Arduino Slides With Neopixels

Agenda
 What is Arduino?
 What can I make with Arduino?
 Getting started
 Digital Inputs and Outputs
 Analog Inputs and Outputs
 Neopixels
 Putting It All Together
 Summary

What is Arduino?
“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.“
http://www.arduino.cc/

What is Arduino?
 A programming environment for Windows,
Mac or Linux
 A hardware specification
 Software libraries that can be reused in your
programs
All for FREE!*
* Except the price of the hardware you purchase

What is Arduino?
 There are many types of hardware for
different needs

Arduino UNO
 The most commonly used Arduino board
 We will be using this board in this workshop

Arduino UNO
• Microprocessor – Atmega328
• 16 Mhz speed
• 14 Digital I/O Pins
• 6 Analog Input Pins
• 32K Program Memory
• 2K RAM
• 1k EEPROM
• Contains a special program
called a “Bootloader”
• Allows programming from
USB port
• Requires 0.5K of Program
Memory

Arduino UNO
• USB Interface
• USB client device
• Allows computer to
program the
Microprocessor
• Can be used to
communicate with
computer
• Can draw power from
computer to run Arduino

Arduino UNO
• Power Supply
• Connect 7V – 12V
• Provides required 5V to
Microprocessor
• Will automatically pick USB or
Power Supply to send power to
the Microprocessor

Arduino UNO
• Indicator LEDs
• L – connected to digital pin
13
• TX – transmit data to
computer
• RX – receive data from
computer
• ON – when power is
applied

Arduino UNO
• Quartz Crystal which provides
16Mhz clock to Microprocessor

Arduino UNO
• Reset Button
• Allows you to reset the
microprocessor so
program will start from the
beginning

Arduino UNO
• Input/Output connectors
• Allows you to connect
external devices to
microprocessor
• Can accept wires to
individual pins
• Circuit boards “Shields”
can be plugged in to
connect external devices

Arduino Shields
 Many companies have created
Shields that can be used with
Arduino boards
 Examples
Motor/Servo interface
SD memory card interface
Ethernet network interface
GPS
LED shields
Prototyping shields

What can I make with Arduino?
 Alarm Clock
 http://hackaday.com/2011/07/04/alarm-clock-forces-you-to-play-tetris-to-prove-you-are-awake/

 Textpresso
 http://www.geekwire.com/2012/greatest-invention-textspresso-machine-change-coffee-ordering/

 Automatic Pet Water Dispenser
 http://hackaday.com/2011/05/24/automated-faucet-keeps-your-cat-watered/

Let’s GO!
 Get the hardware
Buy an Arduino UNO
Buy (or repurpose) a USB cable
 Get the software
http://arduino.cc/en/GuideHomePage
 Follow the instructions on this page to install
the software
 Connect the Arduino to your computer
 You are ready to go!

Lab 1
 Blink the onboard LED
Congratulations!!!

Review the Sketch
/*
Blink
. . .
*/
// set the LED on
// wait for a second
 These are comments
 The computer ignores them
 Humans can read them to learn about the
program

Review the Sketch
void setup() {
pinMode(13, OUTPUT);
}
 Brackets { and } contain a block of code
Each line of code in this block runs sequentially
 void setup() tells the program to only run
them once
When the board turns on
When the reset button is pressed

Review the Sketch
void setup() {
pinMode(13, OUTPUT);
}
 Tells the Arduino to setup pin 13 as an Output
pin
 Each pin you use needs be setup with pinMode
 A pin can be set to OUTPUT or INPUT

Review the Sketch
void loop() {
digitalWrite(13, HIGH);
delay(1000);
digitalWrite(13, LOW);
delay(1000);
}
 void loop () runs the code block over and over
until you turn off the Arduino
 This code block only runs after setup is
finished

Review the Sketch
void loop() {
delay(1000);
delay(1000);
}
 HIGH tells the Arduino to turn on the output
 LOW tells the Arduino to turn off the output
 13 is the pin number

Review the Sketch
void loop() {
delay(1000);
delay(1000);
}
 Code runs very fast
 Delay tells the Arduino to wait a bit
 1000 stands for 1,000 milliseconds or one
second

Change the Sketch
void loop() {
delay(500);
delay(500);
}
 Change the 1000’s to 500
 Upload the code to the Arduino
 What happens now?

Arduino Digital Pins
 These pins are used to communicate with the
outside world
 When an output pin is HIGH, it can provide 5V
at 40mA maximum
Trying to get more than 40mA out of the pin will
destroy the Microprocessor!
 When the output pin is LOW, it provides no
current
 You can use a transistor and/or a relay to
provide a higher voltage or more current

Connecting a new LED
 Most LEDs will work with 5V at 20mA or
30mA
 Make sure to check them before connecting
to your Arduino! – Use your volt meter
 An LED requires a resistor to limit the current
Without the resistor, the LED will draw too much
current and burn itself out

Connecting a new LED
 LEDs are polarized devices
 One side needs to be connected to + and one
side needs to be connected to –
 If you connect it backwards, it will not light
 Usually:
Minus is short lead and flat side
Plus is long lead and rounded side
 A resistor is non-polarized
It can be connected either way

Lab 2
 Connect the two LEDs on the breadboard
 Modify the code to blink the second LED, too
 Blink them all

Input
 The pins can be used to accept an input also
 Digital pins can read a voltage (1) or no
voltage (0)
 Analog pins can read voltage between 0V and
5V. You will read a value of 0 and 1023.
 Both of these return a value you can put into a
variable and/or make decisions based on the
value

Input
 Example
int x;
x = digitalRead(2);
if ( x == HIGH ) {
} else {
}

Push Button
 A push button can be connected to a
digital pin
 There is an open circuit normally
 There is a closed circuit when pressed
 If connected between 5V and a pin, we
get 5V when pressed, but an open circuit
when not pressed
 This is a problem – we need 0V when not
pressed

Push Button
 There is a solution
 A resistor to 5V will make the pin HIGH when
the button is not pressed
 Pressing it will make the pin LOW
 The resistor makes sure we don’t connect 5V
directly to Ground

Push Button
 This is a common method for using push
buttons
 The resistor is called a “Pull Up Resistor”
 The Arduino has built in pull up resistors on
the digital pins
 We need to enable them when we need them

Push Button
 This code enables the pull up resistor:
pinMode(2, INPUT);
Or, the one line version:
pinMode(2, INPUT_PULLUP);

Lab 3
Connect a push button
Load the basic button code
Turn LEDs on/off based on button press
Load the toggle code. Pay attention to
reactions to your button presses, and count in
the Serial terminal.
Try again with the debounce code. Did that
help?

Other Sensors/Devices
 There are many other devices you can
connect to an Arduino
Servos to move things
GPS to determine location/time
Real Time Clock to know what time it is
Accelerometers, Chemical detectors…
LCD displays
Memory cards
More!

Let’s Go Analog
 So far we’ve dealt with the on/off digital
world.
 Many interesting things we want to measure
(temperature, light, pressure, etc) have a
range of values.

The Potentiometer
 Very simple analog input – used to control
volume, speed, and so on.
 It allows us to vary two resistance values.

The Serial Port
 You can communicate between the Arduino
and the computer via the USB cable.
 This can help you out big time when you are
debugging.
 It can also help you control programs on the
computer or post information to a web site.
Serial.begin(9600);
Serial.println(“Hello World.”);

Lab 3
 Connect potentiometer
 Upload and run code
 Turn the knob
 Watch the value change in the Serial Monitor

The Voltage Divider
 There are many, many sensors based on
varying resistance: force sensors, light
dependent resistors, flex sensors, and more
 To use these you need to create a ‘voltage
divider’.

Light Sensor
 R2 will be our photocell
 R1 will be a resistor of our choice
 Rule of thumb is: R1 should be in the middle
of the range.

Lab 4
 Wire up the photocell
 Same code as Lab 3
 Take note of the max and min values
 Try to pick a value for a dark/light threshold.

Analog Output
 Flashing a light is neat, but what about fading
one in and out?
 Or changing the color of an RGB LED?
 Or changing the speed of a motor?

Lab 5
 Wire up the Breadboard
 Load the code. Take note of the for loop.
 Watch the light fade in and out
 Experiment with the code to get different
effects

Making Things Move
 So far we’ve communicated with the world by
blinking or writing to Serial
 Let’s make things move!

Servos
 Used in radio controlled planes and cars
 Good for moving through angles you specify
#include <Servo.h>
Servo myservo;
void setup() {
myservo.attach(9);
}
void loop() {}

Lab 6
 Wire up the breadboard
 Upload the code
 Check it out, you can control the servo!
 The map function makes life easy and is very,
very handy:
map(value, fromLow, fromHigh, toLow,
toHigh);

Lab 6 (part 2)
 Upload the code for random movement.
 Watch the values in the Serial monitor. Run
the program multiple times. Is it really
random?
 Try it with ‘randomSeed’, see what happens.

Lab 7: Neopixels
 Neopixels are Adafruit’s ‘rebranding’ of
WS2812B Addressable RGB LEDs (‘Neopixel’
is way catchier)
 You can chain them together and control as
many pixels as you want (or can power) with a
single pin!
 You can buy strips and rings of them.
 However, the code is not built in to the
Arduino IDE, so you have to install a library
 This is something you often need for new 55

Wire it Up
 Wire it up as shown below. (Wire color is
important
56

Installing the Library
 Get the library from
https://github.com/adafruit/Adafruit_NeoPixe
l
 Go to Sketch->Import Library->Add Library
 Find the file you just downloaded
 Restart the IDE after Importing it (otherwise
you won’t see the examples)
57

Code
 Open the ‘NeopixelsWorkshop.ino’ file in the
‘NeopixelsWorkshop’ folder.
#include <Adafruit_NeoPixel.h>
// Which pin on the Arduino is connected to the
NeoPixels?
#define PIN 7
// How many NeoPixels are attached to the Arduino?
#define NUMPIXELS 2
// When we setup the NeoPixel library, we tell it how
many pixels, and which pin to use to send signals.
Adafruit_NeoPixel pixels = Adafruit_NeoPixel(NUMPIXELS,
PIN, NEO_GRB + NEO_KHZ800);
58

…and more code
 Our ‘strip’ is an object. We call functions or
‘methods’ tied to it:
void setup() {
strip.begin();
strip.show(); // Initialize all pixels to
'off'
}
59

…and more
 To set a pixel’s color, specify the number
(start at zero). Do this for as many pixels as
you want, then call the function to show these
colors.
pixels.setPixelColor(1, pixels.Color(i,255-
i,0));
pixels.show();
 Can you guess what this program does before
you upload it?
60

Other Senses
 With a piezo or small speaker, your Arduino
can make some noise, or music (or ‘music’).
 As with game controllers, vibrating motors
can stimulate the sense of touch.
 Arduino projects exist that involve smell
(breathalyzer, scent generators).
 For taste…KegBot? ZipWhip’s cappuccino
robot?

Lab 8 – The Light Theremin
 Combine previous projects (photocell and the
piezo playing music) to create an instrument
that generates a pitch based on how much
light is hitting the photocell
 Feel free to get really creative with this.
 For extra creativity points, do something
totally different.

Summary
 We have learned
The Arduino platform components
how to connect an Arduino board to the computer
How to connect LEDs, buttons, a light sensor, a
piezo buzzer, and servos
How to send information back to the computer

Resources
 http://www.arduino.cc
 Getting Started With Arduino (Make:
Projects) book
 Beginning Arduino book
 Arduino: A Quick Start Guide book
 The adafruit learning system:
https://learn.adafruit.com/

Where to buy stuff
 Adafruit http://www.adafruit.com/
 Spark Fun http://www.sparkfun.com/
 Maker Shed http://www.makershed.com/
 Digikey http://www.digikey.com/
 Mouser http://www.mouser.com/
 Radio Shack http://www.radioshack.com/
 Find parts: http://www.octopart.com/
 Sometimes Amazon has parts too
 Ebay can have deals but usually the parts are
shipped from overseas and take a long time

Where to get help
 http://arduino.cc/forum/
 Your local Hackerspace!

Electronics 101
 Electronic devices depend on the movement of
electrons
 The amount of electrons moving from one
molecule to another is called Current which is
measured in Amps
 Batteries provide a lot of electrons that are ready
to move
 The difference in potential (the number of free
electrons) between two points is called
Electromotive Force which is measured in Volts

Electronics 101
 Materials that allow easy movement of
electrons are called Conductors
Copper, silver, gold, aluminum are examples
 Materials that do not allow easy movement of
electrons are called Insulators
Glass, paper, rubber are examples
 Some materials are poor conductors and poor
insulators.
Carbon is an example

Electronics 101
 Materials that aren’t good conductors or good
inductors provide Resistance to the
movement of electrons
 Resistance is measured in Ohms

Electronics 101
 Electrons flow from the negative
terminal of the battery through the
circuit to the positive terminal.
 But – when they discovered this,
they thought current came from the
positive terminal to the negative
 This is called conventional current
flow
I
Oops!

Electronics 101
 There needs to be a complete circuit for
current to flow
No Flow! Current will Flow!

Electronics 101
 Volts, Amps and Ohms are related
 This is called Ohms Law
I = Current in Amps
E = EMF in Volts
R = Resistance in Ohms

Electronics 101
 Example
 BAT = 9 volts
 R1 = 100 ohms
 How many amps?
 I = 0.09 Amps or 90mA

Electronics 101
 When dealing with really big numbers or
really small numbers, there are prefixes you
can use
k = kilo = 1,000 (e.g. 10 kHz = 10,000 Hz)
M = mega = 1,000,000 (e.g 1 MHz = 1,000 kHz)
m = milli = 1/1,000 (e.g 33mA = 0.033A)
u = micro = 1/1,000,000 (e.g 2uV = 0.000002V)
n = nano = 1/1,000,000,000
p = pico = 1/1,000,000,000,000

Arduino Slides With Neopixels

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