Arduino Light Sensor Circuit Tutorial

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// Makes LED on your Arduino development board blink at different rate, depending on the amount of light on the sensor.
 
// Select input pin for the photocell light sensor.
int LDR = 0;
// Select the pin for the LED
int ledPin = 13;
// Variable to store the value coming from the sensor.
int val = 0;
 
void setup() {
  // Declare LDR as an input pin.
  pinMode(LDR, INPUT);
  // Declare ledPin as output led pin, in this case it's the surface mounted led on Arduino.
  pinMode(ledPin, OUTPUT);
}
 
void loop() {
  // Read current value from the sensor.
  val = analogRead(LDR);
  // Turn led on.
  digitalWrite(ledPin, HIGH);
  // Delay depending on val.
  delay(val);
  // Turn led off.
  digitalWrite(ledPin, LOW);
  // Delay depending on val.
  delay(val);
}