꽤 오래 붙잡고있었는데 잘 안되서 질문드립니다.
 
초음파센서에 잡힌 물체의 거리에 따라 그래프가 증감하는 형식의 코드입니다.
그래프 증감은 잘 되지만 문제는 아무 물체가 잡히지 않으면 그래프를 비워놓고싶은데 꽉 차있습니다.. 도와주십쇼
 
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27,16,2);
 
int trig_pin = 3;
int echo_pin = 4;
float duration = 0;
int distance = 0;
int i = 0;
int j = 0;
 
int start_flag = 1;
 
byte b00[8] {00,00,00,00,00,00,00,00};
byte b16[8] {16,16,16,16,16,16,16,16};
byte b24[8] {24,24,24,24,24,24,24,24};
byte b28[8] {28,28,28,28,28,28,28,28};
byte b30[8] {30,30,30,30,30,30,30,30};
byte b31[8] {31,31,31,31,31,31,31,31};
 
void setup()
{
  ss_mode_setup();
 
  lcd.createChar(0,b00);
  lcd.createChar(1,b16);
  lcd.createChar(2,b24);
  lcd.createChar(3,b28);
  lcd.createChar(4,b30);
  lcd.createChar(5,b31);
 
  lcd.init();
  lcd.backlight();
 
  lcd.init();
  lcd.backlight();
}
 
void loop()
{
  if(start_flag == 1)
  {
  ss_mode();
}
}
 
void ss_mode_setup()
{
  lcd.createChar(0,b00);
  lcd.createChar(1,b16);
  lcd.createChar(2,b24);
  lcd.createChar(3,b28);
  lcd.createChar(4,b30);
  lcd.createChar(5,b31);
 
  lcd.init();
  lcd.backlight();
 
  pinMode(trig_pin, OUTPUT);
  pinMode(echo_pin, INPUT);
  Serial.begin(9600);
}
 
void ss_mode()
{
  digitalWrite(trig_pin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trig_pin, LOW);
 
  duration = pulseIn(echo_pin, HIGH);
  distance = duration / 29 / 2;
 
  lcd.setCursor(0,1);
  lcd.print("U:");
  lcd.setCursor(2,1);
  lcd.print("              ");
  
  int i = distance / 5;
  int j = distance % 5;
 
  Serial.print(distance);
  Serial.print(" ");
  Serial.print(i);
  Serial.print(" ");
  Serial.print(j);
 
  lcd.setCursor(2,1);
  if(i >= 14) // 14이상이면
  {
    for(int k = 0; k<14; k++)
    {
      lcd.write(5);
    }
  }
  else if(i<14)
  {
    for(int k = 0; k<i; k++)
    {
      lcd.write(5);
    }
  }
  lcd.setCursor(i+2,1);
  lcd.write(j);
}