LCD Displaying Date, Time From DS1307 And Temperature From LM35

Date and time is useful for many applications. Most visitors to my blog search for rtc stuff. The following sketch show a simple application using a LCD shield, a RTC Sensor shield and a LM35 temperature sensor to display date, time and enviromnental temperature. To use the sketch, you need to download the RTClib library.

There is a new version using Time.h library and showing weekday.

Output:

Sketch:

// Date and time functions using a DS1307 RTC connected via I2C and Wire lib
// 2010-02-04 <jcw@equi4.com> http://opensource.org/licenses/mit-license.php
// $Id: ds1307.pde 4773 2010-02-04 14:09:18Z jcw $
// Added LCD display and LM35 temperature function by Befun Hung 2011-10-13
// Take out displayDateTime procedure from loop() by Befun Hung 2013-05-03
// The sketch works on Arduino IDE 0022

#include <Wire.h>
#include <RTClib.h>
#include <LiquidCrystal.h>
LiquidCrystal lcd(8, 9, 4, 5, 6, 7);

RTC_DS1307 RTC;
// change potPin value to 0, 1, 2 for A0, A1, A2 respectly
int potPin = 3;
float temperature = 0;

void setup () {
    Serial.begin(9600);
    Wire.begin();
    RTC.begin();
    lcd.begin(16, 2);
    lcd.print("*cheaphousetek*");
    delay(5000);
    lcd.clear();
    
    // following line sets the RTC to the date & time this sketch was compiled
    // RTC.adjust(DateTime(__DATE__, __TIME__));
}

void loop() {
  displayDateTime();
}

void printTenths(long value) {
  // prints a value of 123 as 12.3
  Serial.print(value / 10);
  Serial.print('.');
  Serial.print(value % 10);
  Serial.println();
  lcd.setCursor(10, 1);
  lcd.print(value / 10);
  lcd.setCursor(12, 1);
  lcd.print('.');
  lcd.setCursor(13, 1);
  lcd.print(value % 10);
}

void displayDateTime() {
    DateTime now = RTC.now();
    int span = 10;
    long aRead = 0;
    unsigned long tmp;
      
    tmp = now.year();
    Serial.print(now.year(), DEC);
    lcd.setCursor(0, 0);
    lcd.print(tmp);
    Serial.print('/');
    lcd.setCursor(4, 0);
    lcd.print("-");
    
    tmp = now.month();
    if (now.month() < 10) {
      Serial.print('0');
      Serial.print(now.month(), DEC);
      lcd.setCursor(5, 0);
      lcd.print('0');
      lcd.setCursor(6, 0);
      lcd.print(tmp);
    }
    else {
      Serial.print(now.month(), DEC);
      lcd.setCursor(5, 0);
      lcd.print(tmp);
    }
    Serial.print('/');
    lcd.setCursor(7, 0);
    lcd.print('-');
    
    tmp = now.day();
    if (now.day() < 10) {
      Serial.print('0');
      Serial.print(now.day());
      lcd.setCursor(8, 0);
      lcd.print('0');
      lcd.setCursor(9, 0);
      lcd.print(tmp);
    }
    else {
      Serial.print(now.day(), DEC);
      lcd.setCursor(8, 0);
      lcd.print(tmp);
    }
    Serial.print(' ');
    
    tmp = now.hour();
    if (now.hour() < 10) {
      Serial.print('0');
      Serial.print(now.hour(), DEC);
      lcd.setCursor(0, 1);
      lcd.print('0');
      lcd.setCursor(1, 1);
      lcd.print(tmp);
    }
    else {
      Serial.print(now.hour(), DEC);
      lcd.setCursor(0, 1);
      lcd.print(tmp);
    }
    Serial.print(':');
    lcd.setCursor(2, 1);
    lcd.print(':');
    
    tmp = now.minute();
    if (now.minute() < 10) {
      Serial.print('0');
      Serial.print(now.minute(), DEC);
      lcd.setCursor(3, 1);
      lcd.print('0');
      lcd.setCursor(4, 1);
      lcd.print(tmp);
    }
    else {
      Serial.print(now.minute(), DEC);
      lcd.setCursor(3, 1);
      lcd.print(tmp);
    }
    Serial.print(':');
    lcd.setCursor(5, 1);
    lcd.print(':');
    
    tmp = now.second();
    if (now.second() < 10) {
      Serial.print('0');
      Serial.print(now.second(), DEC);
      lcd.setCursor(6, 1);
      lcd.print('0');
      lcd.setCursor(7, 1);
      lcd.print(tmp);
    }
    else {
      Serial.print(now.second(), DEC);
      lcd.setCursor(6, 1);
      lcd.print(tmp);
    }
    Serial.print (' ');
    lcd.setCursor(8, 1);
    lcd.print(' ');
    // Serial.println();
    
    for (int i=0;i<span;i++) {
      aRead = aRead + analogRead(potPin);
      // Serial.print(aRead);
      // Serial.print(' ');
    }
    // aRead = aRead / span;
    temperature = (aRead / span * 500.0 / 1024.0);
    // Serial.print(aRead);
    // Serial.print(' ');
    // Serial.print(temperature);
    // Serial.print(' ');
    printTenths(long (temperature * 10));
    lcd.setCursor(14, 1);
    lcd.print(char(223));
    lcd.setCursor(15, 1);
    lcd.print('C');
        
    delay(200);
    
    // Serial.print(" since 2000 = ");
    // Serial.print(now.get());
    // Serial.print("s = ");
    // Serial.print(now.get() / 86400L);
    // Serial.println("d");
    
    // calculate a date which is 7 days and 30 seconds into the future
    // DateTime future (now.get() + 7 * 86400L + 30);
    
    // Serial.print(" now + 7d + 30s: ");
    // Serial.print(future.year(), DEC);
    // Serial.print('/');
    // Serial.print(future.month(), DEC);
    // Serial.print('/');
    // Serial.print(future.day(), DEC);
    // Serial.print(' ');
    // Serial.print(future.hour(), DEC);
    // Serial.print(':');
    // Serial.print(future.minute(), DEC);
    // Serial.print(':');
    // Serial.print(future.second(), DEC);
    // Serial.println();
    
    // Serial.println();
    // delay(3000);
}