const int TRIGPIN = 2; 
const int ECHOPIN = 3;
int merah = 12;
int hijau = 13;
long time;
int jarak;

void setup() {
Serial.begin(9600);
pinMode (ECHOPIN, INPUT);
pinMode (TRIGPIN, OUTPUT);
pinMode (merah, OUTPUT);
pinMode (hijau, OUTPUT);
pinMode (2, OUTPUT);
}

void loop() {
digitalWrite(2, HIGH);
digitalWrite(TRIGPIN, LOW);
delayMicroseconds(2);
digitalWrite(TRIGPIN, HIGH);
delayMicroseconds(10);
digitalWrite(TRIGPIN, LOW);

time = pulseIn (ECHOPIN, HIGH);
jarak = time/58;
delay(1000);

if (jarak<50){
 digitalWrite (merah, HIGH);
 digitalWrite (hijau, LOW);
}
else{
digitalWrite (hijau, HIGH );
digitalWrite (merah, LOW );
}

Serial.print("jarak = ");
Serial.print(jarak);
Serial.print(" cm");
Serial.println;();

}