/*
 * A simple programme that will change the intensity of
 * an LED based  * on the amount of light incident on 
 * the photo resistor.
 * 
 */

//PhotoResistor Pin
int lightPin = 0; //the analog pin the photoresistor is 
                  //connected to
                  //the photoresistor is not calibrated to any units so
                  //this is simply a raw sensor value (relative light)
//LED Pin
int ledPin = 9;   //the pin the LED is connected to
                  //we are controlling brightness so 
                  //we use one of the PWM (pulse width
                  // modulation pins)
void setup()
{
  pinMode(ledPin, OUTPUT); //sets the led pin to output
}
 /*
 * loop() - this function will start after setup 
 * finishes and then repeat
 */
void loop()
{
 int lightLevel = analogRead(lightPin); //Read the
                                        // lightlevel
 lightLevel = map(lightLevel, 0, 900, 0, 255); 
         //adjust the value 0 to 900 to
         //span 0 to 255



 lightLevel = constrain(lightLevel, 0, 255);//make sure the 
                                           //value is betwween 
                                           //0 and 255
 analogWrite(ledPin, lightLevel);  //write the value
}

A video of the photo-resistor working for your viewing pleaure.

A photograph of my finished product.

A “Fritzing” Diagram of my circuit.

Source code for the project. The code below was taken from

ARDX.org

/*
 * A simple programme that will change the intensity of
 * an LED based  * on the amount of light incident on 
 * the photo resistor.
 * 
 */

//PhotoResistor Pin
int lightPin = 0; //the analog pin the photoresistor is 
                  //connected to
                  //the photoresistor is not calibrated to any units so
                  //this is simply a raw sensor value (relative light)
//LED Pin
int ledPin = 9;   //the pin the LED is connected to
                  //we are controlling brightness so 
                  //we use one of the PWM (pulse width
                  // modulation pins)
void setup()
{
  pinMode(ledPin, OUTPUT); //sets the led pin to output
}
 /*
 * loop() - this function will start after setup 
 * finishes and then repeat
 */
void loop()
{
 int lightLevel = analogRead(lightPin); //Read the
                                        // lightlevel
 lightLevel = map(lightLevel, 0, 900, 0, 255); 
         //adjust the value 0 to 900 to
         //span 0 to 255



 lightLevel = constrain(lightLevel, 0, 255);//make sure the 
                                           //value is between 
                                           //0 and 255
 analogWrite(ledPin, lightLevel);  //write the value
}

 

 

 

 

/*
 * A simple programme that will change the intensity of
 * an LED based  * on the amount of light incident on 
 * the photo resistor.
 * 
 */

//PhotoResistor Pin
int lightPin = 0; //the analog pin the photoresistor is 
                  //connected to
                  //the photoresistor is not calibrated to any units so
                  //this is simply a raw sensor value (relative light)
//LED Pin
int ledPin = 9;   //the pin the LED is connected to
                  //we are controlling brightness so 
                  //we use one of the PWM (pulse width
                  // modulation pins)
void setup()
{
  pinMode(ledPin, OUTPUT); //sets the led pin to output
}
 /*
 * loop() - this function will start after setup 
 * finishes and then repeat
 */
void loop()
{
 int lightLevel = analogRead(lightPin); //Read the
                                        // lightlevel
 lightLevel = map(lightLevel, 0, 900, 0, 255); 
         //adjust the value 0 to 900 to
         //span 0 to 255



 lightLevel = constrain(lightLevel, 0, 255);//make sure the 
                                           //value is betwween 
                                           //0 and 255
 analogWrite(ledPin, lightLevel);  //write the value
}

 

/*
 * A simple programme that will change the intensity of
 * an LED based  * on the amount of light incident on 
 * the photo resistor.
 * 
 */

//PhotoResistor Pin
int lightPin = 0; //the analog pin the photoresistor is 
                  //connected to
                  //the photoresistor is not calibrated to any units so
                  //this is simply a raw sensor value (relative light)
//LED Pin
int ledPin = 9;   //the pin the LED is connected to
                  //we are controlling brightness so 
                  //we use one of the PWM (pulse width
                  // modulation pins)
void setup()
{
  pinMode(ledPin, OUTPUT); //sets the led pin to output
}
 /*
 * loop() - this function will start after setup 
 * finishes and then repeat
 */
void loop()
{
 int lightLevel = analogRead(lightPin); //Read the
                                        // lightlevel
 lightLevel = map(lightLevel, 0, 900, 0, 255); 
         //adjust the value 0 to 900 to
         //span 0 to 255



 lightLevel = constrain(lightLevel, 0, 255);//make sure the 
                                           //value is between 
                                           //0 and 255
 analogWrite(ledPin, lightLevel);  //write the value
}

I feel like I should make a “Great Gatsby” joke about the green light but that’s not pertinent

this is a really unpleasant-to-look-at fritzing diagram I’m sorry I need to get used to using the program better

the code comes from the web address given in the instruction booklet:

/*
 * A simple programme that will change the intensity of
 * an LED based  * on the amount of light incident on 
 * the photo resistor.
 * 
 */

//PhotoResistor Pin
int lightPin = 0; //the analog pin the photoresistor is 
                  //connected to
                  //the photoresistor is not calibrated to any units so
                  //this is simply a raw sensor value (relative light)
//LED Pin
int ledPin = 9;   //the pin the LED is connected to
                  //we are controlling brightness so 
                  //we use one of the PWM (pulse width
                  // modulation pins)
void setup()
{
  pinMode(ledPin, OUTPUT); //sets the led pin to output
}
 /*
 * loop() - this function will start after setup 
 * finishes and then repeat
 */
void loop()
{
 int lightLevel = analogRead(lightPin); //Read the
                                        // lightlevel
 lightLevel = map(lightLevel, 0, 900, 0, 255); 
         //adjust the value 0 to 900 to
         //span 0 to 255



 lightLevel = constrain(lightLevel, 0, 255);//make sure the 
                                           //value is betwween 
                                           //0 and 255
 analogWrite(ledPin, lightLevel);  //write the value
}

Irresistible.

 

/*
 * A simple programme that will change the intensity of
 * an LED based  * on the amount of light incident on 
 * the photo resistor.
 * 
 */

//PhotoResistor Pin
int lightPin = 0; //the analog pin the photoresistor is 
                  //connected to
                  //the photoresistor is not calibrated to any units so
                  //this is simply a raw sensor value (relative light)
//LED Pin
int ledPin = 9;   //the pin the LED is connected to
                  //we are controlling brightness so 
                  //we use one of the PWM (pulse width
                  // modulation pins)
void setup()
{
  pinMode(ledPin, OUTPUT); //sets the led pin to output
}
 /*
 * loop() - this function will start after setup 
 * finishes and then repeat
 */
void loop()
{
 int lightLevel = analogRead(lightPin); //Read the
                                        // lightlevel
 lightLevel = map(lightLevel, 0, 900, 0, 255); 
         //adjust the value 0 to 900 to
         //span 0 to 255



 lightLevel = constrain(lightLevel, 0, 255);//make sure the 
                                           //value is betwween 
                                           //0 and 255
 analogWrite(ledPin, lightLevel);  //write the value
}

Youtube Video

https://www.youtube.com/watch?v=uNPaaZP4_Yo

Final Photo

Fritzing Diagram

The Source Code

/*
 * A simple programme that will change the intensity of
 * an LED based  * on the amount of light incident on 
 * the photo resistor.
 * 
 */

//PhotoResistor Pin
int lightPin = 0; //the analog pin the photoresistor is 
                  //connected to
                  //the photoresistor is not calibrated to any units so
                  //this is simply a raw sensor value (relative light)
//LED Pin
int ledPin = 9;   //the pin the LED is connected to
                  //we are controlling brightness so 
                  //we use one of the PWM (pulse width
                  // modulation pins)
void setup()
{
  pinMode(ledPin, OUTPUT); //sets the led pin to output
}
 /*
 * loop() - this function will start after setup 
 * finishes and then repeat
 */
void loop()
{
 int lightLevel = analogRead(lightPin); //Read the
                                        // lightlevel
 lightLevel = map(lightLevel, 0, 900, 0, 255); 
         //adjust the value 0 to 900 to
         //span 0 to 255



 lightLevel = constrain(lightLevel, 0, 255);//make sure the 
                                           //value is betwween 
                                           //0 and 255
 analogWrite(ledPin, lightLevel);  //write the value
}

 

/*
 * A simple programme that will change the intensity of
 * an LED based  * on the amount of light incident on 
 * the photo resistor.
 * 
 */

//PhotoResistor Pin
int lightPin = 0; //the analog pin the photoresistor is 
                  //connected to
                  //the photoresistor is not calibrated to any units so
                  //this is simply a raw sensor value (relative light)
//LED Pin
int ledPin = 9;   //the pin the LED is connected to
                  //we are controlling brightness so 
                  //we use one of the PWM (pulse width
                  // modulation pins)
void setup()
{
  pinMode(ledPin, OUTPUT); //sets the led pin to output
}
 /*
 * loop() - this function will start after setup 
 * finishes and then repeat
 */
void loop()
{
 int lightLevel = analogRead(lightPin); //Read the
                                        // lightlevel
 lightLevel = map(lightLevel, 0, 900, 0, 255); 
         //adjust the value 0 to 900 to
         //span 0 to 255



 lightLevel = constrain(lightLevel, 0, 255);//make sure the 
                                           //value is between 
                                           //0 and 255
 analogWrite(ledPin, lightLevel);  //write the value
}

Here’s a video.

I could not open the Fritzing.org website and now I have to go to the dentist so I made this makeshift diagram that I hope suffices. I apologize.

Heres a photo of my arduino all wired up.

Heres the code

/*
 * A simple programme that will change the intensity of
 * an LED based  * on the amount of light incident on 
 * the photo resistor.
 * 
 */

//PhotoResistor Pin
int lightPin = 0; //the analog pin the photoresistor is 
                  //connected to
                  //the photoresistor is not calibrated to any units so
                  //this is simply a raw sensor value (relative light)
//LED Pin
int ledPin = 9;   //the pin the LED is connected to
                  //we are controlling brightness so 
                  //we use one of the PWM (pulse width
                  // modulation pins)
void setup()
{
  pinMode(ledPin, OUTPUT); //sets the led pin to output
}
 /*
 * loop() - this function will start after setup 
 * finishes and then repeat
 */
void loop()
{
 int lightLevel = analogRead(lightPin); //Read the
                                        // lightlevel
 lightLevel = map(lightLevel, 0, 900, 0, 255); 
         //adjust the value 0 to 900 to
         //span 0 to 255



 lightLevel = constrain(lightLevel, 0, 255);//make sure the 
                                           //value is betwween 
                                           //0 and 255
 analogWrite(ledPin, lightLevel);  //write the value
}