A 10 Day timed event, at certain time of day. Ideas?

Greetings

I have depended on the TimeAlarms.h library for many things, but of all TA's possible alarm time settings, I have not found a way to schedule a 10 Day event interval to occur at a certain time of day. I could schedule 10 days by using a 864000 second setting, but that wouldn't have a hh/mm/ss time value.

Is anyone else creating scheduled events at a specific time, on 10 - 14 day intervals, etc.? Example: every 10 days, at 15:30. Thanks

You would be best using a time source for that - either an RTC module, or reading network time via a network interface.

Does your Arduino definitely need to do the timing? It's easy enough to buy a domestic time switch if you just want something to switch on/off at certain times.

I have the Arduino mini/nano already on a common board with a high accuracy RTC, and GPRS/GSM module.

Yes, these events should be controlled internally by my project module, in one small enclosure.

I'm considering counting each day as it passes (with a Daily hh/mm/ss timed event) adding +1 to a variable each day. Then when that value reaches XX days, the code would invoke the XXth day hh/mm/ss alarm/event, and reset the day variable. This feels simpler to me than using Julian days, if there is no alternative library, etc..

If your ROTC is ds1307, use adafruit rtclib library. The sample code has calculation on time in the future.