#include <NewPing.h>
#include <SoftwareSerial.h>

int pinledverde=7;
int pinledrojo=8;
#define echo 2
#define trig 3
#define MAX_DISTANCE 200
const byte rxPin = 0;
const byte txPin = 1;
int distance;
long duration;

SoftwareSerial mySerial (rxPin, txPin);
NewPing sonar(trig, echo, MAX_DISTANCE);

void setup() {
  pinMode(pinledverde,OUTPUT);
  pinMode(rxPin, INPUT);
  pinMode(txPin, OUTPUT);
  mySerial.begin(9600);
}

void loop() {

  delay(800);
 int uS = sonar.ping_median();
 mySerial.print("Distancia: ");
 int output=uS / US_ROUNDTRIP_CM;
 mySerial.println(output);
 mySerial.println("cm");

  if ((uS / US_ROUNDTRIP_CM)>20){
    digitalWrite(pinledrojo,HIGH);
    digitalWrite(pinledverde,LOW);
  }
  else{
    digitalWrite(pinledrojo,LOW);
    digitalWrite(pinledverde,HIGH);
  }

}