Proximity Sensor Theremin

Khoa Nguyen

Walter Hudson

Dennis Gilbert

G. Hewage Thushara

Group 9: ThereminSlide 1

OUTLINENeeds and Objectives

Design

Design Implementation

Testing and Results

Team work and Lessons

Group 9: ThereminSlide 2

Needs and Objectives• Practicum project requirements• 1 actuator• 1 sensor• 1 processing module

• Motivation of project• Implement core knowledge into a working project• Actually build something• Experience the steps of project development,

organization, design and testing

And, of course, to be cool and creative enough to get an A …

Group 9: ThereminSlide 3

Needs and Objectives

• Traditional Theremin• Plays music without contact• Controls frequency and volume• Antennas act as sensors

• Proximity Sensor Theremin• Use proximity sensors as alternatives• Use a MCU for digital signal processing of volume

and frequency• Have same functionality with integrated speaker

Moog Theremin

Group 9: ThereminSlide 4

Needs and Objectives• Objective: Functional Prototype• Initial Approach

Volume Sensor

Frequency Sensor

MCU

•ADC Conversion•Output PWM•Indicator LEDs•Record •Playback•Battery power

• Analog voltage

• Analog voltage

User Interface•Switches

Speaker• Create sound

Sensor Module Microprocessor Module Speaker Module

Group 9: ThereminSlide 5

Microprocessor Module

• Accept all voltage levels of sensor inputs

• Operation modes: playback, record, loop

• Indicator LEDs

• On board memory for 10s of recorded music

• Pushbutton interface

Sensor Module

• Measure distance up to 400mm

• Reaction time <50ms

• Accountable for background noise

Speaker Module

• Audible range sound >5m

• Master volume control

• 50mW -1W power without heat sink

• frequency range 300Hz -3.4kHz

Design • Module Requirements Specifications• Test Plan: acceptance, integration, unit

Group 9: ThereminSlide 6

DesignSensor Module

• IR sensors with individual LED and phototransistor

IR LEDPhototransistor

IR LEDPhototransistor

5VDC Supply

VDC output

VDC output

Hand position

Hand position

• Optimize signal range• Background noise is unpredictable under different light

conditions

5VDC Supply

Group 9: ThereminSlide 7

Design

MCUATMega

328P

5VDC Supply

VDC output volume sensorPWM for Frequency

Indicator LEDs•Main power•Record•Playback

Interface Switches•Main power •Record•Reset

ACITVE LOW

5VDC

VDC output freq sensorPWM for Volume

ADC

PWM outputsFrequency

• 16 bit resolution Volume

• 8 bit resolution

8MHz internal RC oscillator

Microprocessor Module

Group 9: ThereminSlide 10

DesignSpeaker Module

Speaker

5VDC Supply

PWM Freq

NMOS

GND

PWM Vol

Volume PWM• Fixed at 31250Hz• Duty cycle varies from 0 -50%

Frequency PWM • Fixed 50% duty cycle• variable frequency approx.

480Hz – 5500Hz

• By anding signal average DC level is controlled- Volume

Group 9: ThereminSlide 8

DesignSoftware Algorithm Play through

read adc from sensors

Is measurement > max value?

yes Mode 1 play through

Measure freq sensor

Update freq PWM timer

Measure volume sensor

Update volume PWM timer

Is measurement < min value?

no

no

yesMode 0 No output

Turn off freq PWM

Turn off volume PWM

Executable on timer overflow interrupt

Return main idle loop

Group 9: ThereminSlide 9

Design Software Algorithm Record Interrupt

REC pushbutton pressed

Is vec index at max?

Incr

emen

t ind

ex

Are vectors fully populate?no

yes

Mask pushbutton interrupt

Mode 3Playback

Update freq PWM timer from freq vec

Executable on timer overflow interrupt

Mode 2 REC / play through

Measure freq sensor

Update freq PWM timer

Store freq sensor measurement

Measure volume sensor

Update volume PWM timer

Store volume sensor measurement

Update vol PWM timer from vol vec

Rese

t ind

ex

no

yes

Resettable on reset pushbutton interrupt

Group 9: ThereminSlide 11

Design Implementation Behavioral Schematic

Group 9: ThereminSlide 12

Design ImplementationPCB Board Wire Diagram

Group 9: ThereminSlide 13

Design ImplementationOff -Board Wire Diagram

Group 9: ThereminSlide 14

Design ImplementationPCB Board Layout

Top Fill Ground Plane Bottom Fill Ground Plane

Group 9: ThereminSlide 15

Design Implementation• Project Box• Locate Frequency and volume Sensors on opposite sides• Speaker placed on top• Create a DJ tool

Group 9: ThereminSlide 16

Testing and ResultsMicroprocessor Module• AVR Studio 5 with Debugger• Prototype type board with LEDs and Pushbuttons• Code blocks were modularized tested/ integrated

Sensor Module• Different sensors were tested for voltage outputs• Ambient level • Optimizing dynamic range of sensors

Speaker Module• Most difficult was creating waveform• Configuration was prototyped in capstone lab• High voltage levels from inductive speaker kick back

Group 9: ThereminSlide 17

Microprocessor Module

• Accept all voltage levels of sensor inputs

• Operation modes: playback, record, loop

• Indicator LEDs

• On board memory for 10s of recorded music

• Pushbutton interface

Sensor Module

• Measure distance up to 400mm

• Reaction time <50ms

• Accountable for background noise

Speaker Module

• Audible range sound >5m

• Master volume control

• 50mW -1W power without heat sink

• frequency range 300Hz -3.4kHz

• Results of Alpha Test

Testing and Results

Group 9: ThereminSlide 18

Team work and LessonsExperience of work division in

• Individual tasks:• Work in parallel: quickly done• Limitations on learning

• Whole team does every step:• Work in series: slower process• Every member knows every process, equal learning

opportunity• Some members do more some do less

Group 9: ThereminSlide 19

Team work and LessonsWhat we got and learned

• Divide and conquer

• No conflict between team members

• Design process is in constant flux waterfall/ spiral method

• “Work in series” is better for learning and preparing for capstone

• “Work in parallel” is better for Capstone project and real working environment

• Achieve the ultimate goal: have fun with the project

Thank you for your attentionQ&A