Need Help with Piezo Buzzer and Ultrasonic Sensor code

Projects Programming
10

I did not have a sensor so I used a POT.
Add/delete/change lines as needed.
You should be able to modify the code to your ultrasonic application.
Change hysteresis as needed.

int duration;
int distance;
int hysteresis = 5;       // minimum acceptable change
boolean buzzState = false;  // false = buzzer is off
unsigned long buzzDelay;  //Time the buzzer will be On
unsigned long buzzMilli;  //Time the buzzer went On
int lastDistance;  // = the last read distance value

void setup() 
{
  Serial.begin (9600);
  buzzState = false;
  pinMode(4,OUTPUT);
}

void loop()
{
  duration = analogRead(A0);
  distance = (duration);
  if (distance >= 200 || distance <= 0)
  {
    Serial.println("Out of range");
  }
  else
  {
    Serial.print(distance);
    Serial.println(" cm");
  }

  // Has the distance changed significantly?
  if ((lastDistance + hysteresis) < distance || (lastDistance - hysteresis) > distance)
  {
    lastDistance = distance;
    buzzDelay = distance;
    buzzMilli = millis();
    buzzState = true; // indicate the buzzer is now on
    digitalWrite(4,HIGH);  //turn on the buzzer
  }

  if (buzzState == true && (millis() - buzzMilli >= buzzDelay))    //is time left and is the buzzer ON?
  {
    digitalWrite(4,LOW); //turn off the buzzer
    buzzState = false;  //indicate the buzzer is now off
  }
}   
   // END of loop()