dean brock, rebecca bruce and susan reiser, ccsc se 2009 using arduino material taken from todbot...

Dean Brock, Rebecca Bruce and Susan Reiser, CCSC SE 2009

Using ArduinoUsing Arduino

Material taken from Todbot Material taken from Todbot blog Bionic Arduinoblog Bionic Arduino


What is the Arduino


Arduino Duemilanove• 13 digital input/output pins

– Including 6 with PWM for analog output

• 6 analog input pins• USB connection

– For serial I/O and uploading board• ATmega168 or ATmega328 processor

– 16k or 32k for program, 1k or 2k for data

• Arduino bootloader• ~ $30• More Info


Other Arduino Boards

• Arduino Mega– Lots of I/O pins and lots (128k) of program space

– ~ $65• LilyPad

– For wearable applications– ~ $20

• Boarduino– Fits within a breadboard– ~ $20, but must be soldered!


Activity 1• Start the Arduino IDE from the terminal window with the command: arduino

• Make sure to connect the PC to the Arduino using the USB cable.

• Designate the connection port and processor type.

• Try out the “blink” example– Select: File > Examples > Digital > Blink


Connect the USB Cable


Select Connection and Type

atmega328


Arduino IDE


Status Messages


Activity 1 Modified---Add an External LED to

pin 13• File > Examples > Digital > Blink

• LED’s have polarity – Negative indicated by flat side of the housing and a short leg

www.instructables.com


Terminology


Arduino Control

• Very much like Processing/Java– if, then, while, switch– Functions, expressions

• setup()– Runs once at beginning (or reset)

• loop()– Runs continuously

•Like draw()


Arduino Digital I/O

• pinMode(pin, mode)– Sets pin to either INPUT or OUTPUT

• digitalRead(pin)– Reads HIGH or LOW from a pin

• digitalWrite(pin, value)– Writes HIGH or LOW to a pin

• Electronic stuff you can ignore– Output pins can provide 40 mA of current

– Writing HIGH to an input pin installs a 20KΩ pullup


Arduino Timing

• delay(ms)– Pauses for a few milliseconds

• delayMicroseconds(us)– Pauses for a few microseconds


Circuits


All holes in each of the four long columns are connected internally.Use these to route power and ground.

Connect this columnto GND (0 volts)

Connect this columnto GND (0 volts)

Connect thiscolumn to 5V

Connect thiscolumn to 5V

There are ten holes that form the rows.These are divided into two sets of five holes.All holes in each set of five are connected

Breadboard Fundamentals


Activity 2• File > Examples > Digital > Melody

• Speakers have polarity. Positive indicated by small + or dot on piezoelectric speaker.


Activity 2• Get a breadboard and a piezoelectric speaker

• Assemble as shown

Image credit: Tod Kurt

• Try out the built-in “melody” example– Select: File > Examples > Digital > toneMelody

• Try this version of Melody.pde


Digital? Analog?• Digital has two values: on and off• Analog has many (infinite) values• Computers don’t really do analog, they quantize

• Remember the 6 analog input pins---here’s how they work



Analog to Digital• Number of states or “bins” is the resolution

• Arduino resolution is 10-bits (1024 values)

• 5/1024 = 4.8 mV smallest voltage change you can measure

Image credit: Eoin Brazil


Analog Output

• Computers can’t output analog voltages– Only digital voltages (0 volts or 5 volts)

• Simulating an analog signal with Pulse Width Modulation (PWM)– Can’t directly supply 2.5V, but can pulse the output on and off really fast to produce the same effect---the same effective voltage.


Analog Output

Vary the effective voltage by modulating the width of the high pulse



Activity 3• Hardware Needed:

– Resistor (in 220-500 Ohm range)– Breadboard– LED– Wire

• Assemble as shown(MOVE the piezo speaker to pin 7)

–Select: File > Examples > Analog > Fading



PWM is Everywhere

• Lamp dimmers, motor, speed control, power supplies, noise making, etc.

• Now on to analog input using sensors---DON’T DISASSEMBLE your breadboards


Sensing the Dark: Photoresistors

• a.k.a. a photocell or light-dependent resistor

• It is a variable resistor– Brighter light => lower resistance

• Create a voltage divider to use the photoresistor



Activity 4

• Hardware Needed:– Resistor (approx. 10k Ohm)– Breadboard– Photoresistor– Wire

• Assemble as shown



A Theremin• Create a theremin using the photoresistor– A spooky sound machine

•Works by measuring your body’s electric field

– We’ll use light to control the tone produced

• We’ll also control the brightness of the LED using the photoresistor.

• Verify your breadboard configuration!


Theremin Breadboard Configuration

Hardware Needed: Resistors, Breadboard, Wire, Photoresistor, Piezo speaker, LED


The Theremin Program

Load and run the TherminAndLEDprogram


Sensors

• There are many analog sensors that could be used in place of the photoresistor

• Check out our “theremin” demos created using other sensors



Communication Between the Arduino and Your

Computer

ArduinoProgram

ProcessingProgram

ArduinoBoard

YourComputer

Serial (TTL)Communication


Processing• Includes libraries supporting serial communication, video capture, audio processing…

• VERY IMPORTANT: enter the following command in the terminal window to update the serial library:~brock/bin/serialfix

• Start Processing from the terminal window


Activity 5 • Hardware Needed:

– Resistor (10k Ohm)– Breadboard– Photoresistor– Wire

• Don’t reassemble - this is the same schematic as Activity 4.



Activity 5

• Open SimpleWrite.pde into the Arduino IDE.

• Open SimpleRead.pde into Processing.


Serial Communication in Arduino


Serial Communication in Processing


Clarifications

• SimpleWrite spends the first second sampling the photocell readings and setting limits.

• The Arduino program restarts when the Processing program starts.

• If the Processing program begins behaving badly, try pressing the restart button on the Arduino.


Project 2

• Project 2

dean brock, rebecca bruce and susan reiser, ccsc se 2009 using arduino material taken from todbot...

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