light intensity sensor using arduino

 * led will glow according to the intensity of light

components required

• arduino uno
• ldr
• led
• 10k resistor
• wires

code

 

int sensorPin = A0;  

int ledPin = 13; 

int ledPin2 = 12;

int ledPin3= 11;

int ledPin4= 10;

int p = 0; 

void setup() {

  // declare the ledPin as an OUTPUT:

  Serial.begin(9600);

  pinMode(ledPin, OUTPUT);  

  pinMode(ledPin2, OUTPUT);

  pinMode(ledPin3,OUTPUT);

  pinMode(ledPin4,OUTPUT);

}

void loop() {

  // read the value from the sensor:

  p = analogRead(sensorPin);    

  // turn the ledPin on

  Serial.println(p);

if(p<820) 

  {

    digitalWrite(ledPin,p);

    digitalWrite(ledPin3,HIGH);

    digitalWrite(ledPin2, HIGH);

    digitalWrite(ledPin4,HIGH);

  }

  else

  {

   

    

    digitalWrite(ledPin, LOW);

    digitalWrite(ledPin3,HIGH);

    digitalWrite(ledPin4,HIGH);}

    if(p<850) //

    { }

    

    else

    { digitalWrite(ledPin3,LOW);

    digitalWrite(ledPin2, LOW);

    digitalWrite(ledPin, LOW);

    digitalWrite(ledPin4,HIGH);

    

 

  }

  if(p>870)

  {digitalWrite(ledPin4,LOW);

  digitalWrite(ledPin,LOW);

  }

}

  

connections

• connect the led to the arduino board pins(13,12,11,10)
• connect a 10 k resistor in series with the ldr,
• connect the free end of resistor to the +5v pin of arduino
• connect the free end of ldr to ground
• connect the a0 pin to the ldr 
• connect all the -ve terminal of led to ground
• connect arduin to pc 
• run the code

 

 

 TIP:- u can change the values according to ur surroundings
       :- open serial monitor for viewing the ldr values.( tools->serial monitor)