Matthew Campbell Brian Granaghan Benjamin Adcock Eleazar Kenyon 3/16/2010 MIDI Hero Design Project Preliminary Design Review1 Project Advisor: Dr. William.

Matthew CampbellBrian GranaghanBenjamin Adcock

Eleazar Kenyon

3/16/2010MIDI Hero Design Project

Preliminary Design Review 1

Project Advisor: Dr. William D. Hunt

Georgia Institute of TechnologySchool of Electrical & Computer

Engineering

Current highly successful products include:◦ Rock Band◦ Guitar Hero

Appeal:◦ Provides an interactive musical experience for the

musically unskilled

Shortcomings:◦ Restricts users to “playing” a limited number of

preprogrammed songs◦ Cannot be integrated with live music◦ Does not allow improvisation



Current highly successful products include:◦ Korg Kaoss Pad

Appeal:◦ Provides a versatile platform to add simple

harmonies

Shortcomings:◦ Requires musical experience◦ Does not restrict note selection



MIDI Hero◦ Generates MIDI output from touch input◦ Allows user to develop simple accompanying

harmonies with minimal effort.◦ Enables friends and/or audience members to

accompany a musician in a live performance.

Will be marketed to musicians◦ Live performances (coffee shop, etc.)◦ Casual jam session (friend, child, etc.)

Retails for approximately $330



Item Price

Labor Costs of Development* $9360

5-Wire Touchpad $58.00

Product Housing $15.00

AC Adapter – 12V,1.5A $6.98

PCB $47.50

AVR Programmer $34.00

Other Components $11.29

Parts Total………………………………

$172.77

Grand Total…………………………….

$9532.77

Average Variable Cost……………….

$228.77



*Labor Cost is calculated based on 4 engineers working 6 hours a week for 13 weeks at $30/hr.

*Labor Cost is calculated based on 4 engineers working 6 hours a week for 13 weeks at $30/hr.

Goals:

◦ Allow a musically unskilled operator

◦ to use an intuitive touch interface

◦ to choose from a range of restricted notes

◦ selected by analyzing chord information

◦ generating a single-note harmony

◦ and providing real-time accompaniment to a performing musician.



◦ MIDI input/output◦ Standalone/Slave

Modes◦ Touchpad note

selection◦ LED Tempo Indicators

(standalone mode)◦ Rotary Encoder

controlled menu◦ LCD Status Indicator◦ 13” x 11” x 4.75”

Housing◦ AutoCOMP Chord

Detector interface



• Western music follows a tonal structure• Musical score follows key and chord structure• Each key (e.g. C Major) consists of a root note

and six other tones• Chords consistent with a given key consist of

specific subsets of these seven notes

• Western music follows a tonal structure• Musical score follows key and chord structure• Each key (e.g. C Major) consists of a root note

and six other tones• Chords consistent with a given key consist of

specific subsets of these seven notes

3/16/2010 8MIDI Hero Design Project

Preliminary Design Review

• C Major chord consists of three notes (red)• Some notes (red and orange) sound pleasant

with any chords within the key of C• These five notes form a pentatonic scale

• C Major chord consists of three notes (red)• Some notes (red and orange) sound pleasant

with any chords within the key of C• These five notes form a pentatonic scale



• Our algorithm will take chord information from MIDI in and choose notes from pentatonic scale

• Our algorithm will take chord information from MIDI in and choose notes from pentatonic scale

MIDI InMIDI In Determine key,Choose notes

Determine key,Choose notes



• User can use touchpad to select from available notes

• User selection sent to synthesizer via MIDI output

• User can use touchpad to select from available notes

• User selection sent to synthesizer via MIDI output

TouchpadTouchpad



MIDI OutMIDI Out

Dimensions: 13” x 11” x 4.75” Weight: ~6 lb.

Touch

Screen

LCD RPGLEDs

MIDI InMIDI Out

VDC

On/Off

Mode Selection

8.5” x 6.5” 5-wire resistive touchpad

Axis Layout:◦ X Axis controls Pitch

(increasing from L to R)

◦ Y Axis controls note velocity (increasing from bottom to top)

◦ Output voltage digitized by ADC



Problem:◦ Single axis dynamic

reading capabilities Solution:

◦ Dynamically switch bias voltages Microcontroller alternatively

selects axis by inverting touchpad supply voltages Implemented using TTL

inverter

TTL implementation is effective, but causes reduced resolution



Problem:◦ Prohibitively large fall

time after finger is removed

◦ Screen acts as a capacitor, slowly discharging through ADC input

Solutions:◦ Ground ADC pin in

between sampling cycles

◦ Enables high time resolution readings



Enables device to operate as a stand alone system

Internal tempo displayed using LEDs Configuration parameters modified using

LCD and RPG◦ Tempo◦ Chord progression◦ Key



Signal Properties:◦ Asynchronous 31250 baud◦ 1.5 mA current loop◦ Opto-isolated; current on is logical 0◦ 1 start bit, 8 data bits, 1 stop bit

Data Stream:◦ Each message starts of a one status byte, which

specifies the message type and channel.◦ Subsequent bytes are parameters ranging from 0-

127; the highest bit is reserved for denoting if a byte is a status byte.



The ATMega328P features a single hardware UART.

Both MIDI and LCD are controlled via UART.

Potential Solutions:◦ Design and implement second UART in software

Requires additional pins, hence additional microcontroller Would increase cost and complexity significantly

Final Design Solution◦ Use tri-state buffer to control signal route, alternatively

addressing LCD and MIDI out.





Project Tasks & Milestones Completion Deadline

Software Implementation

Touchpad-ADC interface Completed

MIDI encoding and transmission Completed

Implement user menu/LCD/RPG interface April 2, 2010

Implement note selection algorithm April 2, 2010

Combine sub-blocks into final program loop April 9, 2010

Other Tasks

Construct Wooden Housing Completed

Finalize circuit schematic/assemble device April 9, 2010

Network MIDI Hero with AutoCOMP April 23, 2010

Testing and debugging April 30

Final design review and demonstration (tentative) May 3-7, 2010

Reduce physical form factor◦ Metal/Plastic Housing

Multi-touch capability Enable user programmable chord patterns Integrate with AutoCOMP Chord Detection

◦ Upgrade processor

Implement integrated audio synthesizer and DAC



Matthew Campbell Brian Granaghan Benjamin Adcock Eleazar Kenyon 3/16/2010 MIDI Hero Design Project Preliminary Design Review1 Project Advisor: Dr. William.

Documents

project advisor

chord structureeach

chord informationgenerating

given key

key of cthese

notes redsome

root note

successful products