Delay question

Using Arduino Programming Questions
1

I'm a beginner so please excuse my ignorance.

If I want to program an 8 hr. delay do I program 480000ms or is there an "hour, minute, second" command in the programming language? Also can someone recommend a method of energy conservation to minimize the electrical consumption during a lengthy delay? Thanks.

2

As far as I know, millis is the only game in town unless you add hardware such as a real time clock. Don't forget to declare any variables you use to store millis as unsigned long and any constants you use will need a UL suffix e.g. 60000UL. For power consumption help, search the forum for watchdog timer.

Edit: BTW - 480000ms is eight minutes.

3

Have a look at the TimeAlarms library.
Set an alarm to go off in 8 hours and run a function that you specify.
Job done.

4

Thanks wildbill. Oops, I meant 28800000ms - see what I mean? Dealing with ms for lengthy timing gets somewhat unwieldy.

UKHeliBob:
Have a look at the TimeAlarms library. Set an alarm to go off in 8 hours and run a function that you specify. Job done.

Where would you suggest I look for TimeAlarms library info?

5

UKHeliBob:
Have a look at the TimeAlarms library.
Set an alarm to go off in 8 hours and run a function that you specify.
Job done.

D'oh! of course!

6

Which Arduino board? There is no way to shutdown the USB chip on boards such as Uno and Mega AFAIK,
so putting the microcontroller into a sleep mode won't drastically reduce current consumption. Usually you'd
need an real-time-clock chip if going that route as running the microcontroller's 16MHz clock is a large part
of the current consumption.

Its worth searching these forums carefully there have been several lengthy threads on this sort of thing.

7

PlayStationFarm:
Where would you suggest I look for TimeAlarms library info?

Google? :slight_smile:

TimeAlarms is included in the Time library:

http://playground.arduino.cc/Code/time

Unfortunately the playground does not include documentation for it though. But see the example sketch--and the readme file in the library folder that you install.

And google. LMGTFY - Let Me Google That For You

Cheers,
John

8

I meant 28800000ms - see what I mean? Dealing with ms for lengthy timing gets somewhat unwieldy.

so, don't do it. Let the compiler take the strain8UL * 60UL * 60UL * 1000UL.
Of course, you could also name the constants.

9

PlayStationFarm:
Also can someone recommend a method of energy conservation to minimize the electrical consumption during a lengthy delay?

See this for tips on saving power: http://www.gammon.com.au/power