Outputs - Getting Started with Intel Galileo - page 46

If you've got everything right, you should see a fading LED! Just like those
fancy computers! Let's take a look at the code in Example 3-2 .
Example 3-2. The Arduino fade example
int led = 9 ; //
int brightness = 0 ; //
int fadeAmount = 5 ; //
void setup () { //
pinMode ( led , OUTPUT ); //
}
void loop () { //
analogWrite ( led , brightness ); //
brightness = brightness + fadeAmount ; //
if ( brightness == 0 || brightness == 255 ) { //
fadeAmount = - fadeAmount ; //
}
delay ( 30 ); //
}
Store the integer 9 into a new variable called led . This is the pin
number connected to the LED.
Store the integer 0 into a new variable called brightness . This is where
the sketch will keep track of the brightness level.
Store the integer 5 into a new variable called fadeAmount . This will
define the amount of steps in brightness to take each time the
brightness is changed.
Start the setup function, which is only executed once at the start of
the sketch.
Set led (pin 9) as an output.
Start the loop function, which is executed over and over again after
the setup function is finished.
Set led (pin 9) to the PWM value as determined by the variable
brightness . The first time executing this loop, it will be 0 (completely
off) because the value of brightness was initialized as 0 at the
beginning of the sketch.
Take the current value of brightness , add fadeAmount to it and then
assign that amount to brightness . In other words, add fadeAmount to
brightness .
If brightness equals 0 or 255, execute the code within the curly
brackets.