Using one of the analog ports you can also dim and LED and change the brightness dynamically. It must be a pin on the Arduino that has the capability for analog outputs such as pins 11, 10, 9, 6, 5, 3 on the Arduino UNO. The frequency output is at approximately 980Hz and it is writing a PWM (pulse width modulation) so this can also be used to control motors as you will see in later chapters.

Using the Arduino IDE to dim an LED on pin 9

/*

Fading

This example shows how to fade an LED using the analogWrite() function.

The circuit:

* LED attached from digital pin 9 to ground.

Created 1 Nov 2008

By David A. Mellis

modified 30 Aug 2011

By Tom Igoe

http://www.arduino.cc/en/Tutorial/Fading

This example code is in the public domain.

*/

int ledPin = 9;    // LED connected to digital pin 9

void setup() {

// nothing happens in setup

}

void loop() {

// fade in from min to max in increments of 5 points:

for (int fadeValue = 0 ; fadeValue <= 255; fadeValue += 5) {

// sets the value (range from 0 to 255):

analogWrite(ledPin, fadeValue);

// wait for 30 milliseconds to see the dimming effect

delay(30);

}

// fade out from max to min in increments of 5 points:

for (int fadeValue = 255 ; fadeValue >= 0; fadeValue -= 5) {

// sets the value (range from 0 to 255):

analogWrite(ledPin, fadeValue);

// wait for 30 milliseconds to see the dimming effect

delay(30);

}

}

Remember in order to use that patch below you will need to have the MaxuinoSimpleStart program open.