Transcript Automatic Guitar Tuner

Automatic Guitar Tuner
TRENTON AHRENS, ALEX CAPO, ERNESTO WONG
GROUP 1
Goals
•Design a guitar that will automatically tune to a selected tuning preference
•Interact with an android application
•Gain necessary skills required to succeed in the engineering field
Motivation
•Tuning can be time consuming
•Difficult without extra equipment especially for beginners
•The interest in music
Specifications
•Tune within 30 seconds
•Within a noticeable difference of +/- 5 cents (100 cents/semitone)
•Small profile
•5 tuning preferences
•At least 50 cycles per battery charge
•Operate outside with moderate humidity
4-String Bass
Overall System Block Diagram
Division of Labor
Ernesto
• Android app development
• Code for tuning algorithm
Trenton
• Signal Processing
• Pickups
• Mounting
Alex
• Power supply
• Mounting
• Code for tuning algorithm
Mobile Application
•User Interface
•Android Platform Version 4.4.X+
•Android Studio
•Java
•Bluetooth communication with microcontroller
Android Studio
Bluetooth Communication
•Built in Bluetooth capabilities on phone
•HC-05 Bluetooth module
Microcontroller
•ATMega328p chip
•6 analog inputs 10-Bit ADC
•6 PWM outputs
•20 MHz operating freq.
Pickups
•Magnetic field seen by the pickups will induce an analog voltage that will be read by the ADC
inputs
•Polyphonic
•Extracted from a Power Gig controller
Analog-Digital Conversion
•Threshold crossing
•Fast Fourier Transform
Standard Tuning For a 4 String Bass Guitar
String
1 (thinnest)
2
3
4 (thickest)
Note
Frequency (Hz)
G
D
A
E
98
73.42
55
41.2
DC Offset & Amplification
•Guitar signal from pickups is about 20mV-40mV
•ADC 0-5V
Tuning Mechanism
•Atmega328P controls the tuning algorithm
•Reflective sensors to determine number of turns
•H-Bridge for bi-directional rotation
•QTR-1RC Reflective Sensor (Pololu)
•L293DNE Dual H-Bridge (Texas Instruments)
Motor Mounting Bracket
Power
•Battery Power – NiMH (Nickel Metal Hydride) rechargeable batteries
•6xAA battery holster (Adafruit) = 7.2 V 2500 mAh
Components to be Powered
•Atmega328P (Amazon) 1.8-5V Operating voltage 0.2mA current draw while active
•4x ROB-12472 Standard Gear Motor (Sparkfun) 3-12V operating voltage 95mA current draw @
12 V
•4xMotor(95mA) + Atmega328P(0.2mA) = 380.2mA
•2500mAh/380.2mA = 6.57 hours battery life
•2500mAh/95.2mA = 26.26 hours battery life (realistically)
Component Decisions
•6-String Electric Guitar vs. 4-String Bass Guitar
•Polyphonic vs. Single Coil
•ATmega328p
•Gearmotor vs. Stepper vs. Servo
•NiMH vs. Li ion
•IC H-Bridge vs. DIY H-Bridge
•Android > Apple
Difficulties
•Mounting of motors
•Emulating the code
•Reading signals
Budget
Part
Cost
4-String Bass Guitar
$0
Pickups
$20.50
4x Gear motors ROB-12472
$ 119.96
Arduino Uno
$25.75
HC-05 Bluetooth module
$8.40
Shaft couplers & motor mounts
$46.00
4x Sensors (QTR-1RC)
$12.45
2x H-Bridge (L293DNE)
$14.49
Funding provided by Boeing : $200
Total: $247.55
Progress
Overall
PCB
Mounting
and Wiring
Code
Android App
Parts
Acquisition
0%
20%
40%
60%
80%
100%
Future Plans
1. Design adequate motor mount
2. Signal processing/motor tuning algorithm implementation
3. Finish and test Android application functionality
4.Design and order PCB
5.Combine all subsystems into final product and test
Questions?