A companion library to the Time library called TimeAlarm has been added to the Time library download: http://www.arduino.cc/playground/Code/Time
The Alarm library makes it easy to perform tasks at specific times or after specific intervals.
Tasks to be scheduled at a particular time of day are called Alarms,
tasks scheduled after an interval of time has elapsed are called Timers.
These tasks can be created to continuously repeat or to occur once only.
An alarm can be specified to trigger a task repeatedly at a particular time of day:
Alarm.alarmRepeat(8,30,0, MorningAlarm);
This would call the function MorningAlarm at 8:30 am every day.
If you want the alarm to trigger only once you can use the alarmOnce method:
Alarm.alarmOnce(8,30,0, MorningAlarm);
This calls a MorningAlarm() function in a sketch once only (when the time is next 8:30am)
Timers trigger tasks that occur after a specified interval of time has passed.
The timer interval can be specified in seconds, or in hour, minutes and seconds.
Alarm.timerRepeat(15, Repeats); // timer task every 15 seconds
This calls the a Repeats() function in your sketch every 15 seconds.
If you want a timer to trigger once only, you can use the timerOnce method:
Alarm.timerOnce(10, OnceOnly); // called once after 10 seconds
This calls the onceOnly() function in a sketch 10 seconds after the timer is created.
Here is an example sketch that illustrates this functionality:
//This sketch triggers daily alarms at 8:30 am and 17:45 pm.
//A Timer is triggered every 15 seconds, another timer triggers once only after 10 seconds.
#include <Time.h>
#include <TimeAlarms.h>
void setup()
{
setTime(8,29,0,1,1,10); // set time to 8:29:00am Jan 1 2010
// create the alarms
Alarm.alarmRepeat(8,30,0, MorningAlarm); // 8:30am every day
Alarm.alarmRepeat(17,45,0,EveningAlarm); // 5:45pm every day
Alarm.timerRepeat(15, Repeats); // timer for every 15 seconds
Alarm.timerOnce(10, OnceOnly); // called once after 10 seconds
}
void loop(){
digitalClockDisplay();
Alarm.delay(1000); // wait one second between clock display
}
// functions to be called when an alarm triggers:
void MorningAlarm(){
Serial.println("Alarm: - turn lights off");
}
void EveningAlarm(){
Serial.println("Alarm: - turn lights on");
}
void Repeats(){
Serial.println("15 second timer");
}
void OnceOnly(){
Serial.println("This timer only triggers once");
}
void digitalClockDisplay()
{
// digital clock display of the time
Serial.print(hour());
printDigits(minute());
printDigits(second());
Serial.println();
}
void printDigits(int digits)
{
Serial.print(":");
if(digits < 10)
Serial.print('0');
Serial.print(digits);
}
Note that the loop code calls Alarm.delay(1000) - Alarm.delay must be used
instead of the usual arduino delay function because the alarms are serviced in the Alarm.delay method.
Failing to regularly call Alarm.delay will result in the alarms not being triggered
so always use Alarm.delay instead of delay in sketches that use the Alarms library.
More details are in the readme.txt file in the download
