Auto-Chromatic Auto-Chromatic Instrument TunerInstrument Tuner

Erin SmithErin Smith

Advisor: Dr. James IrwinAdvisor: Dr. James Irwin

Date: November 20th, 2000Date: November 20th, 2000

Presentation OverviewPresentation Overview

Project SummaryProject Summary Milestones & Critical ProblemsMilestones & Critical Problems Future WorkFuture Work

Project SummaryProject Summary

Brief Overview of OperationBrief Overview of Operation State of Received TunerState of Received Tuner Proposed ModificationsProposed Modifications

Overview of OperationOverview of Operation

The auto-chromatic tuner is a self The auto-chromatic tuner is a self contained tool that is used to contained tool that is used to determine the pitch and intonation determine the pitch and intonation of a musical instrument in real of a musical instrument in real timetime

Functional DescriptionFunctional Description

InputsInputs– MicrophoneMicrophone– Pitch selectorPitch selector– Power/Mode SwitchPower/Mode Switch

OutputsOutputs– Pitch indicatorPitch indicator– Digital tuning indicatorDigital tuning indicator– SpeakerSpeaker

8031 Microcontroller8031 Microcontroller

E b 6

Auto-Chromatic Tuner

Off

Auto Manual

Tuning

Audible Pitch

G YY RR

LED Display

Pitches:G: Green LED ± 5 centsY: Yellow LED ± 5-15 centsR: Red LED ± 15-50 cents

OctaveUp

PitchUp

Tuning

PitchDown

OctaveDown

Microprocessor

ThresholdDetector

AmplifierMicrophone Timer/Counter

Overflow

Bus

Divide By 2 Tree

Bus

Power/ModeSwitch

Mode

Switched DC Power to all sub-systems

Clock

DC Power

PitchSelector

Bus

Bus

FunctionGenerator

Bus

SpeakerDriver

Speaker Selected Pitch Out

AudioIn

DisplayControlBus Analog Meter

PitchIndicator

PitchIndicator

Tuning LED’s

Automatic Gain Control

FrequencyLook-UpTable

- Parts which do not work, or have not been included yet

Microprocessor

ThresholdDetector

AmplifierMicrophone Timer/Counter

Overflow

Bus

Divide By 2 Tree

Bus

Power/ModeSwitch

Mode

Switched DC Power to all sub-systems

Clock

DC Power

PitchSelector

Bus

Bus

FunctionGenerator

Bus

SpeakerDriver

Speaker Selected Pitch Out

AudioIn

DisplayControlBus Analog Meter

PitchIndicator

PitchIndicator

Tuning LED’s

Automatic Gain Control

FrequencyLook-UpTable

- Parts which were modified

Start

InitializationMode

Read Mode/Power Switch

Auto Tune

Manual Tune Setup and Start Counter

Adjust FrequencyDriver

CounterOverflow

TuningMode

YesRead Counter

Display Results

No

Audible ReferencePitch

Display Pitch

State of Received TunerState of Received Tuner

Auto-tune worked with pre-selected Auto-tune worked with pre-selected octave onlyoctave only

Manual tune supposedly worked, or Manual tune supposedly worked, or had some portion workinghad some portion working

Analog and Digital Tuning workedAnalog and Digital Tuning worked Display worked correctlyDisplay worked correctly Pieces of software worked, but not Pieces of software worked, but not

all in one programall in one program

State of Received TunerState of Received Tuner

Tuner did not work as expected when Tuner did not work as expected when connected to power supplyconnected to power supply

Programmer was faulty, PAL’s were Programmer was faulty, PAL’s were brokenbroken

Unit did not work until mid-MarchUnit did not work until mid-March Analog meter ceased to work (not sure Analog meter ceased to work (not sure

if problem with hardware or software)if problem with hardware or software) No software located for manual tuneNo software located for manual tune

Proposed ModificationsProposed Modifications

Manual Tune completionManual Tune completion Automatic Gain ControlAutomatic Gain Control Expand Digital TuningExpand Digital Tuning Auto-Tune Mode completionAuto-Tune Mode completion

Manual TuneManual Tune

Software for Manual Tune could Software for Manual Tune could not be locatednot be located

Scope was too large, given that no Scope was too large, given that no code was available to work fromcode was available to work from

Due to time constraints, was not Due to time constraints, was not able to complete Manual Tune able to complete Manual Tune modemode

Automatic Gain ControlAutomatic Gain Control

Attempted several different Attempted several different configurations in the Springconfigurations in the Spring– Gain circuit with VaristorGain circuit with Varistor– Circuit with an FETCircuit with an FET

VaristorVaristor

VinVin VoutVout

Gain circuit with Varitstor in parallelGain circuit with Varitstor in parallel

gndgnd

VinVinVoutVout

Low amplitude signalLow amplitude signal

Gain circuit with FET in feedback loop Gain circuit with FET in feedback loop

LPFLPF

Automatic Gain ControlAutomatic Gain Control

Found article with an AGC circuit Found article with an AGC circuit which involves a digital which involves a digital potentiometerpotentiometer

Parts did not come in, so AGC Parts did not come in, so AGC could not be implementedcould not be implemented

CONTROL +

x(t) y(t)

Eref

E(t)_

AGC Circuit which utilizes a Digital Potentiometer

Digital TuningDigital Tuning

Wanted to expand digital tuning from 5 Wanted to expand digital tuning from 5 LED’s to 9 LED’sLED’s to 9 LED’s

Intended to take place of analog meterIntended to take place of analog meter Expanded the truth/logic tablesExpanded the truth/logic tables Not enough memory or bits available to Not enough memory or bits available to

implement the expansionimplement the expansion Required major re-design of hardware Required major re-design of hardware

and doing the wire wrapping over againand doing the wire wrapping over again

test_vectors([A15, A14, A13, A12, A11, A10, A9, A8, A7, WR] -> [dac,pitch]) [ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0] -> [ 0, 0]; [ 0, 0, 0, 0, 0, 0, 0, 0, 1, 0] -> [ 0, 0]; [ 0, 0, 0, 0, 0, 0, 0, 1, 0, 0] -> [ 0, 0]; [ 0, 0, 0, 0, 0, 0, 0, 1, 1, 0] -> [ 0, 0]; [ 0, 0, 0, 0, 0, 0, 1, 0, 0, 0] -> [ 0, 0]; [ 0, 0, 0, 0, 0, 0, 1, 0, 1, 0] -> [ 0, 0];

([A15, A14, A13, A12, A11, A10, A9, A8, A7, WR] -> [dbt_en]) [ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0] -> [ 0]; [ 0, 0, 0, 0, 0, 0, 0, 0, 0, 1] -> [ 0]; [ 0, 0, 0, 0, 0, 0, 0, 0, 1, 0] -> [ 0]; [ 0, 0, 0, 0, 0, 0, 0, 0, 1, 1] -> [ 0]; [ 0, 0, 0, 0, 0, 0, 0, 1, 0, 0] -> [ 0]; [ 0, 0, 0, 0, 0, 0, 0, 1, 0, 1] -> [ 0]; [ 0, 0, 0, 0, 0, 0, 0, 1, 1, 0] -> [ 0]; [ 0, 0, 0, 0, 0, 0, 0, 1, 1, 1] -> [ 0]; [ 0, 0, 0, 0, 0, 0, 1, 0, 0, 0] -> [ 0]; [ 0, 0, 0, 0, 0, 0, 1, 0, 0, 1] -> [ 0]; [ 0, 0, 0, 0, 0, 0, 1, 0, 1, 0] -> [ 0]; [ 0, 0, 0, 0, 0, 0, 1, 0, 1, 1] -> [ 0];

Excerpts of Expansion of the Truth Tables Excerpts of Expansion of the Truth Tables (formerly only A15-A11 needed)(formerly only A15-A11 needed)

E b 6

Auto-Chromatic Tuner

Off

Auto Manual

Tuning

Audible Pitch

G BB YY OO RR

LED/LCD Display

Pitches:G: Green LED ± 3 centsB: Blue LED ± 4-10 centsY: Yellow LED ± 11-20 centsO: Orange LED ± 21-30 centsR: Red LED ± 31-50 cents

Octave:Pitch:

Tuning

Auto-Tune ModeAuto-Tune Mode

Worked with pre-selected octave onlyWorked with pre-selected octave only Learned how Timer 0 Overflow worked in Learned how Timer 0 Overflow worked in

relationship to counting the periodrelationship to counting the period When overflow occurred, decremented When overflow occurred, decremented

the octave and reset the divide by 2^nthe octave and reset the divide by 2^n Once a pitch is successfully detected, Once a pitch is successfully detected,

reset the divide by 2^n to the 9th reset the divide by 2^n to the 9th octaveoctave

Device is then ready to search againDevice is then ready to search again

Milestones & CriticalMilestones & CriticalProblemsProblems

Critical ProblemsCritical Problems– Unit did not work initiallyUnit did not work initially– Not enough memory to expand LED’sNot enough memory to expand LED’s– Lack of software for manual tuneLack of software for manual tune– Parts for AGC did not come inParts for AGC did not come in

Milestones & CriticalMilestones & CriticalProblemsProblems

MilestonesMilestones– Getting unit up and runningGetting unit up and running– Expanding tables for LED’sExpanding tables for LED’s– Determined a good duty cycle and Determined a good duty cycle and

waveform for the Audible Reference waveform for the Audible Reference Pitch with a function generatorPitch with a function generator

– Determined design for AGC circuitDetermined design for AGC circuit– Successfully implementing Auto Tune Successfully implementing Auto Tune

ModeMode

Future WorkFuture Work

Manual TuneManual Tune Audible Reference PitchAudible Reference Pitch Expanded LED DisplayExpanded LED Display PackagingPackaging Automatic Gain ControlAutomatic Gain Control New Hardware:microphone, New Hardware:microphone,

speaker, CPU, and memoryspeaker, CPU, and memory

Any Questions?Any Questions?