void main()
{
    printf("Press START\n");  // message for human...
    start_press();   // wait for START button press    
    
    printf("driving fast\n");
    forward(100,2.0);
    beep();
    sleep(1.0);
    printf("driving slowly\n");
    forward(20,3.5);
}   // this bracket ends the main function

/* Function to drive forward at given speed for given time */
void forward( int speed, float time )
{
    motor(1, speed);   // turn on both motors at given speed
    motor(2, speed);
    sleep(time);       // wait for given time
    alloff();          // turn off again
}