#include <Servo.h>
Servo myservo ;
#define TRIGGER 3
#define ECHO 2
uint8_t cm_cal;
uint8_t buzz=13;
uint16_t pos = 0; 
void setup() {
  Serial.begin(9600);
  myservo.attach(4);
  pinMode(TRIGGER, OUTPUT);
  pinMode(ECHO, INPUT);
  pinMode(buzz,OUTPUT);
}

void loop() {
  digitalWrite(TRIGGER, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIGGER, LOW);
  uint16_t duration = pulseIn(ECHO, HIGH);
  cm_cal=duration/58;
  Serial.println(cm_cal);
  delay(1000);
  if(cm_cal<250 && cm_cal>200)
  {
    tone(buzz,500,1000); 
    delay(1000);
  }
  if(cm_cal<200 && cm_cal>100)
  {
    tone(buzz,1000,250); 
    delay(250);
  }
  if(cm_cal<=100)
  {
    tone(buzz,1000);
    for (; pos <= 180; pos += 1)
    { 
      myservo.write(pos);
      delay(15);
    }
  }
}