class RTC – real time clock

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

Constructor

class omc048.RTC
Create an RTC object.

Methods

RTC.datetime((datetimetuple)) → 8-tuple

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 (and subseconds is reset to 255).

The 8-tuple has the following format:

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

weekday is 1-7 for Monday through Sunday.

subseconds counts down from 255 to 0

RTC.wakeup(timeout)

Set the RTC wakeup timer to trigger repeatedly at every timeout milliseconds. This trigger can wake the logger from the sleep state pyb.standby().

If timeout is None then the wakeup timer is disabled.

RTC.info() → integer

Get information about the startup time and reset source.

  • The lower 0xffff are the number of milliseconds the RTC took to start up.

  • Bit 0x10000 is set if a power-on reset occurred.

  • Bit 0x20000 is set if an external reset occurred

RTC.calibration(cal) → integer

Get or set RTC calibration.

With no arguments, calibration() returns the current calibration value, which is an integer in the range [-511 : 512]. With one argument it sets the RTC calibration.

The RTC Smooth Calibration mechanism adjusts the RTC clock rate by adding or subtracting the given number of ticks from the 32768 Hz clock over a 32 second period (corresponding to 2^20 clock ticks.) Each tick added will speed up the clock by 1 part in 2^20, or 0.954 ppm; likewise the RTC clock it slowed by negative values. The usable calibration range is: (-511 * 0.954) ~= -487.5 ppm up to (512 * 0.954) ~= 488.5 ppm

Example usage

The following code shows an example to set date and time and to print the date and time.

import omc048

rtc = omc048.RTC()

rtc.datetime((2020, 4, 21, 2, 13, 0, 0, 0))
print(rtc.datetime())