/*
 * Aim: PWM by variation of intensity of LED brightness
 */

 //global variables
 int led = 10;
 int button1 = A1;  //increment button
 int button2 = A2;  //decrement button
 int brightness = 0;
 int fadeAmount = 20;

void setup() 
{
  pinMode(button1, INPUT);
  pinMode(button2, INPUT);
  pinMode(led, OUTPUT);
}

void loop()
{
  analogWrite(led, brightness);
  if(digitalRead(button1)) brightness += fadeAmount;
  if(digitalRead(button2)) brightness -= fadeAmount;
  brightness = constrain(brightness, 0, 255);

  delay(30);
}