int echo=2;
int tri=3;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(tri,OUTPUT);
  pinMode(echo, INPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  long duration, jarak;
  digitalWrite(tri, LOW);
  delayMicroseconds(2);
  digitalWrite(tri, HIGH);
  delayMicroseconds(10);
  digitalWrite(tri, LOW);
  //delayMicroseconds(10);
  duration=pulseIn(echo,HIGH);
  jarak=(duration/2)/29.1;
  Serial.println("jarak");
  Serial.println(jarak);
  Serial.println("cm");
}