int trig=10;
int echo=11;
void setup()
{
  pinMode(trig,OUTPUT);
	pinMode(echo,INPUT);
  
  for(int i=1;i<=8;i++)
    pinMode(i,OUTPUT);
}

void loop()
{
long dur;
float cm;
 	
digitalWrite(trig,LOW);
delayMicroseconds(2);
digitalWrite(trig,HIGH);
delayMicroseconds(10);
digitalWrite(trig,LOW);
delayMicroseconds(2);
  
dur=pulseIn(echo,HIGH);

cm=micro2cm(dur);
  

  check(240,270,0,cm);
  check(210,240,1,cm);
  check(180,210,2,cm);
  check(150,180,3,cm);
  check(120,150,4,cm);
  check(90,120,5,cm);
  check(60,90,6,cm);
  check(20,60,7,cm);
  delay(100);
  ledoff();
}


float micro2cm(long microsec)
{
return (0.034*microsec/2);
}

void ledon(int n)
{
 for(int i=8;i>=8-n;i--)
   digitalWrite(i,HIGH);

}

void ledoff()
{
for(int i=1;i<=8;i++)
    digitalWrite(i,LOW);
  
}

void check(int from, int to, int n, long cm)
{
	if ((cm>=from) && (cm<to)) ledon(n);
}