int Pin_pwm1=3;
void setup() {
  // put your setup code here, to run once:
  pinMode(Pin_pwm1, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  for(int i=0;i<255;i+=5)
  {
    analogWrite(Pin_pwm1,i);
    delay(10);
  }
}