RTCLib - Difference of two times

Projects Programming
1

Hi!

Using adafruit's RTCLib, I am making an alarm.
To do this, I set my alarm, then display "alarm-rtc.now()"
First issue:
There is not DateTime minus operator defined. I would add my own, but I've never written an operator definition.

To fix this, I instead use "alarm-TimeSpan(rtc.now().unixtime())." This, however, returns a MASSIVE number.
For "Apr 4th, 2017, 2:30:00" minus "Apr 4th, 2017, 2:32:00" I get "Apr 21, 2106, 6:00:00"
This is, as is obvious, very incorrect!

Any help?
Thanks!

2

With 69 posts, you should have learned by now to POST YOUR CODE, using code tags.

1 Like
3

Hey, I gave you all the code you needed :stuck_out_tongue:
My code is massive - more than just an alarm, actually - rather an OS. 16 files, 30-100 lines each, as such, it wouldn't be worthwhile to post (or easy to sift through and find the relevant parts).

--Back on topic! :slight_smile: --
I realize now this is kind of an abuse of the DateTime and TimeSpan functions. I think the correct way to do this is:

uint32_t diff=alarm.unixtime()-rtc.now().unixtime();
byte sec=diff%60;
byte min=(diff/60)%60;//Relying on integer dividing to floor this!
byte hr=diff/3600;//Relying on integer dividing to floor this!

Edit: fixed a derp in code

4

Hey, I gave you all the code you needed :stuck_out_tongue:

Ahh, how silly of me! You don't know what causes the problem, but you do know how much information we will need to fix it for you.