#define POTI A0
float potiV;
#define PIN_TRIG 3
#define PIN_ECHO 2
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27,16,2);
float cm;
uint8_t timing;
float pegel;
float posi;
float posi1;
long readUltrasonicDistance(int triggerPin, int echoPin)
{
  pinMode(triggerPin, OUTPUT);
  digitalWrite(triggerPin, LOW);
  delayMicroseconds(2);
  digitalWrite(triggerPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(triggerPin, LOW);
  pinMode(echoPin, INPUT);
  return pulseIn(echoPin, HIGH);
}
void setup() {
  Serial.begin(9600);
  pinMode(PIN_TRIG, OUTPUT);
  pinMode(PIN_ECHO, INPUT);
  Serial.println("test");
  lcd.init();
  lcd.backlight();
}
void loop() {
  int po = analogRead(POTI);
  potiV = ((float)po/1023.0)*5.0;
  Serial.println(potiV);
Serial.println(readUltrasonicDistance(3, 2));
  delay(25);
 cm = 0.01710132535271483539974348011971 * readUltrasonicDistance(3, 2);
 Serial.println(cm);
 if (cm<=50){
   digitalWrite(4,HIGH);
 }else{
   if(cm<300){
     digitalWrite(4,HIGH);
     delay(cm);
     digitalWrite(4, LOW);
     delay(cm);
    }
  }
  timing++;
  if(timing==5){
  lcd.clear();
  timing=0;
  }
  lcd.setCursor(0,0);
  lcd.print(cm, 1);
  lcd.setCursor(6,0);
  lcd.print("cm");
  lcd.setCursor(9,0);
  lcd.print(potiV);
  lcd.setCursor(14,0);
  lcd.print("V");
  pegel=potiV/1;
  posi=pegel*3.2;
  for (uint8_t posi1 =0;posi1<posi;posi1++){
    
    lcd.setCursor(posi1,1);
    lcd.print(char(255));
  }
  lcd.print("                ");
}