Ultrasonic range finder using Amarino Evaluation shield

HCSR04.ino

#include <LiquidCrystal.h>
LiquidCrystal lcd(13, 12, 10, 9, 8, 7);

int TrigPin = 4;
int EchoPin = 2;

void setup()
{
  lcd.begin(16, 2);
  Serial.begin(9600);
  pinMode(TrigPin,OUTPUT);
  pinMode(EchoPin,INPUT);
}
void loop()
{
  int distance,duration;
  
  digitalWrite(TrigPin,HIGH);//TrigPin prepare high of more than 10us
  delayMicroseconds(11);
  digitalWrite(TrigPin,LOW);
  duration = pulseIn(EchoPin, HIGH);//EchoPin received high start counting until the receiver to the low,return to the count valu
  duration = duration/29/2;//Calculating the distance  cm
                           // The speed of sound is 340 m/s or 29 microseconds per centimeter.
  lcd.clear();
  lcd.print("Distance:");
  lcd.print(duration); 
  Serial.print(duration);//Serial display distance
  lcd.print("cm");
  Serial.print("cm");
  Serial.println();
  delay(1000);
}