Master`s Thesis
Arduino based laser control
A Degree's Thesis
Submitted to the Faculty of the
Escola Tècnica d'Enginyeria de Telecomunicació de
Barcelona
Universitat Politècnica de Catalunya
by
Ferran Bernal Muñoz
In partial fulfilment
of the requirements for the degree in
SCIENCE AND TELECOMMUNICATION TECHNOLOGIES
ENGINEERING
Advisor: Jose Antonio Lázaro Villa
Barcelona, January 2015
Abstract
The first idea was to realize a tuneable laser for optic communications control using an
Arduino platform for the electronic part. When the project advanced, that idea should be
simplified due the problems appeared. Then the main goal was to control a DFB
(Distributed Feedback Laser) laser with a moderate range of wavelength tuneability by
temperature control.
To control that kind of lasers some variables should be managed. These variables are
controlled electrically. To compute all the variables a communication between Arduino
and MATLAB was opened. This software provides a computation power higher and the
possibility of save the variables’ values. Moreover, a DMX MosFet Receiver device was
added to provide the electric power that Arduino is not able to do. Then it has been tried
to implement and integrate a laser’s software and hardware protection, a temperature
measurer for laser’s temperature and a PID control to stabilize it.
1
Resum
La idea principal va ser realitzar el control de un làser de comunicacions òptiques
sintonitzable utilitzant una plataforma Arduino pel control de tota la part electrònica. A
mesura que va avançar el projecte, aquesta idea va ser simplificada degut als problemes
trobats i va passar a considerar-se com objectiu controlar un làser DFB (Distributed
Feedback Laser) amb un marge d’ona sintonitzable controlant la temperatura.
Pel control d’aquest tipus de làsers s’han de controlar diferents variables les quals son
modificades a nivell electrònic. Per controlar tot això es va afegir una comunicació entre
la placa Arduino i MATLAB ja que aquest software al PC proporciona una potencia de
càlcul molt més gran. També es va afegir una plataforma DMX MosFet per donar més
potència elèctrica a la placa Arduino, massa bàsica per aquesta tasca. Amb tot això s’ha
intentat implementar e integrar una protecció hardware i software pel diode làser, un
mesurador de la temperatura interna del làser i un control PID per la mateixa.
2
Resumen
La principal idea fue realizar el control de un láser de comunicaciones ópticas
sintonizable utilizando una plataforma Arduino para el control de toda la parte electrónica.
A medida que el proyecto fue avanzando, ésta idea se simplificó debido a los problemas
encontrados y pasó a considerarse como objetivo controlar un láser DFB (Distributed
Feedback Laser) con un margen de onda sintonizable controlando la temperatura.
Para el control de este tipo de láseres se deben controlar distintas variables las cuales
son manejadas a nivel electrónico. Para controlar todo esto se añadió una comunicación
entre la placa Arduino y MATLAB, ya que éste software en el PC proporciona una
potencia de cálculo mucho mayor. También se añadió una plataforma DMX MosFet para
dar más potencia eléctrica a la placa Arduino, demasiado básica para esta tarea. Con
todo esto se ha intentado implementar e integrar una protección hardware y software
para el diodo láser, un medidor de la temperatura interna del láser y un control PID para
la misma.
3
It is for that people who has suffered
and enjoyed the engineering with me
4
Acknowledgements
First of all, I want to recognise my supervisor Jose Lázaro for guide me during the entire
project and give me support in the different areas of the project. He also has spent many
hours with me in the laboratory trying to find solutions for the different problems
especially with the PID design and implementation. Without his dedication this project
would not have been possible.
Finally, I have to thank the entire people who have helped me in the everyday things
which made that project easier in different ways: family, friends, university-mates...
5
Revision history and approval record
Revision
Date
Purpose
0
10/01/2015
Document creation
1
05/02/2015
Document revision
DOCUMENT DISTRIBUTION LIST
Name
e-mail
Ferran Bernal Muñoz
[email protected]
Jose Antonio Lázaro Villa
[email protected]
Written by:
Reviewed and approved by:
Date
10/01/2015
Date
XX/MM/YYYY
Name
Ferran Bernal
Name
Jose A. Lázaro
Position
Project Author
Position
Project Supervisor
6
Table of contents
Abstract ............................................................................................................................ 1
Resum .............................................................................................................................. 2
Resumen .......................................................................................................................... 3
Acknowledgements .......................................................................................................... 5
Revision history and approval record ................................................................................ 6
Table of contents .............................................................................................................. 7
List of Figures ................................................................................................................... 9
List of Tables: ................................................................................................................. 10
1.
2.
Introduction.............................................................................................................. 11
1.1.
Objectives and Motivation................................................................................. 11
1.2.
Technical description ........................................................................................ 11
1.3.
Work plan ......................................................................................................... 12
1.4.
Incidences ........................................................................................................ 16
Background: ............................................................................................................ 17
2.1.
DFB communications Laser.............................................................................. 17
2.1.1.
Tuneable Laser ......................................................................................... 17
2.1.1.1. Gain Section............................................................................................ 18
2.1.1.2. Coupler Section ....................................................................................... 18
2.1.1.3. Reflector Section ..................................................................................... 19
2.1.1.4. Phase Section ......................................................................................... 19
3.
4.
2.2.
MATLAB ........................................................................................................... 20
2.3.
Arduino ............................................................................................................. 21
2.4.
MATLAB + Arduino ........................................................................................... 21
Instrumentation used: .............................................................................................. 23
3.1.
Power Supply ................................................................................................... 23
3.2.
Multimeter ........................................................................................................ 23
3.3.
JDS Uniphase Laser......................................................................................... 23
3.4.
Laser plinth ....................................................................................................... 24
3.5.
ThorLabs TED 200-C Temperature Controller .................................................. 25
Sub-systems Description: ........................................................................................ 26
4.1.
DMX Master Shield + DMX MosFet Receiver ................................................... 26
4.2.
Arduino – MATLAB communication .................................................................. 27
4.2.1.
MATLAB Interface for Arduino: .................................................................. 27
7
5.
6.
4.2.2.
Arduino Target for Simulink: ...................................................................... 28
4.2.3.
Communicate Arduino with MATLAB by Serial port: .................................. 28
4.2.4.
Final communication protocol .................................................................... 28
4.2.5.
MATLAB GUI............................................................................................. 29
4.3.
Laser’s protections ........................................................................................... 29
4.4.
Temperature measurement using Arduino Board as Oscilloscope .................... 31
4.5.
PID control for temperature .............................................................................. 32
Results .................................................................................................................... 34
5.1.
Laser protection ................................................................................................ 34
5.2.
Software results ................................................................................................ 34
5.3.
Temperature measurer ..................................................................................... 36
5.4.
PID warm up control ......................................................................................... 36
Budget ..................................................................................................................... 38
6.1.
Project costs ..................................................................................................... 38
7.
Conclusions and future development: ...................................................................... 39
8.
Bibliography: ............................................................................................................ 40
Appendices: .................................................................................................................... 42
Glossary ......................................................................................................................... 43
8
List of Figures
Fig. 1 Gantt diagram with the final development of the project ........................................ 16
Fig. 2 Detail of the 4-sections of a Tunable Laser with the wavelength path as shown in
[1] ................................................................................................................................... 17
Fig. 3 Output Power versus Gain current fixing three other currents and temperature as
shown in [1] .................................................................................................................... 18
Fig. 4 Wavelength versus Coupler Section current fixing three other currents and
temperature as shown in [1]............................................................................................ 18
Fig. 5 Reflector Section current increase characteristics fixing three other currents and
temperature as shown in [1]............................................................................................ 19
Fig. 6 Reflector Section current versus wavelength fixing the three other currents as
shown in [1] .................................................................................................................... 19
Fig. 7 Phase Section current versus wavelength fixing three other currents and
temperature as shown in [1]............................................................................................ 20
Fig. 8 Arduino UNO Board .............................................................................................. 21
Fig. 9 Power supply used during the tests ...................................................................... 23
Fig. 10 Profile’s plinth (left) and Thorlabs’ plinth (right). .................................................. 24
Fig. 11 DB9 connectors pins for the Profile’s plinth ......................................................... 24
Fig. 12 ThorLabs TED 200 C temperature controller....................................................... 25
Fig. 13 DMX Master Shield stacked on an Arduino UNO connected to a DMX MosFet
Receiver ......................................................................................................................... 27
Fig. 14 Electronic circuit to protect the laser ................................................................... 29
Fig. 15 Protection circuit integrated................................................................................. 30
Fig. 16 Circuit designed for software protection. ............................................................. 31
Fig. 17 Laser temperature measurement system ............................................................ 31
Fig. 18 Room’s temperature measurement with noise measurement digitalized ............. 32
Fig. 21 Laser protection integrated in the plinth .............................................................. 34
Fig. 22 Scan Window from the MATLAB GUI ................................................................. 35
Fig. 23 Tune Window from the MATLAB GUI ................................................................. 35
9
List of Tables:
Table 1 Work Package #01............................................................................................. 12
Table 2 Work package #02 ............................................................................................. 12
Table 3 Work package #03 ............................................................................................. 13
Table 4 Work package #04 ............................................................................................. 13
Table 5 Work package #05 ............................................................................................. 14
Table 6 Work Package #06............................................................................................. 14
Table 7 Work package #07 ............................................................................................. 15
Table 8 Milestones summary .......................................................................................... 15
Table 9 Connection dependencies for Profile’s laser plinth ............................................. 24
Table 10 Project costs .................................................................................................... 38
10
1.
Introduction
1.1.
Objectives and Motivation
The first idea for this project was to control a tuneable laser easily from a computer. That
would be very useful because at the moment that kind of laser was managed by putting
manually from a power supply the different currents required in the laser. To tune the
laser a table with all the outputs for different inputs should be done manually and select
the inputs to achieve an output from there.
1.2.
Technical description
But which are the difficulties about controlling that kind of laser and why is it required to
be done easier using a computer?
The first thing is to know how that laser works. The main idea is that the laser controls the
emitted light wavelength and its amplitude varying four different currents but it is
important to know at this point that the behaviour when varying these currents is not lineal.
Then it is important to record the laser’s output when varying the different currents, and
that’s why we want the computer.
In the computer it was decided to use MATLAB software to do a scanning for the different
currents characterizing the laser and generate a table with the behaviour of it. Moreover,
this software is useful to manage, save and treat the obtained data for different purposes.
Now the problem is how to connect the computer with the laser?
For this purpose the idea was to use an Arduino Uno board which provides an easy mode
to connect the computer with the outside world through sensors and to manage outside
variables using different devices prepared for this kind of boards. The board was used to
catch information from the sensors located in the laser, but it was not its only use. An
Arduino Uno board was combined with the DMX Shield and the DMX MosFet Receiver
from Tinkerkit to manage from the computer through the Arduino the different currents to
introduce to the laser to make it work properly.
Once the project was ongoing and different problems and incidences appeared the
necessity of changing the initial scope became apparent. That new scope was to simplify
the laser type to make easier manage it. The new communications laser had only one
input current which activates or deactivates the diode to emit.
To manage that laser it is important to stabilize its temperature into the laser cavity.It has
to be stable to provoke a stable behaviour, but when the laser is emitting light it is
warming up. To solve this problem there are temperature controllers in the market, but
because its price the decision was to design and implement a PID control for the
temperature of the laser.
It had to be taken into account that a laser is not a cheap device which can be used
without taking care of it. One thing to take care for a correct laser management is that the
light is emitted by a diode which could not be connected in a wrong way because it could
damage the laser if it stocks enough voltage to break the diode. Then it was designed a
hardware and software protection for the laser.
11
In conclusion, the main goal of control a laser easily from a computer is not a trivial thing.
All the used devices have their own complexity and should be characterized and
controlled first in their own. After that all the system should be integrated and tested to
finally try to manage the laser.
1.3.
Work plan
Project: Review Tunable Laser Documentation
WP ref: 01
Major constituent: Documentation
Sheet 01 of 07
Short description:
Planned
date:15/09/2014
start
Read the PhD thesis from Victor M. Polo about the
tunable
lasers
and
their
utilities
in
optical Planned end date:01/10/2014
communications to understand the utility and define the
Start event: 15/09/2014
ARDUINO board function in the system.
End event: 01/10/2014
Internal task T1: Read the document and note the doubts Deliverables:
to ask to the supervisor.
Dates:
Internal task T2: Define the electric specifications to do
the laser work in the expected range.
Table 1 Work Package #01
Project: ARDUINO
WP ref: 02
Major constituent: Software and testing
Sheet 02 of 07
Short description:
Planned
01/10/2014
start
date:
Do some tests to see if the ARDUINO UNO board is
enough to tune the laser as we want (check output Planned end date:01/11/2014
currents and clock speed).
Start event:01/10/2014
Develop the ARDUINO software to manage the laser
End event:15/11/2014
tuning it.
Integrate, if necessary, the board with a DMX MosFet
Receiver to manage the needed currents by the laser.
Internal task T1: Develop the ARDUINO code to tune the Deliverables:
laser easily
Dates:
Internal task T2: Test the board with the DMX MosFet
Receiver to check they work properly together
Table 2 Work package #02
12
Project: MATLAB GUI
WP ref: 03
Major constituent: Software
Sheet 03 of 07
Short description:
Planned
01/11/2014
start
date:
end
date:
Develop a MATLAB interface to connect a computer with
the ARDUINO board to control the tunable laser easily.
Planned
25/11/2014
Start event:01/11/2014
End event:01/12/2014
Internal task T1: Develop the connection between Deliverables:
MATLAB and ARDUINO and the process program
Dates:
Internal task T2: Develop the interface to make easier
manage the tuning of the laser
Table 3 Work package #03
Project: Redefine Scope
WP ref: 04
Major constituent: Project management
Sheet 04 of 07
Short description:
Planned
01/12/2014
Redefine the scope of the project its objective and plan
the next steps
Planned
05/12/2014
start
date:
end
date:
Start event:01/12/2014
End event: 05/12/2014
Internal task T1: Redefine the scope and the main goals Deliverables:
of the project
Dates:
Table 4 Work package #04
13
Project: PID controller
WP ref: 05
Major constituent: Hardware and software
Sheet 05 of 07
Short description:
Planned
05/12/2015
start
date:
Design, implement and integrate a PID control to
maintain the temperature in the laser when the diode is Planned
end
working
10/01/2015
date:
Start event: 05/12/2015
End event: Internal task T1: Design and implement a temperature Deliverables:
measurer.
Dates:
Internal task T2: Characterize the PID control to warm up
and cool.
Internal task T3: implement and test the PID control.
Table 5 Work package #05
Project: Diode laser protection
WP ref: 06
Major constituent: Software & Hardware
Sheet 06 of 07
Short description:
Planned
20/12/2014
Design and implement the hardware and software
protection for the diode laser.
Planned
31/12/2014
start
date:
end
date:
Start event:20/12/2014
End event: 10/01/2015
Internal task T1: Design, implement and test the Deliverables:
hardware laser diode protection
Dates:
Internal task T2: Design, implement and test the software
laser diode protection
Table 6 Work Package #06
14
Project: Project Documentation
WP ref: 07
Major constituent: Documentation
Sheet 06 of 07
Short description:
Planned
15/01/2015
start
date:
Collect all the information used during the project and
write the final document to deliver for the evaluation.
Planned end date: 30/01/2015
Start event: 20/01/2015
End event:
Internal task T1: Collect the information used during the Deliverables:
project
Degree’s
thesis
document
Internal task T2: Write the final document to deliver to
evaluation
Dates:
02/02/2015
Table 7 Work package #07
Milestiones
WP#
Task#
Short title
Milestone / deliverable
Date (week)
01
01
Read laser doc
-
1
01
02
Define laser specs
-
2
02
01
Develop ARDUINO code
-
7
02
02
Test the Arduino with
DMX
ARDUINO code working
properly
8
03
01
Develop MATLAB code
-
10
03
02
Develop ARDUINOMATLAB connection
Connection Arduino-PC
13
04
01
Redefine scope
-
14
05
01
Temperature measurer
Temperature measurer
15
05
02
PID control
characterization
PID constants
18
05
03
PID implementation and
test
PID control
06
01
Hardware protection
Hardware protection
19
06
02
Software protection
Software protection
-
07
01
Documentation
Final thesis document
-
20
Table 8 Milestones summary
15
Fig. 1 Gantt diagram with the final development of the project
Next there is the order of the different packages:
1234567-
1.4.
Review Tunable Laser Documentation
Arduino Development
MATLAB GUI
Redefine Scope
PID Control
Diode Laser Protection
Project Documentation
Incidences
There have been some important incidences which have done the initial plan fall. For that
incidences is for which finally it was decided to manage a DFB laser which is easier to
manage and can implement practically all the functionality designed at the start of the
thesis.
The first incidence found was that the TinkerKit website was closed. That means that it
was so difficult to find important information about the DMX Shield and the DMX MosFet
Receiver used in the project. Finally it was impossible to find any tutorial or basic
document with first steps to work with these devices and it was so difficult to find the
official libraries to install into the Arduino program to work properly with the devices. All
this made harder to work with these devices and took more time to start testing them and
know how they work internally.
The second incidence has been with the PID control to maintain constant the laser’s
temperature. The first tests were done with a pump laser which was too simply and did
not have integrated a Thermistor to measure the temperature in the laser but it was not
specified. Then it was spent some time until we realized that the laser did not have those
components and the problem was not when computing the temperature measure.
Another problem found which has to see with the PID is that when trying to characterize it
using the DMX MosFet we obtained strange measures which had to see with the DMX
MosFet and its behaviour. After performing lots of different tests I have not been able to
does it work as is supposed, and the PID control has not been properly implemented. In
the next sections there are more details about this big issue.
16
2.
Background:
Here is a summary about the information found during the first stage of the project. It is
about the four big items which would be combined to design and integrate a whole
system.
2.1.
DFB communications Laser
A distributed feedback laser (DFB) is a type of laser diode which emits light when current
is applied through the diode. When the current is the appropriate laser starts to emit, but
this provokes other effects which should be taken in care.
The most important is that the internal temperature rises. It is important because a DFB
laser is not an electronic device which works properly in a temperature range. Every
temperature degree of difference makes the laser works in a different way modifying the
wavelength or the output power. Then it is important to have this parameter into account
to characterize the laser’s output.
2.1.1. Tuneable Laser
A tuneable laser is a kind of laser which can switch its wavelength when varying some
parameters. One of the ways to change the wavelength is changing the temperature. The
problem of this kind of tuning is that is slower and the wavelength range is least than
other tune ways.
The other parameters changed to tune the laser are the configuration of different sections
of the laser. When changing these sections is provoked the named plasma effect. It is
produced by the current injection on the laser cavities and allows wavelength tuning by
refraction index changes.
These four sections are: gain section, coupler section, phase section and sampled
reflector section.
Fig. 2 Detail of the 4-sections of a Tunable Laser with the wavelength path as shown in [1]
17
It is important to notice that varying the current introduced in the gain section does not
produce a wavelength change; it only affects the output power from the laser diode. In the
other three sections, when varying the current it is varied the effective refraction index
which provokes that the wavelength outgoing from the laser cavity varies in function of
the different indices. Next there is a little explanation on how the changes affect the
different sections.
2.1.1.1. Gain Section
It is the section which injection current should be properly introduced to allow the laser
work. When the current is higher than a certain threshold and the other currents are not
null the diode laser starts emitting light. Once this threshold is passed the output power
increases in a logarithmic way as is represented in the figure 3.
Fig. 3 Output Power versus Gain current fixing three other currents and temperature as shown in [1]
2.1.1.2. Coupler Section
This section works as a filter, when increasing the input current in this section there are
lower sampled modes. Then we can observe some nanometres jumps in the figure 4.
Fig. 4 Wavelength versus Coupler Section current fixing three other currents and temperature as
shown in [1]
18
2.1.1.3. Reflector Section
This section is used for fine tuning; increasing the input current does this section selects
lower order cavity modes. In the next figure there are little jumps of about tenths of
nanometres.
Fig. 5 Reflector Section current increase characteristics fixing three other currents and temperature
as shown in [1]
It is important to notice that depending on the bias current in the other sections. There
could appear some non-lineal behaviour in the laser output wavelength. In the figure 6 we
can see how changing the coupler bias current into a different point that the one chose in
the figure 5 it has a big jump eith little current increase.
Fig. 6 Reflector Section current versus wavelength fixing the three other currents as shown in [1]
2.1.1.4. Phase Section
The phase section tunes all the cavities at the same time. It produces some chaotic
wavelengths with non-linear behaviour when changing a little the input current for this
section. In the figure 7 we can see an example of how the output varies when increasing
the current introduced in this section.
19
Fig. 7 Phase Section current versus wavelength fixing three other currents and temperature as shown
in [1]
2.2.
MATLAB
One of the most important parts in this project is about how to manage the data acquired.
For this purpose it was chosen the MATLAB software. First of all it is important to know
what MATLAB is to understand why has been used during the project and which
advantages provide us.
MATLAB is a numerical computing environment which allows matrix manipulations, graph
2-D and 3-D graphics, create easily Graphic User Interfaces, interface with other
programs... It is very used software in the engineering world for its computation power
and the multiple applications it has. Moreover, there is a huge community of developers
which use the software and share for free the tools created by them or publish their
functions to solve specific problems.
In this project it was important to have software which could interact easily with other
programs for example to export data collected to an Excel file or to interact with the
device which controls the electronic part of the laser. Another important point was the
possibility of creating a simple GUI for the final user which is going to manage the laser at
the end.
Finally, there is the need of having software to manage all the different currents to
introduce to the laser, manage and save the data extracted from it, create a friendly GUI
for the final user and connect the computer with an outside device to manage the laser. In
spite of there are other software which can give the characteristics commented below or
inclusive is possible to create an specific software to do all this, for the project it was
chosen MATLAB for its capability of offering all those characteristics in a simple and easy
develop tool.
20
2.3.
Arduino
Arduino is an open-source electronics platform based on easy-to-use hardware and
software. The Arduino boards are systems which provide sets of digital and
analog I/O pins that can be interfaced to various extension boards and other circuits.
Every board has a microcontroller or processor integrated which can run a program and
does the system work without consuming process resources from the computer. There is
an example of an Arduino board in the figure 8. It is very useful for simple programs
which are based on controlling a simple system basing the decision to take on the data
collected from some sensors.
Fig. 8 Arduino UNO Board
The other big point that Arduino has is the easy way to connect a board and the data it
processes with a computer to manage this data in different ways. Every board features
serial communications, including USB in some models, for load the programs created but
to transfer data between both systems too. It allows to use these boards in more complex
systems which need a major process power or to use more memory because they can
work with a very powerful computer easily and work as an interface to connect different
devices to the computer without processing the data more than necessary to send it.
For programming the microcontrollers, the Arduino platform provides an integrated
development environment (IDE) based on the Processing project, which includes support
for C and C++programming languages. Moreover, as happens with MATLAB, Arduino
has a huge developer’s community which are very active in the Arduino’s forum where
there are lots of projects or examples to follow.
2.4.
MATLAB + Arduino
Since 2010 MATLAB started to work into make easier to manage an Arduino board from
a MATLAB session. Then from that moment in every 6-months MATLAB release there
have been news about the Arduino package including new functionalities or new
instructions to execute in MATLAB to produce changes in the board pins or read data
directly from them.
Moreover, since 2012 MATLAB included a package to prototyping, testing and running
Simulink models in an Arduino UNO board. With new releases the number of boards
which can work with Simulink has raised. The fact that a board can work with Simulink is
very useful for control and robotics purposes in which Simulink is very easy-to-use for
designing systems.
21
In summary it is very useful to combine both tools because they are complementary.
MATLAB gives a high computing power in mathematics while Arduino is very powerful to
manage different electronic devices easily from a computer. Then, together they can be
integrated to form a very complex system which, for example, needs to capture
information from some sensors, process it in a complex way and depending on the
results decide what to do managing some other devices.
22
3.
Instrumentation used:
To perform all the tests and reach some of the goals it has been necessary to use some
instrumentation from the Laboratory which is going to be mentioned here with a little
explanation about why has been used.
3.1.
Power Supply
This instrument has been used basically with two purposes. The first one is to feed the
DMX MosFet Receiver which needs a 12-24V of voltage supply to work. The second one
has been as a controlled current source. It has been done setting up desired saturation
intensity and a big voltage referred to the resistance is going to be used. That was useful
when performing tests with laser’s cooler for example.
Fig. 9 Power supply used during the tests
3.2.
Multimeter
A multimeter has been basic during the testing due its multiple functions. First it was
important to measure the internal resistance of different elements from the laser as the
Thermistor, the peltier resistance... Next, it has been very useful to monitor the intensity
through the cooler to characterize it and perform some tests. Another important point has
been to check which pins in the DB9 output of the plinth are connected to the butterfly
pins where the laser is placed.
3.3.
JDS Uniphase Laser
To perform practically all the tests it has been necessary a laser as it is the focus of the
project. The first laser tested was an agree systems pump laser at 980nm. After
performing some tests and watching irregular data collected the conclusion was that this
laser didn’t integrate a TEC system to control temperature then it was useless to perform
the tests required.
Then, after testing some lasers it was finally decided to continue working with the JDS
Uniphase laser because it implemented all the parts which were necessary for the project
scope. It is not a tunable laser but has implemented a Thermistor to compute the
temperature, a thermoelectric peltier cooler to manage the temperature in the laser, an
emitting diode, an integrated wavelength monitor and it was build in a 14-pin butterfly
package for an easy management of the device. For more information you can find the
laser’s datasheet in the appendix
23
3.4.
Laser plinth
It is necessary to connect the laser with other devices used in the project, to do that it has
been used a laser plinth. This consists on a platform to stack the laser and work safely
with it because it has to be taken into account that a laser is not a cheap device.
The laser plinths used provide two DB9 inputs to connect easily the different laser pins
individually customizing a DB9 cable or to connect with different devices to control some
variables from that kind of lasers. At the beginning a Throlabs’ plinth was used to perform
the tests but when the protection circuit was designed an easy way to implement it was to
use the LDH BFY-B Profile’s plinth which has a plate to interconnect the laser’s pins
easily. In the figure 10 there are both plinths used during the project.
Fig. 10 Profile’s plinth (left) and Thorlabs’ plinth (right).
The Profile’s plinth has a particularity, the butterfly pins where the laser is placed are
connected with the pins in the bottom row and the upper row pins are connected to
different pins in the DB9 connectors. Next there is the connection reference from upper
row (right to left watching the picture) to the DB9 connectors:
Fig. 11 DB9 connectors pins for the Profile’s plinth
LD Driver
Upper row pin
TEC Driver
Upper row
6
7
8
9
1
2
4
5
8
6,7
9
10
13
11
12
1
5
4
3
2
2
3
4
5
Table 9 Connection dependencies for Profile’s laser plinth
24
3.5.
ThorLabs TED 200-C Temperature Controller
This is a very useful and necessary instrument when working with lasers. As it has been
explained is very important to stabilize the temperature in a communications laser to
ensure the expected behaviour. What this controller can do is to set a temperature and
maintain it. While it is being done, the controller gives information about the current is
being used and the resistance performed in the Thermistor. It is very useful when doing
tests to check if the temperature measurement or the temperature measurer designed
works properly.
Fig. 12 ThorLabs TED 200 C temperature controller
25
4.
Sub-systems Description:
The control of a tuneable laser is not a trivial task, and then the system which will do it is
not simple and is composed by few simpler systems. As it has been explained before
there are some parameters which should be controlled in the laser to ensure a correct
behaviour. To do this there are some subsystems which have to coexist and work
together to manage the laser properly.
Next there is a description of each subsystem with its development carried out and the
tests realized.
4.1.
DMX Master Shield + DMX MosFet Receiver
Once the tuneable laser specifications were specified it was clear that was necessary a
device to provide four controlled currents to manage the different cavities refraction index.
With that information was seen that an Arduino UNO board wouldn’t provide the desired
currents. It happens because its digital output pins provide as maximum 40mA with a
PWM modulation and the necessity was a DC current. To solve that problem was
proposed to use the DMX MosFet Receiver with the DMX Master Shield.
These two devices are from Tinkerkit!’s company. Both gadgets are conceived to work
with an Arduino board acting as the microcontroller to manage them. Let’s see which are
the characteristics of every device, how do they work and why have been used.
The first device to be analysed is the TinkerKit!’s DMX Master Shield which is used to
drive a series of DMX receivers. Like a regular shield it has to be plugged on top of the
Arduino and it can be stacked on top of other shields. It is used both as output and input.
Another important feature is that every channel can handle 3A of current being a total of
12A given by the whole device. This shield supports up to 512 DMX modules connected
in parallel. There is an important issue to have into account: it is not compatible with
Arduino DUE.
The other device to analyze in this part is the DMX MosFet Receiver which is a DMX
module that mounts four mosfets. Each mosfet supports up to 24V DC and the board
runs at a range from 12V to 24V. This device works also as a standalone USB board; in
fact it mounts a micro-usb connector and the same microcontroller as the Arduino
Leonardo.
Now let’s see how these devices work together with an Arduino board and how they are
integrated in this project. The first thing was done is test the devices together with an
Arduino UNO board with a simple program which select one channel (one of the four
MosFets) and get from it the desired voltage output. To do that the shield should be
stacked on the Arduino UNO board, which is connected to the computer, and connected
to the DMX MosFet as we can see in the figure 13. Once these connections are done, the
MosFet device must be fed with a 12-24V voltage. This device has a one-byte resolution,
it means that it can put an output voltage from 0V up to the feed voltage with steps of one
255-part of the feed voltage. Finally a resistor of 1kΩ is put in a protoboard connected to
one of the channels to test if the output is the correct one.
26
Fig. 13 DMX Master Shield stacked on an Arduino UNO connected to a DMX MosFet Receiver
Once the hardware is ready is time to design a simple program which provokes an output
in a channel to read the voltage in the resistor and see if it is as expected. It was found
the library named “DmxMaster”, its only disadvantage is that it does not work with
Arduino DUE. It was developed a simple sketch which used the functions provided by this
library to setup the shield and change every ten seconds the output in the channel one
between 0 and 255, which is the maximum value.
Once the hardware has been installed and all the devices are integrated together and the
software has been developed some tests should be done to ensure the correct behaviour
of the system. As a result of these tests was found a curious thing, the DMX MosFet
Receiver modules the output voltage by maintaining one of the terminals at the feed
voltage and increasing the other terminal in a value between 0V (for a 255 digital value
chosen) and the feed voltage (for a 0 digital value). A part of that, the system behaved as
expected tested with the resistor.
4.2.
Arduino – MATLAB communication
There are three easy ways to connect your MATLAB code with your arduino. Next there
is a little explanation on what consists each one, the final solution taken and the
development with Arduino and MATLAB.
4.2.1. MATLAB Interface for Arduino:
This lets you control your Arduino board over USB from a MATLAB session, in Windows,
Mac or Linux. It provides simply commands to read or write to some pins from the
Arduino board directly from the MATLAB session. Lastly, there have been added
commands to manage a servo easily from the command window.
This way to connect an Arduino with MATLAB is very useful to perform some simple tests
as read or write values to some pins from the board or manage servos easily. But there is
a very slow communication between because a complex code provided by MATLAB has
to run on the Arduino. This program is the responsible of managing the communication
depending on multiple headers and being configured for any kind of communication
which the package allows to do. This package has been used to perform some simple
tests but not for a final integration between MATLAB and Arduino.
27
4.2.2.
Arduino Target for Simulink:
This lets you use Simulink to create programs that run directly on an Arduino board. The
target (available for Windows only) allows a Simulink model to be automatically converted
to C/C++ code, compiled and downloaded to the Arduino. This is especially useful for
control applications that need to run at high sampling rate and in cases where you don't
want the Arduino to be connected to a host computer.
This was the first option to implement the PID control for the temperature of the laser, but
the multiple drawbacks found discarded this option. The first one is the complexity added
to combine the Simulink models with some code generated to realize other actions in the
laser. But the drawback which discarded definitely this option is the impossibility to
upload a program in the board which uses Arduino libraries to manage the DMX devices.
4.2.3. Communicate Arduino with MATLAB by Serial port:
It is easy to open a Serial Port communication and develop an Arduino code to work with
a MATLAB script. It is the oldest and most complex way to connect an Arduino board with
MATLAB but it has an advantage, you can use libraries in your Arduino code which you
cannot use from MATLAB because they are typical from Arduino. For example, libraries
for specific devices or sensors connected to the Arduino board.
4.2.4. Final communication protocol
The communication by Serial port was the chosen because offered more possibilities and
freedom to develop a program for the board and another for the computer which works
together synchronized. That is the key to make this connection work properly,
synchronization.
First of all, it is important to open first the Serial port by the Arduino program to open it
from MATLAB in second term. When this connection is properly established, it is easy to
read in MATLAB information from the Arduino board because it has a buffer and an
adequate timeout to receive the information. Another thing which Arduino does is to send
the information as a String then from MATLAB it is easy to translate this string to a
number with the str2num() function or read directly the String if it is what was expected.
Once seen the communication from the board to the computer let’s see the other side
communication. This connection is more complex due to the behavior of the functions
used by Serial library from Arduino. For a downside communication it is important to take
into account that it should be indicate the type of the byte which is going to be received
using the instruction Serial.read() to read an input String or Serial.parseInt() to read an
Integer number.
Having all this into account and the necessities from the system there is a little
description of what was necessary to have controlled from the communication. First of all
there should be a communication from the Arduino to the MATLAB to send data collected
from the different sensors, it was easy to do because all the data is sent in the same way
and then MATLAB interprets it. Another important thing was to manage the DMX MosFet
from MATLAB, to do that there were created headers to send to the board indicating the
channel to set and after the header the number between 0 and 255 to set in the channel.
28
Finally, to synchronize all of this it was created an Arduino program with a loop which is
executed while there is no data to read from the computer and when there is data to read
first read a header and depending on that sets one of the DMX MosFet channels. With all
this MATLAB can do all the calculations and decisions depending on the data entered
and Arduino sets the output voltages without a big computing cost.
To end this part, there were performed some simple tests trying to put a desired voltage
from MATLAB through Arduino in the DMX MosFet Receiver adjusting the delays and the
developed code to work properly and as quick as possible.
4.2.5. MATLAB GUI
A good communication was achieved and then a MATLAB program development started.
The goal was to have a friendly GUI which could scan automatically the different current
values for the different inputs in the laser and save its behaviour to later able to tune the
laser easily. The program was being developed should integrate an effective
communication with the Arduino board to manage the DMX MosFet Receiver and read
the outputs from the laser. That means that an Arduino code, to be synchronized with the
MATLAB code, should be developed in parallel.
When this program was in the middle of the development was when the change of scope
became necessary and this part was filed to follow with it if the time allow it. Then finally
there is a useless version of the GUI which needs to implement some code blocks to
work properly. This unfinished version is detailed in the code appendix.
4.3.
Laser’s protections
The laser is being used is a DFB laser, which is at the end a diode. It is important to feed
properly that diode not to break it, because if it is connected backwards there is the
possibility to lose the laser and it is not a cheap device.
To ensure that connection has been designed a circuit to protect the laser from a bad
connection. Moreover, to complement that circuit, a software interruption has been
developed in the Arduino program to stop the system if it has a bad connection.
The hardware protection is a simple electronic circuit which drains the current to ground if
there is a bad connection. In the figure 14 there is the designed circuit with its
connections.
Fig. 14 Electronic circuit to protect the laser
29
Then if the connection is properly done the current pass through the laser diode. But, if
there is a wrong connection, then the entire current pass through the protection diode
maintaining the laser in perfect conditions. In the figure 15 the final circuit implementation
could be seen. It has been implemented on a 28-pin plate to easily integrate it with the
laser’s plinth from Profile. Moreover, this circuit implements the basic connections to
make the laser TEC and the diode work from an outside connection in the DB9 ports.
Fig. 15 Protection circuit integrated
Now that the hardware protection is solved, it is important to stop the system if there is
something wrong. To do that it has been implemented an interruption in the Arduino code
to stop the electronic system if there is a wrong connection. The behaviour of this part is
very simple, when a bad connection is detected, a part of the code starts immediately and
put on 0 all the MosFets stopping the whole system avoiding any possible bad behaviour
or overload.
The problem in this part has been to properly detect when a bad connection has been
done. The Arduino UNO board digital inputs which can read an interruption are 2 and 3.
Both inputs can read voltage values between 0 and 5V which is a problem having into
account that the DMX MosFet sets the output current maintaining an output at 12V and
varying the other one.
The first solution thought was to set as reference voltage for the board the voltage at the
laser’s diode input. Then set up an analogue input as the interruption pin. With this, the
interruption pin reads the difference between the input and the output voltage in the diode.
If the diode is working properly the input voltage is greater than the output and the code is
not interrupted. But if there is a bad connection the input voltage is less than the output
and the interruption code is executed.
This design has not been implemented because the maximum reference voltage for an
Arduino UNO board is not enough for this purpose. This board supports up to 5V of a
reference voltage and it was necessary to introduce values up to 12V.
The final solution proposed was to do a differential circuit to compare both voltages. The
circuit designed consists on an operational amplifier in a closed loop which does the
difference between the voltage in the laser cathode and the anode with the protection of a
diode for negative voltages (when the system works properly). The 4 resistors should be
equal to ensure a difference without amplification and have a value in order of hundreds
of kΩ to ensure this part of the circuit does not consume a lot of intensity. The circuit
design is in the figure 16. This design has not been implemented and tested due to lack
of time.
30
Fig. 16 Circuit designed for software protection.
4.4.
Temperature measurement using Arduino Board as Oscilloscope
It is very important to notice that laser behaviour depends on the temperature. Then, an
important variable to be monitored is the temperature into the laser cavity. To do that, the
laser integrates a Thermistor. A Thermistor is a kind of resistor which resistance depends
on the temperature, more than in standard resistors.
To measure this Thermistor resistance it has been used a simple circuit combined with
the Arduino board. It consists on a voltage divider with a known resistance and the
Thermistor. With this, the next step is to put a known voltage from the Arduino (there is a
pin with constant 5V output) and read the voltage in the middle of the voltage divider to
know the voltage in the Thermistor. In the figure 17 there is a picture with the assembly
done to do measure the temperature.
Fig. 17 Laser temperature measurement system
Once is known the voltage in the Thermistor is time to compute the temperature. First the
resistance in the Thermistor should be known. It is an easy calculation because the
resistor put in the divider is known. Now, to compute the temperature it has been used
the next equation:
31
Where To is the room temperature (298.15 Kelvin=25ºC), B is the parameter equation
which is specified in the laser characteristics, R is the resistance measured in the
Thermistor and Ro is the resistance in the Thermistor at To.
Finally, the calculated temperature is sent to MATLAB and it generates a graphic with its
time evolution. There is an example of measuring the laser temperature at room’s
temperature, which means without exciting it. The figure shows the noise measurement
digitalized by the Arduino A/D converters for the analogue pins. The error read is very
small and provokes a deviation in a 0.4 Kelvin error range.
Fig. 18 Room’s temperature measurement with noise measurement digitalized
4.5.
PID control for temperature
As it has been said before, it is important to control the temperature in the laser to ensure
its expected behaviour. To do that it has been chosen a PID control to maintain a
constant temperature in the laser. A proportional-integral-derivative controller (PID
controller) calculates an error value as the difference between a measured process
variable and an objective value. The controller tries to minimize the error by adjusting the
process manipulating a variable.
In this case the variable to set is the temperature and the variable which is manipulated is
an integrated thermoelectric cooler (TEC). This uses the Peltier effect to create
a heat flux between the junction of two different types of materials.
After performing some tests finally it was decide to use a controller with only proportional
and integral actions. It was done because the derivative action is very sensitive to noise
and it provokes instability. Then some tests were done with only PI actions and the
controller accomplished the expectations.
To tune the proportional and integral constants has been used the process reaction curve
method. It consists on excite the system with a unitary step and measuring the
parameters which characterize the response in the resultant sigmoid. In this case what
has been done is put a current through the cooler and measure the temperature
variations in the laser. It has been done to characterize the warm up and the cool
functions which have different curves. In the figures 19 and 20 there are both curves.
32
Fig. 19 Warm up response to unitary step
Fig. 20 Cool response to unitary step
To get those curves has been necessary to perform some tests and manage the current
introduced to the cooler. Next there is the explanation about how the tests have been
done and the problems found.
The first to do with the PID design was to check the laser’s cooler and the Thermistor
worked properly. It was done with the Thorlabs’ TEC and the results were coherent. Once
this test was performed, the next step was to reproduce the results found with the
temperature controller with a controlled current from the power supply to ensure the
behaviour is the same. When it is ensured is time to do the same test with the DMX
MosFet to check if there is something different, and there was where problems became.
To warm up the laser the behaviour was as expected and there were not problems. But
when trying to cool the laser the readings from the Thermistor gave strange values. In the
results section are the final figures from the last tests performed.
First the problem seems to be the formula to calculate the temperature. To check the
measurer it was performed a test without the laser putting in the site of the Thermistor a
known resistor which should give negative temperature and it worked properly.
After that, the other test carried out was to ensure the DMX MosFet receiver didn’t
provoke a strange behaviour in the readings. To do that the system was checked using 2
Arduino UNO boards. The first one was only to read the temperature and the other one to
manage the DMX MosFet and its output values. The results of this test were exactly the
same as were in the tests with only one board, then the library used didn’t affect the
Serial communication.
33
5.
Results
Here can be found the results for the different sub-systems designed and the analysis of
the different tests performed with the systems.
5.1.
Laser protection
The first important result is a simple hardware and easy to implement laser protection. It
has been integrated in a 28-pin plate easily work with the laser plinth used during the
project. But it is important to notice that this protection is useful to all DFB lasers. In the
next figure the final integration with the plinth could be seen.
Fig. 19 Laser protection integrated in the plinth
Moreover, it has been designed a software protection which only needs the testing of the
auxiliary circuit designed to adapt it to the Arduino UNO board. This software protection
can be taken as model to design other protections as a maximum voltage protection to a
point in the circuit to protect, for example, the cooler.
5.2.
Software results
From the software part has not been achieved a finished package which can be seen as
a result but there are interesting findings to be mentioned.
First of all an effective and powerful Arduino-MATLAB communication has been achieved.
It is important because it provides freedom to compute much interesting and complex
data in a computer and finally manage whatever through an Arduino board. The Serial
communication is the most complex to be established but is quicker and has more power
through the use of headers developed in the project.
Next, using the communication explained before, there has been partially developed a
friendly GUI, which can be found in the Appendix. It is ready to integrate the different
parts of the program which have not worked as expected at the end by the final code
which works properly.
Next there are two images from the main windows developed until now for the GUI. The
first one is the Scan Window where the user sets up the parameters in which is going to
be based the scan performed for a tuneable laser. Once the user clicks on START button
the system checks the inputs and, if everything is correct, starts the scan.
34
Fig. 20 Scan Window from the MATLAB GUI
The other main window developed for this GUI is the Tune Window. The idea is that the
user sets up a configuration for the tuneable laser and read at the same time the
behaviour of it. It allows to perform quick tests having clear the currents around the user
wants to work.
Fig. 21 Tune Window from the MATLAB GUI
Moreover, some simpler sketches have been developed to test or design the different
sub-systems. The software laser protection or the temperature measurer could be an
example of this.
35
5.3.
Temperature measurer
A Thermistor based temperature measurer using an Arduino board has been performed.
It has been developed for the laser used in this project but changing the parameters to
compute the temperature it could be used to read the temperature with any kind of
Thermistor. To monitor the current temperature in the Thermistor it could be opened a
Serial monitor in the Arduino IDE or through a MATLAB code developed to catch this
data and plot it in function of time.
5.4.
PID warm up control
With the PID there have been lots of problems. All the problems came trying to cool the
laser through the DMX MosFet Receiver. Then, it has been possible to stabilize the
temperature at a high value than the room temperature. In the figures 24 and 25 are two
examples about it. The first one is maintaining the temperature at 330 Kelvin and the
second one at 310 Kelvin.
Fig. 24 PID acting at 330 Kelvin
Fig. 25 PID acting at 310 Kelvin
With those tests performed, it was time to try if this part of the PID control could work
together with the laser diode. To do that was necessary to see how the laser is warmed
up when feeding the diode. It could be seen in the figure 26. After that, the test was to try
to put the laser at 310 Kelvin while feeding the diode. In the figure 27 there is the result,
the PID is acting until the goal temperature is achieved and then the laser continues
warming slower due the laser diode off heat.
Fig. 26 Laser temperature when feeding diode at 100mA
Fig. 27 Laser temperature when feeding diode at 100mA and
PID acting until 310 Kelvin
36
After that, so many tests have been performed trying to find and solve the problem when
trying to cool using the DMX MosFet. Finally it has been discarded a problem with the
Arduino reading from the analogue input pin when combined with the DMX devices. It has
been discarded a problem with the Tinkerkit’s device output reading the same input
current to the cooler with the next two graphics:
Fig. 28 Laser temperature when cooler current from DMX
MosFet
Fig. 29 Laser temperature when cooler current from power
supply
As a final result, there are some sub-systems which work properly and some of them
have been properly integrated. Moreover, there is a lot of information about the different
tests performed and there are some conclusions about the development followed which
are interesting for future developments. These conclusions are detailed in the
“Conclusions and future development” chapter.
37
6.
Budget
In this part there are detailed the costs of the prototype until the project has ended. As it
is an unfinished prototype the costs are not closed or the final ones. When the project will
be finished, then should be performed a viability analysis.
6.1.
Project costs
Next there is a table with the costs of all the devices used during the project. It is
important to notice that in the costs are not included some devices which have been used
to test and will not be in the final system. An example of this could be the laser used to
perform the tests or the power supply used during the project.
Item#
Name
Type
Description
Arduino board, UNO
model
Cost
20€
01 Arduino UNO
Hardware
02 MATLAB License
Software
Student’s license
69€
03 DMX Master Shield
Hardware
Shield for the Arduino
board
20€
04 DMX MosFet Receiver
Hardware
4-mosfet device
46€
05 Electronic Components
Hardware
Cables, Diodes, Resistors
15€
06 Personal
Time
Hours dedicated
2880€*
07 Consultants
Time
Hours dedicated by
supervisor
700€**
TOTAL
3750€
Table 10 Project costs
* Next is detailed the personal cost calculation based on the hours dedicated to the
project by the student:
20 weeks * 18hours/week * 8€/hour = 2880€
** In this part the supervisor advices and hours spent have been budgeted approximately
38
7.
Conclusions and future development:
There are some interesting conclusions extracted from this project which are explained
next.
The first conclusion and which has more impact during the project is that the DMX
MosFet Receiver has not become the desired device. This system was chosen to solve
the problems providing the need currents to control a laser which any Arduino board
could provide. But the reality has been that this caused more problems than solved
delaying important parts of the project and finally provoking an unfinished work. The
solution proposed for future developments is to catch a MosFet transistor and
characterize it to be controlled from the Arduino board providing the base voltage to
control the laser’s sub-systems as the DMX is supposed to do. Once it is controlled and
tested, Arduino sells plates easy to integrate with the different boards to weld the
necessary components being easy to build a customized shield.
Another important conclusion is the powerful of the Arduino-MATLAB communication
viewed during the project. The level of communication achieved during the project is
important for future developments to try to fulfill the main goal of control a more complex
laser as a tuneable one. But it is not important only for this project and purpose; its
powerful could be used in many projects which need more compute power or is required
to implement an easy GUI to manage a system easily from the computer. Moreover it is
very useful to collect and save data from sensors connected to an Arduino board and
manage it to find different results.
Then, it is important to notice that the first main goal is not achieved, but is not as far as it
seems. It has not been able to control a laser from a computer through an Arduino board
but when the problem with cooling the laser is solved there will be a PID which only had
to be fine tuned for cooling to control a simple laser. With this consolidated, it is going to
be easy to continue performing the necessary tests to control a tuneable laser and finally
finish developing the GUI which is self-developed.
Finally, as a main conclusion, it could be said that the project has not resulted as
expected but there are some encouraging results which have to be taken into account to
keep working on the project. The first goal for this project is very interesting and useful
and it is important to keep working despite the difficulties to achieve it.
39
8.
Bibliography:
[1] V. M. Polo. “Contribution to the dynamic tuning of tunable laser sources for
modulation and optical packet routing in WDM and access networks”, Department of
Signal Theory and Communications, UPC, Spain, 2006
[2] E. Tous. “Diseño y puesta en marcha de un banco de medidas de caracterización de
diodos láser semiconductores”, UPC, September 2010
[3] Gerard Recktenwald. “Temperature measurement with a Thermistor and an Arduino”,
July 2010.
[4] V. Chausse, J. Medina, A. Miguel, B. Molas, J. Sendra, A. Vidal. “Làser de
femtosegons en forma de 8 basat en EFDA i controlat per Arduino”. UPC.
[5] “Sistemas Eléctronicos de Control 1011a”. UPC, 2011
[6] http://allaboutee.com/2011/07/04/how-to-send-data-from-matlab-to-your-arduino/
[7] http://playground.arduino.cc/Interfacing/Matlab
[8] http://playground.arduino.cc/DMX/DMXShield
[9] https://felixmaocho.wordpress.com/2013/08/05/arduino-manejo-de-interrupciones/
[10] http://es.mathworks.com/help/control/ref/pid.html
[11] https://code.google.com/p/tinkerit/wiki/DmxSimple
[12] http://es.mathworks.com/help/control/ug/control-system-modeling-with-modelobjects.html
[13] http://en.wikipedia.org/wiki/Steinhart%E2%80%93Hart_equation
[14] http://en.wikipedia.org/wiki/Ziegler%E2%80%93Nichols_method
[15] http://en.wikipedia.org/wiki/PID_controller#Overview_of_methods
[16] https://github.com/TinkerKit/DmxMaster
[17] http://stackoverflow.com/questions/15229349/control-simulink-from-m-file
[18] http://es.mathworks.com/hardware-support/arduino-matlab.html
[19] http://es.mathworks.com/hardware-support/arduino-matlab.html
[20] http://arduino.cc/en/Reference/AttachInterrupt
[21] http://arduino.cc/en/pmwiki.php?n=Reference/AnalogReference
[22] http://playground.arduino.cc/Main/PcInt
[23] http://es.mathworks.com/help/matlab/ref/errordlg.html
[24] http://arduino.stackexchange.com/questions/140/how-can-i-communicate-fromarduino-to-matlab
[25] http://forum.arduino.cc/index.php?topic=45519.0
[26] https://github.com/TinkerKit/DmxMaster/blob/master/examples/FadeUp/FadeUp.ino
[27] http://store.arduino.cc/product/T040060
[28] http://arduino.cc/en/Main/arduinoBoardDue
40
[29] http://hyperphysics.phy-astr.gsu.edu/hbasees/electronic/opampvar6.html
[30] http://forum.arduino.cc/index.php?topic=165542.0
[31] http://www.robotshop.com/media/files/pdf/arduino-tinker-it-dmx-manual.pdf
[32] http://es.mathworks.com/pricing-licensing/
[33] http://playground.arduino.cc/Learning/DMX
41
Appendices:
Next there is a list with a little explanation about the files can be found in the .zip folder
attached to the thesis.
1. OSC-LDPM-C-052C [PDF]: contains the JDS Uniphase laser’s datasheet. This is
the laser used during the project tests.
2. LM14S2-Manual [PDF]: contains the Thorlabs’ laser plinth datasheet.
3. DmxMaster-master [Arduino Lib]: Arduino library to control easily a DMX MosFet
Receiver.
4. PID_implem [MATLAB code]: code developed with the PID control to work with
the Arduino file “PID”.
5. Temperature_measurement [MATLAB code]: code developed to measure the
temperature in the laser. It works with the Arduino files “PID” or “TempMeasure”.
6. FirstWindow [MATLAB GUI]: .fig and .m code which contains the first window of
the MATLAB GUI developed.
7. ScanWindow [MATLAB GUI]: .fig and .m code self-developed which contains the
window to put the variables on which the scan is going to be done and the code to
do that scanning.
8. TuneWindow [MATLAB GUI]: .fig and .m code self-developed which contains the
window to put the variables on which the laser should be tuned and the code to do
that tuning.
9. LaserProtector [Arduino code]: code with the interruption to stop the laser currents
when a bad connection is performed.
10. TempMeasure [Arduino code]: code with the temperature computation and Serial
print of it.
11. PID [Arduino code]: code to read the temperature and receive DMX MosFet
values to set up from the MATLAB PID_implem.m code.
12. Connection [Arduino code]: self-developed code to work with the MATLAB GUI to
control a tunable laser from the computer.
42
Glossary
DFB – Distributed Feedback Laser
DMX – DMX512: Digital MultipleX
GUI – Graphical User Interface
IDE – Integrated Development Environment
MATLAB – MATrix LABoratory
MosFet - Metal-oxide-semiconductor Field-effect transistor
PID – Proportional-Integral-Derivative
TEC – Thermoelectric Controller
43
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertisement