const int motorPin = 9;

void setup()
{
pinMode(motorPin, OUTPUT);
Serial.begin(9600);
}

void loop()
{
int onTime = 3000;
int offTime = 3000;

analogWrite(motorPin, 255);
delay(onTime);
analogWrite(motorPin, 0);
delay(offTime);
}

void speedUpandDown()
{
int speed;
int delayTime = 20;

for(speed = 0; speed <= 255; speed++)
{
analogWrite(motorPin,speed);
delay(delayTime);
}

for(speed = 255; speed >= 0; speed--)
{
analogWrite(motorPin,speed);
delay(delayTime);
}
}

void serialSpeed()
{
int speed;

Serial.println("Type a speed (0-255) into the box above,");
Serial.println("then click [send] or press [return]");
Serial.println();

while(true)
{
while (Serial.available() > 0)
{
speed = Serial.parseInt();
speed = constrain(speed, 0, 255);

Serial.print("Setting speed to ");
Serial.println(speed);

analogWrite(motorPin, speed);
}
}
}