const int trigPin = 26; // vrednost 20 je konstantna
const int echoPin = 25;
long duration, cm; 
int on =12;
int off = 13;

void setup() {
  Serial.begin(9600);
  pinMode (trigPin, OUTPUT);
  pinMode (echoPin, INPUT);
  pinMode (on, OUTPUT);
  pinMode (off, OUTPUT);
}


void loop() {
//Sensor pin trigPin pošlje HIGH signal za 
digitalWrite(trigPin, LOW);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
duration = pulseIn(echoPin, HIGH);
cm = (duration/2)/29.1;

if(cm<20)
digitalWrite(on, HIGH);
digitalWrite(off, LOW);
Serial.println("razdalja manjsa od 20cm");
delay (500);

}