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The hardware doesn't allow it, instead the value is reset to 255 upon setting the other calendar/time values.
84 lines
2.5 KiB
ReStructuredText
84 lines
2.5 KiB
ReStructuredText
.. currentmodule:: pyb
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.. _pyb.RTC:
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class RTC -- real time clock
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============================
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The RTC is and independent clock that keeps track of the date
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and time.
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Example usage::
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rtc = pyb.RTC()
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rtc.datetime((2014, 5, 1, 4, 13, 0, 0, 0))
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print(rtc.datetime())
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Constructors
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------------
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.. class:: pyb.RTC()
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Create an RTC object.
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Methods
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-------
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.. method:: RTC.datetime([datetimetuple])
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Get or set the date and time of the RTC.
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With no arguments, this method returns an 8-tuple with the current
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date and time. With 1 argument (being an 8-tuple) it sets the date
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and time (and ``subseconds`` is reset to 255).
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.. only:: port_pyboard
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The 8-tuple has the following format:
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(year, month, day, weekday, hours, minutes, seconds, subseconds)
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``weekday`` is 1-7 for Monday through Sunday.
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``subseconds`` counts down from 255 to 0
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.. only:: port_pyboard
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.. method:: RTC.wakeup(timeout, callback=None)
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Set the RTC wakeup timer to trigger repeatedly at every ``timeout``
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milliseconds. This trigger can wake the pyboard from both the sleep
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states: :meth:`pyb.stop` and :meth:`pyb.standby`.
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If ``timeout`` is ``None`` then the wakeup timer is disabled.
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If ``callback`` is given then it is executed at every trigger of the
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wakeup timer. ``callback`` must take exactly one argument.
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.. method:: RTC.info()
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Get information about the startup time and reset source.
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- The lower 0xffff are the number of milliseconds the RTC took to
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start up.
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- Bit 0x10000 is set if a power-on reset occurred.
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- Bit 0x20000 is set if an external reset occurred
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.. method:: RTC.calibration(cal)
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Get or set RTC calibration.
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With no arguments, ``calibration()`` returns the current calibration
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value, which is an integer in the range [-511 : 512]. With one
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argument it sets the RTC calibration.
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The RTC Smooth Calibration mechanism adjusts the RTC clock rate by
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adding or subtracting the given number of ticks from the 32768 Hz
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clock over a 32 second period (corresponding to 2^20 clock ticks.)
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Each tick added will speed up the clock by 1 part in 2^20, or 0.954
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ppm; likewise the RTC clock it slowed by negative values. The
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usable calibration range is:
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(-511 * 0.954) ~= -487.5 ppm up to (512 * 0.954) ~= 488.5 ppm
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