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Introduction to Arduino
Microcontrollers
Jeff McRaven
[email protected]
Overview
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Background
Microcontroller defined/Why Arduino's?
 Types of Arduino microcontrollers
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What To Get (Hardware and Software)
Arduino C
Electronic Circuits
Projects
Blinking light(s)
 Reading inputs (variable resistors)
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Microcontrollers – One
Definition
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Programmers work in the virtual world.
Machinery works in the physical world.
How does one connect the virtual world to the
physical world?
Enter the microcontroller.
A microcontroller is basically a small-scale
computer with generalized (and programmable)
inputs and outputs.
The inputs and outputs can be manipulated by
and can manipulate the physical world.
Arduino – Official Definition
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Taken from the official web site (arduino.cc):
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Arduino is an open-source electronics prototyping
platform based on flexible, easy-to-use hardware and
software. It's intended for artists, designers,
hobbyists, and anyone interested in creating
interactive objects or environments.
Why Arduino?
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For whatever reason, Arduino microcontrollers
have become the de facto standard.
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Make Magazine features many projects using Arduino
microcontrollers.
Strives for the balance between ease of use and
usefulness.
Programming languages seen as major obstacle.
 Arduino C is a greatly simplified version of C++.
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Inexpensive ($35 retail).
Arduino Types
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Many different versions
Number of input/output channels
 Form factor
 Processor
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Leonardo
Due
Micro
LilyPad
Esplora
Uno
Leonardo
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Compared to the Uno, a slight upgrade.
Built in USB compatibility
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Presents to PC as a
mouse or keyboard
Bugs?
Due
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Much faster processor, many more pins
Operates on 3.3 volts
Similar to the Mega
Micro
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When size matters: Micro, Nano, Mini
Includes all functionality of the Leonardo
Easily usable on a breadboard
LilyPad
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LilyPad is popular for clothing-based projects.
Esplora
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Game controller
Includes joystick, four buttons, linear
potentiometer (slider), microphone, light sensor,
temperature sensor, three-axis accelerometer.
Not the standard set of IO pins.
Arduino Uno Close Up
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The pins are in three groups:
Invented in 2010
 14 digital pins
 6 analog pins
 power
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Where to Start
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Get an Arduino (starter kit)
Download the compiler
Connect the controller
Configure the compiler
Connect the circuit
Write the program
Get frustrated/Debug/Get it to work
Get excited and immediately start next project
(sleep is for wimps)
Arduino Starter Kits
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Start with a combo pack (starter kit)
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Includes a microcontroller, wire, LED's, sensors, etc.
www.adafruit.com
adafruit.com/products/68 ($65)
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www.sparkfun.com
https://www.sparkfun.com/products/11576 ($99.95)
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Radio Shack
Make Ultimate Microcontroller Pack w/ Arduino Kit ($119.99)
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www.makershed.com
http://www.makershed.com/Ultimate_Arduino_Microcontroller_Pack_p/msump1.h
tm ($150)
What to Get – My Recommendation
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Required:
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Arduino (such as Uno)
USB A-B (printer) cable
Breadboard
Hookup wire
LED's
Resistors
Sensors
Switches
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Good Idea:
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Capacitors
Transistors
DC motor/servo
Relay
Advanced:
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Soldering iron & solder
Heat shrink tubing
9V battery adapter
Bench power supply
Arduino Compiler
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Download current compiler from:
arduino.cc/en/Main/software
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Arrogantly refers to itself as an IDE (Ha!).
Run the software installer.
Written in Java, it is fairly slow.
Visit playground.arduino.cc/Main/
DevelopmentTools for alternatives to the
base arduino IDE
Configuring the Arduino Compiler
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Defaults to COM1, will probably need to change
the COM port setting (my work PC uses 7).
Appears in Device Manager (Win7) under Ports
as a Comm port.
Arduino Program Development
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Based on C++ without 80% of the instructions.
A handful of new commands.
Programs are called 'sketches'.
Sketches need two functions:
void setup( )
 void loop( )
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setup( ) runs first and once.
loop( ) runs over and over, until power is lost or
a new sketch is loaded.
Arduino C
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Arduino sketches are centered around the pins
on an Arduino board.
Arduino sketches always loop.
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void loop( ) {} is equivalent to while(1) { }
The pins can be thought of as global variables.
Arduino C Specific Functions
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pinMode(pin, mode)
Designates the specified pin for input or output
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digitalWrite(pin, value)
Sends a voltage level to the designated pin
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digitalRead(pin)
Reads the current voltage level from the designated pin
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analog versions of above
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analogRead's range is 0 to 1023
serial commands
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print, println, write
Compiler Features
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Numerous sample
sketches are included in
the compiler
Located under File,
Examples
Once a sketch is written,
it is uploaded by clicking
on File, Upload, or by
pressing <Ctrl> U
Arduino C is Derived from C++
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These programs blink an LED on pin 13
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avr-libc
#include <avr/io.h>
#include <util/delay.h>
int main(void) {
while (1) {
PORTB = 0x20;
_delay_ms(1000);
PORTB = 0x00;
_delay_ms(1000);
}
return 1;
}
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Arduino C
void setup( ) {
pinMode(13, OUTPUT);
}
void loop( ) {
digitalWrite(13, HIGH);
delay(1000);
digitalWrite(13, LOW);
delay(1000);
}
Basic Electric Circuit
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Every circuit (electric or electronic) must have at
least a power source and a load.
The simplest circuit is a light.
Plug in the light, and it lights up.
Unplug it, the light goes out.
Electricity flows from the power source, through
the load (the light) and then back to the power
source.
Basic LED Circuit
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Connect the positive (+) lead of a power
source to the long leg of an LED.
Connect other leg of the LED to a resistor.
High resistance means a darker light.
 Low resistance means brighter light.
 No resistance means a burned out LED.
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Connect other leg of the resistor to the
negative lead of the power source.
Let the Good Times Roll!
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At this point we have:
Purchased a starter kit, including the Arduino
 Connected and configured the Arduino
 Connected a simple LED circuit
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Let's write some code!
Blink Sketch
void setup( ) {
Connected to one end
pinMode(13, OUTPUT); of the circuit
}
void loop( ) {
digitalWrite(13, HIGH);
delay(1000);
digitalWrite(13, LOW);
delay(1000);
}
Connected to other end
of the circuit
4 LED Blink Sketch
void setup( ) {
pinMode(1, OUTPUT);
pinMode(3, OUTPUT);
pinMode(5, OUTPUT);
pinMode(7, OUTPUT);
}
void loop( ) {
digitalWrite(1, HIGH);
delay (200);
digitalWrite(1, LOW);
digitalWrite(3, HIGH);
delay (200);
digitalWrite(3, LOW);
digitalWrite(5, HIGH);
delay (200);
digitalWrite(5, LOW);
digitalWrite(7, HIGH);
delay (200);
digitalWrite(7, LOW);
}
So What?
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Great. Blinking lights. Not impressed.
Only covered output thus far.
Can use analog inputs to detect a physical
phenomena.
Inputs
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Digital inputs will come to the Arduino as either
on or off (HIGH or LOW, respectively).
HIGH is 5VDC.
 LOW is 0VDC.
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Analog inputs will come to the Arduino as a
range of numbers, based upon the electrical
characteristics of the circuit.
0 to 1023
 .0049 V per digit (4.9 mV)
 Read time is 100 microseconds (10,000 a second)
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Analog Input
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A potentiometer (variable
resistor) is connected to
analog pin 0 to an Arduino.
Values presented to pin 0 will
vary depending upon the
resistance of the
potentiometer.
Analog Input-Application
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The variable resistor can be replaced with a
sensor.
For example, a photo resistor.
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Depending upon the light level at the photo resistor:
Turn on a light
 Increase or decrease the brightness of an LED (or an
LED array)
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Most sensors are simply variable resistors, but
vary their resistance based on some physical
characteristic.
Sensors
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Sensors can be both binary or a range.
Usually, sensors that measure a range of values
vary their resistance to reflect their detection.
Arduinos can only sense voltages, not
resistances.
Sensors that only vary their resistances require a
circuit called a voltage divider to provide the
Arduino a voltage.
Common Sensors
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Dials on a radio are
simply potentiometers
Temperature
Light
Angle
Switches
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did the user throw a
switch or push a button?
Accelerometer (measures
motion and tilt)
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Infrared sensor & light
Hall effect sensor and
magnet
Ball tilt sensor (for
measuring orientation)
Force
“Competitors”to the Arduino
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PIC controller
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Microcontroller programmed with C or assembler
Alternatives to the Arduino line
Pinguino – PIC controller
 MSP430 – Texas Instruments; $4.30
 Others: customs, Teensy, etc.
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Netduino
Computers
Raspberry Pi
 BeagleBones – TI; has computer and controller
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Netduino
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Microcontroller and development tools created by
Microsoft to work with the .NET Micro Framework.
VASTLY better development environment.
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Differences
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visualmicro.com
Other alternatives
Pins on a Netduino are 3.3V (not 5).
Netduinos have a much faster processor.
60K of RAM (versus an Uno's 2K).
Largely compatible with the Arduino, but it is not a
drop-in replacement (can fry it).
Raspberry Pi
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Low end computer, not a controller
Uses Debian Linux
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Programmed with Python
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Arch Linux ARM, Fedora, FreeBSD, Slackware…
BBC BASIC, C, Perl
As it is a computer and not a controller, its role
in these projects is different.
Hierarchy: computers control controllers,
controllers control hardware.
Shields
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Shields are circuit boards that plug into the top
of an Arduino.
They extend the capabilities of an Arduino.
Examples:
Ethernet
 GPS
 Motor
 Prototype
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shieldlist.org
Conclusion
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The Arduino microcontroller is a low cost way
to enter into the hobby of robotics.
The Arduino has two plusses over any other:
The user community
 Extensive online library of code and projects
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Viewed as the "base" system, upon which all
other microcontrollers are built. Compatibility.
So get a kit, and start ushering in the inevitable
takeover of our robotic overlords!
Introduction to Arduino
Microcontrollers
Jeff McRaven
[email protected]