Mini Meteo Station with Arduino Nano

I finished a complex project, a mini Meteo Station based on Arduino Nano.

On a 4x20 I2C LCD I can see the date, time, inside and outside temperature, relative humidity and air pressure (in hPa).


Main features are:
    -Low footprint
    -Precise Date and Time with a DS1307 RTC circuit
    -Humidity with a DHT-11 sensor
    -Baro pressure and interior temperature with a BMP-085
    -External temperature with a DS-18B20
    -Low power (40 mA from one Li-Ion cell with a DC-DC converter with LCD Backlight on, 30 mA).
    -LCD Backlight on demand by push button

Took me about 2 days but I made it!

I intend to make some averages and to compare the pressure over an variable inteval tohave a weather prediction.





Here is the code:


 /*

   Meteo station with Arduino Nano
   by Adrian, YO3HJV
   http://yo3hjv.blogspot.com
  
  
  
  -- LCD on I2C
  -- Barometer and temperature sensor BMP-085 on I2C
  -- Humidity sensor DHT-11 on pin D3
  -- Dallas DS-18B20 temperature sensor on OneWire, pin D2
  -- Backlight Push button on pin A3
 
  */


   #include <Wire.h>
   #include <LCD.h>
   #include <LiquidCrystal_I2C.h>
   #include <Time.h>
   #include <DS1307RTC.h>
   #include <Barometer.h>
   #include <OneWire.h>
   #include <DallasTemperature.h>
   #include <dht11.h>
  
                                          // Data wire is plugged into port 2 on the Arduino
    #define ONE_WIRE_BUS 2                                         
    OneWire oneWire(ONE_WIRE_BUS);                                       
    DallasTemperature sensors(&oneWire);
   
    #define DHT11PIN 3
   
    dht11 DHT11;

  
     
// I2C LCD DISPLAY
   #define I2C_ADDR    0x27
   #define BACKLIGHT_PIN     3
   #define En_pin  2
   #define Rw_pin  1
   #define Rs_pin  0
   #define D4_pin  4
   #define D5_pin  5
   #define D6_pin  6
   #define D7_pin  7

// ******************
 
 
       LiquidCrystal_I2C    lcd(I2C_ADDR, En_pin, Rw_pin, Rs_pin, D4_pin, D5_pin, D6_pin, D7_pin);

    // Variabilele pentru Barometru
       float temperature;  // FLOAT or INT
       float tempext;      // FLOAT or INT
       float pressure;
       float atm;
       float altitude;
   
       Barometer myBarometer;
      
      int BLpin = A3;   // choose the input pin (for a pushbutton)
      int val = 0;      // variable for reading the pin status


  void setup()
    {    
     myBarometer.init();    
     sensors.begin();   // External Temp sensor         
     lcd.begin (20,4);  // initialize the lcd
     lcd.setBacklightPin(BACKLIGHT_PIN, POSITIVE); 
     pinMode(BLpin, INPUT);    // declare pushbutton as input
    }

              void loop()
 {
            
              val = digitalRead(BLpin);  // test BLpin
             
                  if (val == LOW)
                  {        
                  lcd.backlight();  // Backlight ON and...
                  sens();  // ... execute "sens"
                  }
                 
                  else  // if not ...,
                  {
                  lcd.noBacklight();  // Backlight OFF and...
                  sens();  // ...execute "sens"
                  }
}

    void sens()   // Main function
    {
     
       tmElements_t tm;                        //DS1307 RTC
       sensors.requestTemperatures();          // Send the command to get ext temperature
       tempext = sensors.getTempCByIndex(0);  
      

   //BARO + TEMP PE I2C
   // we read all the values from barometric sensor but use only temperature and pressure
   // we might calculate Dew point!
       temperature = myBarometer.bmp085GetTemperature(myBarometer.bmp085ReadUT()); //Get the temperature, bmp085ReadUT MUST be called first
       pressure = myBarometer.bmp085GetPressure(myBarometer.bmp085ReadUP());       //Get the temperature
       altitude = myBarometer.calcAltitude(pressure);                              //Uncompensated caculation - in Meters
       atm = pressure / 101325;
 
 
   //Hygro sensor DHT-11
       int chk = DHT11.read(DHT11PIN);
      
              if (RTC.read(tm))
              {

                 // Hours, minutes, seconds
               
                     lcd.setCursor(12, 0);                                                 
                                lcd2digits(tm.Hour);
                            lcd.print(":");
                                lcd2digits(tm.Minute);
                            lcd.print(":");
                                lcd2digits(tm.Second);
                
                
                 // Only hours and minutes. Uncomment this and comment above
                               
                 /*    lcd.setCursor(14, 0);                                                 
                                lcd2digits(tm.Hour);
                            lcd.print(":");
                                lcd2digits(tm.Minute);
        
                 */
                     lcd.setCursor(0, 0);
                                 lcd.print(tm.Day);
                             lcd.print('/');
                                 lcd.print(tm.Month);
                             lcd.print('/');
                                 lcd.print(tmYearToCalendar(tm.Year));
                            
                     lcd.setCursor(0, 2);
                             lcd.print("In: ");
                                 lcd.print(temperature);  // we can use [lcd.print(int(temperature))] for value without decimals;
                             lcd.print(" *C ");           // otherwise, temp is with two decimals
            
                     lcd.setCursor(0, 3);
                             lcd.print("Ex: ");
                                 lcd.print(tempext);      // the same as above ...
                             lcd.print(" *C ");                          
                     
                     lcd.setCursor(0, 1);
                              lcd.print("P:");
                                 lcd.print(int((pressure) / 100)); // No decimals pressure
                              lcd.print(" hPa");
                             // lcd.print("  ");
   
                     lcd.setCursor(12, 1);
                              lcd.print("Hum. ");
                                 lcd.print((int)DHT11.humidity);
                              lcd.print("%");
   
   
                } else
                    
                  {
                    lcd.clear();
                    lcd.print("RTC HW ERROR!!!"); // This is for RTC comm error
                    delay(10000);
                  }
             
            delay(200);
 
    }  // END  "sens" function


//LCD nice time function

    void lcd2digits(int number)   {
     
        if (number >= 0 && number < 10) {
            lcd.print('0');             }
            lcd.print(number);                   
                                  }



 73 de Adrian, YO3HJV