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This example is for Wiring version 1.0 build 0100+. If you have a previous version, use the examples included with your software. If you see any errors or have comments, please let us know.

Fade an LED brightness by BARRAGAN http://barraganstudio.com
Demonstrates the use of PWM pin 4 dimming an LED using the analogWrite() command On Wiring v1 boards the PWM capable pins are: 29, 30, 31, 35, 36 and 37 On Wiring S board the PWM capable pins are: 4, 5, 6, 7, 19 and 20

    int brightness = 0;    // LED brightness
    int increment = 5;     // brightness increment

    void setup()
    {
      pinMode(4, OUTPUT);  // set PWM pin as output
    }

    void loop()
    {
      brightness = brightness + increment;  // increment brightness for next loop iteration

      if (brightness <= 0 || brightness >= 255)    // reverse the direction of the fading
      {
        increment = -increment;
      }
      brightness = constrain(brightness, 0, 255);
      analogWrite(4, brightness);

      delay(20);  // wait for 20 milliseconds to see the dimming effect
    }