 Using Fourier Transforms, will process frequency of
each string and determine how far off it is from the
correct pitch.
 Accelerometer
 Used for effects similar to star power in Guitar Hero.
 LCD/Touch Screen
 GUI for tuning presets, effects, and feedback to user
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
Capstone PDR
ECEN 4610
7
Now Presenting…
ECEN 4610
Capstone
Cheyenne Aberle
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
Capstone PDR
ECEN 4610
8
Microcontroller
ECEN 4610
Capstone
 TI MSP430 16-bit microcontroller
 32 kHz, 1.8V to 3.6V, ultra-low-power
 Interface to DSP chip through I2C communication
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
Capstone PDR
ECEN 4610
9
DSP Chip
ECEN 4610
Capstone
 Freescale Semiconductor DSPB56371
 24-bit Audio Digital Signal Processor
 Utilizes I2C communication with microprocessor
 180MHz core, 3.3V
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
Capstone PDR
ECEN 4610
10
Filtering
ECEN 4610
Capstone
 Filtering performed in the microcontroller
 Ideally, strum all strings at once and circuit filters
signals, outputs information to each motor controller
for optimized tuning
 The guitar might need to be strummed 3 to 4 times to
provide adequate data for the tuning circuit
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
Capstone PDR
ECEN 4610
11
Motor Design
ECEN 4610
Capstone
 Stepper Motors similar to the Sure Step 83oz-in
motor will be used to turn the tuning knobs on
the guitar head.
 Motors will be mounted on the head with wires
run through the neck of the guitar to the
microcontroller.
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
Capstone PDR
ECEN 4610
12
Power
ECEN 4610
Capstone
 AC to DC Power Converter
 Plugs into 120VAC 60Hz outlet.
 Used to recharge the battery
 Also good application for use at a performance

Ensures guitar always has enough power for tuning during a
show
 Rechargeable Lithium-Ion battery
 Able to supply enough power to tune the guitar a few
times before recharging is necessary.
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
Capstone PDR
ECEN 4610
13
Now Presenting…
ECEN 4610
Capstone
Dan Reed
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
Capstone PDR
ECEN 4610
14
User Interface
ECEN 4610
Capstone
 LCD Touch Screen
 Creates a graphical user interface
 Allows user to select different tuning schemes


Drop D, double drop D, standard, etc
User can also customize tuning scheme
 Most logical would be a lay-over resistive touch
screen for an LCD display
 LED’s
 Next to each string below the bridge.
 Indicates in or out of tune for each string based on the
color (eg. Green for in tune, red for out of tune)
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
Capstone PDR
ECEN 4610
15
Effects
ECEN 4610
Capstone
 Adding effects to the guitar can up-scope this
project if needed
 Distortion, Wah Wah, Reverb, etc…
 The XYZ accelerometer will determine which
effect is enabled based on the direction the
guitar moves.
 Can increase (1) the ease of turning on effects
and (2) the excitement of performances.
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
Capstone PDR
ECEN 4610
16
Implementation
ECEN 4610
Capstone
 PCB will be set into the body of the guitar.
 Motors will be attached to the head of the guitar.
 The LCD touch screen can be mounted in the
front or back of the guitar body, whichever is
more convenient to the user.
 The rechargeable battery will be mounted in the
backside of the guitar body with an input jack for
the AC to DC power converter.
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
Capstone PDR
ECEN 4610
17
Schedule
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
ECEN 4610
Capstone
Capstone PDR
ECEN 4610
18
Division of Labor
 Drew Veldhuizen
 Cheyenne Aberle
 Motor Control
 PCB Design
 Dan Reed
ECEN 4610
Capstone
 DSP
 Mechanical / Control
 Swain Brooks
 PCB Design
 Software
 DSP
 Software
 Group
 Technical and User Manual
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
Capstone PDR
ECEN 4610
19
Now Presenting…
ECEN 4610
Capstone
Swain Brooks
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
Capstone PDR
ECEN 4610
20
ECEN 4610
Capstone
Budget
Item
Guitar
Guitar Strings
Stepper Motors
Motor Drivers
PCB
Microcontroller
DSP Chip
Development Board
Misc (cables, connectors,
shipping, etc)
Accelerometer
Touch Screen
LCD Screen
A/D Converter
D/A Converter
Battery
Battery Charger
Flash Memory
LEDs
#
1
5
6
6
1
1
1
1
Cost Per Item
100
6
19
20
40
13.75
12.88
0
Total
100
30
114
120
40
13.75
12.88
0
1
1
1
1
1
1
3
1
1
10
150
35
100
100
8.91
4
25
25
10
0.1
150
35
100
100
8.91
4
75
25
10
1
Total
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
Notes
Borrowed from Capstone
939.54
Capstone PDR
ECEN 4610
21
Extra Features
ECEN 4610
Capstone
 Accelerometer
 USB output used for recording
 Visualizer on LCD screen and/or LEDs
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
Capstone PDR
ECEN 4610
22
Risks
ECEN 4610
Capstone
 Not everything will fit inside the guitar
 Create external enclosure to house electronics
 Motors might end up being too large to fit on the
head of the guitar
 Separate free standing enclosure for motors
 Touch Screen does not work
 Use LCD and push buttons
 Not enough time for effects
 Not essential for project
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
Capstone PDR
ECEN 4610
23
Fall Back Plan
ECEN 4610
Capstone
 LCD user interface with corresponding buttons.
 Set tuning schemes, not customizable.
 No effects, accelerometer used to activate the
tuning program.
 No battery, just use power cable.
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
Capstone PDR
ECEN 4610
24
Questions
ECEN 4610
Capstone
Any Questions?
Dan Reed
Swain Brooks
Cheyenne Aberle
Drew Veldhuizen
Capstone PDR
ECEN 4610
25