// YWROBOT
// Compatible with the Arduino IDE 1.0
// Library version:1.1
#include <LiquidCrystal_I2C.h>
#include "pitches.h"
#define SPEAKER_PIN 8
#define BACK_PIN 12
#define ECHO_PIN 2
#define TRIG_PIN 3

LiquidCrystal_I2C lcd(0x27,20,4);
// set the LCD address to 0x27 for a 16 chars and 2 line display

float cm = 0.0;
float inches = 0.0;

long readUltrasonicDistance()
{
	//pinMode(TRIG_PIN, OUTPUT);  // Clear the trigger
	digitalWrite(TRIG_PIN, LOW);
	delayMicroseconds(2);
	// Sets the trigger pin to HIGH state for 10 microseconds
	digitalWrite(TRIG_PIN, HIGH);
	delayMicroseconds(10);
	digitalWrite(TRIG_PIN, LOW);
	//pinMode(ECHO_PIN, INPUT);
	// Reads the echo pin, and returns
	// the sound wave travel time in microseconds
	int duration = pulseIn(ECHO_PIN, HIGH);
	return duration * 0.0344 / 2;
}

void setup()
{
  Serial.begin(115200);
	pinMode(BACK_PIN,INPUT_PULLUP);
	pinMode(TRIG_PIN, OUTPUT);
	pinMode(ECHO_PIN, INPUT);
  lcd.init();	// initialize the lcd
  // Print a message to the LCD.
  lcd.backlight();
  lcd.print("--> Distance <--");
	delay(3000);
	lcd.clear();
}

void loop()
{
  cm = readUltrasonicDistance();
	inches = (cm / 2.54);
	float distance = map(cm,0,400,0,200);
  /*
	Serial.print("Inches ");
	Serial.print(inches, 1);
	Serial.print("\t");
  Serial.print("cm ");
	Serial.println(cm, 1);
	*/
	if(digitalRead(BACK_PIN) == 1){
    delay(distance);
    tone(SPEAKER_PIN,NOTE_E4);
    delay(distance);
    noTone(SPEAKER_PIN);
  } else noTone(SPEAKER_PIN);

	lcd.setCursor(0,0);
	lcd.print("Inches");
	lcd.setCursor(4,0);
	lcd.setCursor(12,0);
	lcd.print("cm");
	lcd.setCursor(1,1);
	lcd.print(inches, 1);
	lcd.setCursor(11,1);
	lcd.print(cm, 1);
	lcd.setCursor(14,1);
	delay(100);
	//lcd.clear();
	//Serial.print("Measured distance: ");
  //Serial.println(readUltrasonicDistance());
}