Arduino uno User Manual

them automatically to two decimal digits. The secret lies in the print method
of the Serial class. In recent versions of the Arduino platform, it works for all
possible data types, and when it receives a float variable, it rounds it to two
decimal digits before it gets output. You can specify the number of decimal
digits. For example, Serial.println(3.141592, 4); prints 3.1416 .
Only the output is affected by this; internally it is still a float variable. By the
way, on most Arduinos, float and double values are the same at the moment.
Only on the Arduino Due is double more accurate than float .
So, what does it actually cost to use float variables? Their memory consumption
is 4 bytes—that is, they consume as much memory as long variables. On the
other hand, floating-point calculations are fairly expensive and should be
avoided in time-critical parts of your software. The biggest costs are the
additional library functions that have to be linked to your program for float
support. Serial.print(3.14) might look harmless, but it increases your program’s
size tremendously.
Comment line 37 out and recompile the program to see the effect. It will no
longer work properly, but we can see how this statement affects the program
size. With my current setup, it needs 3,002 bytes without float support for
Serial.print and 5,070 bytes otherwise. That’s a difference of 2,068 bytes!
In some cases, you can still get the best of both worlds: float support without
paying the memory tax. You can save a lot of space by converting the float
values to integers before sending them over a serial connection. To transfer
values with a precision of two digits, multiply them by 100, and don’t forget
to divide them by 100 on the receiving side. We’ll use this trick (including
rounding) later.
Increasing Precision Using a Temperature Sensor
Support for floating-point numbers is an improvement, but it mainly
increases the precision of our program’s output. We could’ve achieved a
similar effect using some integer math tricks. But now we’ll add an even better
improvement that cannot be imitated using software: a temperature sensor.
When I told you that sound travels through air at 343 m/s, I wasn’t totally
accurate, because the speed of sound isn’t constant—among other things, it
depends on the air’s temperature. If you don’t take temperature into account,
the error can grow up to a quite significant 12 percent. We calculate the
actual speed of sound C with a simple formula:
C = 331.5 + (0.6 * t)
Chapter 5. Sensing the World Around Us • 86
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Arduino uno Specifications

General

Form factor	Arduino
Certification	RoHS, FC, CE
Processor model	-
Processor frequency	- MHz
Microcontroller model	ATmega328
Microcontroller frequency	16 MHz
DC input voltage	7-12 V
Operating voltage	5 V
DC current per I/O pin	40 mA
Flash memory	0.032 MB
Maximum internal memory	- GB
SRAM (Static Random Access Memory)	2 KB
EEPROM (Electrically Erasable Programmable Read-Only Memory)	1 KB
Wi-Fi	No
Number of analog I/O pins	6
Number of digital I/O pins	14

Weight and Dimensions

Board dimensions	53.4 x 68.6 mm

Summary

Arduino Uno and the Arduino Platform

The Parts You Need

Chapter 1: Welcome to the Arduino

What Exactly Is an Arduino?

Exploring the Arduino Board

Analog and Digital Signals

Installing the Arduino IDE

Provides step-by-step instructions for installing the Arduino Integrated Development Environment.

Meeting the Arduino IDE

Hello, World!

Introduces the first project: making an LED blink using the Arduino.

Compiling and Uploading Programs

Explains how to compile and upload sketches to the Arduino board.

Chapter 2: Creating Bigger Projects with the Arduino

Managing Projects and Sketches

Changing Preferences

Explains how to customize Arduino IDE settings for better workflow.

The Arduino Programming Language

Using Serial Ports

Explains serial communication for data exchange between Arduino and computer.

Chapter 3: Building Binary Dice

Working with Breadboards

Explains how breadboards work and how to connect components.

Using an LED on a Breadboard

First Version of a Binary Die

Implements the first version of a binary die using three LEDs.

Working with Buttons

Details how pushbuttons work and how to connect them to the Arduino.

Adding Your Own Button

Building a Dice Game

Completes the dice project by adding a guess button and game logic.

Chapter 4: Building a Morse Code Generator Library

Learning the Basics of Morse Code

Building a Morse Code Generator

Starts the implementation of the Telegraph C++ class.

Fleshing Out the Morse Code Generator’s Interface

Defines the Telegraph class interface and Morse code data arrays.

Outputting Morse Code Symbols

Installing and Using the Telegraph Class

Guides on integrating the custom Telegraph library into Arduino IDE.

Chapter 5: Sensing the World Around Us

Measuring Distances with an Ultrasonic Sensor

Introduces ultrasonic sensors and builds a distance measuring device.

Increasing Precision Using Floating-Point Numbers

Increasing Precision Using a Temperature Sensor

Integrates a temperature sensor to refine distance measurements.

Creating Your Own Dashboard

Chapter 6: Building a Motion-Sensing Game Controller

Wiring Up the Accelerometer

Details connecting the ADXL335 accelerometer to the Arduino.

Bringing Your Accelerometer to Life

Reads and outputs raw accelerometer data for three axes.

Finding and Polishing Edge Values

Building Your Own Game Controller

Integrates a pushbutton and refined accelerometer data for a game controller.

Chapter 7: Writing a Game for the Motion-Sensing Game Controller

Writing a GameController Class

Creates a JavaScript class for convenient access to Arduino motion data.

Creating the Game

Implements a Breakout clone using JavaScript and the motion controller.

Chapter 8: Generating Video Signals with an Arduino

How Analog Video Works

Building a Digital-to-Analog Converter (DAC)

Details building a binary-weighted DAC for video signal generation.

Connecting the Arduino to Your TV Set

Describes modifying an RCA cable to connect to the Arduino.

Using the TVout Library

Introduces the TVout library for generating video signals on a TV.

Building a TV Thermometer

Creates a graphical thermometer display on a TV screen using sensors.

Working with Graphics in TVout

Chapter 9: Tinkering with the Wii Nunchuk

Wiring a Wii Nunchuk

Details wiring the Nunchuk controller to Arduino analog pins.

Talking to a Nunchuk

Building a Nunchuk Class

Creates a C++ class for interfacing with the Nunchuk controller.

Using Our Nunchuk Class

Demonstrates reading Nunchuk data (joystick, accelerometer, buttons).

Creating Your Own Video Game Console

Creating Your Own Video Game

Handling the Different Game States

Chapter 10: Networking with Arduino

Using Your PC to Transfer Sensor Data to the Internet

The Arduino and the Internet of Things (IoT)

Registering an Application with Twitter

Tweeting Messages with Processing

Communicating Over Networks Using an Ethernet Shield

Using DHCP and DNS

Chapter 11: Creating a Burglar Alarm with Email Notification

Emailing from the Command Line

Detecting Motion Using a Passive Infrared Sensor

Bringing It All Together

Chapter 12: Creating Your Own Universal Remote Control

Understanding Infrared Remote Controls

Grabbing Remote Control Codes

Cloning a Remote

Using the TvRemote class

Controlling Infrared Devices Remotely with Your Browser

Building an Infrared Proxy

Chapter 13: Controlling Motors with Arduino

What You Need

Lists components for motor control: servo motor, wires, Arduino.

Introducing Motors

First Steps with a Servo Motor

Building a Blaminatr

What If It Doesn’t Work?

Troubleshooting motor control: power consumption, weight, adjustments.

APPENDIX 1: Electronics and Soldering Basics

Current, Voltage, and Resistance

Electrical Circuits

Resistors

Learning How to Solder

APPENDIX 2: Advanced Arduino Programming

The Arduino Programming Language

Bit Operations

APPENDIX 3: Advanced Serial Programming

Learning More About Serial Communication

Serial Communication Using Various Languages

APPENDIX 4: Controlling the Arduino with a Browser

What Are Google Chrome Apps?

Creating a Minimal Chrome App

Exploring the Chrome Serial API

Writing a SerialDevice Class