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class RTC – real time clock

The RTC is an independent clock that keeps track of the date and time.

Example usage:

rtc = machine.RTC()
rtc.datetime((2020, 1, 21, 2, 10, 32, 36, 0))


class machine.RTC(id=0, ...)

Create an RTC object. See init for parameters of initialization.



Get or set the date and time of the RTC.

With no arguments, this method returns an 8-tuple with the current date and time. With 1 argument (being an 8-tuple) it sets the date and time.

The 8-tuple has the following format:

(year, month, day, weekday, hours, minutes, seconds, subseconds)

The meaning of the subseconds field is hardware dependent.


Initialise the RTC. Datetime is a tuple of the form:

(year, month, day[, hour[, minute[, second[, microsecond[, tzinfo]]]]])

Get get the current datetime tuple.


Resets the RTC to the time of January 1, 2015 and starts running it again.

RTC.alarm(id, time, *, repeat=False)

Set the RTC alarm. Time might be either a millisecond value to program the alarm to current time + time_in_ms in the future, or a datetimetuple. If the time passed is in milliseconds, repeat can be set to True to make the alarm periodic.


Get the number of milliseconds left before the alarm expires.


Cancel a running alarm.

RTC.irq(*, trigger, handler=None, wake=machine.IDLE)

Create an irq object triggered by a real time clock alarm.

  • trigger must be RTC.ALARM0

  • handler is the function to be called when the callback is triggered.

  • wake specifies the sleep mode from where this interrupt can wake up the system.



irq trigger source