#define PIN_TRIG 12
#define PIN_ECHO 14
#define ledR 4
#define ledU 5
#define ledZ 19
int duration;
int razdaljaCM;
int zadnjaCM;
int flag;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  pinMode(ledR, OUTPUT);
  pinMode(ledU, OUTPUT);
  pinMode(ledZ, OUTPUT);
  pinMode(PIN_TRIG, OUTPUT);
  pinMode(PIN_ECHO, INPUT);
}

void loop() {
  digitalWrite(PIN_TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(PIN_TRIG, LOW);

 duration = pulseIn(PIN_ECHO, HIGH);
 razdaljaCM=(duration/58);

 Serial.println(razdaljaCM);
  delay(5); // this speeds up the simulation
if (razdaljaCM  <=400 && razdaljaCM > 300)
{
  flag=1;
}

if (razdaljaCM  <=300 && razdaljaCM > 200)
{
  flag=2;
}
if (razdaljaCM  <=200 && razdaljaCM > 100)
{
  flag=3;
}
if (razdaljaCM  <=100 && razdaljaCM > 0)
{
  flag=4;
}

if (razdaljaCM != zadnjaCM)
{
switch(flag)
{
  case 1:
  digitalWrite(ledZ, HIGH);
  digitalWrite(ledU, LOW);
  digitalWrite(ledR, LOW);
  break;

  case 2:
  digitalWrite(ledZ, HIGH);
  digitalWrite(ledU, HIGH);
  digitalWrite(ledR, LOW);

  break;

  case 3:
  digitalWrite(ledZ, HIGH);
  digitalWrite(ledU, HIGH);
  digitalWrite(ledR, HIGH);
  break;

  case 4:
  digitalWrite(ledZ, HIGH);
  digitalWrite(ledU, HIGH);
  digitalWrite(ledR, HIGH);
  
  break;
}
zadnjaCM=razdaljaCM;
}
}