Programming with the Arduino: open-source hardware in an ... · The Arduino (UNO R3) Atmel ATmega328 8-bit microcontroller, 16MHz 14 digital I/O pins 6 analogue input pins (10-bit)

School of Physics & AstronomySchool of Physics & Astronomy

Programming with the Arduino: open-source

hardware in an introductory programming laboratory

Paul [email protected]


Motivation

�Prior to 2013, no formal programming for St Andrews physics students until 3rd

year�Earlier programming experience thought

desirable�Aims to introduce 3 key concepts:

loops, decision making and functions�Available time: 7.5 hours over three

weeks


Context: computing in the St Andrews physics degree

� 2nd year: some Python in modules taught by School of Maths

� 2nd year: 7.5 hours of C in Arduino lab (all physics/astrophysics students)

� 3rd year: Computational Physics module,10 credits, Mathematica (all physics/astrophysics students)

� 3rd year: Computational Astrophysics, 15 credits, Fortran

� 3rd year: 15 hours of LabView as part of physics lab module


The Arduino (UNO R3)Atmel ATmega3288-bit microcontroller, 16MHz

14 digital I/O pins

6 analogue input pins (10-bit)

5V supply via USB, 7-12V external, on-board 5V and 3.3V regulators

HUGE community of users

£21.66 inc VAT (Farnell)Many other variants available (including versions with more grunt)


The Arduino IDE

� Java based, so platform agnostic*

� Programs written in C/C++

� Hardware functions abstracted away from hardware pretty well

� Core function set pretty minimal, but easy to learn

*Disclaimer: I haven’t tried it on Linux


The Arduino IDE

� All Arduino programs MUST contain TWO functions, called ‘setup’ and ‘loop’

� When program compiled, IDE adds these and other code to generate a ‘proper’ C++ file, then compiles that


Why use Arduino?

�Replaced part of an electronics practical, so wanted to retain practical feel

�Very easy to interface to�Built-in analogue to digital converter�Digital input/output�Libraries and examples for most things

you can think of (not always a good thing)


Good things about the Arduino

�Programmed in C/C++�Low barrier to entry (cost, availability,

computer requirements)�Exercises have a good practical feel:

easy to write programs that interact with outside world


Less good things about the Arduino

� (Deliberately) not designed for teaching programming

�Programmed in C/C++�Compiler error messages less than

transparent�Development environment can be restrictive�Occasional driver issues�No console (although serial monitor works out

ok)


Development

�Spring 2012: final-year student project devising trial script (Adam Hollan)

�Single afternoon trial run with 9 volunteers from intended target group

�All student questions to demonstrators recorded

�Spring 2013: final-year student project evaluating first live run (Duncan Downie)


Lab structure

�Three 2.5 hr afternoon sessions�Before starting, students answer pre-lab

questions based on content of lab script


Lab afternoon one

� Introduction to environment� Introduction to syntax�Analogue input: start with a potentiometer

(dull but straightforward), on to thermistor, LDR and analogue accelerometer

�Digital input and output (switches and LEDs)


Lab afternoon two

�Analogue output (using external DAC, with pre-written library functions)

�Decision making (i.e. if and if…else statements)

� Introduction to flowcharts� Loops: for and while �Resistive touchscreen sensor (with pre-

written library functions)


Lab afternoon three

�Write and use program to measure the IV characteristic of a diode

�Develops the automation of an experiment students will already have done by hand

�Designed to link in with previous work and make use of experience of first two afternoons

�Also shows utility of automation of measurement tasks


Lab supporting materials

�Script entirely self-contained�Include text of sample programs so that

students can read in advance�Extensively footnoted to point out

parallels and differences with standard C


Lab supporting materials

� Try hard to separate programming aspect from electronics aspect

� Provide suggested breadboard layouts for exercises: found some students get bogged down in assembling circuits, leaving less time for the main point of the lab


Demonstrator training and support

�Demonstrators work independently through lab few weeks before start

�Deliberate move to develop familiarity�Also uncovers errors in script/libraries

and ensures manageable load for lab time (7.5 hours)

�Typically ~3.5hrs for no C/C++ prior experience


Demonstrator support

�4 demonstrators for ~30 students�Demonstrators encouraged to be pro-

active�More than half required no time outside

scheduled periods�Of those who did, an hour was

adequate


Approx. costs for 40 sets (inc.VAT)

Arduino boards & cables:

£880

Touchscreens: £330

Accelerometers: £330

PCBs: £400

Other components: £400

Most of these one-offs, less than £100 per year


Difficulties

�Mark distribution is poor, and marks generally high (~80%)

�Tension between teaching a skill and having to put a number on the end result

�Lab doesn’t discriminate amongst the most capable students effectively


Evaluation (2013)

�Comprehensive questionnaire�Recruited volunteers to record audio of

their lab experience along with their written text, using LiveScribe pens

�Most surprising sources of difficulty related to experimental technique rather than programming


Student reception (2013 evaluation)

�Overall, pretty positive: they didn’t hate it, and no-one died

�Asked students to respond to a series of questions or statements on a five-point Likert scale


Feedback

How difficult did you find this lab compared to other second year labs?

(N=79)

3.2


Feedback

How enjoyable did you find the Arduino lab?

(N=79)

3.3


Feedback

This lab opened up a whole new area of physics to me

(N=77)

4.2


Feedback

Overall impression:

(N=78)

5.1


Feedback

Overall impression: perceived gain from the lab

(N=78)

5.3


Example applications from elsewhere

10 by 10 temperature sensor array

Eric Ayars, California State University, Chico

(Very instructive blog,http://hacks.ayars.org/)

used with permission



Example applications from elsewhere


Orthopaedic rehab studies using Arduinobased data acquisition systems of accelerometer and goniometer data obtained from the knee

Graham Brooker,AFCR, University of Sydney


Our plans for Arduino

�From spring next year: take-home lab�Give all students a box with necessary

kit�Keep same amount of available contact

time�If successful, consider adding extra

content


Simple demos

Documents

Programming with the Arduino: open-source hardware in an ... · The Arduino (UNO R3) Atmel ATmega328 8-bit microcontroller, 16MHz 14 digital I/O pins 6 analogue input pins (10-bit)