– Owl-duino – Peter Hathaway

January 2011

My first arduino project: A light-sensitive model owl.

When the lights go down (night), it “comes to life”

I was inspired by a ‘Birdmobile’ model of a ‘Little owl’ which I had constructed over the New Year period. Such a beautiful thing and very life-like given it’s made only from cut-and-glued printed card.

I wanted to use simple arduino functions and basic electronic components to add some further unexpected characteristics to the Little Owl such as an authentic hooting call, light-sensitivity and flashing eyes. OK, so the eyes of a real-life owl don’t “flash”, but are the eyes not the owls most appealing feature?

As with learning many new concepts and processes, I realised I would better understand the arduino micro-processor system when applying its potential functionality to my own project, rather than just copying verbatim from an exercise book (which I also did)*

It was frustrating and I tried and tried to make the most simple things happen. At a point of apparent impasse, I consulted a clever friend of mine who had been using arduino fairly extensively for his PhD thesis and he pointed out where I was going wrong.

Now the Owl-duino lives! …sort of.

– A light dependant resistor embedded in the owl’s forehead senses when the light levels drop and activates the functions.

– Bright White LEDs flash behind the translucent eyes made of yellow cellophane ‘Quality Street’ wrappers.

– A piezo speaker emits a sequence of (rather unconvincing) tones to imitate a “Twit-Twoooooo-oo-oo!”

– The eyes flash again, triumphantly and this loop continues until the light returns.

I will expand on this by adding electro-mechanical components to add movement such as flapping wings and head movements. I also like the idea (suggested by my arduino-fixing friend) of adding an RFID tag reader so that the owl can recognise and respond to objects within range e.g. a small yellow chicken toy (containing a tag) could prompt the excited hunter instinct in the owl whereas the presence of a human (perhaps with a tag concealed in a ring) could cause the owl to retreat in caution.

*”Getting Started with Arduino”; Make Projects; ISBN-10: 0596155514

Here is the arduino code:

#define LEFT_EYE 13

#define RIGHT_EYE 8

#define LDR 7

int speakerPin = 9;

int val = 0;

int length = 14; // the number of notes

char notes[] = ” a aCba”; // a space represents a rest

int beats[] = {2,1,1,1,5,1,1,};

int tempo = 100;

///////////////////////////////////////////////////////////////////////////////////

void setup() {

pinMode(LEFT_EYE, OUTPUT);

pinMode(RIGHT_EYE, OUTPUT);

pinMode(LDR, INPUT);

pinMode(speakerPin, OUTPUT);

}

void loop(){

val = digitalRead(LDR);

if (val == LOW) {

//digitalWrite(LEFT_EYE, HIGH);

//digitalWrite(RIGHT_EYE, HIGH);

flash_eyes();

playing();

} else {

digitalWrite(LEFT_EYE, LOW);

digitalWrite(RIGHT_EYE, LOW);

}

///////////////////////////////////////////////////////////////////////////////////

/*functions from this point forward */

///////////////////////////////////////////////////////////////////////////////////

void playTone(int tone, int duration) {

for (long i = 0; i < duration * 1000L; i += tone * 2) {

digitalWrite(speakerPin, HIGH);

delayMicroseconds(tone);

digitalWrite(speakerPin, LOW);

delayMicroseconds(tone);

}

void playNote(char note, int duration) {

char names[] = { ‘c’, ‘d’, ‘e’, ‘f’, ‘g’, ‘a’, ‘b’, ‘C’, ‘O’, ‘W’, ‘L’ };

int tones[] = { 1915, 1700, 1519, 1432, 1275, 1136, 1014, 956, 980, 700, 600,};

// play the tone corresponding to the note name

for (int i = 0; i < 8; i++) {

if (names[i] == note) {

playTone(tones[i], duration);

}

void playing(){

for (int i = 0; i < length; i++) {

if (notes[i] == ‘ ‘) {

delay(beats[i] * tempo); // rest

} else {

playNote(notes[i], beats[i] * tempo);

}

// pause between notes

delay(tempo / 2);

}

void flash_eyes(){

digitalWrite(LEFT_EYE, HIGH);

digitalWrite(RIGHT_EYE, HIGH);

delay(50);

digitalWrite(LEFT_EYE, LOW);

digitalWrite(RIGHT_EYE, LOW);

delay(50);

digitalWrite(LEFT_EYE, HIGH);

digitalWrite(RIGHT_EYE, HIGH);

delay(50);

digitalWrite(LEFT_EYE, LOW);

digitalWrite(RIGHT_EYE, LOW);

delay(50);

digitalWrite(LEFT_EYE, HIGH);

digitalWrite(RIGHT_EYE, HIGH);

delay(50);

digitalWrite(LEFT_EYE, LOW);

digitalWrite(RIGHT_EYE, LOW);

delay(50);

}