[time-nuts] Maxim DS3232 and I2C

[Chris Albertson]

Even on the primitive chips that don't have mutlipbyte reads and buffers.
 Just read it twice and see it the two reads are the same.   On the one in
the thousand case where they differ, read a third time.   Problems only
happen if you are so unlucky to read the time just before the seconds flip
over and as I said, you detect a second flip by reading twice.

But it appearts this chip is more sophisticated and has buffers


On Fri, Feb 14, 2014 at 2:20 PM, d0ct0r <time at patoka.org> wrote:

> I would like to ask an advise for following:
>
> Lets say I have a DS3232 RTC connected by I2C to some MCU. The maximum
> allowed I2C bus speed is 400KHZ. And I need to read time (HH:MM:SS) from
> it. It will be THREE SEPARATE REQUESTS for each part (hours, minutes and
> seconds). My concern: what if I start to read time at the edge, when it
> will change itself inside of DS3232 ? Potentially, I could get weird
> results, like hours and minutes stay the same, but seconds has changed. Or
> even worth - hours is the same, but seconds and minutes has changed. Is
> there any method to read all three values (HH:MM:SS) by one single requests
> ? Or is there any other workaround for this issue ? Or it is not issue at
> all ? Thanks !
>
>
> --
> WBW,
>
> V.P.
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-- 

Chris Albertson
Redondo Beach, California