int IN1=5;
int IN2=6;
int IN3=7;
int IN4=8;
int ENA=9;
int ENB=10;
void setup()
{
 for (int i = 5; i <11; i ++) 
   {
     pinMode(i, OUTPUT);   
   }
}
void loop()
{
   // rotate CW
  digitalWrite(IN1,LOW);
  digitalWrite(IN2,HIGH);
  analogWrite(ENA,200); 
  digitalWrite(IN3,LOW);
  digitalWrite(IN4,HIGH); 
  analogWrite(ENB,200); 
  delay(1000);
  // pause for 1S
  analogWrite(ENA,0); 
  analogWrite(ENB,0); 
  delay(1000); 
  // rotate CCW
  digitalWrite(IN1,HIGH);
  digitalWrite(IN2,LOW);
 
  analogWrite(ENA,100); 
  digitalWrite(IN3,HIGH);
  digitalWrite(IN4,LOW); 
  analogWrite(ENB,100); 
  delay(1000);
  // pause for 1S
  analogWrite(ENA,0); 
  analogWrite(ENB,0); 
  delay(1000); 
}