Detailed Design ReviewProject P13363

Members:Justine Converse (IE)

James Cover (CE)Alexander Eschbach (EE)

Jason Hang (ME)Ashley Trode (EE)

Guide: Gerald Garavuso

Our Focus

•Mount sensor on 2 keys (1 white and 1 black key)

• Microcontroller will be able to get input from sensor and output a MIDI recognizable signal

• Sensors will be mapped in two dimensions to be able to control two separate music parameters. One dimension will be able to change a user selected parameter (i.e. volume, vibrato, etc.) over each individual key and the other dimension will change pitch bend over all keys at the same time

• MIDI mapping will be the limitation to which parameters can be mapped

• Will use blackberry trackball for sensor

Engineering Specs/Requirements

System/Flowchart

System Diagram

What we decided last time

Conduct further research and testing for two concepts...

*Blackberry trackball/trackpad

*Capacitive touch sensor

Capacitive Touch Testing (Initial)

• Simple RC circuit built with square wave input

• Touched leads of the capacitor

• Discovered that touching both leads has a more noticeable effect

Capacitive Touch Testing (Initial)

• One capacitor testing

• Rise time changes if a touch exists

• Left (no touch), Right (touch)

Capacitive Touch Testing (Sensor)• Touchpad breakout board is from

sparkfun

• Twelve electrode capacitive touch inputs per chip

• Microcontroller is needed to interpret the signal

• Microcontroller can tell when touchpads are contacted and when they are released

• The time touched could be used for sensitivity

Schematics - Capacitive Touch Circuit

Trackball Testing (Sensor)• Trackball breakout board is from sparkfun

• 4 directions and a push button can be detected and outputted as a digital signal using four hall effect sensors and a push button

• The frequency of the digital signal is controlled by the speed of the trackball

• The position can be found by counting how many digital highs there are in a certain amount of time

Schematics -Trackball Circuit

Risk Assessment

Decision Based on Testing & Risks

• Move forward with Trackball Sensoro Easier to program

Repeatable results Less data to manipulate

Schematics - Main Circuit Board

Will consist of• Microcontroller (still need to pick)

• power regulator

• inputs of trackball sensors

• MIDI circuit

Pseudocode (Interface Test Program)

• Initialize Microcontrollero Board Setup (Pin IN/OUT)o Interrupt Setup (Enable, Edge trigger)

• Wait for interrupt from trackballo Turn on LEDo Delayo Turn off LEDo Clear Interrupt

Pseudocode (System)

• Initialize Microcontrollero Board Setupo Interrupt Setup o System Setup

Buttons to change parameters Sensitivity Musical parameter per axis

• Wait for interrupt from trackballo Start timero Count number of rotations in time periodo Determine magnitude + speed

• Modify incoming MIDI signal

System Diagram

Timing Diagram

Pseudocode - MIDI

• Send 'Note On' Messageo Key press

• Send 'Aftertouch' Messageo Sensor data

• Send 'Note Off' Messageo Release key

MIDI - Background• MIDI - Musical Instrument Digital Interface

• An electronic musical instrument industry standard protocol set in 1983

• Allows for easy communication and compatibility between digital musical instruments, computers, and other related devices

• Captures note events and music parameters adjustments and encodes them in a digital message

• This digital message can then be interpreted and decoded into music

MIDI - Types of Messages

• Channel Messages - used for controlling one or more of the 16 MIDI channels or for controlling musical notes using a specific MIDI channel

• System Exclusive Messages - longer MIDI messages that are used for a variety of purposes

• System Common Messages - Some standardized features that are used for controlling the playback of songs in MIDI format

• System Real-Time Messages- Used for timing and clock signals

MIDI - Channel Message Digital Signal

MIDI - Issues

• Individual control of certain parameters is impossible within the MIDI specification

• Creating a message that complies with the MIDI specification that other devices will understand

MIDI - Resolution

• Additional software is required for full control of all parameters

• Find contacts that know more about the MIDI specification or know where to find related resourcesoMusic shops

oRIT library

oManufacturers

oOrganization that controls/owns standard

Test Plan (Software)

• Play 1 key without sensor, get output

• Play 1 key with sensor, get output o Fast and shorto Fast and longo Slow and shorto Slow and longo Sensitivityo Multidirectional

• Play two keys, get outputo One with sensor, one withouto Both with sensor

Test Plan (Hardware)

• Unaltered keys

o Normal Play

Have a pianist play the keyboard normally

Measure the forces applied to the keys

o Maximum Play

Play the keys aggressively

Measure the forces applied on the keys

• Altered keys

o Normal Play

Apply the force measured from playing normally

o Maximum Play

Apply the force measured from playing aggressively

High Level Plan

• Overall system plan for the location of the componentso Sensoro Wireso Microcontroller

circuit board Microcontroller circuit location

Placement of Sensor on Key

• Discussed where pianist place their fingers when playing.

• Realized that there is no set location, usually all over the keys.

• Determined where NOT to place the sensors.

• Constrained to structure of the white and black key.

• Black key has a very limited amount of space.

• Extra material necessary to support sensor as well.

Key Drawings

- SolidWorks Model of keys

- SolidWorks Model key insert

Key Drawing

• SolidWorks Model of black key with key insert, PCB board and trackball sensor

Drawing of the Key Insert

Bill of Materials

Plan for MSD II

Conclusions/Questions

Electrical

• How to create a MIDI recognizable signal, will our design work?

• Choice in microcontroller

• Do the capacitors and resistors need to be close to the hall effect sensors?

Mechanical

• Best way to put sensor into key?