Interfacing sensors
and motors to the
Arduino board
Physical Computing 2009
By Farshid Jafari Harandi
Input/Output Interfacing
Input :
Getting data from environment
Input
processor
Output
Interacting with the environment
1
Output
Inputs
Introduced so far:
Buttons
Potentiometers
Piezo
Serial data from PC
Pictures from :
http://ctheds.wordpress.com/2007/10/30/connecting-a-potentiometer-to-the-arduino-analog-in/
http://www.plantautomation-technology.com/contractors/sensing/oen/
More Inputs
How to extend number of inputs
RFID
QR codes
Advanced sensors (SC2 next week)
Definition and pictures from
2
Extending number of inputs
Read more than one input in
parallel
Convert it to serial
Read the serial data in Arduino
and translate it to parallel
Picture from:
http://www.tpub.com/content/neets/14185/css/14185_151.htm
Radio Frequency IDentification, RFID
Dedicated ID
Transmitted wirelessly
Types of tags:
Passive
Powered with RF electromagnetic waves
Active
Powered with battery/line
Pictures and references from:
http://en.wikipedia.org/wiki/Radio-frequency_identification
3
Quick Response Codes, QR codes
A two dimensional code
Developed to be read quickly
Maximum 2,953 bytes
Error correction possibility
Pictures and references from:
http://en.wikipedia.org/wiki/Barcode
http://en.wikipedia.org/wiki/Radio-frequency_identification
Outputs
Introduced so far:
LEDs
Piezo/Speaker
Pictures from:
http://www.arduino.cc/
4
More outputs
Relays
Transistors
Lamps
DC motors
Servo motors
Stepper motors
Serial to parallel shift-out
Picture from:
http://www.psartus.com/products/actuators.htm
Need for current!
How to know the current
needed ?
Arduino sinks/sources a
max. of 40mA
Some loads need higher
currents
Picture from :
http://www.electronics-radio.com/articles/test-methods/meters/how-to-measure-current.php
5
Current amplification
Relays
Transistors: BJT or
MOSFET
Drivers
Pictures from:
http://en.wikipedia.org/wiki/Relay
http://en.wikipedia.org/wiki/H-bridge
http://en.wikipedia.org/wiki/Transistor
Back EMF
Generated while driving
inductive loads like motors
and relays
Is damped with a diode or
more
Picture from:
http://worldtechnical.blogspot.com/2008_10_01_archive.html
6
Lamps
Produce light
Are way less efficient than LEDs
Draw much more currents compared
to LEDs
Do not need any resistor in series!
Picture from:
http://www.diytrade.com/china/4/products/4935803/MINIATURE_LAMP_PILOT.html
Brushed DC motors
Work with DC current
Are capable of drawing lots of
current
Can be easily reversed by
changing polarity
Are relatively cheap
Need driver circuitry
Run continuously
Have two wires
Picture from:
http://www.optms.net/China_DC_motor.html
7
Servo motors
Work with DC current
Are relatively cheap
Do NOT need driver circuitry
Run continuously or are
position controlled
Draw tolerable amounts of
current
Are capable of holding/braking
Have three wires
Picture from:
http://www.parallax.com/
Stepper motors
Work with DC current
Are capable of drawing lots of
current
Can be easily reversed by
giving different steps to follow
Are relatively expensive
Need driver circuitry
Move in very precise steps
Have more than three wires
Picture from:
http://www.ecmarsh.com/cnc/electronics.htm
8
More about motors
Electric motors and generators :
http://www.animations.physics.unsw.edu.au/jw/electricmotors.html
Extending number of outputs
Translate the data to a
byte and send it serially
from Arduino
Convert it to parallel
Output data in parallel
Picture from:
http://www.tpub.com/content/neets/14185/css/14185_151.htm
9
Questions ?
THE END
10