DateTime Library

Download: DateTime.zip

The example was slightly modified with a default time, so it will run without needing a separate program to set the time. DateTime works on Teensy without modifications.

Hardware Requirements

Basic Usage

description, blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah

DateTime.Hour
DateTime.Minute
DateTime.Second
DateTime.Day
DateTime.DayofWeek
DateTime.Month
DateTime.Year

Example Program

// DateTime.pde
// example sketch for the DateTime library

#include 
#include <DateTimeStrings.h>

#define TIME_MSG_LEN  11   // time sync to PC is HEADER followed by unix time_t as ten ascii digits
#define TIME_HEADER  255   // Header tag for serial time sync message

void setup(){
  Serial.begin(19200);
  pinMode(13,OUTPUT); // we flash the LED each second
  DateTime.sync(1262304000L);  // default start, Jan 1, 2010
}

void  loop(){
  unsigned long  prevtime;
  if( getPCtime()) {  // try to get time sync from pc
    Serial.print("Clock synced at: ");
    Serial.println(DateTime.now(),DEC);
  }
  if(DateTime.available()) { // update clocks if time has been synced
    digitalWrite(13,LOW);  // first flash the LED
    prevtime = DateTime.now();
    while( prevtime == DateTime.now() )  // wait for the second to rollover
        ;
    DateTime.available(); //refresh the Date and time properties
    digitalClockDisplay( );   // update digital clock

    // send our time to any app at the other end of the serial port
    Serial.print( TIME_HEADER,BYTE); // this is the header for the current time
    Serial.println(DateTime.now());
    digitalWrite(13,HIGH);
  }
  delay(100); 
}

boolean getPCtime() {
  // if time sync available from serial port, update time and return true
  while(Serial.available() >=  TIME_MSG_LEN ){  // time message consists of a header and ten ascii digits
    if( Serial.read() == TIME_HEADER ) {        
      time_t pctime = 0;
      for(int i=0; i < TIME_MSG_LEN -1; i++){   
        char c= Serial.read();          
        if( c >= '0' && c <= '9'){   
          pctime = (10 * pctime) + (c - '0') ; // convert digits to a number    
        }
      }   
      DateTime.sync(pctime);   // Sync Arduino clock to the time received on the serial port
      return true;   // return true if time message received on the serial port
    }  
  }
  return false;  //if no message return false
}

void digitalClockDisplay(){
  // digital clock display of current date and time
  Serial.print(DateTime.Hour,DEC);
  printDigits(DateTime.Minute);
  printDigits(DateTime.Second);
  Serial.print(" ");
  Serial.print(DateTimeStrings.dayStr(DateTime.DayofWeek));
  Serial.print(" ");
  Serial.print(DateTimeStrings.monthStr(DateTime.Month));
  Serial.print(" ");
  Serial.print(DateTime.Day, DEC); 
  Serial.print(", ");
  Serial.println(DateTime.Year + 1900, DEC);
}

void printDigits(byte digits){
  // utility function for digital clock display: prints preceding colon and leading 0
  Serial.print(":");
  if(digits < 10)
    Serial.print('0');
  Serial.print(digits, DEC);
}

Details