SCIENTIFIC ARDUINO PROGRAMMING - INFN Sezione di Roma

71 Pages·2016·4.46 MB·English

SCIENTIFIC ARDUINO PROGRAMMING
Arduino programming for scientists
A free addendum to "Scienti(cid:12)c Programming"
GIOVANNI ORGANTINI
Sapienza Universita(cid:18) di Roma & INFN{Sez. di Roma
March 4, 2016

Contents
zero Introduction 5
zero.1 What is Arduino? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
zero.2 What this booklet is intended for . . . . . . . . . . . . . . . . . . . . 7
zero.3 How to use this booklet . . . . . . . . . . . . . . . . . . . . . . . . . 7
zero.4 Supporting this work . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
due How Arduino works 9
due.1 Arduino basic architecture . . . . . . . . . . . . . . . . . . . . . . . . 9
due.2 Program development . . . . . . . . . . . . . . . . . . . . . . . . . . 11
due.3 Using Arduino on Linux . . . . . . . . . . . . . . . . . . . . . . . . . 13
tre Arduino basic programming 15
tre.1 The (cid:12)rst Arduino sketch . . . . . . . . . . . . . . . . . . . . . . . . . 15
tre.2 I/O with Arduino . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
tre.3 Showing data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
quattro Program execution control 19
quattro.1 The selection structure . . . . . . . . . . . . . . . . . . . . . . . . . . 19
quattro.2 The iteration structure . . . . . . . . . . . . . . . . . . . . . . . . . . 20
sei Saving data 23
sei.1 Using Serial communications. . . . . . . . . . . . . . . . . . . . . . . 23
sei.2 Connecting to the Internet . . . . . . . . . . . . . . . . . . . . . . . . 27
sei.2.1 Con(cid:12)guring the Ethernet shield . . . . . . . . . . . . . . . . . . . 28
sei.2.2 Using the Ethernet shield to collect data . . . . . . . . . . . . . . 30
sei.3 Using an SD card . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
sette Arduino speci(cid:12)c functions 37
sette.1 Setting up pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
sette.2 Writing and reading digital pins . . . . . . . . . . . . . . . . . . . . . 38
iii
sette.3 timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
sette.4 Analog pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
otto Measuring with Arduino 45
otto.1 Voltages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
otto.2 Distances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
otto.3 Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
otto.4 Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
otto.5 Magnetic (cid:12)eld . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
otto.6 Acceleration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
1
scientific arduino programming { Vers. March 4, 2016
© 2015 Giovanni Organtini, Sapienza Universit(cid:18)a di Roma & INFN{Sez. di Roma
This work is licensed under a Creative Commons Attribution{
NonCommercial{NoDerivs 3.0 Unported License. You can (cid:12)nd all the
details about this license on www.creativecommons.org for details. You
arefreetocopy,distributeandtransmitthiswork.Youmustattributethe
work as a work of Giovanni Organtini ([email protected]),
who does not endorse you or your use of this work. You may not use this
work for commercial purposes. You may not alter, transform, or build upon this work.
You can support the development of this manual by making a donation on PayPal using
the e{mail address [email protected].
This work was partly supported by Farnell Element14 who kindly provided some of the
parts described in the text.
Contacts:
Prof. Giovanni Organtini
Sapienza Universit(cid:18)a di Roma
Dip.to di Fisica
P.le Aldo Moro, 2
00185 ROMA (Italy)
Tel: [phone] Fax: [phone]
e{mail: [email protected]

Technical note
This book has been written using LATEX, an open source, high{quality typesetting ap-
plication. Schematics have been realised using fritzing, an open source application to
draw electronics schemas.
Arduino itself is an open source initiative. We strongly support this kind of projects,
not only because their open nature makes them inexpensive, but mainly because the
open standard guarantee a very high quality of the tools (they can be contributed by
thousandsofdevelopers)andmostlybecausetheyprovideaformidabletoolforlearning.
Weinviteyoutootosupporttheopeninitiativesyouuse:youcandothatinavariety
of ways. You can, for example, donate money to the developers, to recognise their e(cid:11)ort,
or you may prefer to buy products from those who make them available to anyone as
open source projects. That is the case of Arduino, for example. You can certainly (cid:12)nd
ArduinoclonesthatarecheaperthanthoseyoucangetfromtheArduinoo(cid:14)cialstore,or
fromothero(cid:14)cialstoresoflegalArduino{compatibleboards,butsavingfewdollarsdoes
nothelpmuch,infact.Ontheotherhandyoucreateadamagetothosewhoaretryingto
changethestandardbusinessmodelbasedonhidinginformationandpatents.Asyoucan
readontheArduinowebsite,youcandownloadandusetheirreferencedesignsand"you
are free to use and adapt [those designs] for your own needs without asking permission
or paying a fee". We believe this is really a revolutionary paradigm with respect to the
commonly adopted one, that is suitable to increase dramatically both knowledge and
welfare all around the world.
3

Chapter zero
Introduction
This paper is an introduction to Arduino programming for students who learned C on
"Scienti(cid:12)c Programming" by L.M. Barone, E. Marinari, G. Organtini and F. Ricci{
Tersenghi [1], edited by World Scienti(cid:12)c (or its italian counterpart "Programmazione
Scienti(cid:12)ca" edited by Pearson). "Scienti(cid:12)c Programming" is an innovative textbook on
computer programming thought for science students, who does not care about writing
Hello World!onascreen,butareinterestedinusingacomputerasatooltodoscience.
Chapter 0 of "Scienti(cid:12)c Programming" is about how computing and programming
is important for a scientist. Chapter 1 is about information representation (there is no
need for a Chapter uno here, since information is represented exactly in the same way
on Arduino boards).
Oneoftheauthorsof"Scienti(cid:12)cProgramming"(GiovanniOrgantini),startedtoteach
Arduino programming in his course about computing and programming for physicists,
being the Arduino board a great resource for physicists and engineers. As well as in the
case of C++ he wrote these notes in the style of [1], keeping the same chapter structure
andaverysimilarstyle.Inthisbooklet,chaptershavethesamenumberingof[1],except
the numbering is given in italian, as a tribute to the italian origin of the Arduino board,
invented by Massimo Banzi and his colleagues in Ivrea (TO), Italy1. Each chapter uses
notions that can be learned in the corresponding chapter in [1]. In fact, Arduino can be
programmedinC++language,butataverybasiclevelitcanbethoughtasadialectofthe
C language, sharing mostly the same syntax. You can learn some basics of C++ reading
another free addendum to "Scienti(cid:12)c Programming", by the same author, available on
the Scienti(cid:12)c Programming website. However, you can obtain good results just knowing
some C language: the chosen language for "Scienti(cid:12)c Programming". For these reasons,
some chapter number is missing: the corresponding content is exactly the same of [1].
Students wishing to learn some Arduino programming without owning a copy of [1]
shall not be scared: those students should not have too much di(cid:14)culties in learning how
to write programs for Arduino if they are able to write C programs.
1ThenameArduinocomesfromtheirhauntinIvrea:apubcalledafterthenameofanancientking
ofIvreawhosenamewasArduino.
5
6 CHAPTER ZERO. INTRODUCTION
zero.1 What is Arduino?
Arduinoisaninexpensive,commerciallyavailableelectronicboardwithamicrocontroller
and some I/O capabilities. It exists in various versions, that share the same, simple pro-
gramming language. The huge success of Arduino, with respect to other microcontroller
boards, was due to the fact that both hardware and software were released as Open
Source projects: you can read, study and even expand its capabilities both in terms
of software as well as in terms of hardware. All the information are shared under the
Creative Commons Attribution-ShareAlike 3.0 License.
YoucanuseArduinoformanydi(cid:11)erentpurposes:fromteachingtohomeautomation1,
from scienti(cid:12)c purposes to commercially available devices, as well as to have fun (you
can be surprised about the many ways in which people use Arduino). Thanks to its very
simple interface to I/O ports you can control many di(cid:11)erent devices, both digital and
analogical. For example, you can measure voltages using analog inputs or drive a DC
motor using a digital output port. You can as well switch on and o(cid:11) an LED or a relay
usingdigitaloutputportsandtransmit/receivedatato/frommorecomplexdevicessuch
as GSM boards. The job of (at least a large part of) physicists is to measure something:
Arduino is then a very useful tool both to control measuring apparata or as a device
to take measurements by itself (for many purposes it can be accurate enough to replace
professional, and expensive, instruments).
The design of Arduino boards is such that its form factor is (almost) independent on
the Arduino version. The (cid:12)rst Arduino boards used a microcontroller whose chip took
a somewhat large space; nowadays the same chip is available in a much smaller form
factor, however the size and the shape of the Arduino board is still the same (and in
fact there is plenty of free space on it). That choice has one big advantage: third party
manufacturers can easily design, produce and sell boards that extend the functionalities
of any Arduino, and users can easily connect them to it. In fact, those board, called
shields have a set of pins that just plug into the corresponding pins on the Arduino
board and no speci(cid:12)c electrical connection is needed to make them work. You can buy,
forfewbucks,boardsdesignedtoprovideInternetorGSMconnectivity,GPScapabilities,
stepper motor control and much more.
UsingArduino,anyonewithaverybasicknowledgeofsomeelementaryelectronicsis
able to build complex electronic devices e(cid:11)ortlessly: the complexities of the electronics
are translated into software, hence even people not used to work with analog and digital
devicessuchasdiodes,transistors,operationalampli(cid:12)ers,integratedcircuits,logicports,
etc., can realise interesting projects. Tutorials can easily be found on the Internet for
various tasks: given the Open Source nature of the project, people are encouraged to
share their projects with others so anyone can bene(cid:12)t of other’s experience.
1The author, for example, built a device able to switch on and o(cid:11) home appliances remotely just
placingaphonecall.