Using arduino and raspberry pi for internet of things

Using Arduino and Raspberry Pi
for Internet of Things
Sudar Muthu (@sudarmuthu)
http://hardwarefun.com/
http://github.com/sudar

Who am I?
 Research Engineer by profession
 I build robots as a hobby
 Playing with Arduino for more than 4 years
 Blogger about Arduino at http://hardwarefun.com
 Moderator for Arduino India forum
http://hardwarefun.com 2

Objective
 Introduce Arduino
 Introduce Raspberry Pi
 Emphasis on IoT
 See how both can be used for IoT

Arduino

What is Arduino?
 Visual Basic for hardware
 Includes both Hardware and software
Photo credit Arduino team

Different Arduino types
 Arduino Uno (The one I am going to use today)
 Arduino Mega
 Arduino Due
 Lillypad
 Arduino BT
 Arduino Ethernet
 .. and clones

Getting to know the Arduino

Specs (Uno, Leonardo)
Type Value
Microcontroller ATmega328
Operating Voltage 5v
Digital I/O Pins 14 (of which 6 provide PWM output)
Analog Input Pins 6
Flash Memory 32 KB (ATmega328) of which 0.5 KB used
by bootloader
SRAM 2 KB (ATmega328)
EEPROM 1 KB (ATmega328)
Clock Speed 16 MHz

Identify these components in
 Microcontroller
 Power jacket
 USB jacket
 Digital pins
 Analog pins
 Reset button
Arduino

Arduino
 Voltage Regulator
 Power Pins (how many are there?)
 Ground Pins (how many are there?)
 Vin Pin
 Rx and Tx Pins
 ICSP Headers

 Power Led
 Rx and Tx Led’s
 Test Led
 Crystal
 Anything else?
Arduino

Powering up Arduino

Different ways to power up Arduino
 Using USB cable
 Using DC power jacket
 Giving voltage directly into Vin pin
 Giving regulated voltage directly into 5V pin

Setting up Arduino

Testing the setup with a “Hello
World” program

Blinking LED

Making a LED blink
 Insert a LED in pin 13
 Open File->Examples->Basics->Blink
 Select Tools->Boards->Arduino Uno
 Select File->Upload (or press ctrl+u)
 You should get the message “Done upload”
 Your Led should blink
 Congrats you can program Arduino now 

People with electronics background
Did I miss anything?

People with electronics background
Did I miss anything?
Hint: Ohm’s Law

Anatomy of an Arduino sketch

Printing values through Serial
 Uno has one UART hardware port, using which we
can exchange information with computer
 Very useful for debugging
 Works at a specified baud rate
 Use Serial Monitor to read values
 SoftwareSerial is also available

Breadboard Basics

How to use a breadboard
 The first two and the last two rows are connected
 In all the other rows, columns are connected
 Connect the first and last row to power
 Connect the second and second last row to ground

Digital Input and Output

Digital Input

Digital Output
The LED blink that we did at “setting up Arduino” is
Digital output

Analog Input

Reading Analog values from sensors
 Connect the LDR on pin A0 and Gnd
 LDR’s resistance varies based on the amount of light
present
 Read the current value using analogRead()
 Print the value in Serial Monitor

Control an LED based on light
void setup(){
pinMode(13, OUTPUT);
}
void loop(){
int val = analogRead(A0);
if (val > 50) {
digitalWrite(13, HIGH);
} else {
digitalWrite(13, LOW);
}
}

Analog Output

Analog Output
 What is PWM?
 Analog like behavior using digital output
 Works by switching the LED on and off regularly
 Changing the brightness of a Led

This is just the tip of an
iceberg
There are tons of other
features to Arduino which I
have not talked about

Internet of Things

"Internet of Things" by Wilgengebroed on Flickr

LoT is an overloaded term
But I like this definition…
“The Internet of Things is the interconnection of
uniquely identifiable embedded computing devices
within the existing Internet infrastructure”

Connecting Arduino to Internet
 Ethernet Shield
 WIFI Shield
 3G Shield
 Using another intermediate component

Demo of network connectivity
using Arduino

Let’s take a break 

Credit Card Sized
Computer

GPIO Pins
http://hardwarefun.com 41 http://learn.adafruit.com/assets/3052

Setup Python
sudo apt-get install python-dev
sudo apt-get install python-rpi.gpio

Set the status of GPIO Pins
https://github.com/sudar/r http://hardwarefun.com asp4b3erry-pi-sketches/blob/master/led-blink/led-blink.py

Set the status of GPIO Pins
import RPi.GPIO as GPIO
import time
GPIO.setmode(GPIO.BOARD)
GPIO.setup(12, GPIO.OUT)
try:
while True:
GPIO.output(12, GPIO.HIGH)
time.sleep(1)
GPIO.output(12, GPIO.LOW)
time.sleep(1)
finally:
GPIO.cleanup()
https://github.com/sudar/raspberry-http://hardwarefun.com 44 pi-sketches/blob/master/led-blink/led-blink.py

Demo
Let there be Light
https://github.com/sudar/r http://hardwarefun.com 45aspberry-pi-sketches/blob/master/led-blink/led-blink.py

Changing the brightness of the LED
import time
p = GPIO.PWM(12, 50) # channel=12 frequency=50Hz
p.start(0)
try:
while True:
for dc in range(0, 101, 5):
p.ChangeDutyCycle(dc)
time.sleep(0.1)
for dc in range(100, -1, -5):
p.ChangeDutyCycle(dc)
time.sleep(0.1)
finally:
p.stop()
GPIO.cleanup()
https://github.com/sudar/raspberry-pi-sketches/blob/master/led-blink/pwm.py

Demo
Can you see the brightness changing?
https://github.com/sudar/raspberry-http://hardwarefun.com 47 pi-sketches/blob/master/led-blink/pwm.py

Reading the status of the Pin
import time
GPIO.setup(11, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
try:
while True:
if GPIO.input(11):
print "Button is on"
else:
print "Button is off"
time.sleep(0.1)
finally:
GPIO.cleanup()
https://github.com/sudar/raspberry-pi-sketches/blob/master/button-input/button-input.py

Reading the status of the Pin

Demo
What happens when the button is pressed?

Combining Input and Output
import time
GPIO.setup(11, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
try:
while True:
if GPIO.input(11):
print "Button is on"
GPIO.output(12, 1)
else:
GPIO.output(12, 0)
time.sleep(0.1)
finally:
GPIO.cleanup()
https://github.com/sudar/raspberry-pi-sketches/blob/master/button-and-led/button-and-led.py

Combining Input and Output

Demo
Let’s control the LED by pressing the button

What more can be done?

More protocols
 I2C
 SPI
 Serial

Interacting with webcam
 “PyGame” provides easy interface
 Can get fancy using “opencv”
 Both USB and GPIO interface are supported

Distributed Computing
 Each Pi can be used as cheap node
 Form grids using a cluster of Pi’s
 Can share CPU, memory and disk space
http://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/
distributed-computing/

Limitations
 No built-in Analog to Digital support
 Can’t run Inductive load (motors)
 Is not real-time (CPU might be busy)
 No “safe circuits” present
 Operates at 3.3V and is not directly compatible with
Arduino voltage

Arduino vs Raspberry Pi
for IoT

Advantages of Raspberry Pi
 Entire Linux software stack is available
 It is very easy to connect to internet
 Can be programmed using variety of programming
languages

Disadvantage of Raspberry Pi
 Accessing hardware is not real-time. If the CPU is
busy, then interfacing with hardware can be delayed
 No built-in Analog to Digital converter available
 Does not have enough power to drive inductive loads
 The hardware design is not open source. Even though
it is not a big deal, for some people it might a deal
breaker

Advantages of Arduino
 Very easy to get started
 Very easy to extend it and has tons of user
contributed shields and libraries. Shields are available
to do pretty much anything
 Can be used to for real-time applications
 Everything (both hardware, software and IDE) are
open source
 Not much programming knowledge needed to do
basic stuff

Disadvantages of Arduino
 Not very powerful when compared with Raspberry Pi
(Micro processor vs Micro controller)
 You need to program using either Arduino or C/C++
(or assembly if you really want to)
 Connecting to internet is slightly difficult (you have
shields and libraries, but is not straight forward), but
not impossible.

In Short..
Feature Raspberry Pi Arduino
Processor Speed 700 MHz 16 MHz
Programming Language No limit Arduino, C/C++
Real-time Hardware No real-time In real-time
Analog to Digital Convertor No Yes
Hardware Design Closed source Open source
Internet Connection Very easy Not easy, but doable

My Solution?

Use both together 
Best of both worlds
http://learn.adafruit.com/assets/3199 http://learn.adafruit.com/assets/2123

Links
 Source code - https://github.com/sudar/raspberry-pi-sketches/
 My blog - http://hardwarefun.com
 Python GPIO - https://code.google.com/p/raspberry-gpio-
python/
 Distributed computing using Pi -
http://www.cl.cam.ac.uk/projects/raspberrypi/tutorial
s/distributed-computing/

Links
 Arduino – http://arduino.cc
 Asimi – A simple bot using Arduino
http://hardwarefun.com/project/asimi
 Getting started with hardware programming
http://hardwarefun.com/tutorials/getting-started-with-hardware-
programming
 Getting started with Arduino
http://hardwarefun.com/tutorials/getting-started-with-arduino-
and-avr

Questions
Thank You
Sudar Muthu (@sudarmuthu)
http://hardwarefun.com/
https://github.com/sudar/arduino-robotics-workshop
https://github.com/sudar/raspberry-pi-sketches

Using arduino and raspberry pi for internet of things

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