Photoresistor

/**

 * @file: photoresistor example

 *

 * @description 

 * serial monitor output from photoresistor

 * turns LED off when it is dark

 * photoresistor, 100K resistor

 */

// include additional headers

 //global declarations

#define LED 13 //define a pin for LED

#define PHOTOR 5  //define a pin for Photo resistor

const int threshold = 20; // will depend on what resistor is used

//--- Function: Setup ()

void setup()

{ 

 pinMode(LED, OUTPUT); // setup LED

 Serial.begin(9600); // setup serial output

}

//--- Function: loop ()

void loop()

{

 Serial.println(analogRead(PHOTOR)); // reading values to serial monitor

 if(analogRead(PHOTOR) > threshold )

 { 

     digitalWrite(LED, HIGH); // turns on LED when it is dark

     Serial.println("high"); 

 }

 else

 {

     digitalWrite(LED, LOW); 

     Serial.println("low"); 

 }

 delay(200);

}