Transcript MIDI Hero - School of Electrical and Computer Engineering at

Matthew Campbell
Brian Granaghan
Benjamin Adcock
Eleazar Kenyon
Project Advisor: Dr. William D. Hunt
Georgia Institute of Technology
School of Electrical & Computer Engineering
MIDI Hero Design Project
Preliminary Design Review
3/16/2010
1

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
MIDI Hero Design Project
Preliminary Design Review
3/16/2010
2

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 Design Project
Preliminary Design Review
3/16/2010
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
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
MIDI Hero Design Project
Preliminary Design Review
3/16/2010
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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.
MIDI Hero Design Project
Preliminary Design Review
3/16/2010
5

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 Hero Design Project
Preliminary Design Review
3/16/2010
6
◦ 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
MIDI Hero Design Project
Preliminary Design Review
3/16/2010
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• 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
MIDI Hero Design Project
Preliminary Design Review
3/16/2010
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• 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
MIDI Hero Design Project
Preliminary Design Review
3/16/2010
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MIDI In
Determine key,
Choose notes
• Our algorithm will take chord information from
MIDI in and choose notes from pentatonic scale
MIDI Hero Design Project
Preliminary Design Review
3/16/2010
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MIDI Out
Touchpad
• User can use touchpad to select from available
notes
• User selection sent to synthesizer via MIDI output
MIDI Hero Design Project
Preliminary Design Review
3/16/2010
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Dimensions: 13” x 11” x 4.75”
Weight: ~6 lb.
LEDs
LCD
Touch
Screen
RPG
MIDI Out
MIDI In
Mode Selection
On/Off
VDC

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
MIDI Hero Design Project
Preliminary Design Review
3/16/2010
15

Problem:

Solution:
◦ Single axis dynamic
reading capabilities
◦ 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
MIDI Hero Design Project
Preliminary Design Review
3/16/2010
16

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
MIDI Hero Design Project
Preliminary Design Review
3/16/2010
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


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
MIDI Hero Design Project
Preliminary Design Review
3/16/2010
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
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 0127; the highest bit is reserved for denoting if a
byte is a status byte.
MIDI Hero Design Project
Preliminary Design Review
3/16/2010
19

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.
MIDI Hero Design Project
Preliminary Design Review
3/16/2010
20
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
MIDI Hero Design Project
Preliminary Design Review
3/16/2010
21

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
MIDI Hero Design Project
Preliminary Design Review
3/16/2010
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