int fanPin = D3;

bool shouldActivate = false;

void setup() {
    
  Particle.function( "activate", activateFan );
  pinMode(fanPin, OUTPUT);
}

void loop() {
    
  if( shouldActivate ) {
    doFan(  );
    shouldActivate = false;

  }
  delay( 100 );
}

void doFan() {
  
  for( int i = 0; i < 5; i++ ) {
      
    digitalWrite(fanPin, HIGH);
    delay( 300 ) ;
    digitalWrite(fanPin, LOW);
    delay( 100 );
  }
}

int activateFan( String command ) {
  
  shouldActivate = true;
  return 1;
}