detailed design review project p13363 members: justine converse (ie) james cover (ce) alexander...
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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?