thanks I finally did it after your help.
#include <LiquidCrystal.h> // includes the LiquidCrystal Library
LiquidCrystal lcd(1, 2, 4, 5, 6, 7); // Creates an LCD object. Parameters: (rs, enable, d4, d5, d6, d7)
const int trigPin = 12;
const int echoPin = 13;
long duration;
int distance;
int count;
#include <elapsedMillis.h>
elapsedMillis timeElapsed;
void setup() {
lcd.begin(16,2); // Initializes the interface to the LCD screen, and specifies the dimensions (width and height) of the display
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
}
void loop() {
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
duration = pulseIn(echoPin, HIGH);
distance= duration*0.034/2;
if (distance > 20)
{ timeElapsed=0;}
if (timeElapsed > 5000 && distance < 20)
{
count++;
timeElapsed=0;
}
lcd.setCursor(0,0); // Sets the location at which subsequent text written to the LCD will be displayed
lcd.print("sjdah: "); // Prints string "Distance" on the LCD
lcd.print(count); // Prints the distance value from the sensor
delay(10);
}