Photoresistor

Parts

-Arduino microcontroller and carrier board

-LiPo battery

-Photoresistor

-Jumper wires

-10kOhm resistor

Prepare the breadboard

Connect the photoresistor to GND, other leg to an A5.

Connect a resistor (around 10k is a good value, higher values gives higher readings) from pin 5 to +5V.

PhotoR 10K

GND o---/\/\/--.--/\/\/---o +5

|

Pin A5 o-----------

For a different setup:

Program the Microcontroller

/**
 * @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);
}