Kinetis Microcontrollers中的主题 Re: Timing with RTC alarm

Timing with RTC alarm

PO220 — Wed, 28 Sep 2016 13:50:26 GMT

I use RTC alarm to interrupt at specific seconds

I have problems that look like a 1s delay... Is interrupt set at the END of the second that match with alarm register ?

I'm not sure what I read in datasheet :

When the time counter is enabled, the SR[TAF] is set whenever the TAR[TAR] equals the TSR[TSR] and
the TSR[TSR] increments.

TAR = TSR and then interruption + TSR increments (not 1 second delay with alarm register)

or TAR = TSR and then TSR increments and then interruption ? (1 second delay after alarm register match)

Thank you in advance

PS : I'm using a K64

Re: Timing with RTC alarm

jeremyzhou — Fri, 30 Sep 2016 08:30:47 GMT

Hi,

According to the reference manual, the equation below is correct.

TAR = TSR and then TSR increments and then interruption

Hope it helps.

Have a great day,
Ping

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Re: Timing with RTC alarm

PO220 — Sun, 02 Oct 2016 20:56:38 GMT

tanks for confirmation.

I would have naturally done the other solution (any delay with registers equality) ; your confirmation not only confirms reference manual, but also confirms tests : I am therefore not crazy !

Thanks