arduinisten/arduino-0022-linux-x64/examples/5.Control/IfStatementConditional/IfStatementConditional.pde

/*
  Conditionals - If statement
 
 This example demonstrates the use of if() statements.
 It reads the state of a potentiometer (an analog input) and turns on an LED
 only if the LED goes above a certain threshold level. It prints the analog value
 regardless of the level.
 
 The circuit:
 * potentiometer connected to analog pin 0.
 Center pin of the potentiometer goes to the analog pin.
 side pins of the potentiometer go to +5V and ground
 * LED connected from digital pin 13 to ground
 
 * Note: On most Arduino boards, there is already an LED on the board
 connected to pin 13, so you don't need any extra components for this example.
 
 created 17 Jan 2009
 modified 4 Sep 2010
 by Tom Igoe

This example code is in the public domain.
 
http://arduino.cc/en/Tutorial/IfStatement
 
 */
 
// These constants won't change:
const int analogPin = A0;    // pin that the sensor is attached to
const int ledPin = 13;       // pin that the LED is attached to
const int threshold = 400;   // an arbitrary threshold level that's in the range of the analog input

void setup() {
  // initialize the LED pin as an output:
  pinMode(ledPin, OUTPUT);
  // initialize serial communications:
  Serial.begin(9600);
}

void loop() {
  // read the value of the potentiometer:
  int analogValue = analogRead(analogPin);

  // if the analog value is high enough, turn on the LED:
  if (analogValue > threshold) {
    digitalWrite(ledPin, HIGH);
  } 
  else {
    digitalWrite(ledPin,LOW); 
  }

  // print the analog value:
  Serial.println(analogValue, DEC);

}