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
