Download Laser Guitar with Instructional LED Display

Laser Guitar with
Instructional LED Display
Design Review
ECE445
Group: Zitao Liao, Zihan Yao, Siyue Li
TA: Jacob Bryan
Date: 02/2015
Table of Contents
1. Introduction ................................................................................................................................. 3
1.1 Statement of Purpose............................................................................................................. 3
1.2 Objectives .............................................................................................................................. 3
1.2.1 Goals ............................................................................................................................... 3
1.2.2 Functions ........................................................................................................................ 3
1.2.3 Benefits ........................................................................................................................... 3
1.2.4 Features ........................................................................................................................... 3
2. Design ......................................................................................................................................... 4
2.1 Block Diagram ...................................................................................................................... 4
2.2 Block Description .................................................................................................................. 5
2.2.1 Laser Sources .................................................................................................................. 5
2.2.2 Photodiodes .................................................................................................................... 5
2.2.3 Soft Potentiometers......................................................................................................... 5
2.2.4 Audio Output .................................................................................................................. 5
2.2.5 LED Arrays..................................................................................................................... 5
2.2.6 Microcontrollers ............................................................................................................. 5
2.2.6 DAC ................................................................................................................................ 6
2.2.7 Power Supply.................................................................................................................. 6
2.3 Software ................................................................................................................................ 7
2.3.1 Player Motion Sensing Flow .......................................................................................... 7
2.3.2 LED Display Flow .......................................................................................................... 8
2.3.3 MIDI and Sound Generation .......................................................................................... 9
2.4 Schematic ............................................................................................................................ 11
2.4.1 Player Motion Sensing Circuits .................................................................................... 11
2.4.2 LED Decoder Circuits .................................................................................................. 14
2.4.3 Microcontroller Circuit ................................................................................................. 15
2.4.3 DAC peripheral Circuits ............................................................................................... 15
2.4.4 Power Distribution ........................................................................................................ 17
2.5 Simulation and Calculation ................................................................................................. 17
2.5.1 Soft Potentiometer Fret Position Calculation ............................................................... 17
3. Requirements and Verification ................................................................................................. 19
3.1 Requirements and Test Procedure ....................................................................................... 19
3.2 Tolerance Analysis .............................................................................................................. 23
4. Costs and Schedule ................................................................................................................... 23
4.1 Cost Analysis....................................................................................................................... 23
4.1.1 Labor ............................................................................................................................. 23
4.1.2 Parts .............................................................................................................................. 24
4.1.3 Grand Total ................................................................................................................... 24
4.2 Schedule .............................................................................................................................. 25
5. Ethnics....................................................................................................................................... 26
6. Safety ........................................................................................................................................ 27
7. Reference .................................................................................................................................. 29
1. Introduction
1.1 Statement of Purpose
Music instruments evolve concurrently with human technology. Laser musical instruments is one
of the great ideas to combine technology with art, because they are not only able to produce
sound same as other common electronic instruments, but also create amazing visual effects.
Laser guitars have been done in various ways by a lot of people, but this project also stressed on
another functionality. When people start to learn to play the guitar, it is quite difficult to start
with looking at tabs and press corresponding frets. Our goal is to design a laser guitar system
with instructional LED display. The idea is to replace strings with laser and soft potentiometers
such that people will find it easy to press strings and do not hurt their fingers when practice
chords on the guitar.
1.2 Objectives
1.2.1 Goals



Replace the strings with lasers and sensor bars
Use LED near the sensor bar as the instructional display
Use microcontroller to get the input sensor bar and laser and give the analog output to
the speakers, guitar effect pedals etc.
1.2.2 Functions


Place fingers of the right hand on the laser beam and press the sensor bars by the left
hand will produce sound with corresponding frequency.
LED displays above each sensor bar give instructions to help guitar leaners to press
the frets in a correct way.
1.2.3 Benefits



Provide helpful and intuitive instructions for beginners to learn to play guitar.
Less pain on fingers when playing guitar compared to traditional guitar.
Cool visual effects.
1.2.4 Features



Replace traditional strings with lasers which has cool appearance and more attractive
to customers.
Can be tune to different string instruments with different note map and MIDI sound
effects
Instructional functionality.
2. Design
2.1 Block Diagram
Figure 1 Function Block Diagram
Audio
device
Figure 2. Mechanical Layout Block Diagram
2.2 Block Description
2.2.1 Laser Sources
To replace strings with laser beams, four laser sources are power on all the time and shine
straightly on corresponding photodiodes. Considering power consumption and costs, 650nmwavelength, 6mm-diameter, 3-5V, 5mW Mini Dot Diode Module is chosen as the laser source
for this project [5].
2.2.2 Photodiodes
The photodiodes will then switch on and off based on the state that if the laser beam is blocked
by fingers or not and generate digital signals to the microcontrollers. SFH 213 photodiode is
chosen for this project since it has sensitive wavelength range from 400nm to 1100nm, which
should pair quite well with 650nm wavelength laser.
2.2.3 Soft Potentiometers
Soft potentiometer is a kind of sensor that varies its resistance with different pressing positions
on it. Varying resistance can generate different voltage levels, which are send to microcontrollers
for software to determine fret positions.
Membrane 200mm potentiometer is used because of its proper length as the guitar fret for this
project. Its resistance changes linearly from 100ohms to 10K ohms when pressing along the strip.
2.2.4 Audio Output
An analog audio voltage is generated from digital-to-analog IC and drives an audio device such
as headphone or speakers. Additional filters are not required for the DAC output.
2.2.5 LED Arrays
To control large number of LEDs with limited microcontroller digital outputs, a decoder circuit
should be implemented on a PCB that is mounted on the fret. On a real guitar, each string can
only play one note at a time, so each string has a 3-to-8 decoder that takes digital signals from
microcontroller as select bits and drive 6 LEDs with its outputs.
2.2.6 Microcontrollers
Depends on the software implementation, one or two microcontrollers are needed to process
sensor and chord information from PC in parallel processes.
ATmega328 [2] is selected to be the control unit for this project. It is chosen because it meets
the requirement of analog and digital I/O for this project as can be clearly seen in Table x. And
also because it has abundant open-source project available such as Arduino Uno board that
allows fast prototyping.
Digital
Needed
No. Of Pins
Input Digital
Output
Needed
4
12
ATmega328
Digital I/O
Analog Input ATmega328
Needed
Analog Input
14+14(two
units)
4
6
Table 1. Number of pins available and needed in Microcontroller
The first ATmega328 is to monitor voltage levels from four photodiodes by its 4 digital input out
of total 14 channels to determine the on/off states of strings. And voltage levels from soft
potentiometers are sensed by four analog inputs to determine fret positions. And it talks with the
DAC via MIDI protocol for sound generation.
The second microcontroller is to communicate with PC to decide LED display pattern. This
microcontroller is connected to PC via USB. The software analysis which key the user pressed or
which play pattern the user selects and sends out digital signals to decoder arrays for LED
display.
2.2.6 DAC
The digital-to-analog block is to convert MIDI message from microcontroller to analog audio
signal that drives an audio device. VS1053b -Ogg Vorbis/MP3/AAC/WMA/MIDI AUDIO
CODEC audio decoder chip is chosen for the project’s application. It receives MIDI bitstream
through serial input bus and decodes it to analog signal from its built-in 18-bit DAC. It also has
on-chip RAM to store feature codes for sound effects.
The chip features analog output of 1.23V that can directly drive earphone. So additional filters
and amplifying circuits are not required.
2.2.7 Power Supply
5V battery powers four lasers, which are the major power consumptions of this project. For
supplying power to other circuits, the battery voltage is regulated to 5V, 3.3V and 1.8V based on
the rating of different ICs. For the second microcontroller, since it is communicate with PC all
the time to get user input, it is directly powered by the USB.
2.3 Software
2.3.1 Player Motion Sensing Flow
Figure 3.Player Motion Sensing Flow Chart
The procedure of producing the right sound will go through four main steps. They are detecting
the block by fingers, loading the fret positions, detecting the releasing of fingers, send MIDI
signal to the Audio decoder. The first step is checking whether one or more lasers are blocked by
fingers. If this happens, the program should go to the next state. Otherwise, it should keep
checking until the blocking happens.
Then after the blocking, the position of the fret should be checked. The positions where fingers
put on fret determines what frequency should be played, and they will be stored as variables in
the program. Then the next step is to determine whether the finger that blocks the laser has been
moved away, or the string has been released. If not, the program should continue checking the
position of the fret. This will keep updating the fret position value. Otherwise, if the player
changes the hand position on fret before removing the fingers that block lasers, the frequency
will be wrong.
After the block has been removed, the program should go to the next step, which is generating
MIDI signal and send it to the Audio decoder. The generated signal is completely determined by
the position of the fret and it is updated by the last step. After sending MIDI signal, the program
should go back to the initial state and waiting for the player to block the laser next time.
2.3.2 LED Display Flow
Figure 4.LED Display Flow Chart
The instructional LED arrays are controlled by decoders corresponding to each string. The
decoder selection bits are feed in from microcontroller’s digital outputs.
The software has two modes. The Single Chord Mode allows users to input chords that they
wish to learn by pressing corresponding keys on the keyboard. The microcontroller
communicates with the PC via USB and the software will map the Char information to LED
decoder selection bits.
The Song Mode allows users to play along with certain songs. The chord sequence is hard-coded
and the user has to select which sequence to play. Similar to the Single Chord Mode, the
sequence is translated to decoder selection bits.
2.3.3 MIDI and Sound Generation
We decide to use VS1053b audio decoder to produce sound. The VS1053b will receive series bit
input from the microcontroller and it will decode the signal and through the chip on it and then it
will go through a DAC converter [1]. An earphone is necessary to connect to it and sound can be
heard. The audio decoder should directly connect to the Arduino and waiting for the Arduino to
give input. The input of the digital data bit will use MIDI protocol, which is widely used in
electronic music applications. And it is transmitted 31250 bits per second.
The massage of MIDI consists of status bytes and data bytes. The status byte should always start
with 1, and the message byte will start with 0 instead. The status byte will consist of the status at
first four bits and the channel number at the last four bits. And the message byte is varying
according to the status byte.
The massage we will use most is the note massage which consist of NOTE ON and NOTE OFF
message.


NOTE ON message: When the note on message is sent, the sound will start to produce,
and it will not stop until the Note OFF message is sent. The NOTE ON status message
will start with 1001 and the two data bytes will be pitch value and velocity value
respectively, and they determine frequency and amplitude of the produced sound
accordingly.
NOTE OFF message: The note off message will be start with 1000 and the data bytes
defines pitch value and release velocity value. By default the release velocity value
should be set to zero in most of the cases.
So, an example of MIDI NOTE message should be formatted as below:
When playing chords is need, one can send NOTE ON message with one with one pitch first and
NOTE ON message of another pitch before sending the NOTE OFF message of the first one.
Another MIDI message we will use will be Pitch Bend message. This message will be used to
change the pitch that is currently played. The reason to do this is to create the guitar bend effect
and make the sound more realistic.

Pitch Bend message: The status bit will started with 1110 and the massage signal is
consisting of the LSB and MSB. The first message is the LSB and the second message is
MSB. So the pitch value will be vary from 16383 to 0. And if we put 8192 there, no bend
in pitch will occur. In order to mimic the guitar bend effect, we need to send pitch bend
message continuously until the output sounds smooth enough.
Therefore, ideally, after one remove the finger from the block, the Arduino need to send the
serial message to the VS1053B in the following format:
The way for the Arduino to send MIDI message is using serial.begin() function and define it as
31250, which means 31250 bits per second. A simple code for transmit sound from the Arduino
tutorial online is:
void setup() {
// Set MIDI baud rate:
Serial.begin(31250);
}
void loop() {
// play notes from F#-0 (0x1E) to F#-5 (0x5A):
for (int note = 0x1E; note < 0x5A; note ++) {
//Note on channel 1 (0x90), some note value (note), middle velocity (0x45):
noteOn(0x90, note, 0x45);
delay(100);
//Note on channel 1 (0x90), some note value (note), silent velocity (0x00):
noteOn(0x90, note, 0x00);
delay(100);
}
}
// plays a MIDI note. Doesn't check to see that
// cmd is greater than 127, or that data values are
void noteOn(int cmd, int pitch, int velocity) {
Serial.write(cmd);
Serial.write(pitch);
Serial.write(velocity);
}
less than 127:
And the sound generation code will be integrated within the program and consisting the entire
microcontroller.
Since only for strings are mechanically placed on the frets, the note map can either tuned to be a
bass guitar fretboard or ukulele fretboard. For example, for a bass guitar fretboard, the laser
diode detection signals and fret position analog signals should map to notes (frequency in Hz)
following Table 2.
Table 2. Fret to Frequency Mapping
Fret
Open
1
2
3
4
5
6
(Bottom)
String 1
(DI0)
G(196Hz)
G#(208)
A(220)
A#(233)
B(247)
C(262)
C#(277)
String 2
(DI1)
D(147Hz)
D# (156)
E(165)
F(175)
F#(185)
G(196)
G#(208)
String 3
(DI2)
A(110Hz)
A#(117)
B(123)
C(131)
C#(139)
D(147)
D#(156)
String 4
(DI3)
E(82Hz)
F(87)
F#(92)
G(98)
G#(104)
A(110)
A#(117)
String
2.4 Schematic
2.4.1 Player Motion Sensing Circuits
The photodiode acts like a diode when it receives light that has wavelength within its sensitive
range. A pull down resistor is connected in series with the diode such that if the photodiode is on,
the output will be close to Vcc, and pulled to ground when the photodiode is off.
Resistance for photo-diode circuit calculation
The total current of photo-diode can be calculated according to the formula below:
(1)
Due to the fact that photo diode should be reverse biased, the first term in the formula could be
neglected since it is relative small. Then, the total current could be approximated as Ip. Then we
can apply the following formula to calculate photo current:
(2)
It is a measure of the effectiveness of the conversion of the light power into electrical current.
The effectiveness of conversion index could be found on figure 6: With wavelength 650nm, the
effectiveness is arould 70%. The power consumption of the laser is 5mW. Thus, the photo
current is 3.5mA.
In the schematic below, if it is supposed the desired output rage is around 5+ 0.25 Volts, the
resistance can be calculated with ohms law which is 1.43+ 0.07 kΩ.
Figure 5.String Position Sensing Circuits
According to the relative spectral sensitivity plot of the photo diode shown below, the most
sensitive wavelength of light to photo diode is around 650nm - 1000nm. So the diode should be
quite sensitive to the 650nm laser source. The photodiodes are mounted on the surface board and
the leads are extended and soldered to the main processing board.
Figure 6.Relative Spectral Sensitivity of Photo Diode [4]
Potentiometer fret detection circuit detects frets that the player are pressing on.
Figure 7.Potentiometer Fret Detection Circuit
The soft potentiometer used in this project is 200mm Membrane Potentiometer. Its physical
dimension is shown below. The 200mm Model means the Active Length in the figure below is
200mm.
Figure 8.Potentiometer Physical Dimension [3]
The schematic and 3-pin connection of the soft potentiometer are shown below.
Figure 9. 3-Pin Connection of Soft Potentiometer [3]
When pressing different position on the strip, the pressing point is in contact with the main
resistive material such that PIN2 will output the voltage of the resistive part across the pressing
point and ground. The voltage is then feed into analog inputs of the microcontroller to determine
fret position.
2.4.2 LED Decoder Circuits
Figure 10.LED Decoder Circuits
To implement instructional LED display for a guitar, each string should have its own decoder
because in order to display a pattern for a chord, LEDs on each string should be able to light up
independently.
In order to drive six LEDs per string, a 3-to-8 decoder circuit shown in figure 10 is used such
that the microcontroller is able to control 24 LEDs with 14 digital outputs.
Table 3. Decoder Output
(A0A1A2)
LED
000
D0
001
D1
010
D2
011
D3
100
D4
101
D5
2.4.3 Microcontroller Circuit
Figure 11. Microcontroller Pin Out
The microcontroller takes signal from all sensing
2.4.3 DAC peripheral Circuits
The VS1053b -Ogg Vorbis/MP3/AAC/WMA/MIDI AUDIO CODEC takes serial input from the
microcontroller and output analog audio signal.
Figure 12.Auido Decoder Pin Map
The analog outputs LEFT/RIGHT/GBUF from the DAC are directly extended to a standard
audio jack with protection RC circuit shown below.
Analog Output
from Audio
Decoder
Figure 13. Audio Jack Circuit
2.4.4 Power Distribution
The power source for the device are two lithium batteries in series that provides 7.2v. The battery
voltage is regulated to 5V to power main ATmega328 microcontroller. The 5 Volts output is
then step down to 3.3V and 1.8V for Audio Decoder.
Figure 13. Regulators
2.5 Simulation and Calculation
2.5.1 Soft Potentiometer Fret Position Calculation
The fret positions are determined based on the potentiometer voltage readings. Since the
potentiometer voltage is continuous with infinite resolution, in order to distinguish different frets,
boundaries voltage has to be set at different positions.
First of all, the potentiometer strip has to be physically divided into 7 areas to represent 6 fret
position and open string as shown below.
6
5
4
3
2
Figure 14. Soft Potentiometer Fret Division
1
Open
The potentiometer will output Vcc when it is not pressed on anywhere of the strip, and will
output zero if the bottom is pressed, and the voltage changes linearly in between.
To determine the voltage boundaries for each fret, for example, for the first fret, the boundary
between first fret and open string is drawn at 20mm from the right side, and the voltage level
corresponding to this position is calculated as:
𝑉1 = 𝑉𝑐𝑐 ∗
200−20
200
= 0.9 ∗ 𝑉𝑐𝑐
(3)
Even though the potentiometer itself has infinite resolution of voltage v.s. distance, the ADC of
the microcontroller has a finite resolution of 10 bits that can convert voltage level into integer
data type. So the minimum distance difference the microcontroller can sense is given by:
𝑅𝑒𝑠𝑜𝑙𝑢𝑡𝑖𝑜𝑛 =
𝐿𝑒𝑛𝑔𝑡ℎ
210
=
200𝑚𝑚
1024
= 0.2𝑚𝑚
(4)
Because of this resolution, the boundaries between frets can be drawn more carefully by putting
an “invalid zone” to mimic the actual fret bar on the guitar. When user presses in this invalid
zone, there will be no frequency information generated. For each fret, there will be 2mm “invalid
zone” as shown below:
Figure 12. Single Fret Dimension
Based on all the discussion above, the active fret regions and voltage reading are mapped in the
following table. In the actual implementation, the boundary values have to be calibrated for each
potentiometer.
Table 4. Frets and Voltage Mapping
Active Fret Region
Open
1
2
3
4
5
6
Distance to the
Left (Zero
Voltage Point)
(mm)
200-181
179-151
149-121
119-91
89-61
59-31
29-0
Voltage Level (V)
5.0-4.525
4.4753.775
3.7253.025
2.9752.275
2.2251.525
1.4750.775
<0.725
Microcontroller
Analog Read(int)
1024-927
916-773
762-619
609-465
455-312
302-158
148-0
3. Requirements and Verification
3.1 Requirements and Test Procedure
Module Name
Requirements
Testing procedures
Power Supply
Linear regulator will generate 3 voltage
levels from the 7.2V battery supply:
5V, 3.3V, 1.8V.
Measure the output voltage of the
linear regulator
Lasers
1.Voltage: 5V ± 0.25V DC
1.Connect four laser diodes in
parallel to the power supply to test
DC voltage and DC current
2.Power must be smaller than 5mW
2.Connect the multimeter to the laser
diode in the circuit to test DC
voltage and DC current passing it
3.Read the value of voltage and
current in turn when it approaches
steady state
4. Calculation the power and total
power consumed in the circuit=V*I
Photo Diode
1.Photo diode should be operated
complete opposed from the bright state
and dark state.
1.Connect the photo diode to the
multimeter while keep the
surrounding region in relative
darkness
2.The dark current:1nA
2.Record the current in the dark
3.The forward current:80mA
Laserphotodiode
circuit
1. The circuit will trigger a high
voltage when the laser is turned on.
1. Connect the circuit as shown
above.
2. Make sure the output high is
between the 5±0.25V.(Distinguishable
with the output low voltage)
2. Connect the multimeter to the
output.
3. Record dark voltage and current.
3. The circuit will trigger a low voltage
when the laser is turned off.
4. Turn on the laser.
4. Make sure the output low is between
0V-1V.
5. Record forward output voltage
and current.
6. If the output voltage is out of the
desired range, use the record from
step 3 and 5 to adjust the value of
resistor.
Soft
Potentiometer
1.Power must be under 1 W
2.The active area should be between
0mm to 200mm
1.Connect soft potentiometer to the
power supply to test DC voltage and
DC current(between 0mm and
200mm)
3.The total resistance: 10kΩ ± 2kΩ
2.Read the value of voltage and
current in turn when it approaches
4.Operating temperature: -40℃ to 50℃ steady state
5.The actual resistance all over the soft
pot should be accompanied with the
theoretical value
3. Calculate the power and total
power consumed in the soft
potentiometer
4.Calculate the total resistance;
R=V/I
5.Move the testing probe from
200mm to the 180mm,
160mm,1140mm and finally to the
20mm.
6.Record the value of voltage and
current in each step and put them in
the form.
7.Calculate the resistance of soft pot
in each step
Micro
controller
Hardware
Hardware-Software
1.Operating voltage: 5V
1.Check the number of pins: both
digital pins and analog pins
2.Input voltage:6V-20V, no more than
20V
3.It has 14 digital I/O pins, of which 6
pins provide PWM outputs, these pins
mainly provide the output to the
decoder which connected to the LED
4.It has 6 analog input pins to detect
fret
5.DC current for each I/O pin: less than
40mA
6.The microcontroller must be
programmable with sufficient memory
to hold
Software:
2. Connect the microcontroller to
PC/external environment.
3. Check the laser-diode circuit:
connect the laser-diode circuit with
the digital pins of microcontroller.
Record the output showed on the
PC. Here we regard the off state as
0, on state as 1.
4. Connect the soft potentiometer
circuit with the analog pins of
microcontroller.
5. Check the soft potentiometer
circuit:
6. Check microcontroller to decoder
circuit: the same as the 5th step:
record the microcontroller output of
24 frets.
1. The algorithm should strictly follow
the flow chart described above.
2. The algorithm should provide the
correct output corresponding to the
voltage input from the laser-to-diode
circuit.
Laser
On-----1
Off-----0
3. The algorithm should provide the
digital signal through MIDI protocol to
the music instrument shield.
The sixteen fret should have the correct
corresponding digital output:1-24
4.The algorithm should provide the
correct signal to the LED decoders
Decoder-LED
circuit
1. The decoder correctly decodes the
input from microcontroller.
1.Connect inputs of decoder to the
test circuit. The test circuit is
comprised of switches to produce
2. The state of LEDs is strictly coherent the digital signal.
with the fret which is pressed.
2.Set the switches to simulate
Each column of frets have its own 3-to- decoder information delivered by
8 decoder.
microcontroller. For every frets have
its related LED and binary code.
Eg: for the 3st fret of the first column,
Check if decoder information is
its input sequence to decoders should
strictly coherent with the activity of
be 010 111 111 111.
LED.
For the 5th fret of the third column, its
input sequence to decoders should be
111111100111.
111 is the empty state.
3.2 Tolerance Analysis
The component that might affect the overall performance of the device most is the soft
potentiometer. The goal of tolerance analysis is to find the range of voltage of each fret position.
Since the resistance of the potentiometer changes in a continuous sequence, it is hard draw
boundaries between notes. Thus, it is required to test and calculate the voltage at the boundary.
Also, it is mandatory to calibrate the boundary voltages on each soft potentiometer.
The second tolerance analysis is to find the tolerance voltage or the range of voltage to provide
the correct digital input to the microcontroller. Because there is a voltage drop due to the photo
diode and thus it can not provide the perfect high voltage.
The third tolerance analysis is to find the most effective orientation and distance of the laser
pointing to the photo-diode. It is known that photodiode has its most sensitive part to the light
and most sensitive wavelength. Thus, it is necessary to find the angle of orientation of the laser
to improve the effectiveness of design. Also, the intensity of laser will gradually decrease during
the transmission. Accordingly, it is also required find the distance between the laser and diode
that is large enough to make player feel comfortable plucking different strings as well as within
the diode’s sensitive range.
4. Costs and Schedule
4.1 Cost Analysis
4.1.1 Labor
Name
Hourly Rate
Total Hours Invested
Hourly Rate * 2.5
*Time Invested
Siyue Li
$40
145
$14500.00
Zihan Yao
$40
145
$14500.00
Zitao Liao
$40
145
$14500.00
435
$43500.00
Total
4.1.2 Parts
Item
Quantity
Cost($)
Photodiode SFH 213
10
4.00
650nm-wavelength, 6mmdiameter, 3-5V, 5mW Mini
Dot Diode Module
4
50.12
Arduino Uno
2
38.94
batteries
36
6.00
Membrane 200mm Soft
Potentiometer
6
78.00
PCB
1
33.00
Resistors and wire
N/A
1.00
LED
50
20.00
VS1053 Codec Shield
1
29.95
Frame board
1
9.99
Total
271.0
4.1.3 Grand Total
Section
Total($)
Labor
43500
Parts
271.0
Total
43771.0
4.2 Schedule
Week
2/9
2/16
2/23
Task
Begin choosing specific parts
Siyue Li
Revise proposal
Zitao Liao
Order parts and devices
Zihan Yao
Test the laser and diodes
Siyue Li
Design CAD Model for the guitar frame
Zitao Liao
Design the laser-photo diode circuit
Zihan Yao
Zitao Liao
Design the soft pot to MCU circuit
Zihan Yao
Siyue Li
Design the PCB part for soft pot and laser-diode circuit
Zitao Liao
Microcontroller coding, digital inputs and analog inputs
Zihan Yao
Create MIDI protocol in microcontroller and establish
communicate with DAC
3/16
Siyue Li
Design decoder circuit for LED
Test the functionality of laser-diode circuit
3/9
Zihan Yao
Submit proposal
Test the soft pot resistance,and sensor bar to MCU
3/2
Responsibility
Siyue Li
Create note to frequency mapping
Zitao Liao
Design PCB for the instructional LED
Zihan Yao
Integrated the PCB parts
Deadline for sending CAD model to Machine Shop
Siyue Li
Zitao Liao
3/23
Spring Break
Zihan Yao
Siyue Li
Zitao Liao
3/30
Test the input signal to the microcontroller
Finish the decoder part design for LED
4/6
Zitao Liao
Prepare presentation
Zihan Yao
Zitao Liao
Finalize the code and test the instructional part
Zihan Yao
Siyue Li
Revise of the functionality of audio part
Zitao Liao
Revise of the functionality of digital signal inputs part
Zihan Yao
Prepare presentation
4/27
Siyue Li
Finalize the frame for laser guitar
Final paper, functionality of design, description of blocks,
analysis
4/20
Siyue Li
Test the interface between MCU and music shield
Design the specific code of instructional LED on MCU
4/13
Zihan Yao
Siyue Li
Revise final paper
Zitao Liao
Finalize final paper
Zihan Yao
Check in supplies
Lab Checkout
Siyue Li
Zitao Liao
5. Ethnics
As electrical Engineers, during the whole designing process, we should follow the IEEE codes of
Ethics without exception. And the following is the IEEE Code of Ethics
This project develops an instructional part of laser guitar for the starters. It is probably to save
the time of starters to get familiar with the basic performance on the guitar. It is believed that it
will also relieved the pain along with playing guitar for long time because original strings have
already been replaced by lasers. As a consequence, the project is consistent with the first code of
IEEE Code of Ethics.
1. to accept responsibility in making decisions consistent with the safety, health, and
welfare of the public, and to disclose promptly factors that might endanger the public or the
environment;
Through the developing of the project, we learn and apply corresponding technology and its
applications. Moreover, we try to modify it to fit it into our part. It could be reflected from
designing audio part and laser-to-diode circuit. Thus, it is consistent with the fifth and sixth
code of the IEEE Code of Ethics:
1.to improve the understanding of technology; its appropriate application, and potential
consequences;
2.to maintain and improve our technical competence and to undertake technological
tasks for others only if qualified by training or experience, or after full disclosure of
pertinent limitations;
We have peer review sessions to provide suggestions to other groups. Also, instructors and
people from other groups could give advices and criticism of technical work on our project at the
design review sessions. During the process of designing, my teammates and I exchanges the
opinions with each other and make decisions through thoroughly discussions. It is consistent
with the seventh and ninth code of the IEEE code of Ethics.
3.to seek, accept, and offer honest criticism of technical work, to acknowledge and
correct errors, and to credit properly the contributions of others;
9. to assist colleagues and co-workers in their professional development and to support
them in following this code of ethics.
These codes are not just restrictions but also guidance, since follow these codes will make us
more productive and effective while doing this project. The IEEE code required us to support
and help our teammates. And we believe following these codes will help us to do the project
better.
6. Safety
Our project is designed to play by musicians and guitar learners, and they may not possess
sufficient electrical engineering and physics knowledge. So it is very crucial to make our design
safe. Our design will use 12V battery as basic power sources. Therefore it is unlikely to get
electrical shock when playing or designing the product. Nevertheless, we always need to put
safety into consideration and here are some safety rules that we should keep in mind:
1. We should be careful while performing soldering, since temperature at the surface of the
solder gun can be extremely high and it can cause serious injury if not handle correctly.
2. The laser beams should never point directly to human eyes. Before turn on laser beams,
we should double check where the laser beams are pointed to. Directly shine the laser to
one’s eyes may cause serious damage to the eyesight and even permanent blindness.
3. Electronic devices are sharp or heavy in some cases they may cut finger. So we need to
be careful when handling these devices and equipment.
If any serious situation happened, we need to call 911 at once, and push the fire alarm if
necessary, but I need to avoid such situation from happening by following the safety rules of the
laboratory and keep safety in mind at all time.
7. Reference
[1] VS1053 SparkFun Music Instrument Shield
https://www.sparkfun.com/datasheets/Components/SMD/vs1053.pdf
[2] ATmega328 microcontroller
http://www.atmel.com/Images/doc8161.pdf
[3] SoftPot Membrane Potentiometer - 200mm Datasheet
https://www.sparkfun.com/datasheets/Sensors/Flex/SoftPot-Datasheet.pdf
[4] SFH 213 Silicon PIN Photodiode Datasheet
http://www.mouser.com/ds/2/311/SFH%20213%20FA,%20Lead%20(Pb)%20Free%20Product%20%20RoHS%20Complian-318895.pdf
[5]
Pc 650nm 6mm 3V 5mW Mini Dot Diode Module Head WL Red
http://www.amazon.com/650nm-Mini-Diode-Module-Head/dp/B00LITXF40
[6] Arduino MIDI Tutorial
http://arduino.cc/en/tutorial/midi