Arduino distant measure using US-100

us100.pde

// Use US-100 to find distance and display into LCD

// LCD Ref: http://www.dfrobot.com/wiki/index.php?title=I2C/TWI_LCD1602_Module_%28SKU:_DFR0063%29
// US-100 Ref: http://www.doc88.com/p-610738935623.html

#include <Wire.h> 
#include <LiquidCrystal_I2C.h>

// Setup of LCM1602 driven by PCF85741
// A4 - SDA
// A5 - SCL
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Setup US-100
// D2 - ECHO 
// D3 - TRIG
unsigned int ECHO = 2;
unsigned int TRIG = 3;

// used for calculate distance
unsigned long time_echo_us   = 0;
unsigned long len_mm         = 0;

void setup() {
  Serial.begin(9600);
  
  lcd.init();
  lcd.backlight();
  
  pinMode(ECHO, INPUT);
  pinMode(TRIG, OUTPUT);
}

void loop() {
  digitalWrite(TRIG, HIGH);
  delayMicroseconds(50);  
  digitalWrite(TRIG, LOW);
  
  time_echo_us = pulseIn(ECHO, HIGH);
  if (time_echo_us > 1) {
    len_mm = (time_echo_us * 34 / 100) / 2;

    lcd.clear();
    lcd.print("Dist: ");
    lcd.print(len_mm, DEC);
    lcd.println("mm");
  }
  
  delay(1000);
}