//Cortez, Shara Joy M.
//NW-301

const int trigPin = 7; 
const int echoPin = 8; 
int buzzer = 12;  

void setup() {  
  Serial.begin(9600);  
  pinMode(trigPin, OUTPUT); 
  pinMode(echoPin, INPUT); 
  pinMode(3, OUTPUT); 
  pinMode(4, OUTPUT); 
  pinMode(5, OUTPUT); 
  pinMode(buzzer, OUTPUT);  
}  

void loop() {  
  digitalWrite(trigPin, LOW);  
  delayMicroseconds(2);  
  digitalWrite(trigPin, HIGH);  
  delayMicroseconds(10);  
  digitalWrite(trigPin, LOW);  
  
  long duration = pulseIn(echoPin, HIGH);  
  int distance = duration * 0.0343 / 2;  
  
  Serial.print("Distance: ");  
  Serial.print(distance);  
  Serial.println(" cm");  
  delay(100); 
  if(distance>100)  
{  
  digitalWrite(3, HIGH);  
  digitalWrite(4, LOW);  
  digitalWrite(5, LOW);  
  digitalWrite(buzzer, 0);  
}  
else if(distance>25)  
{  
  digitalWrite(3, LOW);  
  digitalWrite(4, HIGH);  
  digitalWrite(5, LOW);  
  digitalWrite(buzzer, 1);  
  tone(buzzer, 5000, 400);  
  delay(400);  
  digitalWrite(buzzer, 0);  
  tone(buzzer, 5000, 400);  
  delay(400);  
}  
else  
{  
  digitalWrite(3, LOW);  
  digitalWrite(4, LOW);  
  digitalWrite(5, HIGH);  
  digitalWrite(buzzer, 1);  
  tone(buzzer, 1000, 100);  
  delay(100);  
  digitalWrite(buzzer, 0);  
  tone(buzzer, 1000, 100);  
  delay(100);  
}
}