int RL_EN = 5; // băm xung
int R_PWM = 2;// điều khiển chiều quay
int L_PWM = 3;// điều khiển chiều quay

void setup() {
 pinMode(RL_EN, OUTPUT);
 pinMode(R_PWM, OUTPUT);
 pinMode(L_PWM, OUTPUT);

 digitalWrite(R_PWM, HIGH);
 digitalWrite(L_PWM, HIGH); //STOP
}
void loop() {
 int i;
 digitalWrite(R_PWM, HIGH);
 digitalWrite(L_PWM, LOW); //clockwise
 
  for(i = 0; i <= 255; i= i+10) //Speed up 
  { 
   analogWrite(RL_EN, i); 
   delay(500);
  }
  for(i = 255; i >= 0; i= i-10)//Speed down
  { 
   analogWrite(RL_EN, i);
   delay(500);
  }
  
 delay(1500); //breaks
 digitalWrite(R_PWM, LOW);
 digitalWrite(L_PWM, HIGH);  //counter-clockwise

  for(i = 0; i <= 255; i= i+10) //Speed up 
  { 
   analogWrite(RL_EN, i); 
   delay(500);
  }
  for(i = 255; i >= 0; i= i-10) //Speed down
  { 
   analogWrite(RL_EN, i);
   delay(500);
  }  
}