#include <NewPing.h>

#define trig_pin 11
#define echo_pin 12
#define max_afstand 200

NewPing sonar(trig_pin,echo_pin,max_afstand);


void setup() {

Serial.begin(9600);
pinMode(2, OUTPUT);
}

void loop() {
delay(50);
int cm = sonar.ping_cm();

if (cm<20){
Serial.println("stoppen");
digitalWrite(2, HIGH);
}

else {
Serial.println(cm);
digitalWrite(2, LOW);
}
}