Ardx eg-spar-web-rev10

We’re a plucky little design company focusing on producing
“delightfully fun open source products”
To check out what we are up to
http://www.oomlout.com
A Few Words
ABOUT THIS KIT
The overall goal of this kit is fun. Beyond this, the aim is to get
you comfortable using a wide range of electronic components
through small, simple and easy circuits. The focus is to get each
circuit working then giving you the tools to figure out why. If you
encounter any problems, want to ask a question, or would like to
know more about any part, extra help is only an e-mail away help@oomlout.com.
ABOUT .: OOMLOUT :.
ABOUT PROBLEMS
We strive to deliver the highest level of quality in each and every thing we produce. If you ever find an
ambiguous instruction, a missing piece, or would just like to ask a question, we’ll try our best to help out.
help@oomlout.com
(we like hearing about problems it helps us improve future versions)
All of the projects at SparkFun and .:oomlout:. are open source. What does this mean? It means
everything involved in making this kit, be it this guide, 3D models, or code is available for free
download. But it goes further, you're also free to reproduce and modify any of this material, then
distribute it for yourself. The catch? Quite simple, it is released under a Creative Commons (By -
Share Alike) license. This means you must credit .:oomlout:. in your design and share your
developments in a similar manner. Why? We grew up learning and playing with open source
software and the experience was good fun, we think it would be lovely if a similar experience was
possible with physical things.
More details on the Creative Commons CC (By - Share Alike) License can be found at
http://ardx.org/CCLI
ABOUT OPEN SOURCE HARDWARE
ABOUT SPARKFUN
SparkFun is an energetic young company seeking to make electronics fun, accessible,
and approachable to everyone - from kids in elementary school to PhD-toting engineers.
http://www.sparkfun.com/
Thanks For Choosing .:oomlout:.
and SparkFun

01
TBCN
table of contents.: WHERE TO FIND EVERYTHING :.
Before We Start
{ASEM} Assembling the Pieces 02
{INST} Installing the Software 03
{PROG} A Small Programming Primer 04
{ELEC} A Small Electronics Primer 06
The Circuits
{CIRC01} Getting Started - (Blinking LED) 08
{CIRC02} 8 LED Fun - (Multiple LEDs) 10
{CIRC03} Spin Motor Spin - (Transistor and Motor) 12
{CIRC04} A Single Servo - (Servos) 14
{CIRC05} 8 More LEDs - (74HC595 Shift Register) 16
{CIRC06} Music - (Piezo Elements) 18
{CIRC07} Button Pressing - (Pushbuttons) 20
{CIRC08} Twisting - (Potentiometers) 22
{CIRC09} Light - (Photo Resistors) 24
{CIRC10} Temperature - (TMP36 Temperature Sensor) 26
{CIRC11} Larger Loads - (Relays) 28
{CIRC12} Colorful Light - (RGB LED) 30
{CIRC13} Measuring Bends - (Flex Sensor) 32
{CIRC14} Fancy Sensing - (Soft Potentiometer) 34

02
01 ASEM
assembling the
pieces
Breadboard
x1
Arduino
x1
Arduino Holder
x1
.: PUTTING IT TOGETHER :.
.: For an introduction to what an Arduino is, visit :.
.: http://ardx.org/INTR :.

Vista, Seven
Step 5: Add new Hardware
Skip searching the internet
(click the next box when prompted to do so)
Install from a specific location
(click “Install from a list or specific location (Advanced)")
Choose the Location
Duemilanove Board
c:program filesarduino-00
rrdriversFTDI USB Drivers
Uno Board
rrdrivers
Finished
Run Device Manager
Start > Run > devmgmt.msc
Choose the Arduino
Other Devices > Arduino Uno (Uno)
Update Driver
click “Update Driver”
Select Driver
click “Browse My Computer for Driver Software”
c:program filesarduino-00rrdrivers
Finished
03
02 INST
installing
(software and hardware)
.: NOTE: :.
.: Encountering problems? :.
.: Would like more details? Using Linux? :.
.: http://ardx.org/LINU :.
Step 1: Download the software
Go to
http://arduino.cc/en/Main/Software
download the software for your operating system
Windows XP Mac OSX
Step 2: Unzip the Software
Unzip
arduino-00 -win.zip
Recommended Path
c:Program Files
rr(rr- version #)
Step 3: Shortcut Icon
Open
Right Click
Arduino.exe (send to>Desktop (create shortcut))
rr rr- version #)(
Step 4: Plug In Your Arduino
Plug your Arduino in:
Using the included USB cable, plug your Arduino
board into a free USB port.
Wait for a box to pop up
Step 5: Add new Hardware
.: INSTALLING THE IDE :.
This is the program used to write code for the Arduino. It may
seem a little daunting at first but once you have it installed and
start playing around, its secrets will reveal themselves.
Step 5: Plug In Your Arduino
Plug your Arduino in:
Using the included USB cable, plug your Arduino
board into a free USB port.
Finished
Step 2: Open The .dmg
Open (mount)
arduino-00 -mac.dmgrr(rr- version #)
Step 4: Install Drivers
.:Duemilanove Boards Only:.
Go to
"Arduino" device
FTDI Drivers for Intel Macs ( _ _ ).pkg
(FTDI Drivers for PPC Macs ( _ _ ).pkg
Restart
Double Click & Install
rrrr
rrrr
Step 3: Copy The Application
Go to
"Arduino" (in the devices section of finder)
Move
"Arduino" Application to the
"Applications" folder

// (single line comment)
It is often useful to write notes
to yourself as you go along
about what each line of code
does. To do this type two
forward slashes and everything
until the end of the line will be
ignored by your program.
{ } (curly brackets)
Used to define when a block
of code starts and ends (used
in functions as well as loops).
04
03 PROG
programming
primer
.:A Small Programming Primer:.
The Arduino is programmed in the C language. This is a quick little primer targeted at people
who have a little bit of programing experience and just need a briefing on the idiosyncracies of C
and the Arduino IDE. If you find the concepts a bit daunting, don't worry, you can start going
through the circuits and pick up most of it along the way. For a more in-depth intro, the
Arduino.cc website is a great resource.
STRUCTURE
void setup(){ }
All the code between the two
curly brackets will be run once
when your Arduino program
first runs.
Each Arduino program
(often called a sketch) has
two required functions
(also called routines).
void loop(){ }
This function is run after setup
has finished. After it has run
once it will be run again, and
again, until power is removed.
SYNTAX
; (semicolon)
Each line of code must be
ended with a semicolon (a
missing semicolon is often
the reason for a program
refusing to compile).
One of the slightly
frustrating elements of C is
its formatting requirements
(this also makes it very
powerful). If you remember
the following you should be
alright.
/* */(multi line comment)
If you have a lot to say you can
span several lines as a
comment. Everything between
these two symbols will be
ignored in your program.
A program is nothing more
than instructions to move
numbers around in an
intelligent way. Variables are
used to do the moving.
long (long)
Used when an integer is not
large enough. Takes 4 bytes (32
bits) of RAM and has a range
between -2,147,483,648 and
2,147,483,647.
int (integer)
The main workhorse, stores a
number in 2 bytes (16 bits).
Has no decimal places and will
store a value between -32,768
and 32,767.
boolean (boolean)
A simple True or False
variable. Useful
because it only
uses one bit of
RAM.
char (character)
Stores one character using the
ASCII code (ie 'A' = 65). Uses
one byte (8 bits) of RAM. The
Arduino handles strings as an
array of char’s.
float (float)
Used for floating point math
(decimals). Takes 4 bytes (32
bits) of RAM and has a range
between -3.4028235E+38
and 3.4028235E+38.
ARDUINO PROGRAMMING IN BRIEF
VARIABLES

05
03 PROG
programming
primer
MATH OPERATORS
= (assignment) makes something equal to something else (eg. x
= 10 * 2 (x now equals 20))
% (modulo) gives the remainder when one number is divided by
another (ex. 12 % 10 (gives 2))
+ (addition)
- (subtraction)
* (multiplication)
/ (division)
Operators used for
manipulating numbers.
(they work like simple
math).
COMPARISON OPERATORS
== (equal to) (eg. 12 == 10 is FALSE or 12 == 12 is TRUE)
!= (not equal to) (eg. 12 != 10 is TRUE or 12 != 12 is FALSE)
< (less than) (eg. 12 < 10 is FALSE or 12 < 12 is FALSE or 12 < 14 is TRUE)
> (greater than) (eg. 12 > 10 is TRUE or 12 > 12 is FALSE or 12 > 14 is
FALSE)
Operators used for
logical comparison.
CONTROL STRUCTURE
if(condition){ }
else if( condition ){ }
else { }
This will execute the code between
the curly brackets if the condition
is true, and if not it will test the
else if condition if that is also
false the else code will execute.
Programs are reliant on
controlling what runs
next, here are the basic
control elements (there
are many more online).
for(int i = 0; i <
#repeats; i++){ }
Used when you would like to
repeat a chunk of code a number
of times (can count up i++ or
down i-- or use any variable)
DIGITAL
digitalWrite(pin, value);
Once a pin is set as an OUTPUT,
it can be set either HIGH (pulled
to +5 volts) or LOW (pulled to
ground).
pinMode(pin, mode);
Used to set a pin's mode, pin
is the pin number you would
like to address 0-19 (analog 0-
5 are 14-19). The mode can
either be INPUT or OUTPUT.
int digitalRead(pin);
Once a pin is set as an INPUT
you can use this to return
whether it is HIGH (pulled to
+5 volts) or LOW (pulled to
ground).
ANALOG
int analogWrite(pin,
value);
Some of the Arduino's pins support
pulse width modulation (3, 5, 6, 9, 10,
11). This turns the pin on and off very
quickly making it act like an analog
output. The value is any number
between 0 (0% duty cycle ~0v) and
255 (100% duty cycle ~5 volts).
The Arduino is a digital
machine but it has the ability
to operate in the analog
realm (through tricks).
Here's how to deal with
things that aren't digital.
int analogRead(pin);
When the analog input pins are set
to input you can read their voltage.
A value between 0 (for 0
volts) and 1024 (for
5 volts) will be
returned.
.:For a full programming reference visit:.
http://ardx.org/PROG

DC Motor What it Does: No. of Leads:
Spins when a current is passed through it. 2
Identifying: Things to watch out for:
This one is easy, it looks like a motor. - Using a transistor or relay that is rated
Usually a cylinder with a shaft coming out for the size of motor you're using.
of one end. More Details:
http://ardx.org/MOTO
Hobby Servo What it Does: No. of Leads:
Takes a timed pulse and converts it into 3
an angular position of the output shaft. Things to watch out for:
Identifying: - The plug is not polarized so make sure
A plastic box with 3 wires coming out one it is plugged in the right way.
side and a shaft with a plastic horn out More Details:
the top. http://ardx.org/SERV
06
04 ELEC
electronics
primer
.:A Small Electronics Primer:.
ELECTRONICS IN BRIEF
No previous electronic experience is required to have fun with this kit. Here are a few details
about each component to make identifying, and perhaps understanding them, a bit easier. If
at any point you are worried about how a component is used or why it's not working the
internet offers a treasure trove of advice, or we can be contacted at help@oomlout.com
COMPONENT DETAILS
LED
(Light Emitting Diode)
What it Does: No. of Leads:
Emits light when a small current is 2 (one longer, this one connects to positive)
passed through it. (only in one direction) Things to watch out for:
Identifying: - Will only work in one direction
Looks like a mini light bulb. - Requires a current limiting resistor
More Details:
http://ardx.org/LED
Resistors What it Does: No. of Leads:
Restricts the amount of current that can 2
flow through a circuit. Things to watch out for:
Identifying: - Easy to grab the wrong value (double
check the colors before using)Cylinder with wires extending from either
More Details:end. The value is displayed using a color
http://ardx.org/RESIcoding system (for details see next page)
Transistor What it Does: No. of Leads:
Uses a small current to switch or amplify a 3 (Base, Collector, Emitter)
much larger current. Things to watch out for:
Identifying: - Plugging in the right way round (also a
current limiting resistor is often needed on the base pin)Comes in many different packages but you
More Details:can read the part number off the package.
http://ardx.org/TRAN(P2N2222AG in this kit and find a datasheet online)
Diode What it Does: No. of Leads:
The electronic equivalent of a one way 2
valve. Allowing current to flow in one Things to watch out for:
direction but not the other. - Will only work in one direction (current will
flow if end with the line is connected to ground)Identifying:
More Details:Usually a cylinder with wires extending from
http://ardx.org/DIODeither end. (and an off center line indicating polarity)

07
04 ELEC
electronics
primer
Piezo Element
What it Does:
A pulse of current will cause it to click. A No. of Leads:
stream of pulses will cause it to emit a 2
tone. Things to watch out for:
Identifying: - Difficult to misuse.
In this kit it comes in a little black barrel, More Details:
but sometimes they are just a gold disc. http://ardx.org/PIEZ
Potentiometer
Produces a variable resistance dependant 3
on the angular position of the shaft. Things to watch out for:
Identifying: - Accidentally buying logarithmic scale.
They can be packaged in many different More Details:
form factors, look for a dial to identify. http://ardx.org/POTE
IC (Integrated Circuit)
Packages any range of complicated 2 - 100s (in this kit there is one with 3 (TMP36) and
one with 16 (74HC595)electronics inside an easy to use package.
Things to watch out for:Identifying:
- Proper orientation. (look for marks showing pin 1)The part ID is written on the outside of the
More Details:package. (this sometimes requires a lot of
http://ardx.org/ICIClight or a magnifying glass to read).
Photo Resistor
Produces a variable resistance dependant 2
on the amount of incident light. Things to watch out for:
Identifying: - Remember it needs to be in a voltage
Usually a little disk with a clear top and a divider before it provides a useful input.
curvy line underneath. More Details:
http://ardx.org/PHOT
Pushbutton What it Does: No. of Leads:
Completes a circuit when it is pressed. 4
Identifying: Things to watch out for:
A little square with leads out the bottom - these are almost square so can be
and a button on the top. inserted 90 degrees off angle.
More Details:
http://ardx.org/BUTT
0 - Black 5 - Green 20% - none
1 - Brown 6 - Blue 10% - silver
2 - Red 7 - Purple 5% - gold
3 - Orange 8 - Grey
4 - Yellow 9 - White
first digit
second digit
# of zeros
tolerance
Examples:
green-blue-brown - 560 ohms
red-red-red - 2 200 ohms (2.2k)
brown-black-orange - 10 000 ohms (10k)
RESISTOR COLOR CODE LEAD CLIPPING
Some components in this kit come with very long wire
leads. To make them more compatible with a breadboard
a couple of changes are required.
LEDs:
Clip the leads so the long lead is ~10mm (3/8”) long and
the short one is ~7mm (9/32”).
Resistors:
Bend the leads down so they are 90 degrees to the
cylinder. Then snip them so they are ~6mm
(1/4”) long.
Other Components:
Other components may need clipping.
Use your discretion when doing so.
COMPONENT DETAILS (CONT.)

Arduino
pin 13
LED
(light emitting diode)
resistor (330ohm)
(orange-orange-brown)
gnd
(ground) (-)
08
CIRC-01
WHAT WE’RE DOING:
.:Getting Started:.
.:(Blinking LED):.
LEDs (light emitting diodes) are used in all sorts of clever things
which is why we have included them in this kit. We will start off
with something very simple, turning one on and off, repeatedly,
producing a pleasant blinking effect. To get started, grab the parts
listed below, pin the layout sheet to your breadboard and then plug
everything in. Once the circuit is assembled you'll need to upload the program. To do this plug the
Arduino board into your USB port. Then select the proper port in Tools > Serial Port > (the
comm port of your Arduino). Next upload the program by going to File > Upload to I/O
Board (ctrl+U). Finally, bask in the glory and possibility that controlling lights offers.
If you are having trouble uploading, a full trouble shooting guide can be found here: http://ardx.org/TRBL
Wire
5mm Yellow LED
x1
330 Ohm Resistor
Orange-Orange-Brown
x1
2 Pin Header
x4
CIRC-01
Breadboard Sheet
x1
Parts:
.:download:.
breadboard layout sheet
http://ardx.org/BBLS01S
.:view:.
assembly video
http://ardx.org/VIDE01
The Internet
longer lead
+
THE CIRCUIT:
Schematic

NOT WORKING? (3 things to try)
CODE (no need to type everything in just click)
09
CIRC-01
File > 1.Basic > Blink
(example from the great arduino.cc site, check it out for other ideas)
Examples >
/* Blink
* Turns on an LED on for one second, then off for one second,
* repeatedly.
* Created 1 June 2005 By David Cuartielles
* http://arduino.cc/en/Tutorial/Blink
* based on an orginal by H. Barragan for the Wiring i/o board
*/
int ledPin = 13; // LED connected to digital pin 13
// The setup() method runs once, when the sketch starts
void setup() { // initialize the digital pin as an output:
pinMode(ledPin, OUTPUT); }
// the loop() method runs over and over again,
// as long as the Arduino has power
void loop() {
digitalWrite(ledPin, HIGH); // set the LED on
delay(1000); // wait for a second
digitalWrite(ledPin, LOW); // set the LED off
delay(1000); // wait for a second
}
More details, where to buy more parts, where to ask more questions:
http://ardx.org/CIRC01
LED Not Lighting Up?
LEDs will only work in one
direction. Try taking it out and
twisting it 180 degrees.
(no need to worry, installing it
backwards does no permanent
harm).
Changing the pin: Control the brightness:
The LED is connected to pin 13 but we can use any of Along with digital (on/off) control the Arduino can control
the Arduino’s pins. To change it take the wire plugged some pins in an analog (brightness) fashion. (more details on
into pin 13 and move it to a pin of your choice (from 0- this in later circuits). To play around with it.
13) (you can also use analog 0-5, analog 0 is 14...) Change the LED to pin 9: (also change the wire)
ledPin = 13; -> int ledPin = 9;
Then in the code change the line:
int ledPin = 13; -> int ledPin = newpin; Replace the code inside the { }'s of loop() with this:
analogWrite(ledPin, new number);Then upload the sketch: (ctrl-u)
Change the blink time: (new number) = any number between 0 and 255.
Unhappy with one second on one second off? 0 = off, 255 = on, in between = different brightness
Fading:In the code change the lines:
digitalWrite(ledPin, HIGH); We will use another included example program. To open go to
delay(time on); //(seconds * 1000)
File > Examples > 3.Analog > Fading
digitalWrite(ledPin, LOW);
Then upload to your board and watch as the LED fades in anddelay(time off); //(seconds * 1000)
then out.
Still No Success?
A broken circuit is no fun, send
us an e-mail and we will get
back to you as soon as we can.
help@oomlout.com
Program Not Uploading
This happens sometimes,
the most likely cause is a
confused serial port, you
can change this in
tools>serial port>
MAKING IT BETTER
MORE, MORE, MORE:

Wire
10
CIRC-02
.:8 LED Fun:.
.:Multiple LEDs:.
We have caused one LED to blink, now it's time to up the
stakes. Lets connect eight. We'll also have an opportunity to
stretch the Arduino a bit by creating various lighting
sequences. This circuit is also a nice setup to experiment with
writing your own programs and getting a feel for how the Arduino works.
Along with controlling the LEDs we start looking into a few simple programming methods to
keep your programs small.
for() loops - used when you want to run a piece of code several times.
arrays[] - used to make managing variables easier (it's a group of variables).
5mm Yellow LED
x8
330 Ohm Resistor
Orange-Orange-Brown
x8
2 Pin Header
x4
CIRC-02
Breadboard Sheet
x1
.:download:.
.:view:.
assembly video
LED
resistor
330ohm
gnd
pin 3pin 2 pin 4 pin 5
LED
resistor
330ohm
gnd
pin 7pin 6 pin 8 pin 9
WHAT WE’RE DOING:
The Internet
THE CIRCUIT:
Schematic
Parts:

MAKING IT BETTER
MORE, MORE, MORE:
Operating out of sequence
With eight wires it's easy to cross
a couple. Double check that the
first LED is plugged into pin 2 and
each pin there after.
11
CIRC-02
Download the Code from ( http://ardx.org/CODE02 )
(and then copy the text and paste it into an empty Arduino Sketch)
Some LEDs Fail to Light
It is easy to insert an LED
backwards. Check the LEDs
that aren't working and ensure
they the right way around.
Switching to loops: Extra animations:
Tired of this animation? Then try the other twoIn the loop() function there are 4 lines. The last
sample animations. Uncomment their lines and uploadthree all start with a '//'. This means the line is
the program to your board and enjoy the new lighttreated as a comment (not run). To switch the
animations. (delete the slashes in front of row 3 and then 4)program to use loops change the void loop()
code to:
Testing out your own animations://oneAfterAnotherNoLoop();
oneAfterAnotherLoop(); Jump into the included code and start changing
//oneOnAtATime();
things. The main point is to turn an LED on use//inAndOut();
digitalWrite(pinNumber, HIGH); then to turn
Upload the program, and notice that nothing has
it off use digitalWrite(pinNumber, LOW); .changed. You can take a look at the two
functions, each does the same thing, but use Type away, regardless of what you change you won't
different approaches (hint: the second one uses break anything.
a for loop).
Starting Afresh
Its easy to accidentally
misplace a wire without
noticing. Pulling everything out
and starting with a fresh slate
is often easier than trying to
track down the problem.
//LED Pin Variables * will then turn them off
int ledPins[] = {2,3,4,5,6,7,8,9};
//An array to hold the void oneAfterAnotherNoLoop(){
//pin each LED is connected to int delayTime = 100;
//i.e. LED #0 is connected to pin 2 //the time (in milliseconds) to pause
//between LEDs
void setup() digitalWrite(ledPins[0], HIGH); //Turns on LED #0
{ //(connected to pin 2)
for(int i = 0; i < 8; i++){ delay(delayTime); //waits delayTime milliseconds
//this is a loop and will repeat eight times ...
pinMode(ledPins[i],OUTPUT); ...
//we use this to set LED pins to output digitalWrite(ledPins[7], HIGH); //Turns on LED #7
} //(connected to pin 9)
} delay(delayTime); //waits delayTime milliseconds
//Turns Each LED Off
void loop() // run over and over again digitalWrite(ledPins[7], LOW); //Turns off LED #7
{ delay(delayTime); //waits delayTime milliseconds
oneAfterAnotherNoLoop(); ...
//this will turn on each LED one by
//one then turn each oneoff -----more code in the downloadable version------
//oneAfterAnotherLoop();
//this does the same as onAfterAnotherNoLoop
//but with much less typing
//oneOnAtATime();
//inAndOut();
}
/*
* oneAfterAnotherNoLoop() - Will light one then
* delay for delayTime then light the next LED it

12
CIRC-03
.:Spin Motor Spin:.
.:Transistor & Motor:.
The Arduino's pins are great for directly controlling small electric
items like LEDs. However, when dealing with larger items (like a
toy motor or washing machine), an external transistor is required. A
transistor is incredibly useful. It switches a lot of current using a
much smaller current. A transistor has 3 pins. For a negative type (NPN)
transistor, you connect your load to collector and the emitter to ground. Then when a small current
flows from base to the emitter, a current will flow through the transistor and your motor will spin
(this happens when we set our Arduino pin HIGH). There are literally thousands of different types of
transistors, allowing every situation to be perfectly matched. We have chosen a P2N2222AG a rather
common general purpose transistor. The important factors in our case are that its maximum voltage
(40v) and its maximum current (200 milliamp) are both high enough for our toy motor (full details
can be found on its datasheet http://ardx.org/2222).
(The 1N4001 diode is acting as a flyback diode for details on why its there visit: http://ardx.org/4001)
Wire
Transistor
P2N2222AG (TO92)
x1
10k Ohm Resistor
Brown-Black-Orange
x1
2 Pin Header
x4
Toy Motor
x1
Arduino
pin 9
resistor
(10kohm)
gnd
(ground) (-)
Collector Emitter
Base
Motor
+5 volts
Transistor
P2N2222AG
The transistor will have
P2N2222AG printed on it
(some variations will have
different pin assignments!)
Diode
(1N4001)
x1
Diode
.:download:.
.:view:.
assembly video
.:NOTE: if your arduino is resetting you need to install the optional capacitor:.
WHAT WE’RE DOING:
THE CIRCUIT:
Schematic
Parts:
The Internet
CIRC-03
Breadboard Sheet
x1

Still No Luck?
If you sourced your own
motor, double check that it will
work with 5 volts and that it
does not draw too much
power.
13
CIRC-03
Motor Not Spinning?
If you sourced your own
transistor, double check with
the data sheet that the pinout
is compatible with a
P2N2222AG
(many are reversed).
Controlling speed: In the loop() section change it to this
We played with the Arduino's ability to control the // motorOnThenOff();
motorOnThenOffWithSpeed();brightness of an LED earlier now we will use the same
// motorAcceleration();feature to control the speed of our motor. The Arduino
Then upload the program. You can change the speeds by
does this using something called Pulse Width
changing the variables onSpeed and offSpeed.
Modulation (PWM). This relies on the Arduino's ability to
operate really, really fast. Rather than directly Accelerating and decelerating:
controlling the voltage coming from the pin the Arduino Why stop at two speeds, why not accelerate and decelerate
will switch the pin on and off very quickly. In the the motor. To do this simply change the loop() code to read
// motorOnThenOff();computer world this is going from 0 to 5 volts many
// motorOnThenOffWithSpeed();times a second, but in the human world we see it as a
motorAcceleration();
voltage. For example if the Arduino is PWM'ing at 50%
we see the light dimmed 50% because our eyes are not Then upload the program and watch as your motor slowly
quick enough to see it flashing on and off. The same accelerates up to full speed then slows down again. If you
feature works with transistors. Don't believe me? Try it would like to change the speed of acceleration change the
out. variable delayTime (larger means a longer acceleration time).
Still Not Working?
Sometimes the Arduino board
will disconnect from the
computer. Try un-plugging and
then re-plugging it into your
USB port.
(then simply copy the text and paste it into an empty Arduino Sketch)
int motorPin = 9; //pin the motor is connected to
void setup() //runs once void motorOnThenOffWithSpeed(){
{ int onSpeed = 200;// a number between
pinMode(motorPin, OUTPUT); //0 (stopped) and 255 (full speed)
} int onTime = 2500;
int offSpeed = 50;// a number between
void loop() // run over and over again //0 (stopped) and 255 (full speed)
{ int offTime = 1000;
motorOnThenOff(); analogWrite(motorPin, onSpeed);
//motorOnThenOffWithSpeed(); // turns the motor On
//motorAcceleration(); delay(onTime); // waits for onTime milliseconds
} analogWrite(motorPin, offSpeed);
// turns the motor Off
/* delay(offTime); // waits for offTime milliseconds
* motorOnThenOff() - turns motor on then off }
* (notice this code is identical to the code we
void motorAcceleration(){used for
int delayTime = 50; //time between each speed step* the blinking LED)
for(int i = 0; i < 256; i++){*/
//goes through each speed from 0 to 255void motorOnThenOff(){
analogWrite(motorPin, i); //sets the new speedint onTime = 2500; //on time
delay(delayTime);// waits for delayTime millisecondsint offTime = 1000; //off time
}digitalWrite(motorPin, HIGH);
for(int i = 255; i >= 0; i--){// turns the motor On
//goes through each speed from 255 to 0delay(onTime); // waits for onTime milliseconds
analogWrite(motorPin, i); //sets the new speeddigitalWrite(motorPin, LOW);
delay(delayTime);//waits for delayTime milliseconds// turns the motor Off
}delay(offTime);// waits for offTime milliseconds
}}
MAKING IT BETTER
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WHAT WE’RE DOING:
Parts:
The Internet
THE CIRCUIT:
Schematic
14
CIRC-04
.:A Single Servo:.
.:Servos:.
Spinning a motor is good fun but when it comes to projects
where motion control is required they tend to leave us
wanting more. The answer? Hobby servos. They are mass
produced, widely available and cost anything from a couple of
dollars to hundreds. Inside is a small gearbox (to make the movement more powerful) and
some electronics (to make it easier to control). A standard servo is positionable from 0 to
180 degrees. Positioning is controlled through a timed pulse, between 1.25 milliseconds (0
degrees) and 1.75 milliseconds (180 degrees) (1.5 milliseconds for 90 degrees). Timing
varies between manufacturer. If the pulse is sent every 25-50 milliseconds the servo will run
smoothly. One of the great features of the Arduino is it has a software library that allows
you to control two servos (connected to pin 9 or 10) using a single line of code.
Wire
3 Pin Header
x1
Mini Servo
x1
2 Pin Header
x4
Arduino
pin 9
gnd
(ground) (-)
gnd
(black)
signal
(white)
+5v
(red)
Mini Servo
+5 volts
(5V)
.:download:.
.:view:.
assembly video
CIRC-04
Breadboard Sheet
x1

Still Not Working
A mistake we made a time or
two was simply forgetting to
connect the power (red and
brown wires) to +5 volts and
ground.
15
CIRC-04
File > Examples > Servo > Sweep
(example from the great arduino.cc site, check it out for other great ideas)
Servo Not Twisting?
Even with colored wires it is
still shockingly easy to plug a
servo in backwards. This might
be the case.
Potentiometer control:
void loop() {
We have yet to experiment with inputs but if you would like int pulseTime = 2100; //(the number of microseconds
//to pause for (1500 90 degrees
to read ahead, there is an example program File > Servo > // 900 0 degrees 2100 180 degrees)
digitalWrite(servoPin, HIGH);Knob. This uses a potentiometer (CIRC08) to control the
delayMicroseconds(pulseTime);
digitalWrite(servoPin, LOW);servo. You can find instructions online here:
delay(25);
http://ardx.org/KNOB }
Great ideas:Self timing:
Servos can be used to do all sorts of great things, here are a few ofWhile it is easy to control a servo using the Arduino's included
our favorites.library sometimes it is fun to figure out how to program
something yourself. Try it. We're controlling the pulse directly
Xmas Hit Counter
so you could use this method to control servos on any of the http://ardx.org/XMAS
Arduino's 20 available pins (you need to highly optimize this
code before doing that). Open Source Robotic Arm (uses a servo controller as well as the Arduino)
http://ardx.org/RARM
int servoPin = 9;
void setup(){ Servo Walker
pinMode(servoPin,OUTPUT);
http://ardx.org/SEWA}
// Sweep
// by BARRAGAN <http://barraganstudio.com>
#include <Servo.h>
Servo myservo; // create servo object to control a servo
int pos = 0; // variable to store the servo position
void setup() {
myservo.attach(9); // attaches the servo on pin 9 to the servo object
}
void loop() {
for(pos = 0; pos < 180; pos += 1) // goes from 0 degrees to 180 degrees
{ // in steps of 1 degree
myservo.write(pos); // tell servo to go to position in variable 'pos'
delay(15); // waits 15ms for the servo to reach the position
}
for(pos = 180; pos>=1; pos-=1) // goes from 180 degrees to 0 degrees
{
myservo.write(pos); // tell servo to go to position in variable 'pos'
delay(15); // waits 15ms for the servo to reach the position
}
}
Fits and Starts
If the servo begins moving then
twitches, and there's a flashing
light on your Arduino board, the
power supply you are using is
not quite up to the challenge.
Using a fresh battery instead of
USB should solve this problem.
MAKING IT BETTER
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There is a half moon
cutout, this goes at the top
WHAT WE’RE DOING:
Parts:
The Internet
THE CIRCUIT:
Schematic
16
CIRC-05 .:8 More LEDs:.
.:74HC595 Shift Register:.
Time to start playing with chips, or integrated circuits (ICs) as they like to
be called. The external packaging of a chip can be very deceptive. For
example, the chip on the Arduino board (a microcontroller) and the one we
will use in this circuit (a shift register) look very similar but are in fact rather
different. The price of the ATMega chip on the Arduino board is a few dollars
while the 74HC595 is a couple dozen cents. It's a good introductory chip, and once you're comfortable playing
around with it and its datasheet (available online http://ardx.org/74HC595 ) the world of chips will be your oyster.
The shift register (also called a serial to parallel converter), will give you an additional 8 outputs (to control LEDs
and the like) using only three Arduino pins. They can also be linked together to give you a nearly unlimited
number of outputs using the same four pins. To use it you “clock in” the data and then lock it in (latch it). To do
this you set the data pin to either HIGH or LOW, pulse the clock, then set the data pin again and pulse the clock
repeating until you have shifted out 8 bits of data. Then you pulse the latch and the 8 bits are transferred to the
shift registers pins. It sounds complicated but is really simple once you get the hang of it.
(for a more in depth look at how a shift register works visit: http://ardx.org/SHIF)
Wire
Shift Register
74HC595
x1
330 Ohm Resistor
Orange-Orange-Brown
x8
2 Pin Header
x4
CIRC-05
Breadboard Sheet
x1
Red LED
x8
LED
resistor
(330ohm)
gnd
(ground)(-)
pin
4
pin
3
pin
2
0
1
2
3
4
5
6
7
data
clock
latch
+5V
gnd
74HC595
+5 volts
.:download:.
.:view:.
assembly video

Not Quite Working
Sorry to sound like a broken
record but it is probably
something as simple as a
crossed wire.
17
CIRC-05
The Arduino’s power
LED goes out
This happened to us a couple
of times, it happens when the
chip is inserted backwards. If
you fix it quickly nothing will
break.
//between LED updatesDoing it the hard way:
for(int i = 0; i < 8; i++){An Arduino makes rather complex actions very easy, shifting out data is
changeLED(i,ON);
one of these cases. However one of the nice features of an Arduino is delay(delayTime);
}you can make things as easy or difficult as you like. Let's try an
for(int i = 0; i < 8; i++){
example of this. In your loop switch the line: changeLED(i,OFF);
delay(delayTime);updateLEDs(i) -> updateLEDsLong(i);
}Upload the program and notice nothing has changed. If you look at the
Uploading this will cause the lights to light up one after another and then off
code you can see how we are communicating with the chip one bit at a
in a similar manner. Check the code and wikipedia to see how it works, or
time. (for more details http://ardx.org/SPI ).
shoot us an e-mail if you have questions.
Controlling individual LEDs:
More animations:Time to start controlling the LEDs in a similar method as we did in
Now things get more interesting. If you look back to the code from CIRC02 (8
CIRC02. As the eight LED states are stored in one byte (an 8 bit value)
LED Fun) you see we change the LEDs using digitalWrite(led, state), this is
for details on how this works try http://ardx.org/BINA. An Arduino is
the same format as the routine we wrote changeLED(led, state). You can use
very good at manipulating bits and there are an entire set of operators
the animations you wrote for CIRC02 by copying the code into this sketch and
that help us out. Details on bitwise maths ( http://ardx.org/BITW ).
changing all the digitalWrite()'s to changeLED()'s. Powerful? Very. (you'll also
need to change a few other things but follow the compile errors and it worksOur implementation.
Replace the loop() code with itself out).
int delayTime = 100; //the number of milliseconds
//to delay
Frustration?
Shoot us an e-mail, this circuit
is both simple and complex at
the same time. We want to
hear about problems you have
so we can address them in
future editions.
help@oomlout.com
(copy the text and paste it into an empty Arduino Sketch)
//Pin Definitions
//The 74HC595 uses a serial communication
//link which has three pins
digitalWrite(latch, LOW);int data = 2;
int clock = 3;
//Pulls the chips latch lowint latch = 4;
shiftOut(data, clock, MSBFIRST, value);
//Shifts out 8 bits to the shift registervoid setup() //runs once
{
pinMode(data, OUTPUT);
digitalWrite(latch, HIGH);pinMode(clock, OUTPUT);
//Pulls the latch high displaying the datapinMode(latch, OUTPUT); }
}
void loop() // run over and over again
---------- More Code Online ----------{
int delayTime = 100;
//delay between LED updates
for(int i = 0; i < 256; i++){
updateLEDs(i);
delay(delayTime); }
}
/*
* updateLEDs() - sends the LED states set
* in value to the 74HC595 sequence
*/
void updateLEDs(int value){
MAKING IT BETTER
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WHAT WE’RE DOING:
Parts:
The Internet
THE CIRCUIT:
Schematic
Arduino
pin 9
gnd
(ground) (-)
Piezo
Element
18
CIRC-06
.:Music:.
.:Piezo Elements:.
To this point we have controlled light, motion, and
electrons. Let's tackle sound next. But sound is an
analog phenomena, how will our digital Arduino cope?
We will once again rely on its incredible speed which will let it
mimic analog behavior. To do this, we will attach a piezo element to one of the
Arduino's digital pins. A piezo element makes a clicking sound each time it is pulsed
with current. If we pulse it at the right frequency (for example 440 times a second to
make the note middle A) these clicks will run together to produce notes. Let's get to
experimenting with it and get your Arduino playing "Twinkle Twinkle Little Star".
Wire
Piezo Element
x1
2 Pin Header
x4
CIRC-06
Breadboard Sheet
x1
.:download:.
.:view:.
assembly video

MAKING IT BETTER
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19
CIRC-06
Can't Think While the
Melody is Playing?
Just pull up the piezo element
whilst you think, upload your
program then plug it back in.
No Sound
Given the size and shape of
the piezo element it is easy to
miss the right holes on the
breadboard. Try double
checking its placement.
char names[] = { 'c', 'd', 'e', 'f', 'g', 'a', 'b',Playing with the speed:
'C' };The timing for each note is calculated based on int tones[] = { 1915, 1700, 1519, 1432, 1275, 1136,
variables, as such we can tweak the sound of each note 1014, 956 };
or the timing. To change the speed of the melody you Composing your own melodies:
need to change only one line. The program is pre-set to play 'Twinkle Twinkle Little Star'
int tempo = 300; ---> int tempo = (new #) however the way it is programmed makes changing the song
Change it to a larger number to slow the melody down,
easy. Each song is defined in one int and two arrays, the int
or a smaller number to speed it up.
length defines the number of notes, the first arrayTuning the notes:
notes[] defines each note, and the second beats[]If you are worried about the notes being a little out of
defines how long each note is played. Some Examples:tune this can be fixed as well. The notes have been
Twinkle Twinkle Little Starcalculated based on a formula in the comment block at int length = 15;
char notes[] = {"ccggaagffeeddc "};the top of the program. But to tune individual notes just
int beats[] = { 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1,
adjust their values in the tones[] array up or down 1, 1, 2, 4 };
Happy Birthday (first line)until they sound right. (each note is matched by its
int length = 13;
name in the names[] (array ie. c = 1915 ) char notes[] = {"ccdcfeccdcgf "};
int beats[] = {1,1,1,1,1,2,1,1,1,1,1,2,4};
Tired of Twinkle Twinkle
Little Star?
The code is written so you can
easily add your own songs,
check out the code below to
get started.
/* Melody
* (cleft) 2005 D. Cuartielles for K3
* digitalWrite(speakerPin,
* This example uses a piezo speaker to play melodies. It sends LOW);
* a square wave of the appropriate frequency to the piezo, delayMicroseconds(tone);
* generating the corresponding tone. }
* }
* The calculation of the tones is made following the
* mathematical operation: void playNote(char note, int duration) {
* char names[] = { 'c', 'd', 'e', 'f', 'g', 'a', 'b', 'C' };
* timeHigh = period / 2 = 1 / (2 * toneFrequency) int tones[] = { 1915, 1700, 1519, 1432, 1275, 1136, 1014, 956
*
};* where the different tones are described as in the table:
// play the tone corresponding to the note name*
for (int i = 0; i < 8; i++) {* note frequency period timeHigh
if (names[i] == note) {* c 261 Hz 3830 1915
playTone(tones[i], duration);* d 294 Hz 3400 1700
}* e 329 Hz 3038 1519
}* f 349 Hz 2864 1432
}* g 392 Hz 2550 1275
* a 440 Hz 2272 1136
void setup() {* b 493 Hz 2028 1014
pinMode(speakerPin, OUTPUT);* C 523 Hz 1912 956
}*
* http://www.arduino.cc/en/Tutorial/Melody
void loop() {*/
for (int i = 0; i < length; i++) {
if (notes[i] == ' ') {int speakerPin = 9;
delay(beats[i] * tempo); // restint length = 15; // the number of notes
} else {char notes[] = "ccggaagffeeddc "; // a space represents a rest
playNote(notes[i], beats[i] * tempo);int beats[] = { 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 2, 4 };
}int tempo = 300;
// pause between notes
delay(tempo / 2); }void playTone(int tone, int duration) {
}for (long i = 0; i < duration * 1000L; i += tone * 2) {
digitalWrite(speakerPin, HIGH);
delayMicroseconds(tone);

WHAT WE’RE DOING:
Parts:
The Internet
THE CIRCUIT:
Schematic
20
CIRC-07
.:Button Pressing:.
.:Pushbuttons:.
Up to this point we have focused entirely on outputs, time to
get our Arduino to listen, watch and feel. We'll start with a
simple pushbutton. Wiring up the pushbutton is simple. There is
one component, the pull up resistor, that might seem out of place.
This is included because an Arduino doesn't sense the same way we do (ie button pressed,
button unpressed). Instead it looks at the voltage on the pin and decides whether it is HIGH
or LOW. The button is set up to pull the Arduino's pin LOW when it is pressed, however, when
the button is unpressed the voltage of the pin will float (causing occasional errors). To get the
Arduino to reliably read the pin as HIGH when the button is unpressed, we add the pull up
resistor.
(note: the first example program uses only one of the two buttons)
Wire
Pushbutton
x2
330 Ohm Resistor
Orange-Orange-Brown
x1
2 Pin Header
x4
CIRC-07
Breadboard Sheet
x1
Red LED
x1
10k Ohm Resistor
Brown-Black-Orange
x2
Arduino
pin 13
LED
resistor
(330 ohm)
gnd
(ground) (-)
pin 2
pushbutton
pin 3
+5 volts
Arduino
resistor
(pull-up)
(10k ohm)
.:download:.
.:view:.
assembly video

MAKING IT BETTER
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Light Not Fading
A bit of a silly mistake we
constantly made, when you
switch from simple on off to
fading remember to move the
LED wire from pin 13 to pin 9.
21
CIRC-07
File > Examples > 2.Digital > Button
/*
* Button
* by DojoDave <http://www.0j0.org>
*
* Turns on and off a light emitting diode(LED) connected to digital
* pin 13, when pressing a pushbutton attached to pin 7.
* http://www.arduino.cc/en/Tutorial/Button
*/
int ledPin = 13; // choose the pin for the LED
int inputPin = 2; // choose the input pin (for a pushbutton)
int val = 0; // variable for reading the pin status
void setup() {
pinMode(ledPin, OUTPUT); // declare LED as output
pinMode(inputPin, INPUT); // declare pushbutton as input
}
void loop(){
val = digitalRead(inputPin); // read input value
if (val == HIGH) { // check if the input is HIGH
digitalWrite(ledPin, LOW); // turn LED OFF
} else {
digitalWrite(ledPin, HIGH); // turn LED ON
}
}
Light Not Turning On
The pushbutton is square
and because of this it is easy
to put it in the wrong way.
Give it a 90 degree twist and
see if it starts working.
On button off button: Fading up and down:
The initial example may be a little underwhelming (ie. I Lets use the buttons to control an analog signal. To do this
don't really need an Arduino to do this), let’s make it a you will need to change the wire connecting the LED from pin
little more complicated. One button will turn the LED on 13 to pin 9, also change this in code.
int ledPin = 13; ----> int ledPin = 9;
the other will turn the LED off. Change the code to:
Next change the loop() code to read.int ledPin = 13; // choose the pin for the LED
int inputPin1 = 3; // button 1 int value = 0;
int inputPin2 = 2; // button 2 void loop(){
if (digitalRead(inputPin1) == LOW) { value--; }
void setup() { else if (digitalRead(inputPin2) == LOW) { value++; }
pinMode(ledPin, OUTPUT); // declare LED as output value = constrain(value, 0, 255);
pinMode(inputPin1, INPUT); // make button 1 an input analogWrite(ledPin, value);
pinMode(inputPin2, INPUT); // make button 2 an input delay(10);
} }
void loop(){
Changing fade speed:if (digitalRead(inputPin1) == LOW) {
digitalWrite(ledPin, LOW); // turn LED OFF
If you would like the LED to fade faster or slower, there is only} else if (digitalRead(inputPin2) == LOW) {
digitalWrite(ledPin, HIGH); // turn LED ON one line of code that needs changing;}
delay(10); ----> delay(new #);}
To fade faster make the number smaller, slower requires aUpload the program to your board, and start toggling the
larger number.LED on and off.
Underwhelmed?
No worries these circuits are all
super stripped down to make
playing with the components
easy, but once you throw them
together the sky is the limit.

WHAT WE’RE DOING:
The Internet
THE CIRCUIT:
Schematic
.:Twisting:.
.:Potentiometers:.
Along with the digital pins, the Arduino also has 6
pins which can be used for analog input. These
inputs take a voltage (from 0 to 5 volts) and convert
it to a digital number between 0 (0 volts) and 1024 (5 volts) (10 bits of
resolution). A very useful device that exploits these inputs is a potentiometer
(also called a variable resistor). When it is connected with 5 volts across its
outer pins the middle pin will read some value between 0 and 5 volts
dependent on the angle to which it is turned (ie. 2.5 volts in the middle). We
can then use the returned values as a variable in our program.
WirePotentiometer
10k ohm
x1
330 Ohm Resistor
Orange-Orange-Brown
x1
2 Pin Header
x4
CIRC-08
Breadboard Sheet
x1
Yellow LED
x1
Arduino
pin 13
LED
(light
emitting
diode)
resistor (330ohm)
(orange-orange-brown)
gnd
(ground) (-)
Potentiometer
+5 volts
Arduino
analog
pin 0
.:download:.
.:view:.
assembly video
22
CIRC-08
Parts:

Not Working
Make sure you haven't
accidentally connected the
potentiometer's wiper to digital
pin 2 rather than analog pin 2.
(the row of pins beneath the
power pins)
File > Examples > 3.Analog > AnalogInput
/* Analog Input
* Demonstrates analog input by reading an analog sensor on analog
* pin 0 and turning on and off a light emitting diode(LED) connected to
digital pin 13.
* The amount of time the LED will be on and off depends on the value obtained by
* analogRead().
* Created by David Cuartielles
* Modified 16 Jun 2009
* By Tom Igoe
* http://arduino.cc/en/Tutorial/AnalogInput
*/
int sensorPin = 0; // select the input pin for the potentiometer
int ledPin = 13; // select the pin for the LED
int sensorValue = 0; // variable to store the value coming from the sensor
void setup() {
pinMode(ledPin, OUTPUT); //declare the ledPin as an OUTPUT:
}
void loop() {
sensorValue = analogRead(sensorPin);// read the value from the sensor:
digitalWrite(ledPin, HIGH); // turn the ledPin on
delay(sensorValue); // stop the program for <sensorValue> milliseconds:
digitalWrite(ledPin, LOW); // turn the ledPin off:
delay(sensorValue); // stop the program for for <sensorValue> milliseconds:
}
Sporadically Working
This is most likely due to a
slightly dodgy connection with
the potentiometer's pins. This
can usually be conquered by
taping the potentiometer down.
Threshold switching: Then change the loop code to.
void loop() {Sometimes you will want to switch an output when a value
int value = analogRead(potPin) / 4;
exceeds a certain threshold. To do this with a analogWrite(ledPin, value);
}
potentiometer change the loop() code to.
Upload the code and watch as your LED fades in relation to
void loop() {
your potentiometer spinning. (Note: the reason we divide theint threshold = 512;
if(analogRead(sensorPin) > threshold){ value by 4 is the analogRead() function returns a value from 0
digitalWrite(ledPin, HIGH);}
to 1024 (10 bits), and analogWrite() takes a value from 0 toelse{ digitalWrite(ledPin, LOW);}
} 255 (8 bits) )
This will cause the LED to turn on when the value is above Controlling a servo:
512 (about halfway), you can adjust the sensitivity by This is a really neat example and brings a couple of circuits
changing the threshold value. together. Wire up the servo like you did in CIRC-04, then open
Fading: the example program Knob (File > Examples > Servo >
Let’s control the brightness of an LED directly from the
Knob ), then change one line of code.
potentiometer. To do this we need to first change the pin int potpin = 0; ----> int potpin = 2;
Upload to your Arduino and then watch as the servo shaft turnsthe LED is connected to. Move the wire from pin 13 to pin
as you turn the potentiometer.9 and change one line in the code.
int ledPin = 13; ----> int ledPin = 9;
Still Backward
You can try operating the
circuit upside down.
Sometimes this helps.
23
CIRC-08
MAKING IT BETTER
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24
CIRC-09
.:Light:.
.:Photo Resistors:.
Whilst getting input from a potentiometer can be useful
for human controlled experiments, what do we use
when we want an environmentally controlled
experiment? We use exactly the same principles but instead
of a potentiometer (twist based resistance) we use a photo resistor (light based
resistance). The Arduino cannot directly sense resistance (it senses voltage) so we
set up a voltage divider (http://ardx.org/VODI). The exact voltage at the sensing
pin is calculable, but for our purposes (just sensing relative light) we can
experiment with the values and see what works for us. A low value will occur when
the sensor is well lit while a high value will occur when it is in darkness.
Wire
Photo-Resistor
x1
330 Ohm Resistor
Orange-Orange-Brown
x1
2 Pin Header
x4
CIRC-09
Breadboard Sheet
x1
Yellow LED
x1
10k Ohm Resistor
Brown-Black-Orange
x1
Arduino
pin 13
LED
resistor
(330ohm)
gnd
(ground) (-)
+5 volts
photo
resistor
resistor
(10k ohm)
Arduino
analog
pin 0
.:download:.
.:view:.
assembly video
WHAT WE’RE DOING:
Parts:
The Internet
THE CIRCUIT:
Schematic

MAKING IT BETTER
MORE, MORE, MORE:
Still not quite working?
You may be in a room which is
either too bright or dark. Try
turning the lights on or off to
see if this helps. Or if you have
a flashlight near by give that a
try.
It Isn't Responding to
Changes in Light.
Given that the spacing of the
wires on the photo-resistor is
not standard, it is easy to
misplace it. Double check its in
the right place.
LED Remains Dark
This is a mistake we continue
to make time and time again,
if only they could make an LED
that worked both ways. Pull it
up and give it a twist.
Reverse the response: Light controlled servo:
Perhaps you would like the opposite response. Don't Let's use our newly found light sensing skills to control a
worry we can easily reverse this response just change: servo (and at the same time engage in a little bit of Arduino
analogWrite(ledPin, lightLevel); ----> code hacking). Wire up a servo connected to pin 9 (like in
analogWrite(ledPin, 255 - lightLevel);
CIRC-04). Then open the Knob example program (the same
Upload and watch the response change: one we used in CIRC-08) File > Examples > Servo >
Knob. Upload the code to your board and watch as it works
Night light:
unmodified.Rather than controlling the brightness of the LED in
Using the full range of your servo:
response to light, let's instead turn it on or off based on
You'll notice that the servo will only operate over a limited
a threshold value. Change the loop() code with.
portion of its range. This is because with the voltage dividingvoid loop(){
int threshold = 300; circuit we use the voltage on analog pin 0 will not range fromif(analogRead(lightPin) > threshold){
digitalWrite(ledPin, HIGH); 0 to 5 volts but instead between two lesser values (these
}else{
values will change based on your setup). To fix this play withdigitalWrite(ledPin, LOW);
}
the val = map(val, 0, 1023, 0, 179); line. For hints on what to}
do visit http://arduino.cc/en/Reference/Map .
/*
* A simple programme that will change the //output
* intensity of an LED based on the amount of }
* light incident on the photo resistor. /*
* * loop() - this function will start after setup
*/ * finishes and then repeat
*/
//PhotoResistor Pin void loop()
int lightPin = 0; //the analog pin the {
//photoresistor is int lightLevel = analogRead(lightPin); //Read the
//connected to // lightlevel
//the photoresistor is not lightLevel = map(lightLevel, 0, 900, 0, 255);
//calibrated to any units so //adjust the value 0 to 900 to 0 to 255
//this is simply a raw sensor lightLevel = constrain(lightLevel, 0, 255);
//value (relative light) //make sure the value is betwween 0 and 255
//LED Pin analogWrite(ledPin, lightLevel); //write the value
int ledPin = 9;//the pin the LED is connected to }
//we are controlling brightness so
//we use one of the PWM (pulse
//width modulation pins)
void setup()
{
pinMode(ledPin, OUTPUT); //sets the led pin to
25
CIRC-09

26
CIRC-10 .:Temperature:.
.:TMP36 Precision Temperature Sensor:.
What's the next phenomena we will measure with our
Arduino? Temperature. To do this we'll use a rather
complicated IC (integrated circuit) hidden in a package
identical to our P2N2222AG transistors. It has three pin's,
ground, signal and +5 volts, and is easy to use. It outputs 10
millivolts per degree centigrade on the signal pin (to allow measuring temperatures below
freezing there is a 500 mV offset eg. 25 C = 750 mV, 0 ). To convert this from the
digital value to degrees, we will use some of the Arduino's math abilities. Then to display it
we'll use one of the IDE's rather powerful features, the debug window. We'll output the value
over a serial connection to display on the screen. Let's get to it.
One extra note, this circuit uses the Arduino IDE's serial monitor. To open this, first upload the
program then click the button which looks like a square with an antennae.
The TMP36 Datasheet:
http://ardx.org/TMP36
° ° C = 500mV
Wire
TMP36
Temperature Sensor
x1
2 Pin Header
x4
CIRC-10
Breadboard Sheet
x1
+5 volts
TMP36
(precision
temperature
sensor)
gnd
(ground) (-)
Arduino
analog
pin 0
gnd
+5v
signal
the chip will have
TMP36 printed
on it
.:download:.
.:view:.
assembly video
WHAT WE’RE DOING:
Parts:
The Internet
THE CIRCUIT:
Schematic

Gibberish is Displayed
This happens because the serial
monitor is receiving data at a
different speed than expected.
To fix this, click the pull-down
box that reads "*** baud" and
change it to "9600 baud".
27
CIRC-10
Nothing Seems to Happen
This program has no outward
indication it is working. To see
the results you must open the
Arduino IDE's serial monitor.
(instructions on previous page)
Outputting voltage: do this first revert to the original code then change:
Serial.println(temperature);This is a simple matter of changing one line. Our
---->
Serial.print(temperature);sensor outputs 10mv per degree centigrade so to get
Serial.println(" degrees centigrade");
voltage we simply display the result of getVoltage().
The change to the first line means when we next output it
delete the line temperature = (temperature - .5) * 100;
will appear on the same line, then we add the informative
Outputting degrees Fahrenheit: text and a new line.
Again this is a simple change requiring only math. To Changing the serial speed:
If you ever wish to output a lot of data over the serial linego degrees C ----> degrees F we use the formula:
( F = C * 1.8) + 32 ) time is of the essence. We are currently transmitting at 9600
add the line baud but much faster speeds are possible. To change this
temperature =
(((temperature - .5) * 100)*1.8) + 32; change the line:
Serial.begin(9600); ----> Serial.begin(115200);before Serial.println(temperature);
Upload the sketch turn on the serial monitor, then change
More informative output: the speed from 9600 baud to 115200 baud in the pull down
Let's add a message to the serial output to make what
menu. You are now transmitting data 12 times faster.
is appearing in the Serial Monitor more informative. To
Temperature Value is
Unchanging
Try pinching the sensor with
your fingers to heat it up or
pressing a bag of ice against it
to cool it down.
/* --------------------------------------------- void loop()
* | Arduino Experimentation Kit Example Code | // run over and over again
* | CIRC-10 .: Temperature :. | {
* --------------------------------------------- float temperature = getVoltage(temperaturePin);
* //getting the voltage reading from the
* A simple program to output the current temperature //temperature sensor
* to the IDE's debug window
* For more details on this circuit:
temperature = (temperature - .5) * 100;//converting from 10
//TMP36 Pin Variables mv
int temperaturePin = 0;//the analog pin the TMP36's //per degree wit 500 mV offset to
//Vout pin is connected to //degrees ((volatge - 500mV) times
//the resolution is
100)//10 mV / degree centigrade
Serial.println(temperature); //printing the result//(500 mV offset) to make
delay(1000); //waiting a second//negative temperatures an
}
option
/*
void setup() * getVoltage() - returns the voltage on the analog input
{ * defined by pin
Serial.begin(9600); //Start the serial connection */
//with the computer float getVoltage(int pin){
//to view the result open the return (analogRead(pin) * .004882814);//converting from a 0
//serial monitor //to 1024 digital range
//last button beneath the file // to 0 to 5 volts
//bar (looks like a box with an //(each 1 reading equals ~ 5
//antenna)
millivolts}
}
MAKING IT BETTER
MORE, MORE, MORE:

28
CIRC-11
.:Larger Loads:.
.:Relays:.
This next circuit is a bit of a test. We combine what we learned
about using transistors in CIRC03 to control a relay. A relay is
an electrically controlled mechanical switch. Inside the little
plastic box is an electromagnet that, when energized, causes a
switch to trip (often with a very satisfying clicking sound). You can buy relays that vary in size
from a quarter of the size of the one in this kit up to as big as a fridge, each capable of
switching a certain amount of current. They are immensely fun because there is an element of
the physical to them. While all the silicon we've played with to this point is fun sometimes, you
may just want to wire up a hundred switches to control something magnificent. Relays give you
the ability to dream it up then control it with your Arduino. Now to using today's technology to
control the past. (The 1N4001 diode is acting as a flyback diode, for details on why it's there visit: http://ardx.org/4001)
2 Pin Header
x4
CIRC-11
Breadboard Sheet
x1
10k Ohm Resistor
Brown-Black-Orange
x1
330 Ohm Resistor
Orange-Orange-Brown
x2
Red LED
x1
Relay
(SPDT)
x1
Arduino
pin 2
resistor
(10kohm)
gnd
(ground) (-)
Collector Emitter
Base
+5 volts
Transistor
P2N2222AG
Diode
(flyback)
Diode
(1N4001)
x1
the transistor will have
P2N2222AG printed on it
(some variations will have
the pin assignment reversed)
Transistor
P2N2222AG (TO92)
x1
Yellow LED
x1
.:download:.
.:view:.
assembly video
WHAT WE’RE DOING:
Parts:
The Internet
THE CIRCUIT:
Schematic
coil
-
NC
comNO

Watch the Back-EMF Pulse
Replace the diode with an LED. You’ll see it blink each time it “snubs” the coil voltage spike when it turns off.
Controlling a Motor
In CIRC-03 we controlled a motor using a transistor. However if you want to control a larger motor a relay is a good option.
To do this simply remove the red LED, and connect the motor in its place (remember to bypass the 330 Ohm resistor).
MAKING IT BETTER
MORE, MORE, MORE:
No Clicking Sound
The transistor or coil portion of
the circuit isn't quite working.
Check the transistor is plugged
in the right way.
29
CIRC-11
File > 1.Basic > Blink
Examples >
/*
* Blink
*
* The basic Arduino example. Turns on an LED on for one second,
* then off for one second, and so on... We use pin 13 because,
* depending on your Arduino board, it has either a built-in LED
* or a built-in resistor so that you need only an LED.
*
* http://www.arduino.cc/en/Tutorial/Blink
*/
int ledPin = 2; // *********** CHANGE TO PIN 2 ************
void setup() // run once, when the sketch starts
{
pinMode(ledPin, OUTPUT); // sets the digital pin as output
}
void loop() // run over and over again
{
digitalWrite(ledPin, HIGH); // sets the LED on
delay(1000); // waits for a second
digitalWrite(ledPin, LOW); // sets the LED off
delay(1000); // waits for a second
}
Not Quite Working
The included relays are
designed to be soldered rather
than used in a breadboard. As
such you may need to press it
in to ensure it works (and it
may pop out occasionally).
Nothing Happens
The example code uses pin 13
and we have the relay
connected to pin 2. Make sure
you made this change in the
code.

330 Ohm Resistor
Orange-Orange-Brown
x3
2 Pin Header
x4
CIRC-12
Breadboard Sheet
x1
Parts:
.:download:.
http://ardx.org/BBLS12
The Internet
THE CIRCUIT:
Schematic
30
.:Colorful Light:.
.:RGB LEDs:.
When you first started with CIRC01 you were happy just to
get a red LED blinking away. But you're past that now,
right? You want orange, you want teal, you want aubergine!
Fortunately there's a way to shine multiple colors from a single
LED without having to stock up on every shade of the rainbow. To do this we use a RGB
LED. An RGB LED isn't a single LED it's actually three LEDs in one small package: one
Red, one Green and one Blue. When you turn them on their light mixes together and you
get other colors. The color you get is a result of the intensity of the individual red, green
and blue LEDs. We control the intensity with Pulse Width Modulation (PWM) which we've
used before to control LED brightness and motor speed.
WHAT WE’RE DOING:
Wire
5mm RGB LED
x1
resistor
(330ohm)
Arduino
pin 11 pin 10 pin 9
common(gnd)
red
green
blue
gnd
blue
green
red
longest
lead
flat
side
CIRC-12

MAKING IT BETTER
MORE, MORE, MORE:
31
Download the Code from (http://ardx.org/CODE12S)
Seeing Red
The red diode within the RGB LED
may be a bit brighter than the
other two. To make your colors
more balanced, use a higher ohm
resistor. Or adjust in code.
analogWrite(RED_LED_PIN,
redIntensity);
to
redIntensity/3);
http://sparkfun.com/RGB
Looking For More?
(shameless plug)
If you’re looking to do more
why not check out all the
lovely extra bits and bobs
available from
http://www.SparkFun.com
LED Remains Dark or
Shows Incorrect Color
With the four pins of the LED
so close together, it’s
sometimes easy to misplace
one. Try double checking each
pin is where it should be.
/*Cycles through the colors of a RGB LED*/
// Cycle color from green through to blue
// LED leads connected to PWM pins for (blueIntensity = 0;
const int RED_LED_PIN = 9; blueIntensity <= 255;
const int GREEN_LED_PIN = 10; blueIntensity+=5) {
const int BLUE_LED_PIN = 11; greenIntensity = 255-blueIntensity;
analogWrite(BLUE_LED_PIN, blueIntensity);// Used to store the current intensity level
analogWrite(GREEN_LED_PIN, greenIntensity);int redIntensity = 0;
delay(DISPLAY_TIME);int greenIntensity = 0;
}int blueIntensity = 0;
// Cycle cycle from blue through to red// Length of time showing each color
for (redIntensity = 0;const int DISPLAY_TIME = 100; // milliseconds
redIntensity <= 255;
redIntensity+=5) {void setup() {
blueIntensity = 255-redIntensity;// No setup required.
} analogWrite(RED_LED_PIN, redIntensity);
analogWrite(BLUE_LED_PIN, blueIntensity);
void loop() { delay(DISPLAY_TIME);
// Cycle color from red through to green }
for (greenIntensity = 0; }
greenIntensity <= 255;
greenIntensity+=5) { ---------- More Code Online ----------
redIntensity = 255-greenIntensity;
analogWrite(GREEN_LED_PIN, greenIntensity);
analogWrite(RED_LED_PIN, redIntensity);
delay(DISPLAY_TIME);
}
Using HTML-style color codes A land of diffusion
If you're familiar with making web pages you One disadvantage of using a RGB LED made up of
might prefer to specify colors using "hex triplets" three separate LEDs to generate our colors is that
like you do when you use HTML and CSS. A hex sometimes it's possible to see the color of the
triplet specifies a color using a series of letters individual lights. One way to workaround this is to find
and numbers like `#FF0000` for red or a way to make the light more diffuse (or scattered) so
`#800080` for purple. You can learn more about that the individual colors mix together better. The LED
how this works on Wikipedia supplied with your kit is diffused rather than clear to
(http://ardx.org/HEXCOL) and find a list of help improve the effectiveness of the color mixing. If
colors with their associated hex triplets so you the light still isn't diffuse enough you can try putting
don't need to work it out yourself. the LED behind some paper or acrylic; or inside a ping
pong ball or polystyrene ball.Download the code from:
http://ardx.org/RGBMB
CIRC-12

10k Ohm Resistor
Brown-Black-Orange
x1
2 Pin Header
x4
CIRC-13
Breadboard Sheet
x1
Parts:
.:download:.
The Internet
THE CIRCUIT:
32
.:Measuring Bends:.
.:Flex Sensor:.
In life it's important to be flexible. But what do you do
if you want to measure how flexible an object is? You
use a flex sensor. A flex sensor uses carbon on a strip
of plastic to act like a variable resistor or potentiometer
(CIRC-08) but instead of changing the resistance by turning a knob you change it
by flexing (bending) the component. We use a "voltage divider" again (CIRC-08 &
09) to detect this change in resistance. The sensor bends in one direction and the
more it bends the higher the resistance gets--it has a range from about 10K ohm
to 35K ohm. In this circuit we will use the amount of bend of the flex sensor to
control the position of a servo.
WHAT WE’RE DOING:
Wire
Flex Sensor
x1
CIRC-13
3 Pin Header
x1
Mini Servo
x1
Schematic
+5 volts
flex
sensor
resistor
(10k ohm)
analog
pin 0
pin 9
gnd
(ground) (-)
gnd
(black)
signal
(white)
+5v
(red)
Mini Servo

MAKING IT BETTER
MORE, MORE, MORE:
33
http://sparkfun.com/
Servo Moves Once
You may need to modify the
range of values in the call to
the map() function
(details in the making it better
section below)
// Based on }
// File > Examples > Servo > Knob
// Controlling a servo position using a void loop()
// potentiometer (variable resistor) {
// by Michal Rinott // val = analogRead(potpin);// reads the value
// of the potentiometer<http://people.interaction-
//(value between 0 and 1023)
ivrea.it/m.rinott> Serial.println(val);
val = map(val, 50, 300, 0, 179);
#include <Servo.h> // scale it to use it with the servo
// (value between 0 and 180)
Servo myservo; // create servo object to myservo.write(val); // sets the servo
// control a servo // according to the
// scaled value
int potpin = 0; // analog pin used to
// connect the delay(15); // waits for the servo
// potentiometer // to get there
int val; // variable to read the }
//value from the analog pin
void setup()
{
Serial.begin(9600);
myservo.attach(9);// attaches the servo
// servo on pin 9 to the servo object
Calibrating the Range 300) value with the fully bent value.
While the servo is now moving chances are its Applications
range isn’t quite perfect. To adjust the range we
With sensors the real fun comes in using them in neat
need to change the values in the map() function.
and un-expected ways here are a few of our favorite
map(value, fromLow, fromHigh,
flex sensor applications.toLow, toHigh)
One Player Rock Paper Scissors GloveFor full details on how it works:
A glove that lets you play RPS against yourself.http://ardx.org/MAP
http://ardx.org/RPS
To calibrate our sensor we can use the debug
Electronic Plant Bracewindow (like in CIRC-11). Open the debug
Monitor if your plant is bending towards light
window then replace the fromLow value (default
and fix it.
50) with the value displayed when the sensor is
http://ardg.org/BRACE
un bent. Then replace the fromHigh (default
CIRC-13
Servo Not Twisting?
Even with colored wires it is
still shockingly easy to plug a
servo in backwards. This might
be the case.
Servo Not Moving As
Expected
The sensor is only designed
to work in one direction. Try
flexing it the other way.
(where the striped side faces
in on a convex curve)

330 Ohm Resistor
Orange-Orange-Brown
x3
2 Pin Header
x4
CIRC-14
Breadboard Sheet
x1
Parts:
.:download:.
The Internet
THE CIRCUIT:
Schematic
34
.:Fancy Sensing:.
.:Soft Potentiometer:.
A "soft pot" (short for "soft potentiometer") is like a
regular potentiometer of the style seen in CIRC-08
except, it's flat, really thin, flexible and doesn't have a
knob. A potentiometer is also known as a "variable
resistor" and for a soft pot the resistance it provides is determined by where
pressure is applied. Pressure can be applied with your finger, a stylus or a hard
plastic "wiper". By pressing down on various parts of the strip, the resistance
varies from 100 to 10k Ohms allowing you to calculate the relative position on the
strip. You can use this to track movement on the softpot or discrete "button style"
presses. In this circuit we’ll use it to control the color of an RGB LED.
WHAT WE’RE DOING:
Wire
5mm RGB LED
x1
CIRC-14
Soft Potentiometer
x1
resistor
(330ohm)
Arduino
pin 11 pin 10 pin 9
gnd
blue
green
red
longest
lead
+5 volts
Arduino
analog
pin 0
wiper
V+
gnd
soft-pot

MAKING IT BETTER
MORE, MORE, MORE:
35
Seeing Red
The red diode within the RGB LED
may be a bit brighter than the
other two. To make your colors
more balanced, use a higher ohm
resistor. Or adjust in code.
redValue);
to
redValue/3);
http://sparkfun.com/
Bizarre Results
The most likely cause of this is
if you’re pressing the
potentiometer in more than
one position. This is normal
and can actually be used to
create some neat results.
LED Remains Dark or
Shows Incorrect Color
With the four pins of the LED
so close together, it’s
sometimes easy to misplace
one. Try double checking each
pin is where it should be.
// CIRC-14 Example Code int greenValue = constrain(
// Will fade an RGB LED from Red-Green-Blue map(sensorValue, 0, 512, 0, 255),0,255)-
// in relation to the soft pot value constrain(
map(sensorValue, 512, 1023, 0, 255),0,255);
// LED leads connected to PWM pins //calculate the green value (0-255
const int RED_LED_PIN = 9; //Red LED Pin //over 0-512 & 255-0 over 512-1023)
const int GREEN_LED_PIN = 10; //Green LED Pin int blueValue = constrain(
const int BLUE_LED_PIN = 11; //Blue LED Pin map(sensorValue, 512, 1023, 0, 255),0,255);
//calculate the blue value 0-255 over
//512-1023
void setup() {
//no need for any code here // Display the requested color
} analogWrite(RED_LED_PIN, redValue);
analogWrite(GREEN_LED_PIN, greenValue);
void loop() { analogWrite(BLUE_LED_PIN, blueValue);
int sensorValue = analogRead(0); }
//read the Soft Pot
int redValue = constrain(
map(sensorValue, 0, 512, 255, 0),0,255);
//calculate the red Value (255-0
//over the range 0-512)
HSB Color (Hue, Saturation & Brightness) Now when you use the soft pot you’ll notice a much
Our RGB LED displays colors using RGB color cleaner and fuller fade from red through to violet.
codes. However this is often not the easiest way
Faux Buttons
of working with colors (as noted by the less than Because of the way the soft pot works it can also be
reader friendly code above). A much more used to make custom buttons. To do this you define a
intuitive system is HSB. range of values corresponding to a discrete button.
Full Details:
Use the code snippet below and the debug window to
http://ardx.org/HSB
determine desired values.
To convert from RGB to HSB all that is required is
if(analogRead(0) > minValue &&some slightly complicated math. For an example
analogRead(0) < maxValue){
program visit: buttonAction()
http://ardx.org/CODE14MB }
based on www.kasperkamperman.com's original Then cover the soft pot with a drawn/printed button
code: http://ardx.org/KASP pattern
CIRC-14

36
NOTE
notes
.:Notes:.
.:Room for a Few Notes:.

37
NOTE
notes
.:Notes:.
.:Room for a Few Notes:.

This work is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported License
To view a copy of this license visit
http://creativecommons.org/licenses/by-sa/3.0/
Or send a letter to:
Creative Commons, 171 Second Street, Suite 300, San Francisco, California 94105, USA.

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