SparkFun
Inventor ’s Kit
VERSION 4.0a
Your Guide to the SIK
for the SparkFun RedBoard
SparkFun Inventor’s Kit, Version 4.0
WELCOME TO THE
SPARKFUN INVENTOR’S
KIT (SIK) GUIDE.
This is your map for navigating beginning embedded electronics.
This booklet contains all the information you will need to build five
projects encompassing the 16 circuits of the SIK for the SparkFun
RedBoard. At the center of this manual is one core philosophy: that
anyone can (and should) play around with electronics. When you’re
done with this guide, you will have built five great projects and
acquired the know-how to create countless more. Now enough talk
— let’s start something!
For a digital version of this guide with more in-depth information for
each circuit and links explaining relevant terms and concepts, visit:
sparkfun.com/SIKguide
Contents
INTRODUCTION
2
2 The RedBoard Platform
3 Baseplate Assembly
4 RedBoard Anatomy
5 Breadboard Anatomy
6 The Arduino IDE
10 Inventory of Parts
PROJECT 1: LIGHT
12
13 Circuit 1A: Blinking an LED
20 Circuit 1B: Potentiometer
26 Circuit 1C: Photoresistor
31 Circuit 1D: RGB Night-Light
PROJECT 2: SOUND
36
37 Circuit 2A: Buzzer
42 Circuit 2B: Digital Trumpet
47 Circuit 2C: “Simon Says” Game
PROJECT 3: MOTION
53
54 Circuit 3A: Servo Motors
60 Circuit 3B: Distance Sensor
65 Circuit 3C: Motion Alarm
PROJECT 4: DISPLAY
71
72 Circuit 4A: LCD “Hello, World!”
77 Circuit 4B: Temperature Sensor
82 Circuit 4C: “DIY Who Am I?” Game
PROJECT 5: ROBOT
88
89 Circuit 5A: Motor Basics
96 Circuit 5B: Remote-Controlled Robot
102 Circuit 5C: Autonomous Robot
GOING FURTHER
106
1 : intro
The RedBoard Platform
THE DIY REVOLUTION: At SparkFun we believe that an understanding of electronics
is a core literacy that opens up a world of opportunities in the fields of robotics, Internet
of Things (IoT), engineering, fashion, medical industries, environmental sciences,
performing arts and more. This guide is designed to explore the connection between
software and hardware, introducing Arduino code and SparkFun parts as they are
used in the context of building engaging projects. The circuits in this guide progress
in difficulty as new concepts and components are introduced. Completing each circuit
means much more than just “experimenting”; you will walk away with a fun project you
can use — and a sense of accomplishment that is just the beginning of your electronics
journey. At the end of each circuit, you'll find coding challenges that extend your learning
and fuel ongoing innovation.
The SparkFun RedBoard is your
RESET
A COMPUTER FOR THE
PHYSICAL WORLD
7-15V
development platform. At its roots, the
RedBoard is essentially a small, portable
IOREF
push of a button or a reading from a light
5V
sensor) and interpreting that information
GND
LED light or spinning an electric motor).
A1
A2
A3
A4
A5
ON
world of electronics and relating it to the
A0
ISP
comes in; this board is capable of taking the
VIN
ANALOG IN
That’s where the term “physical computing”
GND
POWER
to control various outputs (like blinking an
3.3V
DIGITAL (PWM~)
RESET
START SOMETHING
It is capable of taking inputs (such as the
13
TX
RX
computer, also known as a microcontroller.
SCL
SDA
AREF
GND
13
12
~11
~10
~9
8
7
~6
~5
4
~3
2
TX 1
RX 0
physical world in a real and tangible way.
THE SPARKFUN REDBOARD is one of a multitude of development boards based on
the ATmega328 microprocessor. It has 14 digital input/output pins (six of which can be
PWM outputs), six analog inputs, a 16MHz crystal oscillator, a USB connection, a power
jack, and a reset button. You’ll learn more about each of the RedBoard's features as you
progress through this guide.
2 : intro
Baseplate Assembly
Before you can build circuits, you’ll want to first assemble the breadboard baseplate. This
apparatus makes circuit building easier by keeping the RedBoard microcontroller and the
breadboard connected without the worry of disconnecting or damaging your circuit.
TO BEGIN, collect your parts: the RedBoard,
breadboard, included screwdriver, baseplate and
two baseplate screws.
Your screwdriver has both Phillips and
flatheads. If it is not already in position,
pull the shaft out and switch to the
Phillips head.
PEEL the adhesive backing off the breadboard.
CAREFULLY ALIGN the breadboard over its spot on the baseplate. The text on the
breadboard should face the same direction as the text on the baseplate. Firmly press the
breadboard to the baseplate to adhere it.
ALIGN THE REDBOARD with its spot
on the baseplate. The text on it should
face the same direction as the text on
the breadboard and the baseplate. Using
one of the two included screws, affix the
RedBoard to one of the four stand-off holes
found on the baseplate. The plastic holes
are not threaded, so you will need to apply
pressure as you twist the screwdriver.
Screw the second screw in the stand-off
hole diagonally across from the first. With
that, your baseplate is now assembled.
3 : intro
Anatomy of the SparkFun RedBoard
F
E
B
D
7
~6
~5
4
~3
2
TX 1
RX 0
RESET
SCL
SDA
AREF
GND
13
12
~11
~10
~9
8
H
DIGITAL (PWM~)
13
TX
RX
ON
START SOMETHING
C
G
I
K
A5
A4
A3
A2
A1
ANALOG IN
A0
VIN
GND
GND
POWER
5V
3.3V
IOREF
7-15V
A
RESET
ISP
J
REDBOARD HARDWARE OVERVIEW
A
POWER IN
(BARREL JACK)
B
POWER IN
(USB PORT)
C
LED
(RX: RECEIVING)
Shows when the FTDI chip is receiving data bits from the computer.
D
LED
(TX: TRANSMITTING)
Shows when the FTDI chip is transmitting data bits to the computer.
E
ONBOARD LED
PIN D13
F
PINS AREF,
G R O U N D , D I G I TA L ,
RX, TX, SDA, SCL
G
POWER LED
H
RESET BUTTON
I
ISP HEADER
This is the In-System Programming header. It is used to program the ATMega328
directly. It will not be used in this guide.
J
ANALOG IN,
V O L TA G E I N ,
GROUND, 3.3 AND
5V OUT, RESET
The power bus has pins to power your circuits with various voltages. The analog
inputs allow you to read analog signals.
K
RFU
4 : intro
Can be used with either a 9V or 12V “wall-wart” or a battery pack.
Provides power and communicates with your board
when plugged into your computer via USB.
This LED, connected to digital pin 13, can be controlled
in your program and is great for troubleshooting.
These pins can be used for inputs, outputs, power and ground.
Illuminated when the board is connected to a power source.
A manual reset switch that will restart the RedBoard and your code.
This stands for Reserved for Future Use.
Anatomy of the Breadboard
A breadboard is a circuit-building platform that allows you to
connect multiple components without using a soldering iron.
POWER BUS
H O R I Z O N TA L R O W S
Each side of the breadboard has a pair of
Each series of 5 sockets marked
vertical connections marked – and +
a–e and f–j are connected.
+ POWER: Each + sign runs power
anywhere in the vertical column.
Components connected to a row
will be connected to any other
part inserted in the same row.
– GROUND: Each – sign runs to ground
anywhere in the vertical column.
CENTERLINE
This line divides
the breadboard
in half, restricting
electricity to one
half or the other.
MAKING A
CONNECTION
Most of the
components in this
kit are breadboardfriendly and can be
easily installed and
removed.
5 : intro
The Arduino IDE
IN ORDER TO GET YOUR
REDBOARD UP AND RUNNING,
you'll need to download the newest
version of the Arduino software
from www.arduino.cc (it's free!).
This software, known as the Arduino
IDE (Integrated Development
Environment), will allow you to program the RedBoard to do exactly what you want.
It’s like a word processor for coding. With an internet-capable computer, open up your
favorite browser and type the following URL into the address bar:
DOWNLOAD THE SOFTWARE HERE:
arduino.cc/downloads
1. DOWNLOAD AND INSTALL ARDUINO IDE
Select the installer option appropriate for the operating system you are using. Once
finished downloading, open the file and follow the instructions to install.
2. INSTALL USB DRIVERS
In order for the RedBoard hardware to work with your computer’s operating system,
you will need to install a few drivers. Please go to www.sparkfun.com/FTDI for specific
instructions on how to install the USB drivers onto your computer.
3. CONNECT THE REDBOARD TO A COMPUTER
Use the USB cable provided in the SIK to connect the RedBoard to one of your computer’s
USB inputs.
6 : intro
4. DOWNLOAD AND INSTALL THE SIK CODE
Each of the circuits you will build in the SparkFun Inventor’s Kit has an Arduino
code sketch already written for it. This guide will show you how to manipulate that
code to control your hardware.
DOWNLOAD THE CODE HERE:
sparkfun.com/SIKcode
COPY “SIK GUIDE CODE” INTO “EXAMPLES”
LIBRARY IN ARDUINO FOLDER
Your browser will download the code automatically or ask you if you would like to
download the .zip file. Select “Save File.” Locate the code (usually in your browser’s
“Downloads” folder). You'll need to relocate it to the “Examples” subfolder in your
Arduino IDE installation in order for it to function properly.
Unzip the file “SIK GUIDE CODE.” It should be located in your browser’s “Downloads”
folder. Right-click (or ctrl + click) the zipped folder and choose “unzip.”
MAC OS: Find “Arduino” in your
“Applications” folder in Finder.
Arduino
Right-click (ctrl + click) on “Arduino”
and select “Show Package Contents.”
Open
Show Package Contents
Move to Trash
Copy or move the unzipped “SIK Guide Code” folder from your
“Downloads” folder into the Arduino application’s folder named “Examples.”
Arduino
ARDUINO
Open
Contents
C O NShow
T E N T Package
S
JAVA
Move to Trash
EXAMPLES
WINDOWS: Copy or move the unzipped “SIK Guide Code” files from “Downloads” to the
Arduino application’s “Examples” folder.
LOCAL
DISK (C:)
PROGRAM
FILES
ARDUINO
EXAMPLES
LINUX: Distribution-specific setup instructions for Linux can be found at:
http://arduino.cc/playground/learning/linux
7 : intro
5. OPEN THE ARDUINO IDE:
Open the Arduino IDE software on your computer. Poke around and get to know the
interface. We aren’t going to code right away; this step is to set your IDE to identify
your RedBoard.
E
B
D
C
G
Blink | Arduino 1.8.5
A
K
Blink
H
THE THREE MOST
I M P O R TA N T
COMMANDS IN
THE ARDUINO IDE
I
F
Arduino/Genuino Uno on/dev/cu.usbserialDNO18JWS
GRAPHICAL USER INTERFACE (GUI)
A
VERIFY
Compiles and approves your code. It will catch errors in syntax
(like missing semicolons or parentheses).
B
UPLOAD
Sends your code to the RedBoard. When you click it, you
should see the lights on your board blink rapidly.
C
S AV E
Saves the currently active sketch.
D
OPEN
Opens an existing sketch.
E
NEW
Opens up a new code window tab.
F
DEBUG WINDOW
G
SKETCH NAME
H
CODE AREA
Displays any errors generated by your sketch.
Displays the name of the sketch you are currently working on.
Where you compose or edit the code for your sketch.
I
MESSAGE AREA
J
CONNECTION AREA
Displays the board and serial port currently selected.
K
SERIAL MONITOR
Opens a window that displays any serial information
your RedBoard is transmitting (useful for debugging).
8 : intro
Indicates if the code is compiling, uploading or has errors.
J
IK_Circuit_1A-Blink
IK_Circuit_1A-Potentiometer
IK_Circuit_1A-Photoresistor
IK_Circuit_1A-RGBNightlight
IK_Circuit_1A-Buzzer
IK_Circuit_1A-DigitalTrumpet
NOTE: Your SparkFun RedBoard and the Arduino/Genuino UNO are
IK_Circuit_1A-SimonSays
File
6. SELECT YOUR BOARD AND SERIAL DEVICE
interchangeable, but you won’t find the RedBoard listed in the Arduino
software. Select “ARDUINO/GENUINO UNO” instead.
Arduino
Edit
Sketch
File
Tools
Edit
Sketch
Help
Auto Format
Archive Sketch
Fix Encoding and Reload
Serial Monitor
Serial Plotter
ircuit_01
ircuit_02
ircuit_03
ircuit_04
File Edit
ircuit_05
ircuit_06
ircuit_07
File
Circuit_01
Circuit_02
Circuit_03
Circuit_04
Circuit_05
Circuit_06
Circuit_07
Edit
Tools
Help
Auto Format
Archive Sketch
Fix Encoding and Reload
Serial Monitor
Serial Plotter
Board: “Arduino/Genuino Uno”
Port
Get Board Info
Boards Manager…
TeensyDuino
Teensy 3.6
Teensy 3.5
SELECT YOUR BOARD
Teensy 3.2/3.1
Board: “Arduino/Genuino Uno”
Teensy 3.0
Tools
> Board > Arduino/Genuino UNO
Port
Serial Ports
Teensy LC
Get Board Info
/dev/cu.usbserialDNO18JWS
Teensy++ 2.0
Programmer: “AVRISPmkII”
Teensy 2.0
Burn Bootlader
Arduino AVR Boards
Arduino/Genuino Uno
Arduino Duemilanove or Diecimila
Sketch Tools Help
Arduino Nano
Auto Format
Archive Sketch
SELECT YOUR PORT (WINDOWS)
Fix Encoding and Reload
Circuit_01
Serial Monitor
Circuit_02
Tools > Port > COM#(Arduino/Genuino
UNO)
Serial Plotter
Circuit_03
Circuit_04
Board: “Arduino/Genuino Uno”
Circuit_05
Port
Serial Ports
Circuit_06
Get Board Info
COM1
Circuit_07
COM2
Programmer: “AVRISPmkII”
Burn Bootlader
COM51(Arduino/Genuino UNO)
Sketch
Tools
Help
Auto Format
Archive Sketch
Fix Encoding and Reload
Serial Monitor
Serial Plotter
SELECT YOUR PORT (MAC OS)
Tools > Port > /dev/cu.usbserialXXXXXXXX
Board: “Arduino/Genuino Uno”
Port
Get Board Info
Serial Ports
/dev/cu.usbserialDNO18JWS
Programmer: “AVRISPmkII”
Burn Bootlader
SELECT YOUR PORT (LINUX)
Distribution-specific serial device setup instructions can be found HERE:
http://arduino.cc/playground/learning/linux
9 : intro
Inventory of Parts
The SparkFun Inventor’s Kit contains an extensive array of electronic components. As
you work your way through each circuit, you will learn to use new and more complicated
parts to accomplish increasingly complex tasks.
LEDS
L C D D I S P L AY
POTENTIOMETER
S W I TC H
ULTRASONIC
D I S TA N C E S E N S O R
PIEZO
BUZZER
M OTO R
DRIVER
TJP16527BH2
R
10k
100k
330
A12
GND
A11
ST
BY
A02
B11
B02
B12
B01
MOTOR
DRIVER
GND
PWMB
GND
G E A R M OTO R S
JUMPER
WIRES
1 O K Ω R E S I S TO R S
10k
100k
PWMA
VCC
A01
GND
Echo
Trig
VCC
1652
T
H8106
VM
PUSH
B U T TO N S
3 3 0 Ω R E S I S TO R S
330
P H OTO R E S I S TO R
T E M P E R AT U R E
SENSOR
TMP
BREADBOARD
++ -–
21
20
19
19
18
18
17
17
16
16
15
15
14
14
13
13
12
12
11
11
10
10
9
9
8
8
7
7
6
6
5
5
4
4
3
3
2
2
1
1
a
b
c
d
e
f
g
h
i
j
A5
22
21
20
A4
23
22
A3
24
24
23
A2
25
25
++ -–
7
~6
~5
4
~3
2
TX 1
RX 0
27
26
A1
28
A0
29
VIN
30
GND
j
GND
i
5V
h
3.3V
g
RESET
f
IOREF
e
SCL
SDA
AREF
GND
13
12
~11
~10
~9
8
d
7-15V
c
++ -–
10 : intro
b
ANALOG IN
a
POWER
27
ISP
26
ON
START SOMETHING
28
DIGITAL (PWM~)
13
TX
RX
29
RESET
30
S PA R K F U N R E D B OA R D
++ -–
SERVO
M OTO R
Let’s Get
Started
With Your
First Circuit!
11 : intro
BLINKING
AN LED
A
READING A
POTENTIOMETER
READING A
PHOTORESISTOR
B
C
RGB NIGHT-LIGHT
D
PROJECT 1
NEW IDEAS
Welcome to your first SparkFun Inventor’s Kit
Each project will introduce new
project. Each project is broken up into several
concepts and components, which will
circuits, the last circuit being a culmination of
be described in more detail as you
the technologies that came before. There are five
progress through the circuits.
projects total, each designed to help you learn about
new technologies and concepts. This first project
will set the foundation for the rest and will aid in
helping you understand the fundamentals of circuit
building and electricity!
In Project 1, you will learn about LightEmitting Diodes (LEDs), resistors,
inputs, outputs and sensors. The first
project will be to build and program your own
multicolored night-light! The night-light uses a
sensor to turn on an RGB (Red, Green, Blue) LED
when it gets dark, and you will be able to change the
color using an input knob.
13 : circuit 1a
NEW COMPONENTS INTRODUCED
IN THIS PROJECT
• LEDS
• R E S I S TO R S
• POTENTIOMETERS
• P H OTO R E S I S TO R S
NEW CONCEPTS INTRODUCED IN THIS PROJECT
• POLARITY
• O H M ' S L AW
• D I G I TA L O U T P U T
• A N A L O G V S . D I G I TA L
• ANALOG INPUT
• A N A L O G T O D I G I TA L C O N V E R S I O N
• V O L TA G E D I V I D E R
• P U L S E - W I D T H M O D U L AT I O N
• FUNCTIONS
YOU WILL LEARN
• H OW TO U P L OA D A P R OG R A M TO
YOUR REDBOARD
• CIRCUIT-BUILDING BASICS
• H OW TO CO N T R O L L E D S W I T H
D I G I TA L O U T P U T S
• H OW TO R E A D S E N S O R S
WITH ANALOG INPUTS
Circuit 1A:
Blinking an LED
You can find LEDs in just about any source
of light, from the bulbs lighting your home
to the tiny status lights flashing on your
home electronics. Blinking an LED is the
classic starting point for learning how to
program embedded electronics. It’s the
“Hello, World!” of microcontrollers. In this
circuit, you’ll write code that makes an LED
blink on and off.
LED
330Ω
NEW COMPONENTS
which you can look up using
are small lights made from a silicon diode.
330
10k
YOU
NEED
2 JUMPER WIRES
bands. Each color stands for a number,
100k
LIGHT-EMITTING DIODES (LEDS)
RESISTOR
a resistor chart. One can be
found at the back of this book.
They come in different colors, brightnesses
and sizes. LEDs (pronounced el-ee-dees)
have a positive (+) leg and a negative (-)
leg, and they will only let electricity flow
NEW
CONCEPTS
through them in one direction. LEDs can
POLARITY: Many electronics
also burn out if too much electricity flows
components have polarity,
through them, so you should always use a
meanig electricity can (and
–
+
should) flow through them in
only one direction. Polarized
components, like an LED,
have a positive and a negative
leg and only work when electricity flows
through them in one direction. Some
components, like resistors, do not have
polarity; electricity can flow through them
in either direction.
OHM’S LAW describes the relationship between
the three fundamental elements of electricity:
resistor to limit the current when you wire
voltage, resistance and current. This
an LED into a circuit.
relationship can be represented by this equation:
RESISTORS resist the flow of electricity.
You can use them to protect sensitive
components like LEDs. The strength of a
resistor (measured in ohms) is marked on
the body of the resistor using small colored
V=I•R
V = Voltage in volts
I = Current in amps
14 : circuit 1a
RESET
7
~6
~5
4
~3
2
TX 1
RX 0
SCL
SDA
AREF
GND
13
12
~11
~10
~9
8
R = Resistance in ohms (Ω)
DIGITAL (PWM~)
13
TX
RX
This equation is used to calculate what resistor values
are suitable to sufficiently limit the current flowing to
ON
the LED so that it does not get too hot and burn out.
START SOMETHING
ISP
DIGITAL OUTPUT: When working with
A5
A4
A3
A2
A1
ANALOG IN
A0
VIN
GND
GND
5V
3.3V
RESET
IOREF
7-15V
microcontrollers such as the RedBoard, there
POWER
are a variety of pins to which you can connect
electronic components. Knowing which pins
perform which functions is important when
building your circuit. In this circuit, we will be using what is known as a digital output.
There are 14 of these pins found on the RedBoard. A digital output only has two states:
NEW IDEAS
ELECTRICAL SAFETY: Never work on your circuits while the board is connected to
a power source. The SparkFun RedBoard operates at 5 volts, which, while not enough to
injure you, is enough to damage the components in your circuit.
COMPONENT ORIENTATION & POLARITY: Instructions on how to orient each of
the new components will be given before each circuit diagram. Many components have
polarity and have only one correct orientation, while others are nonpolarized.
RESISTOR
LEADS
Components like resistors need to have
their legs bent into 90° angles in order to
F L AT E D G E
SHORT LEG
–
+
POLARIZED
COMPONENTS
Pay close attention to the LED. The
negative side of the LED is the short leg,
marked with a flat edge.
15 : circuit 1a
correctly fit in the breadboard sockets.
HOOKUP GUIDE
READY TO START HOOKING EVERYTHING UP? Check out the circuit diagram and
hookup table below to see how everything is connected.
F L AT E D G E
e
f
g
h
i
j
1
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
++ -–
7-15V
3.3V
13
13
5V
14
14
15
15
16
16
17
17
18
18
19
19
A2
20
20
A3
21
21
A4
GND
GND
VIN
A0
A1
ON
ANALOG IN
23
ISP
CIRCUIT DIAGRAMS: Each circuit containsA5a circuit diagram, which
22
23
SCL
SDA
AREF
GND
13
12
~11
~10
~9
8
DIGITAL (PWM~)
RESET
12
START SOMETHING
IOREF
11
12
13
TX
RX
10
11
POWER
10
22
7
~6
~5
4
~3
2
TX 1
RX 0
acts as a visual aid designed to make it easier for you to see how your circuit
24
24
25
25
should be built. Each colored line represents a jumper wire connection in the
26
26
27
27
circuit. All wires should have two connection points, which you also see in the
28
++ -–
d
10k
c
100k
b
2
330
a
1
RESET
++ -–
28
29
hookup table below.
30
a
b
c
d
e
f
g
h
i
29
30
j
++ -–
COLORS: Please note that while traditionally red is used for power and
black is used for ground, all wires, no matter their color, function the same.
HOOKUP TABLES: Many electronics beginners find
it helpful to have a coordinate system when building their
circuits. For each circuit, you’ll find a hookup table that
D13
to
J2
…means one end of a
component connects
lists the coordinates of each component or wire and where
to digital pin 13 on
it connects to the RedBoard, the breadboard, or both. The
your RedBoard and
breadboard has a letter/number coordinate system, just
the other connects to
like the game Battleship.
REDBOARD CONNECTION
CONNECTION TYPES
JUMPER WIRES
LED
330Ω RESISTOR
(ORANGE, ORANGE,
BROWN)
D13 to
A1(-) to
E2 to
J2
A2(+)
F2
GND to
J2 on the breadboard
BREADBOARD CONNECTION
E1
In this table, a yellow
highlight indicates that a
component has polarity
and will only function if
properly oriented.
16 : circuit 1a
Open the Arduino IDE
Connect the RedBoard to a USB port on your computer.
Open the Sketch: File > Examples > SIK_Guide_Code-V_4 > CIRCUIT_1A-BLINK
Select UPLOAD to program the sketch on the RedBoard.
Arduino
Tools
Help File
Edit
Sketch
New
Open
Open Recent
Sketchbook
Examples
Close
Save
Save As
Page Setup
Print
Tools
Help
01.Basics
02.Digital
03.Analog
04.Communication
05.Control
06.Sensors
07.Display
08.Strings
09.USB
10.Starter Kit
ArduinoISP
SIK_Guide-Code-v_4
SIK_Circuit_1A-Blink
SIK_Circuit_1A-Potentiometer
SIK_Circuit_1A-Photoresistor
SIK_Circuit_1A-RGBNightlight
SIK_Circuit_1A-Buzzer
SIK_Circuit_1A-DigitalTrumpet
SIK_Circuit_1A-SimonSays
W H AT Y O U
SHOULD SEE
The LED will flash on for two seconds, then
off for two seconds. If it doesn’t, make sure
you have assembled the circuit correctly
and verified and uploaded the code to your
board. See the Troubleshooting section at the
end of this circuit if that doesn’t work. One
of the best ways to understand the code you
uploaded is to change something and see
how it affects the behavior of your circuit.
What happens when you change the number
in one or both of the delay(2000);
lines of code (try 100 or 5000)?
17 : circuit 1a
PROGRAM OVERVIEW
1
Turn the LED on by sending power (5V) to digital pin 13.
2
Wait 2 seconds (2000 milliseconds).
3
Turn the LED off by cutting power (0V) to digital pin 13.
4
Wait 2 seconds (2000 milliseconds).
5
Repeat.
ONBOARD LED PIN 13:
You may have noticed a second,
smaller LED blinking in unison
with the LED in your breadboard
circuit. This is known as the
onboard LED, and you can find
one on almost any Arduino or
Arduino-compatible board. In
most cases, this LED is connected
to digital pin 13 (D13), the
same pin used in this circuit.
NEW IDEAS
CODE TO NOTE: The sketches that accompany each circuit introduce new programming techniques and
concepts as you progress through the guide. The Code to Note section highlights specific lines of code from the
sketch and explains them in greater detail.
CODE TO NOTE
SETUP AND LOOP:
Every Arduino program needs these two functions. Code that goes in
void setup(){} &
between the loop()curly brackets {} runs over and over until the
void loop(){}
RedBoard is reset or powered off.
INPUT OR OUTPUT?:
pinMode(13, OUTPUT);
between the curly brackets {} of setup()runs once. The code in
Before you can use one of the digital pins, you need to tell the RedBoard
whether it is an INPUT or OUTPUT. We use a built-in “function” called
pinMode() to make pin 13 a digital output. You’ll learn more about
digital inputs in Project 2.
18 : circuit 1a
CODE TO NOTE
DIGITAL OUTPUT:
When you’re using a pin as an OUTPUT, you can command it to be
digitalWrite(D13, HIGH);
HIGH (output 5 volts) or LOW (output 0 volts).
Causes the program to wait on this line of code for the amount of
DELAY:
time in between the brackets, represented in milliseconds (2000ms
delay(2000);
= 2s). After the time has passed, the program will continue to the
next line of code.
Comments are a great way to leave notes in your code explaining
COMMENTS:
//This is a comment
/* So is this */
why you wrote it the way you did. Single line comments use two
forward slashes //, while multi-line comments start with a /* and
end with a */.
NEW IDEAS
CODING CHALLENGES: The Coding Challenges section is where you will find suggestions for changes
to the circuit or code that will make the circuit more challenging. If you feel underwhelmed by the tasks in each
circuit, visit the Coding Challenges section to push yourself to the next level.
CODING CHALLENGES
PERSISTENCE OF VISION: Computer screens, movies and the lights in your house all flicker so
quickly that they appear to be on all of the time but are actually blinking faster than the human eye can detect.
See how much you can decrease the delay time in your program before the light appears to be on all the time
but is still blinking.
MORSE CODE: Try adding and changing the delay()
digitalWrite()
values and adding more
commands to make your program blink a message in Morse code.
TROUBLESHOOTING
I get an error when
The most likely cause is that you have the wrong board selected in the Arduino
uploading my code
IDE. Make sure you have selected Tools > Board > Arduino/Genuino Uno.
19 : circuit 1a
TROUBLESHOOTING
I still get an error when
uploading my code
If you’re sure you have the correct Board selected but you still can’t
upload, check that you have selected the correct serial port. You can
change this in Tools > Serial Port > your_serial_port.
Depending on how many devices you have plugged into your computer,
you may have several active serial ports. Make sure you are selecting the
Which serial port is
correct one. A simple way to determine this is to look at your list of serial
the right one?
ports. Unplug your RedBoard from your computer. Look at the list again.
Whichever serial port has disappeared from the list is the one you want
to select once you plug your board back into your computer.
My code uploads, but my
LEDs will only work in one direction. Try taking it out of your
LED won’t turn on
breadboard, turning it 180 degrees and reinserting it.
Jumper wires unfortunately can go “bad” from getting bent too much.
The copper wire inside can break, leaving an open connection in your
Still not working?
circuit. If you are certain that your circuit is wired correctly and that
your code is error-free and uploaded, but you are still encountering
issues, try replacing one or more of the jumper wires for the component
that is not working.
You’ve completed
Circuit 1A!
Continue to circuit 1B to learn about analog signals and potentiometers.
BLINKING
AN LED
A
READING A
POTENTIOMETER
B
READING A
PHOTORESISTOR
C
RGB NIGHT-LIGHT
D
20 : circuit 1a
Circuit 1B:
Potentiometer
of the knob with your RedBoard, you can
make volume controls, speed controls,
angle sensors and a ton of other useful
inputs for your projects. In this circuit,
Potentiometers (also known as “trimpots”
or “knobs”) are one of the basic inputs for
electronic devices. By tracking the position
LED blinks.
POTENTIOMETER
NEW COMPONENTS
7 JUMPER WIRES
RESISTOR
ANALOG INPUTS: So far, we’ve only
dealt with outputs. The RedBoard also has
POTENTIOMETER: A potentiometer is
inputs. Both inputs and outputs can be
a 3-pin variable resistor. When powered
analog or digital. Based on our previous
10k
with 5V, the middle pin outputs a voltage
330Ω
between 0V and 5V, depending
on the position of the knob on
trimpot is a single resistor and a
wiper, which cuts the resistor in two and
input, which can only
sense two values, or
IOREF
13
TX
RX
states.
7-15V
RESET
3.3V
5V
GND
GND
VIN
A0
analog world. There are an infinite number
of colors to paint an object, an infinite
number of tones we can hear, and an
infinite number of smells we can smell.
A3
A4
Digital and some
A5
ON
ANALOG VS. DIGITAL: We live in an
A2
ISP
NEW CONCEPTS
A1
ANALOG IN
some pins labeled
your RedBoard. There are only six pins
that function as analog inputs; they are
labeled A0–A5.
VOLTAGE DIVIDER
signals is their infinite possibilities.
VOLTAGE DIVIDERS are simple
discrete or finite, meaning there is a
limited set of values they can be. The LED
from the previous circuit had only two
states it could exist in, ON or OFF, when
connected to a digital output.
circuits that turn some voltage into a
smaller voltage using two resistors. A
potentiometer is a variable resistor that
can be used to create an adjustable voltage
divider. A wiper in the middle position
means the output voltage will be half of the
input. Voltage dividers will be covered in
more detail in the next circuit.
20 : circuit 1b
7
~6
~5
4
~3
2
TX 1
RX 0
labeled Analog In on
The common theme among these analog
Digital signals deal in the realm of the
SCL
SDA
AREF
GND
13
12
~11
~10
~9
8
DIGITAL (PWM~)
You may have noticed
POWER
both halves.
values versus a digital
START SOMETHING
moves to adjust the ratio between
an analog input can sense a wide range of
RESET
the potentiometer. Internal to the
definition of analog and digital, that means
330
LED
device to control the speed at which your
100k
YOU
NEED
you’ll use a potentiometer as an input
HOOKUP GUIDE
READY TO START HOOKING EVERYTHING UP? Check out the
circuit diagram and hookup table below to see how everything is connected.
F L AT E D G E
e
f
g
h
i
j
1
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
++ -–
7-15V
10k
d
100k
c
330
b
2
RESET
12
3.3V
13
13
5V
14
14
15
15
16
16
17
17
18
18
19
19
A2
20
20
A3
21
21
A4
22
22
A5
23
23
24
24
25
25
26
26
27
27
28
28
b
c
d
e
f
g
h
i
j
A0
A1
ON
30
a
VIN
ISP
29
30
GND
ANALOG IN
29
GND
SCL
SDA
AREF
GND
13
12
~11
~10
~9
8
DIGITAL (PWM~)
IOREF
11
12
START SOMETHING
10
11
13
TX
RX
10
POWER
++ -–
a
1
RESET
++ -–
7
~6
~5
4
~3
2
TX 1
RX 0
++ -–
NEW IDEAS
POTENTIOMETERS are not polarized
and can be installed in either direction.
Note that swapping the 5V and GND pins
will reverse its behavior.
CONNECTION TYPES
JUMPER WIRES
LED
330Ω RESISTOR
(ORANGE, ORANGE,
BROWN)
POTENTIOMETER
REDBOARD CONNECTION
5V to
5V
E25 to
5V (+)
A1(-) to
E2 to
C25 +
GND to
E27 to
GND (-)
GND (-)
BREADBOARD CONNECTION
A0 to
E1 to
E26
GND (-)
D13 to
J2
A2(+)
F2
C26 +
C27
21 : circuit 1b
Open the Arduino IDE
Connect the RedBoard to a USB port on your computer.
Open the Sketch:
File > File > Examples > SIK_Guide_Code-V_4 > CIRCUIT_1B-POTENTIOMETER
Select UPLOAD to program the sketch on the RedBoard.
W H AT Y O U
SHOULD SEE
You should see the LED blink faster
or slower in accordance with your
potentiometer. The delay between each
flash will change based on the position
of the knob. If it isn’t working, make
sure you have assembled the circuit
correctly and verified and uploaded
the code to your board. If that doesn’t
work, see the Troubleshooting section.
PROGRAM OVERVIEW
1
Read the position of the potentiometer (from 0 to 1023) and store it in the variable potPosition.
2
Turn the LED on.
3
Wait from 0 to 1023 milliseconds, based on the position of the knob and the value of potPosition.
4
Turn the LED off.
5
Wait from 0 to 1023 milliseconds, based on the position of the knob and the value of potPosition.
6
Repeat.
22 : circuit 1b
ARDUINO PRO TIP
ARDUINO SERIAL MONITOR: The
Blink | Arduino 1.8.5
Serial Monitor is one of the Arduino IDE’s
many great included features. When
Serial Monitor
Blink
working with embedded systems, it helps
to see and understand the values that your
program is trying to work with, and it can
be a powerful debugging tool when you
run into issues where your code is not
behaving the way you expected it to. This
Arduino/Genuino Uno on/dev/cu.usbserialDNO18JWS
circuit introduces you to the Serial Monitor
by showing you how to print the values
from your potentiometer to it. To see these
Serial Monitor button
in the upper-right of
the Arduino IDE.
values, click the Serial Monitor button,
found in the upper-right corner of the IDE in most recent versions. You can also select
Tools > Serial Monitor from the menu.
You should see numeric
values print out in the
monitor. Turning the
potentiometer changes the
value as well as the delay
between each print.
If you are having trouble
seeing the values, ensure
that you have selected 9600
Serial Monitor printout
and baud-rate menu.
baud and have auto scroll
checked.
CODE TO NOTE
A variable is a placeholder for values that may change
INTEGER VARIABLES:
int potPosition;
in your code. You must introduce, or “declare,”
variables before you use them. Here we’re declaring a
variable called potPosition of type int (integer). We
will cover more types of variables in later circuits. Don’t
forget that variable names are case-sensitive!
23 : circuit 1b
CODE TO NOTE
Serial commands can be used to send and receive data from
your computer. This line of code tells the RedBoard that we
SERIAL BEGIN:
want to “begin” that communication with the computer, the
Serial.begin(9600);
that the baud rate, 9600, is the same as the one we selected
same way we would say “Hi” to initiate a conversation. Notice
in the monitor. This is the speed at which the two devices
communicate, and it must match on both sides.
ANALOG INPUT:
potPosition =
analogRead(A0);
We use the analogRead() function to read the value on an
analog pin. analogRead() takes one parameter, the analog
pin you want to use, A0 in this case, and returns a number
between 0 (0 volts) and 1023 (5 volts), which is then assigned to
the variable potPosition.
This is the line that actually prints the trimpot value to
SERIAL PRINT:
Serial.
println(potPosition);
the monitor. It takes the variable potPosition and prints
whatever value it equals at that moment in the loop(). The
ln at the end of println tells the monitor to print a new
line at the end of each value; otherwise the values would all
run together on one line. Try removing the ln to see what
happens.
CODING CHALLENGES
CHANGING THE RANGE: Try multiplying, dividing or adding to your sensor reading so
that you can change the range of the delay in your code. For example, can you multiply the
sensor reading so that the delay goes from 0–2046 instead of 0–1023?
ADD MORE LEDS: Add more LEDs to your circuit. Don’t forget the current-limiting
resistors. You will need to declare the new pins in your code and set them all to OUTPUT .
Try making individual LEDs blink at different rates by changing the range of each
using multiplcation or division.
24 : circuit 1b
TROUBLESHOOTING
The potentiometer always
reads as 0 or 1023
Make sure that your 5V, A0 and GND pins are properly
connected to the three pins on your potentiometer. It is
easy to misalign a wire with the actual pot pin.
Make sure that you have selected the correct baud rate,
No values or random
9600. Also ensure that you are on the correct serial
characters in
port. The same serial port you use when uploading
Serial Monitor
code to your board is the same serial port you use to
print values to the Serial Monitor.
You’ve completed
Circuit 1B!
Continue to circuit 1C to learn about photoresistors and analog to digital conversion.
BLINKING
AN LED
A
READING A
POTENTIOMETER
B
READING A
PHOTORESISTOR
C
RGB NIGHT-LIGHT
D
25 : circuit 1b
Circuit 1C:
Photoresistor
circuit, you’ll be using a photoresistor,
which changes resistance based on how
much light the sensor receives. Using this
sensor you can make a simple night-light
In circuit 1B, you got to use a
potentiometer, which varies resistance
that turns on when the room gets dark
based on the twisting of a knob. In this
and turns off when it is bright.
YOU
NEED
LED
PHOTORESISTOR
330Ω
RESISTOR 10KΩ
RESISTOR 7 JUMPER WIRES
PHOTORESISTORS are light-
need to use a voltage divider to use our
sensitive, variable resistors. As
photoresistor, a part that doesn’t output
more light shines on the sensor’s
voltage. The resistance of the photoresistor
head, the resistance between its
changes as it gets darker or lighter. That
two terminals decreases. They’re
changes or “divides” the voltage going
an easy-to-use component in
through the divider circuit. That divided
projects that require ambient-
voltage is then read in on the analog to
light sensing.
digital converter of the analog input.
VOLTAGE DIVIDERS CONTINUED:
NEW CONCEPTS
330
100k
10k
resistance (rather, it reads voltage), we
330
100k
Since the RedBoard can’t directly interpret
10k
NEW
COMPONENTS
The voltage divider equation:
ANALOG TO DIGITAL CONVERSION:
In order to have the RedBoard sense analog
signals, we must first pass them through
an Analog to Digital Converter (or ADC).
The six analog inputs (A0–A5) covered
in the last circuit all use an ADC. These
Vout=Vin •
pins sample the analog signal and create
R2
R1+R2
a digital signal for the microcontroller to
assumes that you know three values of
interpret. The resolution of this signal is
the above circuit: the input voltage (Vin),
based on the resolution of the ADC. In the
and both resistor values (R1 and R2). If R1
case of the RedBoard, that resolution is 10-
is a constant value (the resistor) and R2
bit. With a 10-bit ADC, we get 2 ^ 10 = 1024
fluctuates (the photoresistor), the amount
possible values, which is why the analog
of voltage measured on the Vout pin will
signal can vary between 0 and 1023.
also fluctuate.
26 : circuit 1c
HOOKUP GUIDE
READY TO START HOOKING EVERYTHING UP? Check out the circuit diagram and
hookup table below to see how everything is connected.
F L AT E D G E
e
f
g
h
i
++ -–
j
1
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
7-15V
10k
d
100k
c
330
b
2
RESET
12
3.3V
13
13
5V
14
14
15
15
16
16
17
17
18
18
19
19
A2
20
20
A3
21
21
A4
22
22
A5
23
23
24
24
25
25
26
26
27
27
28
28
GND
VIN
A0
A1
c
d
e
f
g
h
i
j
PHOTORESISTORS: The
0
33
photoresistors, like regular resistors,
0k
10
are not polarized and can be installed in
k
10
CONNECTION TYPES
JUMPER WIRES
LED
330Ω RESISTOR
(ORANGE, ORANGE,
BROWN)
either direction.
REDBOARD CONNECTION
5V to
5V(+)
D13 to
J2
E25 to
5V(+)
A1(-) to
E2 to
ON
b
7
~6
~5
4
~3
2
TX 1
RX 0
NEW IDEAS
++ -–
30
a
ISP
29
30
ANALOG IN
29
GND
SCL
SDA
AREF
GND
13
12
~11
~10
~9
8
DIGITAL (PWM~)
IOREF
11
12
START SOMETHING
10
11
13
TX
RX
10
POWER
++ -–
a
1
RESET
++ -–
GND to
A0 to
GND (-)
E26
E27 to
BREADBOARD CONNECTION
E1 to
GND(-)
GND(-)
A2(+)
F2
10KΩ RESISTOR
(BROWN, BLACK,
ORANGE)
B26 to
C27
PHOTORESISTOR
A26 to
B25
27 : circuit 1c
Open the Arduino IDE
Connect the RedBoard to a USB port on your computer.
Open the Sketch:
File > Examples > SIK_Guide_Code-V_4 > CIRCUIT_1C-PHOTORESISTOR
Select UPLOAD to program the sketch on the RedBoard.
W H AT Y O U
SHOULD SEE
The program stores the light level in
a variable. Using an if/else statement,
the variable value is compared to the
threshold. If the variable is above the
threshold (it’s bright), turn the LED off.
If the variable is below the threshold (it’s
dark), turn the LED on. Open the Serial
Monitor in Arduino. The value of the
photoresistor should be printed every so
often. When the photoresistor value drops
below the threshold, the LED should turn
on (you can cover the photoresistor with
your finger for testing).
NEW IDEAS
LIGHT LEVELS: If the room you are in is very bright or dark, you may have to change
the value of the threshold
variable in the code to make your night-light turn on and
off. See the Troubleshooting section for instructions.
PROGRAM OVERVIEW
1
Store the light level in the variable photoresistor.
2
If the value of the photoresistor is above the threshold (it’s bright), turn the LED off.
3
Otherwise, the value of the photoresistor is below the threshold (it’s dark), turn the LED on.
28 : circuit 1c
CODE TO NOTE
IF ELSE STATEMENTS:
The if else statement lets your code react to the world by
if(logic statement){
running one set of code when the logic statement in the
//run if true
round brackets is true and another set of code when the
}
logic statement is false. For example, this sketch uses an
else{
if statement to turn the LED on when it is dark, and else
//run if false
statement to turn the LED off when it is light.
}
Programmers use logic statements to translate things
that happen in the real world into code. Logic statements
LOGICAL OPERATORS:
(photoResistor <
threshold)
use logical operators like ‘equal to’ ==, ‘greater than’
> and ‘less than’ Port, and make sure that you select
the right port.
Start the Serial Monitor in Arduino. Look at the value that the
photoresistor is reading in a bright room (e.g., 915). Cover the
The light never turns
on or always stays on
photoresistor, or turn the lights off. Then look at the new value
that the photoresistor is reading (e.g., 550). Set the threshold
in between these two numbers (e.g., 700) so that the reading
is above the threshold when the lights are on and below the
threshold when the lights are off.
You’ve completed
Circuit 1C!
Continue to circuit 1D to learn about RGB LEDs, functions and pulse-width modulation.
BLINKING
AN LED
A
30 : circuit 1c
READING A
POTENTIOMETER
READING A
PHOTORESISTOR
B
C
RGB NIGHT-LIGHT
D
Circuit 1D: RGB
Night-Light
In this circuit, you’ll take the night-light
concept to the next level by adding an
RGB LED, which is three differently
colored Light-Emitting Diodes (LEDs)
built into one component. RGB stands
for Red, Green and Blue, and these three
colors can be combined to create any
color of the rainbow!
3 330Ω
PHOTORESISTOR
12 JUMPER WIRES
RESISTORS 10KΩ
YOU
NEED
RESISTOR
POTENTIOMETER
blue — inside a normal LED housing. This
RGB LED has all the internal LEDs share
the same ground wire, so there are four
legs in total. To turn on one color, ensure
ground is connected, then power one of the
legs just as you would a regular LED. Don’t
forget the current-limiting resistors. If you
PWM PINS: Only a few of the pins
330
small LEDs — one red, one green and one
NEW IDEAS
100k
RGB LED: An RGB LED is actually three
330
100k
10k
NEW COMPONENTS
10k
RGB LED
on the RedBoard have the circuitry
needed to turn on and off fast enough
for PWM. These are pins 3, 5, 6, 9, 10
and 11. Each PWM pin is marked with
a ~ on the board. Remember, you can
only use analogWrite() on these
pins.
MODULATION): The digitalWrite()
ON
START SOMETHING
RED
COMMON ( GND)
GREEN
BLUE
ANALOG OUTPUT (PULSE-WIDTH
DIGITAL (PWM~)
13
TX
RX
form a new color.
A5
A4
A3
A2
A1
ANALOG IN
A0
VIN
GND
GND
POWER
5V
RESET
IOREF
ISP
7-15V
NEW CONCEPTS
7
~6
~5
4
~3
2
TX 1
RX 0
RESET
3.3V
will see the colors start to blend together to
SCL
SDA
AREF
GND
13
12
~11
~10
~9
8
turn on more than one color at a time, you
off so that it is only on 50 percent of the
command can turn pins on (5V) or off (0V),
time (50% of 5V is 2.5V). By doing this, any
but what if you want to output 2.5V? The
voltage between 0 and 5V can be produced.
analogWrite() command can output 2.5
This is what is known as Pulse-Width
volts by quickly switching a pin on and
Modulation (PWM). It can create many
different colors on the RGB LED.
31 : circuit 1d
HOOKUP GUIDE
READY TO START HOOKING EVERYTHING UP? Check out the circuit diagram and
hookup table below to see how everything is connected.
F L AT E D G E
b
c
d
e
f
g
h
i
++ -–
j
1
2
2
330
3
3
330
4
4
5
5
6
6
7
7
8
8
9
9
7-15V
100k
330
100k
10k
100k
10k
10
11
11
RESET
12
12
3.3V
13
13
5V
14
14
15
15
16
16
17
17
18
18
19
19
A2
20
20
A3
21
21
22
22
23
23
24
24
25
25
26
26
27
27
28
28
29
29
10k
VIN
A0
A1
A5
c
d
e
f
g
h
i
ISP
b
ON
A4
REMINDER
7
~6
~5
4
~3
2
TX 1
RX 0
LIGHT LEVELS: If the room you are in is
very bright or dark, you may have to change
the value of the threshold variable.
++ -–
30
a
START SOMETHING
GND
13
TX
RX
GND
ANALOG IN
30
IOREF
SCL
SDA
AREF
GND
13
12
~11
~10
~9
8
DIGITAL (PWM~)
10
POWER
++ -–
a
1
RESET
++ -–
j
0
33
0k
10
CONNECTION TYPES
k
10
JUMPER WIRES
RGB LED
330Ω RESISTORS
(ORANGE, ORANGE,
BROWN)
REDBOARD CONNECTION
5V to
5V(+)
D10 to
J3
E15 to
5V(+)
E27 to
GND (-)
A5(RED) +
E2 to
D11 to
F2
B26 to
C27
PHOTORESISTOR
A26 to
B25
POTENTIOMETER
B15 +
B16 +
GND (-)
J2
E3 to
B17
A3(GREEN) +
F3
D9 to
A0 to
E17 to GND(-)
A4(GND) +
10KΩ RESISTOR
(BROWN, BLACK,
ORANGE)
32 : circuit 1d
GND to
BREADBOARD CONNECTION
E5 to
E26
E4 to
A1 to
GND(-)
A2(BLUE)
F5
J5
E16
E25 to
5V(+)
Open the Arduino IDE
Connect the RedBoard to a USB port on your computer.
Open the Sketch:
File > Examples > SIK_Guide_Code-V_4 > SIK_CIRCUIT_1D-RGB NIGHT LIGHT
Select UPLOAD to program the sketch on the RedBoard.
W H AT Y O U
SHOULD SEE
This sketch is not dissimilar from
the last. It reads the value from
the photoresistor, compares it to
a threshold value, and turns the
RGB LED on or off accordingly.
This time, however, we’ve added a
potentiometer back into the circuit.
When you twist the trimpot, you
should see the color of the RGB LED
change based on the trimpot’s value.
PROGRAM OVERVIEW
1
Store the light level from pin A0 in the variable photoresistor.
2
Store the potentiometer value from pin A1 in the variable potentiometer.
3
If the light level variable is above the threshold, call the function that turns the RGB LED off.
4
If the light level variable is below the threshold, call one of the color functions to turn the RGB
LED on.
5
If potentiometer is between 0 and 150, turn the RGB LED on red.
6
If potentiometer is between 151 and 300, turn the RGB LED on orange.
7
If potentiometter is between 301 and 450, turn the RGB LED on yellow.
8
If potentiometer is between 451 and 600, turn the RGB LED on green.
9
If potentiometer is between 601 and 750, turn the RGB LED on cyan.
10
If potentiometer is between 751 and 900, turn the RGB LED on blue.
11
If potentiometer is greater than 900, turn the RGB LED on magenta.
33 : circuit 1d
CODE TO NOTE
The analogWrite() function outputs a voltage between
ANALOG OUTPUT (PWM):
analogWrite(RedPin, 100);
0 and 5V on a pin. The function breaks the range
between 0 and 5V into 255 little steps. Note that we are
not turning the LED on to full brightness (255) in this
code so that the night-light is not too bright. Feel free to
change these values and see what happens.
NESTED IF STATEMENTS:
if(logic statement){
if(logic statement){
}
}
A nested if statement is one or more if statements
“nested” inside of another if statement. If the parent
if statement is true, then the code looks at each of the
nested if statements and executes any that are true. If
the parent if statement is false, then none of the nested
statements will execute.
MORE LOGICAL
OPERATORS:
(potentiometer > 0 &&
potentiometer Port, and select the right port.
You’ve completed
Circuit 1D!
Continue to Project 2 to explore using buzzers to make sound.
BLINKING
AN LED
A
READING A
POTENTIOMETER
B
READING A
PHOTORESISTOR
C
RGB NIGHT-LIGHT
D
35 : circuit 1d
BUZZER
D I G I TA L T R U M P E T
A
‘ S I M O N S AY S ’ G A M E
B
C
PROJECT 2
In Project 2, you will venture into the
world of buttons and buzzers while
building your own “Simon Says” game!
“Simon Says” is a game in which the LEDs
flash a pattern of red, green, yellow and
blue blinks, and the user must recreate the
pattern using color-coded buttons before
the timer runs out.
NEW COMPONENTS INTRODUCED
IN THIS PROJECT
• BUZZER
• B U T TO N S
NEW CONCEPTS INTRODUCED
IN THIS PROJECT
• A R R AY S
• BINARY
• D I G I TA L I N P U T S
• P U L L - U P R E S I S TO R S
• FOR LOOPS
• MEASURING ELAPSED TIME
YOU WILL LEARN
• H OW TO M A K E TO N E S
WITH A BUZZER
• H O W T O R E A D A B U T T O N U S I N G
D I G I TA L I N P U T S
• H OW TO P R OG R A M A G A M E
36 : circuit 2a
Circuit 2A: Buzzer
In this circuit, you’ll use the RedBoard and
a small buzzer to make music, and you’ll
learn how to program your own songs
using arrays.
POTENTIOMETER
NEW COMPONENTS
BUZZER: The buzzer uses a small
PIEZO BUZZER
4 JUMPER WIRES
YOU
NEED
frequency on the specified pin. The
frequency and duration can both be passed
to the tone() function when calling it.
magnetic coil to vibrate a metal disc inside
a plastic housing. By pulsing electricity
through the coil at different rates, different
frequencies (pitches) of sound can be
To turn the tone off, you need to call
noTone() or pass a duration of time for it
to play and then stop. Unlike PWM, tone()
can be used on any digital pin.
produced. Attaching a potentiometer to
the output allows you to limit
ARRAYS are used like variables, but they
the amount of current moving
can store multiple values. The simplest
through the buzzer and lower
array is just a list. Imagine that you want
its volume.
to store the frequency for each note of
the C major scale. We could make seven
NEW CONCEPTS
variables and assign a frequency to
RESET BUTTON: The RedBoard has a
each one, or we could use an array and
store all seven in the same list. To refer
built-in reset button. This button will reset
to a specific value in the array, an index
the board and start the code over from the
number is used. Arrays are indexed from
beginning, running setup()then loop().
0. For example, to call the first element in
DIGITAL (PWM~)
13
TX
RX
second element, use array_name[1]; and
so on.
NOTE
USING
VA R I A B L E S
USING AN
A R R AY
FREQUENCY[0]
A5
A4
A3
A2
A1
ANALOG IN
A0
VIN
GND
GND
POWER
5V
3.3V
RESET
IOREF
7-15V
ISP
MUSICAL
START SOMETHING
(HZ)
ON
FREQUENCY
RESET
7
~6
~5
4
~3
2
TX 1
RX 0
SCL
SDA
AREF
GND
13
12
~11
~10
~9
8
the array, use array_name[0]; to call the
A
220
A_FREQUENCY
B
247
B_FREQUENCY
FREQUENCY[1]
TONE FUNCTION: To control the
C
261
C_FREQUENCY
FREQUENCY[2]
D
294
D_FREQUENCY
FREQUENCY[3]
buzzer, you will use the tone() function.
E
330
E_FREQUENCY
FREQUENCY[4]
F
349
F_FREQUENCY
FREQUENCY[5]
G
392
G_FREQUENCY
FREQUENCY[6]
This function is similar to PWM in that
it generates a wave that is of a certain
37 : circuit 2a
HOOKUP GUIDE
READY TO START HOOKING EVERYTHING UP? Check out the circuit diagram and
hookup table below to see how everything is connected.
a
b
c
d
e
f
g
h
i
++ -–
j
1
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
RESET
++ -–
7-15V
RESET
12
3.3V
13
13
5V
14
14
15
15
16
16
17
17
18
18
19
19
A2
20
20
A3
21
21
A4
22
22
A5
23
23
24
24
25
25
26
26
27
27
28
28
potentiometer’s legs are
used in these circuits. The
potentiometer is acting as
GND
GND
VIN
A0
A1
ON
flowing to the speaker and
ISP
the amount of current
ANALOG IN
a variable resistor, limiting
DIGITAL (PWM~)
IOREF
11
12
that only two of the
START SOMETHING
10
11
POWER
10
13
TX
RX
VOLUME KNOB: Notice
SCL
SDA
AREF
GND
13
12
~11
~10
~9
8
7
~6
~5
4
~3
2
TX 1
RX 0
thus affecting the volume as
you turn the knob.
++ -–
29
29
30
30
a
b
c
d
e
f
g
h
i
j
++ -–
REMEMBER!
POLARITY: The buzzer is polarized. To see which leg is positive and which is negative,
flip the buzzer over and look at the markings underneath. Keep track of which pin is
where, as they will be hard to see once inserted into the breadboard. There is also text
on the positive side of the buzzer, along with a tiny (+) symbol.
REDBOARD CONNECTION
CONNECTION TYPES
JUMPER WIRES
GND to
GND(-)
BUZZER
H1(+) to
H3(-)
POTENTIOMETER
38 : circuit 2a
B1 +
B2 +
B3
D10 to
F1
BREADBOARD CONNECTION
E2 to
GND (-)
E1 to
F3
Open the Arduino IDE
Connect the RedBoard to a USB port on your computer.
Open the Sketch:
File > Examples > SIK_Guide_Code-V_4 > SIK_CIRCUIT_2A-BUZZER
Select UPLOAD to program the sketch on the RedBoard.
W H AT Y O U
SHOULD SEE
When the program begins, a song will
play from the buzzer once. To replay
the song, press the reset button on the
RedBoard. Use the potentiometer to
adjust the volume.
PROGRAM OVERVIEW
Play the first note for x number of beats using the play() function.
A: (Inside the play() function): Take the note passed to the play function and compare it to
1
each letter in the notes array. When you find a note that matches, remember the index
position of that note (e.g., sixth entry in the notes array).
B: Get a frequency from the frequency array that has the same index as the note that matched
(e.g., the sixth frequency).
C: Play that frequency for the number of beats passed to the play() function.
2
Play the second note using the play() function
...and so on.
39 : circuit 2a
CODE TO NOTE
The char, or character, variable stores character
values. For example, in this sketch, the play()
function gets passed two variables: a character
CHARACTER VARIABLES:
void play(char note, int
beats)
variable that represents the mucial note we want
to play and an integer variable that represents
how long to play that note. A second array takes
the character variable and associates a frequency
value to it. This makes programming a song easier
as you can just reference the character and not
the exact frequency.
The tone() function will pulse power to a pin at
TONE FUNCTION:
a specific frequency. The duration controls how
tone(pin, frequency,
duration);
long the sound will play. tone() can be used on
any digital pin.
To declare an array, you must give it a name,
DECLARING AN ARRAY:
then either tell Arduino how many positions the
array_name[array_size];
array. An array must contain all the same type of
array will have or assign a list of values to the
variables and be declared as such.
To call one of the values in an array, simply type
CALLING AN ARRAY:
the name of the array and the index of the value.
array_name[index_#];
Don’t forget the index starts at 0, not 1, so to call
the first element, use array_name[0];.
CODING CHALLENGES
CHANGE THE TEMPO OF THE SONG: Experiment with the beatLength;
variable to change the tempo of the song.
MAKE YOUR OWN SONG: Try changing the notes to make a different song. Spaces
“
” can be used for rests in the song.
40 : circuit 2a
TROUBLESHOOTING
The song is too
quiet or too loud
Turn the potentiometer to adjust the volume.
Try pressing the reset button on the RedBoard. If that
No sound is playing
doesn’t work, check your wiring of the buzzer. It’s easy to
misalign a pin with a jumper wire or reverse the buzzer.
You’ve completed
Circuit 2A!
Continue to circuit 2B to explore digital inputs and buttons.
BUZZER
D I G I TA L
TRUMPET
A
B
“ S I M O N S AY S ” G A M E
C
41 : circuit 2a
Circuit 2B: Digital
Trumpet
Learn about digital inputs and buttons
as you build your own digital trumpet!
Buttons are all around us, from the keys
on your keyboard to the buttons on your
remote control.
YOU
NEED
POTENTIOMETER
PIEZO BUZZER
NEW COMPONENTS
BUTTONS: Also known as momentary
switches, buttons only remain in their ON
state as long as they’re being actuated,
or pressed. Most often
momentary switches are
10 JUMPER WIRES
3 PUSH BUTTONS
of as ON or OFF, TRUE or FALSE, HIGH or
LOW. Almost all electronics rely on a base-2
number system to store and manipulate
numbers. The heavy reliance electronics
places on binary numbers means it’s
important to know how the base-2 number
system works.
best used for intermittent
user-input cases: reset
DIGITAL INPUT: In circuit 1A, you
button and keypad buttons.
worked with digital outputs. Each of the
These switches have a nice, tactile, “clicky”
14 digital pins can also be digital inputs.
feedback when you press them.
Digital inputs only care if something is in
one of two states, 0 or 1. Digital inputs are
Note that the different colors are just
aesthetic. All of the buttons included
great for determining if a button has been
pressed or if a switch has been flipped.
behave the same, no matter their color.
PULL-UP RESISTORS: A pull-up
NEW CONCEPTS
BINARY NUMBER SYSTEM: Number
resistor is a small circuit that holds the
voltage HIGH (5V) on a pin until a button is
pressed, pulling the voltage LOW (0V). The
systems are the methods we use to
most common place you will see a pull-up
represent numbers. We’re most used to
resistor is when working with buttons. A
operating within the comfy confines of
pull-up resistor keeps the button in one
a base-10 number system, but there are
state until it is pressed. The RedBoard has
many others. The base-2 system, otherwise
built-in pull-up resistors, but they can also
known as binary, is common when
be added to a circuit externally. This circuit
dealing with computers and electronics.
uses the internal pull-up resistors, covered
Computers, at their lowest level, really only
in more detail in the Code to Note section.
have two ways to represent the state of
anything: 1 or 0, which can also be thought
42 : circuit 2b
HOOKUP GUIDE
READY TO START HOOKING EVERYTHING UP? Check out the circuit diagram and
hookup table below to see how everything is connected.
b
c
d
e
f
g
h
i
++ -–
j
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
7-15V
RESET
12
3.3V
13
13
5V
14
14
15
15
16
16
17
17
18
18
19
19
A2
20
20
A3
21
21
A4
22
22
A5
23
23
24
24
25
25
26
26
27
27
28
28
b
c
d
e
f
g
h
i
j
A0
A1
7
~6
~5
4
~3
2
TX 1
RX 0
ON
30
a
VIN
ISP
29
30
GND
ANALOG IN
29
GND
SCL
SDA
AREF
GND
13
12
~11
~10
~9
8
DIGITAL (PWM~)
IOREF
11
12
START SOMETHING
10
11
13
TX
RX
10
POWER
++ -–
a
1
RESET
++ -–
CONNECTED
++ -–
BUTTONS ARE NOT POLARIZED, but
they do merit a closer look. Each row of legs is
connected internally. When the button is pressed,
CONNECTED
one row connects to the other, connecting all four
pins. If the button’s legs don’t line up with the
rows on the breadboard, rotate it 90 degrees.
GND to
JUMPER WIRES
BUZZER
PUSH BUTTONS
POTENTIOMETER
GND(-)
D2 to
J30
J28 to
GND (-)
H1(+) to
D10 to
E2 to
F1
GND (-)
E1 to
D4 to
J16 to
J18
D3 to
GND (-)
J24
J22 to
GND (-)
F3
H3(-)
D16/D18 to
G16/18
B1 +
B3
B2 +
D22/24 to
G22/24
D28/30 to
G28/30
43 : circuit 2b
Open the Arduino IDE
Connect the RedBoard to a USB port on your computer.
Open the Sketch:
File > Examples > SIK_Guide_Code-V_4 > SIK_CIRCUIT_2B-DIGITAL TRUMPET
Select UPLOAD to program the sketch on the RedBoard.
W H AT Y O U
SHOULD SEE
Different tones will play when
you press different keys.
Turning the potentiometer will
adjust the volume.
PROGRAM OVERVIEW
Check to see if the first button is pressed.
1
A: If it is, play the frequency for c.
B: If it isn’t, skip to the next else if statement.
Check to see if the second button is pressed.
2
A: If it is, play the frequency for e.
B: If it isn’t, skip to the next else if statement.
Check to see if the third button is pressed.
3
A: If it is, play the frequency for g.
B: If it isn’t, skip to the else statement.
4
If none of the if statements are true, turn the buzzer off.
44 : circuit 2b
CODE TO NOTE
To declare a standard input, use the line
INTERNAL PULL-UP
RESISTOR:
pinMode(pin, INPUT );. If you would like to use
one of the RedBoard’s built-in pull-up 20kΩ resistors,
it would look like this:
pinMode(pin, INPUT_
PULLUP);
pinMode(pin, INPUT_PULLUP);. The advantage
of external pull-ups is being able to choose a more
exact value for the resistor.
DIGITAL INPUT:
Check to see if an input pin is reading HIGH
digitalRead(pin);
depending on the reading.
(5V) or LOW (0V). Returns TRUE (1) or FALSE (0)
This is another logical operator. The “is equal to”
symbol == can be confusing. Two equals signs are the
IS EQUAL TO:
same as asking, “Are these two values equal to one
if(digitalRead(pin) ==
LOW )
another?” Contrarily, one equals sign means assigning
a particular value to a variable. Don’t forget to add the
second equals sign if you are comparing two values.
CODING CHALLENGES
CHANGE THE KEY OF EACH BUTTON: Use the frequency table in the comment
section at the end of the code to change the notes that each button plays.
PLAY MORE THAN THREE NOTES WITH IF STATEMENTS: By using
combinations of buttons, you can play up to seven notes of the scale. You can do this in
a few ways. To get more practice with if statements, try adding seven if statements and
using the Boolean AND && operator to represent all of the combinations of keys.
PLAY MORE THAN THREE NOTES WITH BINARY MATH: You can use a clever
math equation to play more than three notes with your three keys. By multiplying each
key by a different number, then adding up all of these numbers, you can make a math
equation that produces a different number for each combination of keys.
45 : circuit 2b
TROUBLESHOOTING
The buzzer is too loud
or too quiet
The RedBoard thinks
one key is always
pressed
Turn the potentiometer to adjust the volume.
Check your wiring. You may have GND and 5V backward if one
or more buttons behave as though they’re pressed all the time.
First, make sure that the wiring is correct. It is easy to misalign
The buttons are
a wire with a button leg. Second, make sure that you have
not working
declared your buttons as inputs and have enabled the internal
pull-up resistors with INPUT_PULLUP.
You’ve completed
Circuit 2B!
Continue to circuit 2C and learn how to build your own game using buttons and LEDs.
BUZZER
D I G I TA L
TRUMPET
A
B
46 : circuit 2b
“ S I M O N S AY S ” G A M E
C
pattern, which the player must remember
100k
The “Simon Says” game uses LEDs to flash a
330
Circuit 2C: “Simon
Says” Game
and repeat using four buttons. This simple
electronic game has been a classic since the
late 1970s. Now you can build your own!
4 LEDS
POTENTIOMETER
PIEZO BUZZER
16 JUMPER WIRES
4 PUSH BUTTONS
4 330Ω
NEW CONCEPTS
FOR LOOPS: A for loop repeats a
YOU
NEED
RESISTORS
brackets, which prints the value of i to the
Serial Monitor.
section of code a set number of times. The
MEASURING DURATIONS OF TIME
loop works by using a counter (usually
WITH MILLIS(): The RedBoard has a
programmers use the letter “i” for this
built-in clock that keeps accurate time.
variable) that increases each loop until it
You can use the millis() command to
reaches a stop value. Here’s an example of
see how many milliseconds have passed
a simple for loop:
since the RedBoard was last powered. By
for (int i = 0; i < 5; i++){
Serial.print(i);
}
storing the time when an event happens
The for loop takes three parameters in
(and thus seconds) that have passed. This
the brackets, separated by semicolons. The
sketch uses this function to set a time limit
first parameter is the start value. In this
for repeating the pattern.
case, integer i starts at 0. The second value
is the stop condition. In this case, we stop
the loop when i is no longer less than 5 (i
< 5 is no longer true). The final parameter
and then subtracting the current time, you
can measure the number of milliseconds
CUSTOM FUNCTIONS: This sketch
uses several user-defined functions. These
functions perform operations that are
is an increment value. i++ is shorthand
needed many times in the program (for
for increase i by 1 each time, but you could
example, reading which button is currently
also increase i by different amounts. This
pressed or turning all of the LEDs off).
loop would repeat five times. Each time
Functions are essential to make more
it would run the code in between the
complex programs readable and compact.
47 : circuit 2c
HOOKUP GUIDE
READY TO START HOOKING EVERYTHING UP? Check out the circuit diagram and
hookup table below to see how everything is connected.
a
b
c
d
e
f
g
h
i
1
2
2
3
4
3
5
6
6
100k
7
8
8
330
9
9
10k
13
100k
3.3V
13
5V
GND
14
10k
GND
15
330
16
100k
17
VIN
16
17
18
A0
18
A1
A3
21
A4
22
22
A5
23
23
21
10k
100k
24
ON
A2
20
7
~6
~5
4
~3
2
TX 1
RX 0
ISP
19
330
20
ANALOG IN
19
SCL
SDA
AREF
GND
13
12
~11
~10
~9
8
DIGITAL (PWM~)
15
24
25
25
26
++ -–
RESET
12
POWER
14
IOREF
11
START SOMETHING
12
10
13
TX
RX
10
11
7-15V
4
10k
5
7
++ -–
j
1
RESET
++ -–
26
330
27
27
28
28
29
29
30
30
a
b
c
d
e
f
g
h
i
BUZZER
LEDS
POTENTIOMETER
PUSH BUTTONS
48 : circuit 2c
GND(-)
D10 to
F1
D9 to
D7 to
J13
D6 to
J18
D5 to
D3 to
J25
D2 to
J30
E2 to
J16 to
GND(-)
J10 to
GND(-)
H1(+) to
H7+ to
B1 +
J22 to
GND(-)
D8 to
D4 to
GND(-)
J28 to
E1 to
J12
J24
F3
GND(-)
H3(-)
H13+ to
H8–
B2 +
H14–
H19+ to
H20–
B3
G10/12
D16/18 to
G16/18
D22/24 to
G22/24
D28/30 to
G28/30
J26 to
J7
J19
D10/12 to
J8 to
330Ω RESISTOR
++ -–
j
GND to
JUMPER WIRES
F L AT E D G E
GND(-)
GND(-)
J14 to
GND(-)
J20 to
GND(-)
H25+ to
H26–
Open the Arduino IDE
Connect the RedBoard to a USB port on your computer.
Open the Sketch:
File > Examples > SIK_Guide_Code-V_4 > SIK_CIRCUIT_2C-SIMON SAYS
Select UPLOAD to program the sketch on the RedBoard.
W H AT Y O U
SHOULD SEE
The circuit will flash all of the LEDs
and play a melody. After a few
seconds, it will flash the first light
in the pattern. If you repeat the
pattern correctly by pressing the
corresponding colored button, then
the game will move to the next round
and add another color to the pattern
sequence. If you make a mistake, the
loss melody will play. If you get to
round 10, the win melody will play.
Press any button to start a new game.
PROGRAM OVERVIEW
Check if a new game is starting. If it is, play the start sequence. Reset the counter that keeps track of
1
rounds, and randomly generate a sequence of numbers from 0 to 3 that controls which LEDs the user will
have to remember.
The game works in rounds that progress from 0 to 10. Each round the game will flash LEDs in a pattern,
2
and then the player has to recreate the pattern by pressing the button(s) that match the LED(s). In the first
round, one LED will flash, and the player will have to press one button. In the eighth round, eight LEDs will
flash, and the player will have to press eight buttons.
3
A loop is used to flash LEDs from the sequence until you have flashed the number of LEDs that matches the
round number (1 for round 1, 2 for round 2, etc.).
49 : circuit 2c
Start a timer, and wait for the player to press a button.
The player has 1.5 seconds to press the correct button.
4
A: If the time limit runs out before a button is pressed, the player loses.
B: If the player presses the wrong button, the player loses.
C: If the player presses the right button, move on to the next number in the sequence.
D: Repeat this process until the player has lost or correctly repeated the sequence for this round.
5
If the player repeats the entire sequence for that round, increase the round number by one (this will add
6
Keep incrementing the round until the player loses or finishes 10 rounds. If the player finishes 10 rounds,
one extra item to the end of the pattern). Then go back to step 3.
play the winning sequence.
CODE TO NOTE
ELAPSED TIME:
millis();
The millis() function returns the number of milliseconds
that have passed since the RedBoard was last turned on.
The name for these variables comes from Boolean logic.
BOOLEAN
VARIABLES:
boolean variable_
name;
The boolean variable type only has two values: 1 or 0
(also known as HIGH or LOW, ON or OFF, TRUE or FALSE).
Using Boolean variables helps save memory on your
microcontroller if you only need to know if something is true
or false. Space in your microcontroller’s memory is reserved
when a variable is declared. How much memory is reserved
depends on the type of variable.
STORING PIN
NUMBERS
IN ARRAYS:
int led[ ] =
{3,5,7,9};
Sometimes you will want to cycle through all of the LEDs or
buttons connected to a project. You can do this by storing a
sequence of pin numbers in an array. The advantage of having
pins in an array instead of a sequence of variables is that you
can use a loop to easily cycle through each pin.
FUNCTIONS TO NOTE
flashLED(#LED
to flash);
50 : circuit 2c
This turns one of the four LEDs on and plays the tone associated
with it.
0 = Red, 1 = Yellow, 2 = Green, 3 = Blue.
FUNCTIONS TO NOTE
allLEDoff();
buttonCheck();
Turns all four LEDs off.
Uses digitalRead() to check which button is pressed. Returns 0, 1, 2
or 3 if one of the buttons is pressed. Returns 4 if no button is pressed.
Flashes the LEDs and plays tones in a sequence. Resets the round
startSequence();
counter and generates a new random sequence for the user to
remember.
winSequence();
loseSequence();
Plays a sequence of tones, turns all of the LEDs on, and then waits for
the player to press a button. If a button is pressed, restarts the game.
Plays a sequence of tones, turns all of the LEDs on, and then waits for
the player to press a button. If a button is pressed, restarts the game.
CODING CHALLENGES
CHANGE THE DIFFICULTY OF THE GAME: Change the difficulty of the game by
changing how fast the player has to press each button or by increasing or decreasing
the number of rounds needed to win. Note that if you increase the number of rounds to
be larger than 16, you will need to change the size of the array (it is set at the top of the
code in a line that looks like this: int buttonSequence[16];
).
CHANGE THE SOUND EFFECTS: Try changing the sequence of notes that plays
when you start, win or lose the game.
2-PLAYER MODE: Try changing the code so that two players can play head-to-head.
51 : circuit 2c
TROUBLESHOOTING
One of the LEDs isn’t
lighting up
The buzzer is too loud
or too quiet
Make sure your LED is oriented in the right direction. If the LED
still doesn’t work, try wiggling the resistor and the wires that
connect to the LED.
Turn the potentiometer to adjust the volume.
Carefully check your wiring for each button. One leg of the
One of the buttons isn’t
button should connect to a pin on the RedBoard; the other leg
working
should connect to the ground rail on the breadboard. Make sure
they are declared correctly.
None of the buttons or
LEDs are working
Make sure you don’t have 5V and GND mixed up. Double check
that you have a GND connection from the RedBoard to the GND
rail on the breadboard.
Jumper wires unfortunately can go “bad” from getting bent
too much. The copper wire inside can break, leaving an open
Still not working?
connection in your circuit. If you are certain that your circuit is
wired correctly and that your code is error-free and uploaded,
but you are still encountering issues, try replacing one or more
of the jumper wires for the component that is not working.
You’ve completed
Project 2!
Continue to Project 3 to explore using servos and sensors.
BUZZER
D I G I TA L
TRUMPET
A
B
52 : circuit 2c
“ S I M O N S AY S ” G A M E
C
SERVO MOTORS
D I S TA N C E S E N S O R
A
B
MOTION ALARM
C
PROJECT 3
Tired of your cat walking all over the
kitchen counter? How about the dog
getting into the garbage? Need a way to
stop your younger sibling from sneaking
into your bedroom? Learn how to protect
against all of these annoyances as you
build a multipurpose motion alarm. The
alarm detects distance and motion using
an ultrasonic distance sensor, and
creates motion using a servo motor.
NEW COMPONENTS INTRODUCED
IN THIS PROJECT
• S E RV O M OTO R
• U L T R A S O N I C D I S TA N C E S E N S O R
NEW CONCEPTS INTRODUCED
IN THIS PROJECT
• PWM DUTY CYCLE
• ARDUINO LIBRARIES
• OBJECTS AND METHODS
• D I G I TA L S E N S O R S
• D ATA S H E E T S
• SERVO MECHANISMS
YOU WILL LEARN
• H OW TO CO N T R O L A S E RV O M OTO R
• H O W T O U S E A N U L T R A S O N I C
D I S TA N C E S E N S O R
• H OW TO M OV E O BJ E C T S U S I N G
SERVO MECHANISMS
53 : circuit 3a
Circuit 3A: Servo
Motors
In this circuit, you will learn how to wire
a servo and control it with code. Servo
motors can be told to move to a specific
position and stay there. Low-cost servo
motors were originally used to steer RC
airplanes and cars, but they have become
popular for any project where precise
movement is needed.
YOU
NEED
POTENTIOMETER SERVO
8 JUMPER WIRES
SCISSORS
(NOT INCLUDED)
NEW COMPONENTS
SERVO MOTORS: Regular DC motors
have two wires. When you hook the wires
up to power, the motor spins around and
around. Servo motors, on the other hand,
have three wires: one
for power, one for
ground and one for
signal. When you send
the right signal through
the signal wire, the
servo will move to a
specific angle and stay
there. Common servos rotate over a range
of about 0° to 180°. The signal that is sent is
ATTACHING YOUR SERVO:
A strip of adhesive Dual LockTM
fastening tape is included in your kit.
Cut two pieces of it to temporarily
affix your servo to your baseplate.
a PWM signal, the same used to control the
NEW CONCEPTS
RGB LED in Project 1.
DUTY CYCLE: Pulse-Width Modulation
Included with
your servo motor
you will find a
variety of motor
mounts that
connect to the
shaft of your servo. You may choose to
attach any mount you wish for this circuit.
It will serve as a visual aid, making it easier
to see the servo spin. The mounts will also
be used at the end of this project.
54 : circuit 3a
(PWM) is a great way to generate servo
control signals. The length of time a PWM
signal is on is
referred to as
the duty cycle.
Duty cycle is
measured in
percentage.
Thus a duty cycle of 50 percent means the
signal is on 50 percent of the time. The
variation in the duty cycle is what tells the
servo which position to go to in its rotation.
ARDUINO LIBRARIES: Writing code
creating a servo object, like this:
that sends precise PWM signals to the
Servo myServo;
servo would be time consuming and
would require a lot more knowledge about
the servo. Luckily, the Arduino IDE has
hundreds of built-in and user-submitted
containers of code called libraries. One of
Objects look a lot like variables, but they
can do much more. Objects can store
values, and they can have their own
functions, which are called methods.
the built-in libraries, the Servo Library,
The most used method that a servo object
allows us to control a servo with just a few
has is .write():
lines of code!
To use one of the built-in Arduino libraries,
all you have to do is “include” a link to its
header file. A header file is a smaller code
file that contains definitions for all the
functions used in that library. By adding
myServo.write(90);
The write method takes one parameter, a
number from 0 to 180, and moves the servo
arm to the specified position (in this case,
degree 90).
a link to the header file in your code, you
Why would we want to go to the trouble of
are enabling your code to use all of those
making an object and a method instead of
library functions. To use the Servo Library,
just sending a servo control signal directly
you would add the following line to the top
over a pin? First, the servo object does the
of your sketch.
work of translating our desired position
#include
into a signal the servo can read. Second,
OBJECTS AND METHODS: To use the
and control more than one servo.
using objects makes it easy for us to add
Servo Library, you will have to start by
SERVO BASICS: Servo motor
connectors are polarized, but there
is no place to attach them directly.
Instead, connect three jumper
wires to the female 3-pin header
on the servo. This will make it so
you can connect the servo to the
breadboard. The servo wires are
color coded to make hookup simple.
GND
CONTROL
5V+
55 : circuit 3a
HOOKUP GUIDE
READY TO START HOOKING EVERYTHING UP? Check out the circuit diagram and
hookup table below to see how everything is connected.
b
c
d
e
f
g
h
i
++ -–
j
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
7-15V
RESET
12
3.3V
13
13
5V
14
14
15
15
16
16
17
17
18
18
19
19
A2
20
20
A3
21
21
A4
22
22
A5
23
23
24
24
25
25
26
26
27
27
28
28
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POTENTIOMETER
SERVO LEADS
56 : circuit 3a
A1
A0 to
E1 to
7
~6
~5
4
~3
2
TX 1
RX 0
++ -–
REDBOARD CONNECTION
CONNECTION TYPES
JUMPER WIRES
j
A0
ON
30
a
VIN
ISP
29
30
GND
ANALOG IN
29
GND
SCL
SDA
AREF
GND
13
12
~11
~10
~9
8
DIGITAL (PWM~)
IOREF
11
12
START SOMETHING
10
11
13
TX
RX
10
POWER
++ -–
a
1
RESET
++ -–
E2
5V to
5V (+)
B1 + B2+
BREADBOARD CONNECTION
5V(+)
E3 to
GND to
GND(–)
GND (-)
B3
WHITE WIRE to
D9
RED WIRE to
5V(+)
BLACK WIRE to
GND(–)
Open the Arduino IDE
Connect the RedBoard to a USB port on your computer.
Open the Sketch:
File > Examples >SIK_Guide_Code-V_4 > SIK_CIRCUIT_3A-SERVO
Select UPLOAD to program the sketch on the RedBoard.
W H AT Y O U
SHOULD SEE
Turning the potentiometer will
cause the servo arm to turn. The
servo will mimic the movement
of the potentiometer, twisting in
the same clockwise or counterclockwise direction. If you’ve
attached a servo mount to the arm
as shown, this movement will be
easier to see.
PROGRAM OVERVIEW
1
Read the value of the potentiometer.
2
Convert the potentiometer value (0–1023) to an angle (20–160).
3
Tell the servo to go to this angle.
CODE TO NOTE
The #include command adds a library to your
INCLUDING LIBRARIES:
Arduino program. After you include a library,
#include
you can use the commands in the library in your
program. This line adds the built-in Servo Library.
The Servo command creates a new servo object
CREATING SERVO OBJECTS:
and assigns a name to it, myServo in this case. If
Servo myServo;
you make more than one servo object, you will
need to give them different names.
57 : circuit 3a
CODE TO NOTE
The .attach(); method tells the servo
object to which pin the signal wire is
SERVO ATTACH:
attached. It will send position signals
myServo.attach(9);
to this pin. In this sketch, pin 9 is used.
Remember to only use digital pins that are
capable of PWM.
As shown in previous circuits, the analog
pin values on your microcontroller vary
from 0 to 1023. But what if we want those
values to control a servo motor that only
RANGE MAPPING:
accepts a value from 0 to 180? The map()
map(potPosition,0,1023,20,160);
function takes a range of values and
outputs a different range that can contain
more or fewer values than the original. In
this case, we are taking the range 0–1023
and mapping it to the range 20–160.
The .write(); method moves the servo
SERVO WRITE:
myServo.write(90);
to a specified angle. In this example, the
servo is being told to go to angle 90.
CODING CHALLENGES
REVERSE THE SERVO DIRECTION: Try making the servo move in the opposite
direction of the potentiometer.
CHANGE THE RANGE: Try altering the map function so that moving the potentiometer
a lot only moves the servo a little or vice versa.
SWAP IN A DIFFERENT SENSOR: Try swapping a light sensor in for the
potentiometer. Then you can make a dial that reads how much light is present!
58 : circuit 3a
TROUBLESHOOTING
The servo doesn’t
move
Check the wiring on your servo. Make sure the red wire on the
servo cord is connected to 5V, the black wire is connected to
GND and the white signal wire is connected to digital pin 9.
Although these servos are supposed to move from 0 to 180
The servo is
twitching
degrees, sometimes sending them to the extremes of their
range causes them to twitch (the servo is trying to move
farther than it can). Make sure you aren’t telling the servo to
move outside of the 20–160 degree range.
You’ve completed
Circuit 3A!
Continue to circuit 3B to learn about using distance sensors.
SERVO MOTORS
A
D I S TA N C E S E N S O R
B
MOTION ALARM
C
59 : circuit 3a
Circuit 3B:
Distance
Sensor
Distance sensors are amazing tools with
all kinds of uses. They can sense the
presence of an object, they can be used
10k
100k
330
in experiments to calculate speed and
acceleration, and they can be used in
robotics to avoid obstacles. This circuit will
walk you through the basics of using an
ultrasonic distance sensor, which measures
distance using sound waves!
TJP16
527BH
2
165 2
VCC
DISTANCE
SENSOR
T
Trig
RESISTORS
Echo
3 330Ω
RGB LED
GND
YOU
NEED
10 JUMPER WIRES
R
NEW COMPONENTS
the datasheet for the distance sensor. In
ULTRASONIC DISTANCE SENSOR:
Distance sensors work by sending pulses of
it, you can find the equation the program
needs to interpret the distance. View the
datasheet at http://sfe.io/HCSR04.
light or sound out from a transmitter, then
timing how long it takes for the signals to
ELSE IF STATEMENTS: In the night-
bounce off an object and return to a receiver
light circuit, you used an if/else statement
(just like sonar). Some sensors use infrared
to run one set of code when a logic
light, some use lasers, and some, like the
statement was true, and another when
HC-SR04 included in your kit, use ultrasonic
it was false. What if you wanted to have
sound (sound so high-pitched that you can’t
more than two options? Else if statements
hear it).
let you run as many logical tests as you
TJP16527BH2
want in one statement. For example, in the
code for this circuit, there is an if statement
that flows like this:
1. If the distance is less than 10, make
GND
Echo
Trig
T
VCC
1652
R
the RGB LED red.
2. Else if the distance is more than
NEW CONCEPTS
DATASHEETS: When working with
electronics, datasheets are your best
10 but less than 20, make the RGB LED
yellow.
3. Else make the RGB LED green.
friend. Datasheets contain all the relevant
To have four or five colors for different
information needed for a part. In this
distances, add more else if statements.
circuit, we are calculating distance based
on the time it takes sound waves to be
transmitted, bounce off an object and then
be received. But, how can we tell distance
from that information? The answer lies in
60 : circuit 3b
Else if statements are different from
nested if statements in that only one of
the statements above can be true, whereas
multiple nested if statements could be true.
HOOKUP GUIDE
READY TO START HOOKING EVERYTHING UP? Check out the circuit diagram and
hookup table below to see how everything is connected.
T
a
b
c
e
f
g
h
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j
1
2
2
VCC
3
4
Trig
4
5
Echo
6
GND
1652
3
++ -–
7-15V
5
6
7
T J P 1 6 5 2 7 B H 2
7
8
9
8
9
13
5V
14
14
15
15
16
16
17
17
18
18
19
19
A2
20
20
A3
21
21
A4
22
22
23
23
24
24
25
25
26
26
27
27
28
28
29
29
j
++ -–
POWER (5V)
TRIGGER PULSE INPUT:
ECHO PULSE OUTPUT:
GROUND (0V)
REDBOARD CONNECTION
CONNECTION TYPES
330Ω RESISTORS
(ORANGE, ORANGE,
BROWN)
D I S TA N C E S E N S O R
5V
GND to
GND (-)
D6 to
J22
D11 to
E4
E6 to
GND(–)
A25(RED) +
E22 to
F22
A3(VCC) +
E24 to
A24(GND) +
E23 to
A4(TRIG) +
Trig
Echo
GND
BREADBOARD CONNECTION
D3 to
D12 to
R
RGB LED
5V to
VCC
1652
F L AT S I D E
JUMPER WIRES
when connecting your circuit.
10k
i
polarized. Take note of the pin labels
10k
h
POLARITY: The distance sensor is
100k
g
A5
7
~6
~5
4
~3
2
TX 1
RX 0
100k
10k
f
330
e
330
100k
d
A1
ON
c
A0
ISP
b
VIN
ANALOG IN
30
a
GND
330
R
30
GND
SCL
SDA
AREF
GND
13
12
~11
~10
~9
8
DIGITAL (PWM~)
3.3V
13
T
RESET
12
START SOMETHING
IOREF
11
12
POWER
10
11
13
TX
RX
10
++ -–
d
1
RESET
++ -–
J25
E5
D5 to
E3 to
J23
5V (+)
GND(–)
A23(GREEN) +
F23
A5(ECHO) +
E25 to
A22(BLUE)
F25
A6(GND)
61 : circuit 3b
Open the Arduino IDE
Connect the RedBoard to a USB port on your computer.
Open the Sketch:
File > Examples > SIK_Guide_Code-V_4 > CIRCUIT_3B-DISTANCE SENSOR
Select UPLOAD to program the sketch on the RedBoard.
W H AT Y O U
SHOULD SEE
Move your hand or a large, flat
object closer and farther away
from the distance sensor. As the
object approaches, the light will
change from green to yellow to
red. Open the Arduino Serial
Monitor to see the distance
being read from the sensor.
PROGRAM OVERVIEW
Check what distance the sensor is reading.
1: If the distance is less than 10 inches, make the RGB LED red.
2: If the distance is between 10 and 20 inches, make the RGB LED yellow.
3: If the distance value is not equal to the fist two conditions, make the RGB LED green.
TROUBLESHOOTING WARNING: HVAC systems in offices and schools have
been known to interfere with the performance of the ultrasonic distance sensor. If
you are experiencing sporadic behavior from your circuit, check your surroundings.
If there are numerous air ducts in the room you are using, try moving to a different
room that does not have ducts. The airflow from these ducts can interfere with the
waves sent from the sensor, creating noise and resulting in bad readings.
62 : circuit 3b
CODE TO NOTE
The float variable, short for floating-point
number, is similar to an integer except it can
FLOAT VARIABLES:
float echoTime;
represent numbers that contain a decimal point.
Floats are good for representing values that need
to be more precise than an integer. Floats allow us
to measure precise distances such as 9.33 inches
instead of just 9 inches.
ELSE IF STATEMENT:
if(logic statement){
//run if first is true
}
else if(second logic
statement){
//run if second is true
}
else{
//run if neither is true
}
Else if statements let you combine more than
one logic statement. Arduino will test each logic
statement in order; if one is true it will run the code
in that section and then skip all of the other sections
of code in the remaining statements.
This function tells the distance sensor to send out
an ultrasonic wave form, measures the time it takes
USER-DEFINED FUNCTION:
to bounce back to the sensor, and then calculates
getDistance();
the distance based on the speed of sound. This
calculation is based off information found in the
distance sensor’s datasheet.
CODING CHALLENGES
CHANGE THE LIMITS OF THE DISTANCE SENSOR: Try editing the values in the
logic statements so that the RGB LED changes color at different distances.
CHANGE THE UNITS OF THE DISTANCE SENSOR: Try editing the code so that the
distance sensor outputs a different unit of length, such as centimeters or feet.
ADD A FOURTH COLOR: Try adding another else if statement so that there are four
different colors instead of three.
63 : circuit 3b
TROUBLESHOOTING
The RGB LED colors aren’t
working or a color is missing
Check the connection for the wire and resistor
connected to each leg of the LED. Ensure the RGB LED is
inserted in the correct orientation.
Open up the Serial Monitor on your computer. You
The distance sensor doesn’t
should see a stream of distances being printed in the
seem to work
monitor. If they are all reading 0 or jumping around,
then check the wiring on your sensor.
Ultrasonic noise pollution will interfere with your
distance sensor readings. If you aim two distance
The distance sensor still
doesn’t work
sensors at each other, they will confuse each other.
Some air-conditioning systems may also emit noises
in the ultrasonic range. Try pointing your sensor
away from the other distance sensors or changing to a
different location.
You’ve completed
Circuit 3B!
Continue to circuit 3C to explore building mechanisms that interact with your circuits.
SERVO MOTORS
A
64 : circuit 3b
D I S TA N C E S E N S O R
B
MOTION ALARM
C
Circuit 3C:
Motion Alarm
Time to take your distance sensor project
to the next level. Let’s imagine you want to
stop your cat from prowling around your
countertop. This circuit uses light, sound
and motion to scare away your cat when it
is detected by the distance sensor. Using a
servo motor, you can add a moving pop-up
to animate your alarm.
3 330Ω
RGB LED
RESISTORS
PIEZO BUZZER
15 JUMPER WIRES
YOU
NEED
SERVO
TJP16
T
VCC
(NOT INCLUDED)
527BH
2
DISTANCE 165
SENSOR
2
Trig
PAPER SCISSORS
Echo
MARKERS/PEN
GND
TAPE PAPER CLIP NEEDLE-NOSE PLIERS
330
100k
10k
R
NEW CONCEPTS
ASSEMBLY
MECHANISMS: This circuit gets really
If you have opted for the extra materials,
fun when you start to use your servo to
use the following instructions to create the
animate the world around you. To do
moving pop-up for your motion alarm.
this, you’ll need to connect your servo to
some physical mechanisms. Tape and hot
glue are easy ways to connect things to
your servo. You can also loop a paper clip
through the small holes in the servo arm to
serve as a linkage.
1. Attach the servo mount of your choice.
The motor mounts also come with screws
to secure the mount to the motor. Once
you are finished with this circuit, you may
choose to add a screw to make for a more
robust mechanism. It is recommended you
upload your code and test the mechanism
before screwing it down.
2. Use needle-nose pliers to bend the
paper clip straight. Bend about 1 inch
of the paper clip 90 degrees. Then bend
the other end so it’s about 1/8 inch long.
Repeat this bend once more, making
a hook shape. You should now have a
linkage rod that looks something like this:
Linkage rods are found on many RC
airplanes, which use servo motors to
control the ailerons, elevators and
rudder.
65 : circuit 3c
3. Attach the hook end of the
linkage rod to the end hole on your
servo mount. The motor should be
reattached to the baseplate with
Dual Lock.
4. Cut out the pop-up image of
your choice. We chose this public
domain menacing cat image
(http://sfe.io/cat). The image you
choose should be about 2.5 inches
x 2.5 inches and can be drawn or
printed. Leave a rectangular strip of paper under the image that is about 2 inches long.
5. Fold along the bottom of the image. Tape the bottom of the
pop-up to the underside of the breadboard baseplate on the
same side to which the servo is connected.
6. Tape the free end of the rod to the back
of your pop-up image, near the center.
7. Once you have the rest of the circuit built and the code
uploaded, you can fine-tune your moving pop-up and make
any necessary adjustments. Remember to wait until these
adjustments have been made before you screw the servo
mount onto the motor.
66 : circuit 3c
HOOKUP GUIDE
READY TO START HOOKING EVERYTHING UP? Check out the circuit diagram and
hookup table below to see how everything is connected.
T
a
b
d
e
f
g
h
i
++ -–
j
2
3VCC
3
4Trig
4
1652
1
2
5Echo
7-15V
5
6
7
7
T J P 1 6 5 2 7 B H 2
6GND
8
9
11
9
10
IOREF
5V
14
14
15
15
16
16
17
17
18
18
19
19
A2
20
20
A3
21
21
A4
22
22
A5
23
23
24
24
25
25
26
26
27
27
28
28
j
++ -–
10k
i
10k
h
100k
g
100k
10k
f
330
e
7
~6
~5
4
~3
2
TX 1
RX 0
330
100k
d
A1
330
c
A0
ON
30
b
VIN
ISP
29
30
GND
ANALOG IN
29
GND
DIGITAL (PWM~)
13
START SOMETHING
3.3V
13
POWER
RESET
12
R
11
12
a
SCL
SDA
AREF
GND
13
12
~11
~10
~9
8
8
13
TX
RX
10
++ -–
c
1
RESET
++ -–
F L AT S I D E
JUMPER WIRES
RGB LED
330Ω RESISTORS
(ORANGE, ORANGE,
BROWN)
D I S TA N C E S E N S O R
PIEZO BUZZER
SERVO LEADS
5V to
5V
GND to
GND (-)
D6 to
J22
D11 to
E4
E3 to
5V (+)
A25(RED) +
E22 to
A24(GND)+
F22
A3(VCC)+
F14 (+)+
E6 to
E23 to
A4(TRIG)+
D3 to
D12 to
GND(–)
A5(ECHO)+
E5
E24 to
A23(GREEN)+
F23
J25
E25 to
D5 to
D10 to
GND(–)
J23
J14
J16 to
GND(–)
A22(BLUE)
F25
A6(GND)
F16(-)
WHITE WIRE to
D9
RED WIRE to
5V(+)
BLACK WIRE to
GND(–)
67 : circuit 3c
Open the Arduino IDE
Connect the RedBoard to a USB port on your computer.
Open the Sketch:
File > Examples > SIK_Guide_Code-V_4 > SIK_CIRCUIT_3C-MOTION ALARM
Select Upload to program the sketch on the RedBoard.
W H AT Y O U
SHOULD SEE
The RGB LED will behave as in
your last circuit. It will be green
when objects are far, yellow
when they are midrange and
red when they are close. When
an object is close, the buzzer
will also beep, and the servo
will rotate back and forth. If you
decided to attach a pop-up, it
will move back and forth.
PROGRAM OVERVIEW
Check what distance the sensor is reading.
1: If the distance is less than 10 inches, make the RGB LED red. Then make the servo rotate back and
forth and make the buzzer beep.
2: If the distance is between 10 and 20 inches, make the RGB LED yellow.
3: If the distance value is not equal to the fist two conditions, make the RGB LED green.
CODE TO NOTE
CONSTANTS:
const int trigPin
= 11;
68 : circuit 3c
Constants are variables that have been marked as “read-only”
and cannot have their value changed as the program progresses.
Constants are great for declaring pin number variables that will
not change throughout the program.
CODE TO NOTE
In circuit 2A, you made songs using a buzzer and the tone()
function, but you gave the function three parameters: a pin
NO TONE
number, a frequency and a duration. You can leave out the third
FUNCTION:
noTone(pin_number);
parameter, and the tone will play until you change it or turn it
off. noTone() turns off a pin that has been activated with the
tone() command.
CODING CHALLENGES
CHANGE THE SERVO BEHAVIOR: Try changing the way your servo behaves
when the distance sensor is triggered.
CHANGE THE ALARM SETTINGS: Try altering the code so the alarm goes off
from much farther or closer distances.
ADD A SECOND MECHANISM: Time to use your imagination! Try your hand
at making different objects move with your servo motor. Don’t have a cat? Make an
interactive pop-up story, room alarm, treat dispenser or automatic fish feeder.
TROUBLESHOOTING
The RGB LED colors aren’t
Check the connection for the wire and resistor connected to
working or a color is
each leg of the LED. Ensure the RGB LED is inserted in the
missing
correct orientation.
Open up the Serial Monitor on your computer. You should
The distance sensor
see a stream of distances being printed in the monitor. If
doesn’t seem to work
they are all reading 0 or jumping around, check the wiring
on your sensor.
Ultrasonic noise pollution will interfere with your
distance sensor readings. If you aim two distance
The distance sensor still
doesn’t work
sensors at each other, they will confuse each other.
Some air-conditioning systems may also emit noises
in the ultrasonic range. Try pointing your sensor
away from the other distance sensors or moving to a
different location.
69 : circuit 3c
TROUBLESHOOTING
Make sure all of your servo wires are connected. Be
sure that the black wire is connected to the negative
The servo doesn’t work
rail and the red wire is connected to the positive rail.
Make sure you are using a digital pin that is capable
of PWM.
The two lines of code that pass angles to the servo
The pop-up is moving too much
motor are myservo.write(45); and myservo.
or not enough
write(135);. Try changing these angle values to
fine-tune your mechanism.
You’ve completed
Circuit 3C!
Continue to Project 4 to learn how to use an LCD in your circuits.
SERVO MOTORS
A
70 : circuit 3c
D I S TA N C E
SENSOR
B
MOTION ALARM
C
LCD “HELLO, WORLD!”
T E M P E R AT U R E S E N S O R
A
“DIY WHO AM I?”
GAME
B
C
PROJECT 4
Printing data to the Arduino Serial
Monitor is a great way to see data from the
RedBoard. But, what if you want to make
your project mobile and see sensor values
away from your computer? This project
will show you how to do exactly that. You’ll
learn about Liquid Crystal Displays
(LCDs) and how to print things like sensor
data and strings of words to the display.
NEW COMPONENTS INTRODUCED
IN THIS PROJECT
• L I Q U I D C R Y S TA L D I S P L A Y ( L C D )
• T M P 3 6 D I G I TA L T E M P E R AT U R E
SENSOR
• 4 X A A B AT T E R Y H O L D E R
NEW CONCEPTS INTRODUCED
IN THIS PROJECT
• CONTRAST
• PIXELS
• ALGORITHMS
• B U T TO N D E B O U N C E
• STRINGS
• POINTERS
YOU WILL LEARN
• H OW TO P R I N T S I M P L E M E S SAG E S
TO A N L C D
• H O W T O U S E A T E M P E R AT U R E
SENSOR
• H O W T O P R I N T S E N S O R D ATA T O
AN LCD
• H OW TO M A K E A N I N T E R AC T I V E
G A M E T H AT I N C O R P O R AT E S T H E
LCD
71 : circuit 4a
Circuit 4A: LCD
“Hello, World!”
Printing “Hello, world!” is usually the first
thing that programming tutorials will have
you do in a new language. This guide starts
by blinking an LED, but now we’re going
to print out real text using a Liquid Crystal
Display (LCD).
YOU
NEED
LCD DISPLAY
POTENTIOMETER
NEW COMPONENTS
CHARACTER LIQUID CRYSTAL
DISPLAY (LCD): Designed to show a
grid of letters, numbers and other special
characters, LCDs are great for printing
data and showing values. When current
is applied to this special kind of crystal,
it turns opaque. This is used in a lot of
calculators, watches and simple displays.
Adding an LCD to your project will make it
16 JUMPER WIRES
a potentiometer, the contrast can be
adjusted. As you rotate the knob on the
potentiometer, you should notice that the
screen will get brighter or darker and that
the characters become more visible or
less visible. The contrast of LCDs is highly
dependent on factors such as temperature
and the voltage used to power them. Thus,
external contrast knobs are needed for
displays that cannot automatically account
for temperature and voltage changes.
super portable and allow you to integrate
up to 32 characters (16x2) of information.
PIXELS: If you look closely at the
characters on the LCD, you will notice
that they are actually made up of lots of
little squares. These little squares are
called pixels. The size of displays is often
represented in pixels. Pixels make up
character space, which is the number of
pixels in which a character can exist.
NEW CONCEPTS
CONTRAST: Pin 3 on the LCD controls
the contrast and brightness of the LCD.
Using a simple voltage divider with
72 : circuit 4a
Here is a capital letter B as
created in pixels. The
character space in this
example is 6 pixels x 8 pixels.
HOOKUP GUIDE
READY TO START HOOKING EVERYTHING UP? Check out the circuit diagram and
hookup table below to see how everything is connected.
b
c
d
e
f
g
h
i
++ -–
j
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
7-15V
RESET
12
3.3V
13
13
5V
14
14
15
15
16
16
17
17
18
18
19
19
A2
20
20
A3
21
21
A4
22
22
A5
23
23
24
24
25
25
26
26
27
27
28
28
29
29
30
30
d
e
5V to
JUMPER WIRES
L C D D I S P L AY
POTENTIOMETER
f
g
h
i
5V
j
A0
A1
ON
c
VIN
ISP
b
GND
ANALOG IN
a
GND
SCL
SDA
AREF
GND
13
12
~11
~10
~9
8
DIGITAL (PWM~)
IOREF
11
12
START SOMETHING
10
11
13
TX
RX
10
POWER
++ -–
a
1
RESET
++ -–
7
~6
~5
4
~3
2
TX 1
RX 0
KNOW YOUR
LCD PINS
1 Ground
2 VDD(5V)
3 Pin3 Contrast adjust (0–5V)
4 Register Select
5 Read/Write Select
6 Enable
7 Data lines d0 (not used)
8 Data lines d1 (not used)
9 Data lines d2 (not used)
10 Data lines d3 (not used)
11 Data lines d4 (4-bit data transfer)
12 Data lines d5 (4-bit data transfer)
13 Data lines d6 (4-bit data transfer)
14 Data lines d7 (4-bit data transfer)
15 Backlight power (5V)
16 Backlight Ground (GND)
++ -–
GND to
GND (-)
D10 to
E26
D11 to
E25
E30 to
GND (-)
E29 to
E15 to
GND (-)
E9 to
5V(+)
E17
D8 to
D12 to
E28
E20
E19 to
E8 to
D9 to
E27
D13 to
E18
GND (-)
GND (-)
E16 to
E10 to
5V(+)
5V(+)
A15-A30 (pin 1 on A15)
A8 +
A9 +
A10
73 : circuit 4a
Open the Arduino IDE
Connect the RedBoard to a USB port on your computer.
Open the Sketch:
File > Examples > SIK_Guide_Code-V_4 > CIRCUIT_4A-LCD HELLO WORLD
Select UPLOAD to program the sketch on the RedBoard.
W H AT Y O U
SHOULD SEE
The LCD screen will show
“Hello, world!” and on the row
below a counter will count
every second that passes.
Adjusting the potentiometer
will change the contrast on the
LCD screen.
PROGRAM OVERVIEW
1
Import the LCD library.
2
Make an LCD object called “lcd” that will be controlled using pins 8, 9, 10, 11, 12 and 13.
3
“Begin” the LCD. This sets the dimensions of the LCD that you are working with (16 x 2). It needs to be
called before any other commands from the LCD library are used.
4
Clear the display.
5
Set the cursor to the top left corner lcd.setCursor(0,0); then print “Hello, world!"
6
Move the cursor to the first space of the lower line lcd.setCursor(0,1); then print the number of
seconds that have passed since the RedBoard was last reset.
74 : circuit 4a
CODE TO NOTE
LCD LIBRARY:
Includes the LiquidCrystal library in your
#include
program.
As with servos, you need to create an LCD
LCD LIBRARY INSTANCE:
object and give it a name (you can make
LiquidCrystal LCD_name(RS_pin,
enable_pin, d4, d5, d6, d7);
more than one). The numbers in the brackets
are pins on the RedBoard that connect to
specific pins on the LCD.
This line initializes the LCD object and tells
LCD BEGIN:
the program the LCD’s dimensions. In this
lcd.begin(16, 2);
case it is 2 rows of 16 characters each.
LCD CLEAR:
This method clears all the pixels on the
lcd.clear();
display.
Moves the cursor to a point on the 16x2 grid
LCD CURSOR:
of characters. Text that you write to the LCD
lcd.setCursor(0,0);
will start from the cursor. This line is starting
back at position (0,0).
LCD PRINT:
Prints a string of characters to the LCD
lcd.print(“Hello, world!”);
starting at the cursor position.
CODING CHALLENGES
CHANGE THE MESSAGE: Try changing the code to display another message.
SHOW HOURS, MINUTES AND SECONDS: Try adding some code so that the
display shows the hours, minutes and seconds that have passed since the RedBoard
was last reset.
COUNT BUTTON PRESSES: By adding a button to the circuit, you can count the
number of times the button was pressed or have the button change what displays.
75 : circuit 4a
TROUBLESHOOTING
Adjust the contrast by twisting the potentiometer. Try both
The screen is blank or
directions until you see characters display. Do not twist
flickering
the potentiometer past its stopping points. Also, check the
potentiometer, and make sure it's wired correctly.
Not working at all
Double check the circuit’s wiring. There are a lot of wires in
this circuit, and it’s easy to mix up one or two.
If you see 16 rectangles (like “
”) on the first row, it may be
due to the jumper wires being loose on the breadboard. This is
Rectangles in first row
normal and can happen with other LCDs wired in parallel with
a microcontroller. Make sure that the wires are fully inserted
into the breadboard, then try pressing the reset button and
adjusting the contrast using the potentiometer.
Jumper wires unfortunately can go “bad” from getting bent
too much. The copper wire inside can break, leaving an open
Still not working?
connection in your circuit. If you’re certain that your circuit is
wired correctly and that your code is error-free and uploaded
but you are still encountering issues, try replacing one or more
of the jumper wires for the component that is not working.
You’ve completed
Circuit 4A!
Continue to circuit 4B to learn about using temperature sensors.
LCD “HELLO, WORLD”
A
76 : circuit 4a
T E M P E R AT U R E S E N S O R
B
“DIY WHO AM I” GAME
C
Circuit 4B:
Temperature
Sensor
Want to create a DIY environmental
monitor or weather station? You can use
a small, low-cost sensor like the TMP36
to make devices that track and respond
to temperature. In this activity you will
also use the LCD screen to display sensor
readings, a common use for LCDs in
electronics projects.
TMP
LCD DISPLAY
POTENTIOMETER
TEMPERATURE SENSOR
NEW COMPONENTS
TMP36 TEMPERATURE SENSOR:
This temperature sensor has three legs.
One connects to 5V, one to ground, and the
voltage output from the third leg varies
19 JUMPER WIRES
YOU
NEED
voltage = analogRead(A0) * 0.004882814;
The number we are multiplying by comes
from dividing 5V by the number of samples
the analog pin can read (1024), so we get:
5 / 1024 = 0.004882814.
proportionally to changes in temperature.
By doing some simple math with this
The second formula takes that 0–5V value
voltage, we can measure temperature in
and calculates degrees Celsius:
degrees Celsius or Fahrenheit.
degreesC = (voltage - 0.5) * 100.0;
TMP
The reason 0.5V is subtracted from the
calculated voltage is because there is a 0.5V
offset, mentioned on page 8 of the TMP36
NEW CONCEPTS
ALGORITHMS: An algorithm is a process
used in order to achieve a desired result.
datasheet found here: http://sfe.io/TMP36.
It’s then multiplied by 100 to get a value
that matches temperature.
Often, the information needed to create
The last formula takes the Celsius
an algorithm lives in the part’s datasheet.
temperature and converts it to a
This sketch uses a few formulas to turn
Fahrenheit temperature using the standard
a voltage value into a temperature
conversion formula:
value, making them all part of the larger
degreesF = degreesC * (9.0/5.0) + 32.0;
temperature-retrieving algorithm. The first
formula takes the voltage read on analog
Together, these three formulas make up the
pin 0 and multiplies it to get a voltage value
algorithm that converts voltage to degrees
from 0V–5V:
Fahrenheit.
77 : circuit 4b
HOOKUP GUIDE
READY TO START HOOKING EVERYTHING UP? Check out the circuit diagram and
hookup table below to see how everything is connected.
TMP
b
c
d
e
f
g
h
i
j
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
++ -–
7-15V
RESET
12
3.3V
13
13
5V
14
14
15
15
16
16
17
17
18
18
19
19
A2
20
20
A3
21
21
A4
22
22
A5
23
23
24
24
25
25
26
26
27
27
28
28
b
c
d
e
f
g
h
i
j
A0
A1
ON
30
a
VIN
ISP
29
30
GND
ANALOG IN
29
GND
SCL
SDA
AREF
GND
13
12
~11
~10
~9
8
DIGITAL (PWM~)
IOREF
11
12
START SOMETHING
10
11
13
TX
RX
10
POWER
++ -–
a
1
RESET
++ -–
7
~6
~5
4
~3
2
TX 1
RX 0
HEADS UP! Double check
++ -–
the polarity of the TMP36
temperature sensor before
powering the RedBoard. It can
V+
GND
5V to
D10 to
JUMPER WIRES
LCD SCREEN
TMP36 SENSOR
POTENTIOMETER
78 : circuit 4b
A0 to
become very hot if it is inserted
TMP
SIGNAL
5V
GND to
E26
GND(-)
D8 to
E28
D9 to
E25
D12 to
E20
D13 to
GND(-)
E29 to
5V(+)
D11 to
E2
E30 to
backward!
E16 to
5V(+)
E15 to
E10 to
5V(+)
E1 to
GND(-)
GND(-)
A15-A30 (pin 1 on A15)
A1 (GND) +
A2 (SIG) +
A8 +
A10
A9 +
A3(5V)
E9 to
E3 to
E17
5V(+)
E27
E19 to
E8 to
E18
GND(-)
GND(-)
Open the Arduino IDE
Connect the RedBoard to a USB port on your computer.
Open the Sketch:
File > Examples > SIK_Guide_Code-V_4 > SIK_CIRCUIT_4B-TEMPERATURE SENSOR
Select UPLOAD to program the sketch on the RedBoard.
W H AT Y O U
SHOULD SEE
The LCD will show the temperature
in Celsius and Fahrenheit. The
temperature readings will update
every second. An easy way to see the
temperature change is to press your
finger to the sensor.
PROGRAM OVERVIEW
1
Get the analog value from the TMP36 and convert it back to a voltage between 0 and 5V.
2
Calculate the degrees Celsius from this voltage.
3
Calculate the degrees Fahrenheit from this voltage.
4
Clear the LCD.
5
Print the degrees C with a label on the first row.
6
Print the degrees F with a label on the second row.
7
Wait for a second before taking the next reading.
79 : circuit 4b
CODE TO NOTE
Many of the sensors that you will use with your microcontroller
work by changing a voltage in some predictable way in response to
a property of the world (like temperature, light or magnetic fields).
VOLTAGE
CONVERSION
ALGORITHMS
Often, you will need to build an algorithm that converts these
voltages to the desired value and units. The temperature sensor is
a great example of this code. We use three equations to convert a
voltage value into degrees in C and F.
voltage = analogRead(A0) * 0.004882814;
degreesC = (voltage - 0.5) * 100.0;
degreesF = degreesC * (9.0/5.0) + 32.0;
CODING CHALLENGES
DISPLAY THE TEMPERATURE IN DEGREES KELVIN: Try adding an equation so
that the temperature is displayed in degrees Kelvin. (You will have to look up the formula
for converting from degrees Celsius or Fahrenheit to Kelvin.)
DISPLAY A BAR GRAPH: By changing the code you can display the temperature as a
bar graph instead of a number.
DISPLAY VALUES FROM ANOTHER SENSOR: You can swap out the TMP36 for a
potentiometer, photoresistor or other sensor and display the new set of values.
ADD AN RGB LED: Add an RGB LED that changes color based on the temperature.
80 : circuit 4b
TROUBLESHOOTING
Make sure that you wired the temperature sensor correctly.
Sensor is
The temperature sensor can get warm to the touch if it is wired
heating up
incorrectly. Disconnect power from your microcontroller, rewire
the circuit, and connect it back to your computer.
Temperature
Try pinching the sensor with your fingers to heat it up or pressing
value is
a bag of ice against it to cool it down. Also, make sure that the
unchanging
wires are connected properly to the temperature sensor.
Values not
printing to
screen
If you see text but no temperature values, there could be an error
in your code. If you see no text at all, adjust the LCD contrast.
You’ve completed
Circuit 4B!
Continue to circuit 4C to learn how to make a “DIY Who Am I?” game.
LCD “HELLO, WORLD”
A
T E M P E R AT U R E S E N S O R
B
“DIY WHO AM I?” GAME
C
81 : circuit 4b
Circuit 4C: “DIY
Who Am I?”
Game
“DIY Who Am I?” is based on the popular
Hedbanz game or HeadsUp! app. It’s a fun
party game in which a player holds an
LCD screen to his/her forehead, and other
players give hints to help the player with
the LCD guess the word on the screen.
YOU
NEED
LCD DISPLAY
POTENTIOMETER
AA BATTERY HOLDER
PUSH BUTTON
DUAL LOCK TAPE
PIEZO BUZZER
20 JUMPER WIRES
4 AA BATTERIES SCISSORS
(NOT INCLUDED)
NEW COMPONENTS
4XAA BATTERY HOLDER: Included in
This simple addition will prevent a word
from getting skipped when you press the
button for the game.
your kit is a 4-cell AA battery holder. The
5-inch cable is
For a more complex example of button
terminated with
debouncing, in the Arduino IDE open File >
a standard barrel
Examples > 02.Digital > Debounce.
jack connector.
STRINGS: Strings are used to print words
The connector
mates with the
barrel jack on
the RedBoard, allowing you to easily make
your project battery powered.
NEW CONCEPTS
BUTTON DEBOUNCE: When working
with momentary buttons, it is usually
necessary to add button debouncing to
your code. This is because the code that
is meant to execute when the button
is pressed may execute faster than
you can press and release the button
(microcontrollers are fast!). The simplest
and even sentences to an LCD or the Serial
Monitor. Strings are actually just an array
of characters with a null character at the
end to let the program know where the end
of the string is.
ARRAY OF STRINGS: In circuit
2A you used an array of characters to
represent musical notes. In this program,
you’ll want to make an array of strings.
Strings use multiple characters to make
words, so you’ll need to use a little trick
to put them in an array. The trick is to use
a pointer. When you declare your array,
you’ll use an asterisk (*) after the char
data type, as follows:
way to debounce a button is to add a
small delay to the end of your code. This
sketch adds a 500 millisecond delay at
the end of loop() to account for this.
82 : circuit 4c
const char* arrayOfStrings =
{“Feynman” “Sagan”, “Tyson”,
“Nye”};
POINTERS: As an advanced
programming topic, pointers can be
difficult to understand at first. For now,
think of pointers as a variable that
“points” to the value contained in a certain
address in memory. In this sketch, the
char* variable points to arrayOfStrings
address and returns the character values to
create a list of strings.
BATTERY HOLDER
ASSEMBLY
Batteries are polarized. They have a
positive end and a negative end. The
battery holder has images indicating which
end goes in which orientation for each cell.
To attach the battery holder to the
breadboard baseplate, first cut two strips of
Dual Lock that are roughly 1 inch x 1 inch
each, or 2.5cm x 2.5cm.
Remove the adhesive backing, and attach
one piece to the back of the battery holder.
Adhere the second piece to the bottom of
the breadboard baseplate (directly in the
middle is recommended, as this will come
into play in Project 5).
Last, press the battery holder to the
baseplate so that the two pieces of Dual
Lock snap together. Insert the batteries into
the holder. Remember that batteries are
polarized. Remove the pack before building
the circuit, so it doesn’t slide around.
STOP!
Disconnect the battery pack from
power while building your circuit.
Working on your circuit while
connected to a power source risks
damaging your components.
83 : circuit 4c
HOOKUP GUIDE
READY TO START HOOKING EVERYTHING UP? Check out the circuit diagram and
hookup table below to see how everything is connected.
b
c
d
e
f
g
h
i
++ -–
j
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
7-15V
RESET
12
3.3V
13
13
5V
14
14
15
15
16
16
17
17
18
18
19
19
A2
20
20
A3
21
21
A4
22
22
A5
23
23
24
24
25
25
26
26
27
27
28
28
GND
VIN
A0
A1
b
c
d
e
f
g
h
5V to
JUMPER WIRES
PUSH BUTTON
POTENTIOMETER
BUZZER
84 : circuit 4c
j
5V
GND to
D10 to
E26
D6 to
J6
E19 to
GND(-)
E8 to
LCD SCREEN
i
D2 to
G6(+) to
G1/G3
A9 to
A10
G8(–)
E25
J1
E16 to
E10 to
A15-A30 (pin 1 on A15)
A8 to
GND(-)
D11 to
GND(-)
D1/D3 to
ON
++ -–
30
a
7
~6
~5
4
~3
2
TX 1
RX 0
ISP
29
30
ANALOG IN
29
GND
SCL
SDA
AREF
GND
13
12
~11
~10
~9
8
DIGITAL (PWM~)
IOREF
11
12
START SOMETHING
10
11
13
TX
RX
10
POWER
++ -–
a
1
RESET
++ -–
D8 to
E28
D9 to
D12 to
E20
D13 to
E30 to
5V(+)
5V(+)
GND(-)
E15 to
J8 to
E29 to
GND(-)
GND(-)
E27
E18
5V(+)
E9 to
J3 to
E17
GND(-)
Open the Arduino IDE
Connect the RedBoard to a USB port on your computer.
Open the Sketch:
File > Examples > SIK_Guide_Code-V_4 > SIK_CIRCUIT_4C-DIY WHO AM I
Select UPLOAD to program the sketch on the RedBoard.
W H AT Y O U
SHOULD SEE
The game begins with the category
of words, then runs through a short
countdown. When the first round starts,
the word to be guessed is displayed at
top left, and a countdown starts in the
bottom right. Each time the button is
pressed (before the timer expires) a new
word is displayed. If you win or lose, a
short song will play.
PROGRAM OVERVIEW
1
Generate a random order for the words to be displayed.
2
Show the starting countdown on the LCD.
Start a loop that will run 25 times (there are 25 words total). For each round:
A: Print the round number and the word to be guessed.
B: Display a countdown timer in the lower right-hand corner
3
of the screen that counts down the time limit for each round.
C: If the time limit runs out, play the losing song, print
“Game Over” and show the player’s final score.
D: If the player presses the button before the
time limit is up, advance to the next word.
4
If the player gets through all 25 words, play the winning song and print “YOU WIN!”
85 : circuit 4c
CODE TO NOTE
ARRAY OF STRINGS:
Makes an array of strings. The strings are stored
const char* array_name [array_
length] =
as constants, so they can’t be changed once the
program starts.
{“string1”, “string2”...};
ROUNDING FUNCTION:
This math function rounds a number up or down to
round(value_to_round);
the nearest whole number.
RANDOM FUNCTION:
This function takes a set of numbers and generates
random(min, max);
a pseudo-random number from that set.
BUTTON DEBOUNCE:
delay(500);
USER FUN
This 500 millisecond delay at the end of the loop
adds button debounce so that erroneous button
presses are not detected by the RedBoard.
FUNCTIONS TO NOTE CTIONS
Makes an array that is a random ordering of the
generateRandomOrder();
numbers from 1–25. This is used to display words
for the game in a random order.
showStartSequence();
gameOver();
winner();
86 : circuit 4c
Shows the category of words on the LCD, then
displays a countdown before the game starts.
Plays a sound and shows the text “Game Over”
along with the player’s final score.
Shows the text “YOU WIN!” and
plays a winning sound.
CODING CHALLENGES
CHANGE THE TIME LIMIT: Changing the time limit variable will change the
difficulty of the game.
CHANGE THE WORDS IN THE WORD LIST: Try changing the categories and
words. The number of words in your words array must match the value of the variable
arraySize
.
CHANGE THE WINNING AND LOSING SONGS: By changing the tones in the
winner()
and gameover()
functions you can change which song plays at the
end of the game.
TROUBLESHOOTING
Adjust the contrast by twisting the potentiometer. If it’s
The screen is blank or
incorrectly adjusted, you won’t be able to read the text.
flickering
Also, check the potentiometer to make sure it’s connected
correctly.
No sound is coming from
the buzzer
The button doesn't work
or words are getting
skipped before they are
guessed
Check the wiring to the buzzer and the polarity. Make sure
you are using the correct pin as defined in your code. You
may add a potentiometer volume knob if you desire.
If the button isn’t working, check your wiring. If words
are being skipped when the button is pressed, increase the
debounce delay found at the end of the loop. It should be
500 milliseconds by default. Increasing this number by tiny
increments will help with this problem.
You’ve completed
Circuit 4C!
Continue to Project 5 to learn how to build your first robot!
LCD “HELLO, WORLD”
A
T E M P E R AT U R E S E N S O R
B
“DIY WHO AM I?”GAME
C
87 : circuit 4c
MOTOR BASICS
R E M O T E- C O N T R O L L E D R O B O T
AUTONOMOUS ROBOT
A
B
C
PROJECT 5
Ah, robots. One of the most iconic and
exciting electronics applications. In
this project, you will learn all about DC
motors and motor drivers by building
your own robot! You’ll first learn motor
control basics. Then you’ll control a
tethered robot by sending it commands
over serial. Last, you will unleash your
robot by removing the tether and making it
autonomous! By adding a distance sensor,
the robot can learn how to avoid obstacles.
88 : circuit 5a
NEW COMPONENTS INTRODUCED
IN THIS PROJECT
• T B 6 6 1 2 F N G M OTO R D R I V E R
• S W I TC H
• DC G E A R M OTO R
• WHEEL
NEW CONCEPTS INTRODUCED
IN THIS PROJECT
• I N P U T V O L TA G E
• I N T E G R AT E D C I R C U I T S
• H - B R I DG E M OTO R D R I V E R
• ASCII CHARACTERS
• CONVERTING STRINGS
• AU TO N O M O U S V E H I C L E S
YOU WILL LEARN
• H OW TO CO N T R O L A M OTO R
U S I N G A M OTO R D R I V E R
• H OW TO S E N D S E R I A L CO M M A N D S
T O C R E AT E A R E M O T E - C O N T R O L L E D
ROBOT
• H O W T O B U I L D A R O B O T T H AT
U S E S S E N S O R S TO R E AC T TO I T S
ENVIRONMENT
Circuit 5A:
Motor Basics
In this circuit, you will learn the basic
concepts behind motor control. Motors
require a lot of current, so you can’t
drive them directly from a digital pin on
the RedBoard. Instead, you’ll use what
is known as a motor controller or motor
driver board to power and spin the motor
B11
B12
PWMB
PWMA
A12
A11
ST
BY
accordingly.
GND
MOT
DRI OR
VER
B02
B01
GEAR MOTOR
YOU
NEED
16 HOOKUP WIRES
SWITCH
GND
A02
VM
VCC
GND
A01
MOTOR DRIVER
NEW COMPONENTS
SWITCHES are components that control
side of the motor. The included wheels just
so happen to fit on the plastic axles.
the open-ness or closed-ness of an electric
TB6612FNG MOTOR DRIVER: If you
circuit. Just like the momentary
switch the direction of current through
buttons used in earlier circuits,
a motor by swapping the positive and
this type of switch can only
negative leads, the motor will spin in
exist in one of two states: open
the opposite direction. Motor controllers
or closed. However, a switch is different in
VM
PWMA
that it will stay in the position it was last in
VCC
A12
until it is switched again.
GND
A11
A01
ST
BY
A02
B11
THE MOTORS in your Inventor’s Kit
have two main parts: a small DC motor
that spins quickly and a plastic gearbox
that gears down the output from the hobby
motor so that it is slower but stronger,
allowing it to move your robot. The motors
B02
B12
B01
PWMB
GND
MOTOR
DRIVER
GND
contain a set of
switches (called
an H-bridge)
that lets you
easily control the
direction of one or
more motors. The
TB6612FNG Motor Driver takes commands
for each motor over three wires (two wires
control direction, and one controls speed),
and then uses these signals to control the
current through two wires attached to your
motor.
NEW CONCEPTS
VOLTAGE IN (VIN): This circuit utilizes
have a clever design allowing you to attach
the VIN pin found with the other RedBoard
things that you want to spin fast (like a
power pins. The VIN pin outputs a voltage
small fan or flag) to the hobby motor, and
that varies based on whatever voltage the
things that you want to be strong (like a
RedBoard is powered with. If the RedBoard
wheel) to the plastic axle sticking out the
is powered through the USB port, then the
89 : circuit 5a
voltage on VIN will be about 4.6–5V.
However, if you power the RedBoard
through the barrel jack (highlighted
in the picture), the VIN pin will reflect
that voltage. For example, if you were
to power the barrel jack with 9V, the
voltage out on VIN would also be 9V.
Notice that the voltage range listed on the
RedBoard near the barrel jack is 7–15V.
This means that the input voltage should
always be at or above 7V or should be at
7
~6
~5
4
~3
2
TX 1
RX 0
SCL
SDA
AREF
GND
13
12
~11
~10
~9
8
or below 15V. Never exceed this range.
DIGITAL (PWM~)
13
TX
RX
INTEGRATED CIRCUITS (ICS) AND
BREAKOUT BOARDS: An Integrated
Circuit (IC) is a collection of electronic
ONcomponents — resistors, transistors,
capacitors, etc. — all stuffed into a tiny
chip and connected together to achieve
START SOMETHING
a common goal. They come in all sorts of
flavors, shapes and sizes. The chip that
powers
ISP the RedBoard, the ATmega328, is
an IC. The chip on the motor driver, the
A5
A4
A3
A2
ANALOG IN
A1
VIN
5V
Integrated circuits are often too
A0
GND
POWER
GND
3.3V
RESET
IOREF
TB6612FNG, is another IC.
small to work with by hand. To make
working with ICs easier and to make
them breadboard-compatible, they
are often added to a breakout board,
which is a printed circuit board that
connects all the IC’s tiny legs to larger
ones that fit in a breadboard. The
motor driver board in your kit is an
example of a breakout board.
The guts of an integrated circuit,
visible after removing the top.
90 : circuit 5a
Once you’re finished with
this project, removing
the motor driver from
the breadboard can
be difficult due to its
numerous legs. To make
this easier, use the
included screwdriver as a
lever to gently pry it out.
Be careful not to bend the
legs as you remove it.
The motors are polarized.
However, motors are unique
in that they will still work
when the two connections are
reversed. They will just spin
in the opposite direction when
hooked up backward. To keep
things simple, always think of
the red wire as positive ( + ) and
the black wire as negative ( - ).
MEET YOUR MOTOR CONTROLLER.
The TB6612FNG Motor Driver may look complicated,
but it’s easy to use. Three pins on the right (PWMA,
A12 and A11) control the two pins on the left (A01
and A02). The same is true for channel
B. Motors require more current,
which is why the VIN voltage is
needed.
Most ICs have polarity and usually
have a polarity marking in one
of the corners. The motor driver is
no exception. Be sure to insert the
motor driver as indicated in the circuit
diagrams. The motor driver pins are
explained in the table on the next page.
91 : circuit 5a
VM
VCC
GND
A01
A02
B02
B01
GND
VM
PWMA
VCC
A12
GND
A11
A01
ST
BY
A02
B11
B02
B12
B01
GND
MOTOR
DRIVER
PWMB
GND
PIN
LABEL
FUNCTION
POWER/INPUT/
OUTPUT
VM
Motor Voltage
Power
VCC
Logic Voltage
Power
PWMA
AIN2
AIN1
STBY
BIN1
BIN2
PWMB
GND
NOTES
This is where you provide power
for the motors (2.2V to 13.5V)
This is the voltage to power
the chip and talk to the
microcontroller (2.7V to 5.5V)
Common Ground for both motor
GND
Ground
Power
voltage and logic voltage (all
GND pins are connected)
Allows the H-bridges to work
STBY
Standby
Input
when high (has a pull-down
resistor, so it must actively be
pulled high)
AIN1/BIN1
AIN2/BIN2
PWMA/
PWMB
A01/B01
A02/B02
92 : circuit 5a
Input 1 for
channels A/B
Input 2 for
channels A/B
PWM input for
channels A/B
Output 1 for
channels A/B
Output 2 for
channels A/B
Input
Input
Input
Output
Output
One of the two inputs that
determine the direction
One of the two inputs that
determine the direction
PWM input that
controls the speed
One of the two outputs
to connect the motor
One of the two outputs to
connect the motor
HOOKUP GUIDE
READY TO START HOOKING EVERYTHING UP? Check out the circuit diagram and
hookup table below to see how everything is connected.
a
b
c
d
e
f
g
h
i
VM
PWMA
1
2
VCC
A12
2
3
GND
A11
3
4
A01
ST
BY
4
5
A02
B11
5
6
B02
B12
6
7
B01
PWMB
7
8
GND
GND
8
MOTOR
DRIVER
9
7-15V
SCL
SDA
AREF
GND
13
12
~11
~10
~9
8
9
RESET
12
3.3V
13
13
5V
14
14
15
15
16
16
17
17
18
18
19
19
A2
20
20
A3
21
21
A4
22
22
A5
23
23
24
24
25
25
26
26
27
27
28
28
b
c
d
e
f
g
i
j
5V to
5V
D9 to
J6
D13 to
J4 to
MOTOR DRIVER
SWITCH
D10 to
D7 to
GND (-)
5V (+)
A4(RED +)
C1-C8 to
F25 +
7
~6
~5
4
~3
2
TX 1
RX 0
++ -–
GND to
J3
GND (-) to
MOTOR
A1
REDBOARD CONNECTION
CONNECTION TYPES
JUMPER WIRES
h
A0
ON
30
a
VIN
ISP
29
30
GND
ANALOG IN
29
GND
DIGITAL (PWM~)
IOREF
11
12
START SOMETHING
10
11
13
TX
RX
10
POWER
++ -–
++ -–
j
1
RESET
++ -–
I26 to
BREADBOARD CONNECTION
GND (-)
J7
D11 to
I27
A2 to
VIN to
J1
5V (+) to
5V (+)
A1
D8 to
D12 to
J5
J2
5V (+)
A3 to
GND (-)
GND (-)
A5(BLACK -)
G1-G8 (VM on C1, PWMA on G1)
F26 +
F27
93 : circuit 5a
Open the Arduino IDE
Connect the RedBoard to a USB port on your computer.
Open the Sketch:
File > Examples > SIK_Guide_Code-V_4 > CIRCUIT_5A-MOTOR BASICS
Select UPLOAD to program the sketch on the RedBoard.
W H AT Y O U
SHOULD SEE
Flip the switch. The motor will spin
at the speed set by the motor speed
variable (default is 0). Open the Serial
Monitor, type any number from 30
to 255 or -30 to -255 , and then press
Enter. Changes in speed will be hard
to notice. Send 0 to stop the motor.
PROGRAM OVERVIEW
1
Check to see if a command has been sent through the Serial Monitor. If a command has been sent, then set
the motor speed to the number that was sent over the Serial Monitor.
Check to see if the switch is ON or OFF.
2
A: If the switch is ON, drive the motor at the motor speed.
B: If the switch is OFF, stop the motor.
PARSING INTEGERS:
Serial.parseInt();
CODE TO NOTE
.parseInt() receives integer numbers from the Serial
Monitor. It returns the value of the number that it receives,
so you can use it like a variable.
This command checks how many bytes of data are being
SERIAL AVAILABLE:
sent to the RedBoard. If it is greater than 0, then a message
Serial.available();
has been sent. It can be used in an if statement to run code
only when a command has been received.
94 : circuit 5a
CODING CHALLENGES
MAKE THE SWITCH CHANGE DIRECTIONS: Change the code so
that the position of the switch changes the direction of the motor instead
YOU
of turning it on and off.
NEED
REPLACE THE SWITCH WITH A BUTTON: Try wiring a button into the circuit
instead of the sliding switch. Now the motor only turns on when you push the button.
REPLACE THE SWITCH WITH A SENSOR: Try changing the code so that the
motor is activated by another sensor, like the photoresistor.
TROUBLESHOOTING
Check the wiring to the motor driver. There are a lot of connections,
Motor not
and it’s easy to mix one of them up with another. Double check
spinning
the polarity of the motor driver. All the text should face the same
direction as everything else.
Switch not
Make sure that you are hooked up to the middle pin and one side pin
working
on the switch, and not both side pins.
Jumper wires unfortunately can go “bad” from getting bent too
much. The copper wire inside can break, leaving an open connection
Still not
in your circuit. If you are certain that your circuit is wired correctly
working?
and that your code is error-free and uploaded but you are still
encountering issues, try replacing one or more of the jumper wires
for the component that is not working.
You’ve completed
Circuit 5A!
Continue to circuit 5B to construct a remote-controlled robot.
MOTOR BASICS
A
REMOTE-CONTROLLED ROBOT
B
AUTONOMOUS ROBOT
C
95 : circuit 5a
B11
B12
PWMB
PWMA
A12
A11
H810
6
2 WHEELS
GND
MOT
DRI OR
VER
B02
B01
In this circuit, you’ll control two motors
and build your own remote-controlled
roving robot! You will also learn how to
read information from a serial command
so that you can use the Serial Monitor to
tell the robot in what direction to move
and how far to move.
2 GEAR MOTORS
SWITCH
16 JUMPER WIRES
GND
A02
VM
VCC
GND
MOTOR DRIVER
A01
YOU
NEED
ST
BY
Circuit 5B:
RemoteControlled
Robot
DUAL LOCK TAPE
BINDER CLIP
SCISSORS
(NOT INCL
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