#include <LiquidCrystal_I2C.h>

#define PIN_TRIG1 2
#define PIN_ECHO1 3
#define PIN_TRIG2 4
#define PIN_ECHO2 5

#define I2C_ADDR    0x27
#define LCD_COLUMNS 16
#define LCD_LINES   2

LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);


const float sensorDistance = 0.5;

// Speed limit (m/s)
const float speedLimit = 10.0;

unsigned long t1 = 0;
unsigned long t2 = 0;

void setup() {
  // Init
  lcd.init();
  lcd.backlight();

  pinMode(PIN_TRIG1, OUTPUT);
  pinMode(PIN_ECHO1, INPUT);

  pinMode(PIN_TRIG2, OUTPUT);
  pinMode(PIN_ECHO2, INPUT);
}


void loop() {

  digitalWrite(PIN_TRIG1, HIGH);
  delayMicroseconds(10);
  digitalWrite(PIN_TRIG1, LOW);

  int duration1 = pulseIn(PIN_ECHO1, HIGH);

  lcd.setCursor(0, 0);
  lcd.print("Dis:");
  lcd.setCursor(4, 0);
  lcd.print("   ");
  lcd.setCursor(4, 0);
  lcd.print(duration1 / 58);
  lcd.setCursor(8, 0);
  lcd.print("CM");

  
  digitalWrite(PIN_TRIG2, HIGH);
  delayMicroseconds(10);
  digitalWrite(PIN_TRIG2, LOW);

  int duration2 = pulseIn(PIN_ECHO2, HIGH);
  lcd.setCursor(0, 1);
  lcd.print("Dis:");
  lcd.setCursor(4, 1);
  lcd.print("   ");
  lcd.setCursor(4, 1);
  lcd.print(duration2 / 58);
  lcd.setCursor(8, 1);
  lcd.print("CM");
}