#include "Wire.h"
#include <dht.h>
#include <LiquidCrystal.h>
#define DS3231_I2C_ADDRESS 0x68
#define DHT22_PIN 9
dht DHT;
char* x = "AM";
unsigned long previousTimer = 0;
unsigned long previousDHT = 0;
const long intervalTimer = 1000;
const long intervalDHT = 2000;
byte temp[8] =
{
    B00100,
    B01010,
    B01010,
    B01110,
    B01110,
    B11111,
    B11111,
    B01110
};
byte drop[8] =
{
    B00100,
    B00100,
    B01010,
    B01010,
    B10001,
    B10001,
    B10001,
    B01110,
};
LiquidCrystal lcd(2, 3, 4, 5, 6, 7);
byte bcdToDec(byte val)
{
  return( (val/16*10) + (val%16) );
}
void readDS3231time(byte *second,
                    byte *minute,
                    byte *hour,
                    byte *dayOfWeek,
                    byte *dayOfMonth,
                    byte *month,
                    byte *year)
{
  Wire.beginTransmission(DS3231_I2C_ADDRESS);
  Wire.write(0);                    // set DS3231 register pointer to 00h
  Wire.endTransmission();
  Wire.requestFrom(DS3231_I2C_ADDRESS, 7);
  // request seven bytes of data from DS3231 starting from register 00h
  *second = bcdToDec(Wire.read() & 0x7f);
  *minute = bcdToDec(Wire.read());
  *hour = bcdToDec(Wire.read() & 0x3f);
  *dayOfWeek = bcdToDec(Wire.read());
  *dayOfMonth = bcdToDec(Wire.read());
  *month = bcdToDec(Wire.read());
  *year = bcdToDec(Wire.read());
}
void displayTime(){
  byte second, minute, hour, dayOfWeek, dayOfMonth, month, year;
  readDS3231time(&second, &minute, &hour, &dayOfWeek, &dayOfMonth, &month, &year);
  lcd.setCursor(0, 1);
  lcd.print("Time: ");
  if (hour > 12){
    hour -= 12;
   if (hour == 12){
      x = "PM";
    }
    x = "PM";
  }
  else if(!hour){
    hour = 12;
    x = "AM";
  }
  lcd.print(hour, DEC);
  lcd.print(":");
  if (minute<10)
  {
    lcd.print("0");
  }
  lcd.print(minute, DEC);
  lcd.print(" ");
  lcd.print(x);
  lcd.setCursor(0,2);
  lcd.print("Date: ");
  switch(month){
    case 1:
      lcd.print("Jan");
      break;
    case 2:
      lcd.print("Feb");
      break;
    case 3:
      lcd.print("Mar");
      break;
    case 4:
      lcd.print("Apr");
      break;
    case 5:
      lcd.print("May");
      break;
    case 6:
      lcd.print("Jun");
      break;
    case 7:
      lcd.print("Jul");
      break;
    case 8:
      lcd.print("Aug");
      break;
    case 9:
      lcd.print("Sep");
      break;
    case 10:
      lcd.print("Oct");
      break;
    case 11:
      lcd.print("Nov");
      break;
    case 12:
      lcd.print("Dec");
      break;
  }
  lcd.print(" ");
  lcd.print(dayOfMonth, DEC);
  lcd.print(", ");
  lcd.print(year + 2000, DEC);
}
void dht22(){
 int chk = DHT.read22(DHT22_PIN);
 lcd.setCursor(3, 4);
 lcd.write(1);
 lcd.print(" ");
 lcd.print(DHT.temperature, 0);
 lcd.print((char)223);
 lcd.print("C ");
 lcd.print(" ");
 lcd.write(2);
 lcd.print(" ");
 lcd.print(DHT.humidity, 0);
 lcd.print("%");
}
void setup()
{
  Wire.begin();
  lcd.createChar(1,temp);
  lcd.createChar(2,drop);
  lcd.begin(20, 4);
  lcd.setCursor(2, 0);
  lcd.print("Thermohygrometer");
}
void loop(){
  unsigned long currentMillis = millis();
  if (currentMillis - previousTimer >= intervalTimer) {
    previousTimer = currentMillis;
  displayTime();
  }
  if (currentMillis - previousDHT >= intervalDHT) {
    previousDHT = currentMillis;
  dht22();
  }
}