Arduino uno User Manual

We begin with the usual pin constants, and in setup we set the modes of the
pins we use. In line 8, we define a global variable named led_state to store the
current state of our LED. It will be LOW when the LED is off and HIGH otherwise.
In loop , we check the button’s current state. When we press the button, its
state switches to HIGH , and we toggle the content of led_state . That is, if led_state
was HIGH , we set it to LOW , and vice versa. At the end, we set the physical LED’s
state to our current software state accordingly.
Our solution is really simple, but unfortunately, it doesn’t work. Play around
with it, and you’ll quickly notice some annoying behavior. If you press the
button, the LED sometimes will turn on and then off immediately. Also, if
you release it, the LED will often remain in a more or less arbitrary state; that
is, sometimes it will be on and sometimes off.
The problem is that the Arduino executes the loop method over and over again.
Although the Arduino’s CPU is comparatively slow, this would happen quite
often—regardless of whether we are currently pressing the button. But if you
press it and keep it pressed, its state will constantly be HIGH , and you’d con-
stantly toggle the LED’s state (because this happens so fast, it seems like the
LED is constantly on). When you release the button, the LED is in a more or
less arbitrary state.
To improve the situation, we have to store not only the LED’s current state,
but also the pushbutton’s previous state:
BinaryDice/MoreReliableSwitch/MoreReliableSwitch.ino
const unsigned int BUTTON_PIN = 7;
const unsigned int LED_PIN = 13;
void setup() {
pinMode(LED_PIN, OUTPUT);
pinMode(BUTTON_PIN, INPUT);
}
int old_button_state = LOW;
int led_state = LOW;
void loop() {
const int CURRENT_BUTTON_STATE = digitalRead(BUTTON_PIN);
if (CURRENT_BUTTON_STATE != old_button_state && CURRENT_BUTTON_STATE == HIGH) {
if (led_state == LOW)
led_state = HIGH;
else
led_state = LOW;
digitalWrite(LED_PIN, led_state);
}
old_button_state = CURRENT_BUTTON_STATE;
}
report erratum • discuss
Working with Buttons • 51
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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