LDR and Arduino

This is a practical use for an LDR. The LED on the arduino turns on when there is low light and turns off when there is plenty. This could be useful as a night light.

Press "Read More " To copy the code:




/*

* LDR and Arduino

*

* Reads an input from LDR, sends it to serial monitor and turns a LED off or on.

*

* Code by Joshua Lopez http://joshualopezarduino.blogspot.com/

*/



// variables

int LDR_pin = 0; // analog pin 0 (connect LDR here)

int LDR_val = 0; // variable use to read input data

int LEDpin = 13; //This is the LED



// a threshold to decide when the LED turns on

int threshold = 500;


void setup(){



// declaration of pin modes

pinMode(LDR_pin, INPUT);

pinMode(LEDpin, OUTPUT);


// begin sending over serial port

Serial.begin(9600);

}



void loop(){

// read the value on analog input

LDR_val = analogRead(LDR_pin);



// if value greater than threshold turn on LED

if (LDR_val < threshold) digitalWrite(LEDpin, HIGH); else digitalWrite(LEDpin, LOW);



// output 'LDR_val' value into the console

Serial.print("LDR = ");

Serial.print(LDR_val);



}