Does the Photon have a real time clock?

General
1

Does the Photon have a read real time clock?

2

And what would this be?

3

I have heard that the Photon has a real time clock in it. Is this true?

4

I see - real time clock (RTC) not read time clock (which I don’t know) :sunglasses:
(I’ll edit your topic and your post accordingly then)

Yes, the Photon has got an RTC.

Have a search on the forum and the docs for RTC and VBAT
e.g. http://docs.particle.io/photon/start/

5

Sorry about that! :smiley:

1 Like
6

How can I use the Photon to print the time in milliseconds over serial with millis()?

7

Guessing by the topic title about RTC you might rather want to know how to print the RTC time, or not?

And I’d go for

  Serial.println(Time.now());

But this only gives you the " since January 1, 1970 (commonly known as “Unix time” or “epoch time”)"
see http://docs.particle.io/photon/firmware/#time-now

1 Like
8

Is the Photon’s built in RTC accurate to the micro second?

9

No it’s not.

10

Sorry I meant milli second not micro second.

11

If you could explain a bit more about your application and why you’re looking for such precision we might be able to help better than when you throw out a question and we just answer that.

Even the question if any clock is accurate to a milli second does not really make sense. Immediately after sync it will be, and after a few hours it might still be, but after a day it most likely will not be and after several days it will definetly not be. Even atomic clocks go off by some milliseconds - it might take some millions of years, but it happens :wink:

So if you want accuracy, you need to resync from time to time.

But have some read here
http://www.st.com/web/en/resource/technical/document/application_note/DM00025071.pdf

BTW: UNIX Epoch time is not even accurate to the second, due to leap seconds :wink: