Auto-chromatic Musical Instrument Tuner

Craig Janus and Robert SchmanskiAdvisor: Dr. James Irwin

Presentation Overview

• Terminology• Project Summary• Functional Description• Block Diagram• Software • Milestones & Critical Problems• Future Work• Progress Summary

Terminology

• Pitch / Fundamental• Octave• Tuning error • Cents

Project Summary

• Determine pitch of note played• Inputs- microphone, mode/power

switch, and pitch selector• Output- pitch indicator, analog and

digital tuning meters, and speaker• 8031 microcontroller

Functional Description

• Inputs– Microphone– Power / mode

switch– Pitch selector

Functional Description (cont.)

• Outputs– Pitch indicator– Analog tuning

indicator– Digital tuning

indicator– Speaker

Functional Description (cont.)

• Operating modes

– Off– Auto tune– Manual tune– Audible

reference pitch

Block Diagram

• Overall Flowchart• Table Look-Up Subroutine

Software

Bitmap Image

Bitmap Image

• Fundamental Determination– Typical Musical Waveform input:

Milestones and Critical Problems

• Input Conditioning Hardware– Schematic:

Milestones and Critical Problems

• Peak Detector Circuit– Schematic:

Milestones and Critical Problems

• Peak Detector Circuit– Critical Problem - Switching Noise:

Milestones and Critical Problems

• Peak Detector Circuit– Switching Noise Solution - LPF:

Milestones and Critical Problems

• Peak Detector Circuit– Solution Results:

Milestones and Critical Problems

• Complete Input Hardware– Response to Vocal Pitch:

Milestones and Critical Problems

• Complete Input Hardware– New Problem:

Milestones and Critical Problems

• Frequency Divider– 74294

• Programmable divide by 2^n• Minimum divide of 2^2

– Need 2^1 to tune zero octave

Milestones and Critical Problems

• Manley Board Difficulties– External Interrupt– Port 1

• Priority on Stand-Alone Microcontroller Hardware and User Interface Hardware

Milestones and Critical Problems

Milestones and Critical Problems

• User Interface– Component Selection

• 16 vs. 7 Segment LED displays• Zero Center Analog Meter

– Interface Simplification• Pitch and Octave Up/Down Buttons vs. Rotary

Switches– GAL for Address Decoding, Display Drive,

and Button Debouncing

Future Work

• Original Design– Automatic Octave Selection– Improve Accuracy– Other Modes (Manual Tune, Reference Pitch)

• New Ideas– Automatic Gain Control– Improve Resolution

Progress Summary• Peak Detector• 2^n Frequency Divider• GAL Usage• Stand alone

microcontroller hardware• Student Research

Exposition

• Auto Tuning Mode– 9 octave range (1-9)– User selected octave

• Tuning Accuracy– 1 cent at A4=440 Hz– 5 cents at ends of table

range

Auto-chromatic Musical Instrument TunerCraig Janus and Bob Schmanski Advisor: Dr. James Irwin, Jr.