/* Program for Smart Blind Stick  */ 

int trigPin1 = 4; 
int echoPin1 = 5; 
int buzzer = 7; 
long duration1; 
int distance1; 

void setup() 
{ 
   pinMode(trigPin1, OUTPUT); 
   pinMode(echoPin1, INPUT); 
   pinMode(buzzer, OUTPUT); 
   Serial.begin(9600); 
}

void loop() 
{ 
   digitalWrite(trigPin1, LOW); 
   delayMicroseconds(5); 
   digitalWrite(trigPin1, HIGH); 
   delayMicroseconds(15); 
   digitalWrite(trigPin1, LOW);
   duration1 = pulseIn(echoPin1, HIGH); 
   distance1= (duration1/2)*0.034;

   if (distance1 <= 100)
   { 
      tone(buzzer,3000); 
      delay(100);
      noTone(buzzer);
      delay(100);
   } 
   else
   { 
      noTone(buzzer); 
   }  
}