int motA0=8;
int motA1=9;
int motB0=10;
int motB1=11;

int sen0=4;
int sen1=5;

int echo=6;
int triger=7;


int vel=150;



void setup() 
{
  pinMode(sen0,INPUT);
  pinMode(sen1,INPUT);
  pinMode(motA0,OUTPUT);
  pinMode(motA1,OUTPUT);
  pinMode(motB0,OUTPUT);
  pinMode(motB1,OUTPUT);
  pinMode(echo,INPUT);
  pinMode(triger,OUTPUT);
  digitalWrite(triger,LOW);
  digitalWrite(motA0,LOW);
  digitalWrite(motA1,LOW);
  digitalWrite(motB0,LOW);
  digitalWrite(motB1,LOW);
  
}

void loop() 
{

  if(distancia()<=20)
  {
    if(digitalRead(sen0)==LOW || digitalRead(sen1)==LOW)//Cambiar los "LOW" por "HIGH" para fondo blanco
    {
      stopP();
      delay(100);
      atras();
      delay(400);
      stopP();
      delay(500);
      derecha();
      delay(300);
      stopP();
      delay(500);
      adelante();
    }
    else 
    {
    adelante();
    }
  }
 else
  {    
    if(digitalRead(sen0)==LOW || digitalRead(sen1)==LOW)//Cambiar los "HIGH" por "LOW" para fondo negro
    {
      stopP();
     delay(100);
      atras();
      delay(400);
      stopP();
      delay(500);
      derecha();
      delay(300);
      stopP();
      delay(500);
      adelante();
    }
   else
    {
      adelanteLento();
    }
  }
  
}


long distancia()
{
  
  long t; 
  long d; 

  digitalWrite(triger, HIGH);
  delayMicroseconds(10);  
  digitalWrite(triger, LOW);
  
  t = pulseIn(echo, HIGH);
  d = t/59;            
  if (d<=3 || d>=25)
  {
    d=1000; 
  }
  
  delay(10);      
  return d;
}


void stopP()
{
  digitalWrite(motA0,HIGH);
  digitalWrite(motA1,HIGH);
  digitalWrite(motB0,HIGH);
  digitalWrite(motB1,HIGH);
}

void atras()
{
  digitalWrite(motA0,HIGH);
  digitalWrite(motA1,LOW);
  digitalWrite(motB0,HIGH);
  digitalWrite(motB1,LOW);
}

void adelanteLento()
{
  digitalWrite(motA0,LOW);
  analogWrite(motA1,vel);
  digitalWrite(motB0,LOW);
  analogWrite(motB1,vel);
}
void adelante()
{
  digitalWrite(motA0,LOW);
  digitalWrite(motA1,HIGH);
  digitalWrite(motB0,LOW);
  digitalWrite(motB1,HIGH);
}
void derecha()
{
  digitalWrite(motA0,LOW);
  digitalWrite(motA1,HIGH);
  digitalWrite(motB0,HIGH);
  digitalWrite(motB1,LOW);
}
void izquierda()
{
  digitalWrite(motA0,HIGH);
  digitalWrite(motA1,LOW);
  digitalWrite(motB0,LOW);
  digitalWrite(motB1,HIGH);
}