Matthew Campbell Brian Granaghan Benjamin Adcock Eleazar Kenyon 3/16/2010 MIDI Hero Design Project Preliminary Design Review1 Project Advisor: Dr. William D. Hunt Georgia Institute of Technology School 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 3/16/2010 MIDI Hero Design Project Preliminary Design Review2

 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 3/16/2010 MIDI Hero Design Project Preliminary Design Review3

 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 3/16/2010 MIDI Hero Design Project Preliminary Design Review4

ItemPrice Labor Costs of Development*$ Wire Touchpad$58.00 Product Housing$15.00 AC Adapter – 12V,1.5A$6.98 PCB$47.50 AVR Programmer$34.00 Other Components$11.29 Parts Total………………………………$ Grand Total…………………………….$ Average Variable Cost……………….$ /16/2010 MIDI Hero Design Project Preliminary Design Review5 *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. 3/16/2010 MIDI Hero Design Project Preliminary Design Review6

◦ 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 3/16/2010 MIDI Hero Design Project Preliminary Design Review7

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 3/16/20108 MIDI 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 3/16/20109 MIDI Hero Design Project Preliminary Design Review

Our algorithm will take chord information from MIDI in and choose notes from pentatonic scale MIDI In Determine key, Choose notes Determine key, Choose notes 3/16/ MIDI Hero Design Project Preliminary Design Review

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 Touchpad 3/16/ MIDI Hero Design Project Preliminary Design Review MIDI Out

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

Touch Screen LCDRPGLEDs

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 3/16/2010 MIDI Hero Design Project Preliminary Design Review15

 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 3/16/2010 MIDI Hero Design Project Preliminary Design Review16

 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 3/16/2010 MIDI Hero Design Project Preliminary Design Review17

 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 3/16/2010 MIDI Hero Design Project Preliminary Design Review18

 Signal Properties: ◦ Asynchronous 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 ; the highest bit is reserved for denoting if a byte is a status byte. 3/16/2010 MIDI Hero Design Project Preliminary Design Review19

 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. 3/16/2010 MIDI Hero Design Project Preliminary Design Review20

3/16/2010 MIDI Hero Design Project Preliminary Design Review21 Project Tasks & MilestonesCompletion Deadline Software Implementation Touchpad-ADC interfaceCompleted MIDI encoding and transmissionCompleted Implement user menu/LCD/RPG interfaceApril 2, 2010 Implement note selection algorithmApril 2, 2010 Combine sub-blocks into final program loopApril 9, 2010 Other Tasks Construct Wooden HousingCompleted Finalize circuit schematic/assemble deviceApril 9, 2010 Network MIDI Hero with AutoCOMPApril 23, 2010 Testing and debuggingApril 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 3/16/2010 MIDI Hero Design Project Preliminary Design Review22