#include <LiquidCrystal.h>

// Připojení:
// rs (LCD pin 4) na Arduino pin 12
// rw (LCD pin 5) na Arduino pin 11
// enable (LCD pin 6) na Arduino pin 10
// LCD pin 15 na Arduino pin 13
// LCD piny d4, d5, d6, d7 na Arduino piny 5, 4, 3, 2
LiquidCrystal lcd(12, 11, 10, 5, 4, 3, 2);
int backLight = 13;    // pin 13 ovládá possvícení LCD
int pingPin = 7; 
int inPin = 8;
long microseconds;  

void setup(void) {
  pinMode(backLight, OUTPUT);
  digitalWrite(backLight, HIGH); 
  lcd.begin(4,20);              
  lcd.clear();                  
  lcd.setCursor(0,0);      
  
}

void loop() {
  
  long duration, inches, cm; 

digitalWrite(pingPin, LOW); 
delayMicroseconds(2); 
digitalWrite(pingPin, HIGH); 
delayMicroseconds(10); 
digitalWrite(pingPin, LOW);
delayMicroseconds(2); 
pinMode(pingPin, OUTPUT); 

pinMode(inPin, INPUT); duration = pulseIn(inPin, HIGH);

cm = microsecondsToCentimeters(duration); 

 
  
  
  if (cm < 5) {
   
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("Vzdalenost: ");
  lcd.print(cm);
  lcd.print("   cm");
  lcd.setCursor(0,2);  
  lcd.print("  !!! P O Z O R !!! ");
  lcd.print("! Jste  moc blizko !");
   
  }
  else
   {
   
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("Vzdalenost: ");
  lcd.print(cm);
  lcd.print("   cm");
  
   
  }
  
  
  delay(300);}

long microsecondsToCentimeters(long microseconds) { return microseconds / 29 / 2;}