Arduino

arduino + photoresistor + led

Added by on August 27th, 2008, filed under Arduino

i spent a little time last night playing with arduino and i thought i’d share this little experiment i put together.


Arduino + Photo Resistor + LED from Joshua McGinnis on Vimeo.

here’s the source:

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/*
 * Power LED on Dark by Joshua McGinnis
 *
 * This basic example uses a photo resistor to determine
 * whether light is present or not. If it is not, an led
 * will be set to high.
 *
 * http://www.joshuamcginnis.com
 */

int photoPin = 1; // designate pin 1 as the analog in for the photo resitor
int val = 0;

int ledPin = 13; // designate pin 1 as the analog in for the photo resitor

void setup()                    // run once, when the sketch starts
{
  Serial.begin(9600);
  pinMode(ledPin,OUTPUT); // set the pin
  pinMode(photoPin,OUTPUT); // set the pin
}

void loop()                     // run over and over again
{

  val = analogRead(photoPin); // set val equal to the resitor input

  if(val == LOW) { // if nothing from photo resistor (low light), turn on led

    digitalWrite(ledPin, HIGH);
    delay(500);

  } else {
    digitalWrite(ledPin, LOW);
  }
  Serial.println(val);
}

About the Author: Joshua McGinnis

Joshua is a web designer and developer for Intuit, Inc. His other interests include guitar, photography, mycology, amateur chemistry, WWII movies and his beautiful wife Catherine.

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Reader Comments (6)

  1. ril3y February 13, 2009 at 10:30 pm

    Very cool stuff man… I just got my arduino trying to see all the different things people are doing with them..

    -ril3y
    http://www.synthetos.com

    Reply
  2. alwolf March 3, 2009 at 6:01 pm

    Hello, I copied and pasted your code above into the IDE and recieve this error:

    In function ‘void setup()’:
    error: ‘ledPin2′ was not declared in this scope

    Do we need to initialize an “ledpin2″ like you did for ledPin?

    Reply
  3. John May 27, 2009 at 6:24 pm

    pinMode(ledPin2,OUTPUT); // set the pin

    should be

    pinMode(photoPin,OUTPUT); // set the pin

    Reply
  4. ricky June 19, 2010 at 3:28 pm

    Its called a protoSheild not a borduino….but a borduino may be another name……

    Reply
  5. Andy December 5, 2010 at 6:15 am

    you really should have a current limiting resistor on your LED — (see how bright it gets in your demo video). Try something in the range of 330ohms or so to prevent damage to your board. that, or use pwm.

    Reply

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